radio frequency energy for bioelectric stimulation of plants

i

RADIO FREQUENCY ENERGY FOR BIOELECTRIC STIMULATION OF

PLANTS

by

Pieter Johannes Jacobus van Zyl

A dissertation submitted in partial fulfilment of the academic

requirements for the degree

Master of Technology [M-TECH]

in the

Faculty of Engineering and the Built Environment

UNIVERSITY OF JOHANNESBURG Johannesburg South Africa

Supervisor

Prof MJ Case as Promoter and Thesis Supervisor

August 2012

ii

ACKNOWLEDGEMENTS

This research work was made possible through the help and support of family friends

and faculty colleagues at the University of Johannesburg

I owe great gratitude to my promoter Prof Mike Case for his support and for

providing direction when most needed Thank you for sharing years and years of RF

experience (and wisdom) in the most understandable way Surely prior to retirement

he had to have been a formidable favourite professor for any young student

Many thanks go to Glynne Case and Melanie Steyn for proofreading and editing the

document

A special thanks to Vikash Rameshar for the construction of the hydroponic

controller It was a privilege to guide him as a student in the design and construction

of this controller as his final B-Tech project Also thank you for helping with the

installation of the hydroponic plant

I am also very grateful for all the academic support and guidance from Hennie van der

Walt Pieter Hansen Johann Fouche and Meera Joseph

Thanks are also due to the Staff Qualifications Project Team namely Pia Lamberti

Tinyiko Shilenge and Dr Riёtte de Lange for all the training and administration

support

I also would like to thank colleagues like Brett Daniel Pat Andrew Phillip Hannes

Eugene and Nico for their interest in the study

Unending appreciation goes to my wife Ohna and children Christopher Grant and

Michael for always having to cope with an occupied study full of journal papers and

loose experimental datasheets

Thanks also go to my father Pieter for love and support throughout this study

iii

ABSTRACT

For securing food production it is essential that every possible method should be

investigated This study is about utilising low power radio frequency (RF) energy

signals from leaky transmission lines for the benefit of plant growth and production in

hydroponic systems Using these lines eliminates common problems like radiation

interference and licence application protocols

Plant cell walls are covered with tightly-bonded positively-charged calcium ions that

affect the inflow of nutrients into the cell As calcium ions have a mass twice that of

the potassium ion the fundamental harmonic of calcium is equal to the first harmonic

of potassium (32Hz) Thousands (10k 1) fewer positive potassium ions also exist

around the cell wall and when stimulated at their resonance frequency (16Hz) they

will bounce against the tightly bonded calcium ions so these calcium ions become

dislodged from the cell wall If this happens more nutrients can enter the cell causing

acceleration in plant growth A suitable electromagnetic wave for such an action is the

amplitude modulated wave especially if it is modulated near the cyclotron resonance

frequency of potassium (16Hz) or its even-harmonics of 3264Hz etc

Applying sufficient energy in the lower modulated frequency when it is the same as

the vibration frequency of the potassium ions surrounding the cell wall these ions will

then acquire some energy from the electrical wave Controlling the process is

important because if too many calcium ions are released it would cause plant stress

and plant structure breakdown The amplitude modulated wave will allow sufficient

time for the calcium ions to return to the cell wall during the period without energy

To apply radio energy to a plant in the form of amplitude modulated signals requires a

medium One such medium is the use of transmitting energy into two leaky

transmission lines to cause worse case standing waves which could then be absorbed

by the plants that are placed in between these transmission lines The energy from the

radio waves is then used to create window periods during which the calcium ions are

dislodged allowing additional nutrients to enter the plant cell enhancing plant growth

and production

iv

From this study it is clear that stimulating plants with low energy radio frequencies

does have a positive effect on the growth of plants in hydroponic systems In addition

what is clear is that there is a significant increase in fruit mass by as much as 56

Furthermore the plants stimulated by RF were generally less infected by insects

Stimulated plants also had an intenser and healthier appearance An unexpected result

of the study was that plant mass increased by an astonishing 523 for the RF

stimulated plants

Key words radio frequency transmission lines plant stimulation hydroponics systems

v

FOREWORD

This research study includes the data from various experiments that were gathered and

analysed However what is not presented are the hundreds of experiments that were

performed as direction finders in 2010

These preliminary experiments were done but are not part of this study and are

therefore not included in this thesis They were however necessary as they provided

much needed direction finders to the researcher about parameters like

Nutrient strengths

Electric field strengths

Electric field density

Carrier frequencies

Radiation intensity

Interference sources

Radio frequency radiation patterns on transmission lines

Standing waves and applicable standing wave ratios

Line termination

Line impedance matchingmismatching

Practical implementable stimulation techniques

vi

TABLE OF CONTENTS

CHAPTER 1 INTRODUCTION - 1 - 11 BACKGROUND - 1 - 12 PROBLEM STATEMENT - 1 - 13 OBJECTIVES - 3 - 14 SCOPE OF RESEARCH - 4 - 15 RESEARCH LIMITS - 5 - 16 OVERVIEW AND MAP - 6 - 17 CHAPTER OVERVIEW - 8 - 18 CONCLUSION - 9 -

CHAPTER 2 BACKGROUND - 10 - 21 INTRODUCTION - 10 - 22 OVERVIEW - 11 - 23 THE PURPOSE OF HYDROPONICS SYSTEMS - 12 - 24 HYDROPONIC METHODS - 13 - 25 OPEN AND CLOSED LOOP SYSTEMS - 16 - 26 THE HYDROPONIC SETUP - 17 - 27 ELECTRICAL CONDUCTIVITY (EC) - 17 - 28 PH CONTROL - 18 - 29 NUTRIENT FORMULATIONS - 19 - 210 COMMON SYMPTOMS OF NUTRIENT DEFICIENCIES IN PLANTS - 19 - 211 ELECTRIC FIELDS - 20 - 212 THE ELECTROMAGNETIC (EM) SPECTRUM - 21 - 213 EXPERIMENTATION WITH ELECTROMAGNETIC WAVES - 21 - 214 CHARACTERISTICS OF THE EM WAVE - 22 - 215 TYPES OF ELECTROMAGNETIC SIGNALS - 23 - 216 POWER DENSITY - 23 - 217 IONISING RADIATION - 24 - 218 NON-IONIZING RADIATION - 25 - 219 SPECIFIC ABSORPTION RATE (SAR) - 25 - 220 PLANT CELL MEMBRANES - 26 - 221 BIOELECTRIC EFFECTS - 27 - 222 PHOTOSYNTHESIS - 27 - 223 BIO-STIMULATION - 28 - 224 QUAD ANTENNAS - 28 - 225 TRANSMISSION LINE RADIATION - 29 - 226 TRANSMISSION LINE CHARACTERISTIC IMPEDANCE - 29 - 227 STANDING WAVE RATIO - 30 - 228 REQUIREMENTS FOR AN ELECTRONIC CONTROLLER - 31 - 229 CONCLUSION - 32 -

CHAPTER 3 LITERATURE SURVEY - 33 - 31 INTRODUCTION - 33 - 32 OVERVIEW - 33 - 33 ELECTROCHEMICAL POTENTIAL AROUND THE PLANT ROOT - 35 - 34 CALCIUM AS A PLANT GROWTH REGULATOR - 36 - 35 ELECTRICITY IN HORTICULTURE - 36 - 36 CALCIUM HOMEOSTASIS IN PLANT CELL NUCLEI - 37 - 37 WEAK MICROWAVES TO OVERCOME SALT STRESS IN SEEDLINGS - 37 - 38 PLANT RESPONSES TO ELECTRICAL STIMULI - 37 -

381 The effects of radio frequency electromagnetic fields - 38 - 382 Oxidative stress limiting root growth due to mobile phone radiation - 38 - 383 Effect of radiofrequency exposure on duckweed - 39 - 384 Effects of pulsed frequencies on plant growth - 40 -

39 PROCESSES FOR ENHANCING PLANT GROWTH - 40 -

vii

391 Electroculture in hydroponics greenhouses - 40 - 392 Electro-charging of growth medium fluid - 41 - 393 Treating plants with high frequency sound waves - 41 - 394 Stimulating plant growth using a helical coil - 42 - 395 Sound waves to open cell walls aiding in the osmoses process - 42 - 396 Electrical control of plant morphogenesis - 42 - 397 Eradication of red palm weevils using high power frequencies - 43 - 398 Digital agriculture - 44 - 399 Medical plants for alleviating poverty - 44 - 3910 The concept of primary perception and the evidence thereof in plants - 45 - 3911 Pyramid Electrical Generator - 45 - 3912 Crop enhancement by air ions - 46 - 3913 Moderate Electro-thermal treatments (MET) - 47 -

310 PLANT SIGNALLING - 47 - 3101 Microwave irradiation - 47 -

311 BIOELECTRIC SIGNALLING - 49 - 3111 Non-random bioelectric signals in plant tissue - 49 - 3112 Biological effects of weak electromagnetic fields - 50 -

312 PLANT GROWTH ALGORITHMS - 51 - 3121 Evaluation of experimental design and computational methods - 51 - 3122 A modern tool for plant growth analysis - 52 - 3123 Plant simulation algorithm of linear antenna arrays - 53 - 3124 Plug-in framework for modeling plant growth - 54 - 3125 Distribution network simulation algorithm - 55 -

313 PLANT GROWTH STATISTICAL INTERFEROMETRY - 56 - 3131 Dynamic range of statistical interferometry to sample plant growth - 56 -

314 OTHER USES FOR ENERGY FIELDS - 57 - 3141 Energy fields for curing diseases - 57 -

315 CONCLUSION - 58 - CHAPTER 4 EXPERIMENTAL DESIGN - 59 -

41 INTRODUCTION - 59 - 42 OVERVIEW - 60 - 43 INSIDE THE PLANT - 62 - 44 PLANT COMMUNICATION - 62 - 45 PLANT GROWTH FACTORS - 63 -

451 Light factor - 63 - 452 Temperature and Humidity - 64 -

46 PLANT RESPONSE SIGNALS - 66 - 461 Awareness of responses expected - 66 - 462 Levels of responses expected - 67 -

47 NUTRIENT AND WATER COMPOSITION - 67 - 471 Individual nutrient data - 67 - 472 Nutrient composition for experiment - 69 - 473 Water compliance - 69 -

48 PH CONTROL - 71 - 49 STRUCTURE DESIGN - 71 - 410 VARIOUS APPLICATION POINTS FOR PLANT STIMULI - 72 - 411 CONSTRAINTS - 73 - 412 MEASUREMENTS - 74 - 413 FREQUENCY EFFECTS - 75 - 414 TYPES OF PLANTS - 76 - 415 GROWTH DYNAMICS - 76 - 416 PREFERRED EXPERIMENTAL SYSTEM - 76 - 417 EXPERIMENTAL EXCLUSIONS - 77 - 418 EVALUATING APPROPRIATE POINTS FOR STIMULUS APPLICATION ON PLANTS IN A HYDROPONICS SYSTEM ndash EXPERIMENT 1 - 77 -

4181 Objective - 77 - 4182 Hypothesis - 77 - 4183 Range - 77 -

viii

4184 Equipment and materials - 78 - 4185 Procedure - 80 - 4186 Effect on nearby neighbouring plants - 84 - 4187 Expected Results - 85 - 4188 Management - 85 -

419 PLANT RESPONSE TO THE APPLICATION OF DIRECT CURRENT (DC) TO PLANTS IN A HYDROPONIC SYSTEM ndash EXPERIMENT 2 - 87 -

4191 Objective - 87 - 4192 Hypothesis - 87 - 4193 Range - 87 - 4194 Equipment and Materials - 87 - 4195 Procedure - 88 - 4196 Effect on nearby neighbouring plants - 89 - 4197 Expected Results - 90 - 4198 Management - 90 -

420 PLANT RESPONSE TO THE APPLICATION OF 16HZ SQUARE WAVE SIGNALS TO PLANTS IN A HYDROPONIC SYSTEM ndash EXPERIMENT 3 - 90 -

4201 Objective - 90 - 4202 Hypothesis - 90 - 4203 Range - 91 - 4204 Equipment and materials - 91 - 4205 Procedure - 92 - 4206 Effect on nearby neighbouring plants - 93 - 4207 Expected Results - 93 - 4208 Management - 94 -

421 EFFECT OF FREQUENCY SPECIFIC RADIO WAVE ENERGY USING A LEAKY TRANSMISSION LINE ON PLANTS IN A HYDROPONIC SYSTEM ndash EXPERIMENT 4 - 94 -


422 CONCLUSION - 98 - CHAPTER 5 EXPERIMENTAL RESULTS ANALYSIS AND DISCUSSION - 99 -

51 INTRODUCTION - 99 - 52 OVERVIEW - 100 - 53 LAYOUT AND SETUP - 101 -

531 The setup - 101 - 532 The structure - 102 - 533 The hydroponic controller - 103 - 534 EC and PH controller - 104 - 535 Probe design - 106 - 536 Nutrient and air pumps - 106 - 537 Hydroponic technique - 107 - 538 Preparation of the nutrient solution - 107 - 539 Nutrient injection - 110 - 5310 Plant nutrient control - 110 - 5311 Test equipment and calibration - 111 - 5312 Probe storage and cleaning - 112 -

54 EXPERIMENTAL PLANTS - 112 - 541 Cultivars - 112 - 542 Plant health - 113 - 543 Identifying common funguses and pests - 115 - 544 Plant production issues - 115 - 545 Electrical potential measurements - 116 -

55 POSSIBLE TYPES OF STIMULATION APPLICATIONS TO PLANTS IN HYDROPONIC SYSTEMS - 117 -

ix

56 EVALUATING APPROPRIATE POINTS FOR STIMULUS APPLICATION ON PLANTS IN A HYDROPONICS SYSTEM - 118 -

561 Introduction - 118 - 562 Electromagnetic fields - 118 - 563 How plants utilize non-changing electromagnetic fields - 119 - 564 Aim hypothesis and range - 119 - 565 Uniform measurements - 119 - 566 Evaluating appropriate stimulus application points - 119 - 567 Plants for observation purposes - 122 - 568 Experimental analysis - 122 - 569 Discussion - 123 -

57 PLANT RESPONSE TO THE APPLICATION OF DIRECT CURRENT (DC) TO PLANTS IN A HYDROPONIC SYSTEM - 124 -

571 Introduction - 124 - 572 Aim hypothesis range and method - 124 - 573 Effect of direct current (DC) on plants in hydroponic systems - 124 - 574 Experimental analysis - 127 - 575 Plants for observation purposes - 127 - 576 Discussion - 127 -

58 PLANT RESPONSE TO THE APPLICATION OF 16HZ SQUARE WAVE SIGNALS TO PLANTS IN A HYDROPONIC SYSTEM - 128 -

581 Introduction - 128 - 582 Aim hypothesis range and method - 129 - 583 Effect of 16Hz wave energy on plants in a hydroponic system - 129 - 584 Experimental analysis - 131 - 585 Plants for observation purposes - 132 - 586 Discussion - 132 -

59 EFFECT OF FREQUENCY SPECIFIC RADIO WAVE ENERGY USING A LEAKY TRANSMISSION LINE ON PLANTS IN A HYDROPONIC SYSTEM - 134 -

591 Introduction - 134 - 592 Effects of frequencies and pulses - 134 - 593 Harmonics - 135 - 594 Modulated signals and their effects - 135 - 595 Transmission lines as radiating antennas - 135 - 596 Aim hypothesis range and method - 136 - 597 Frequency specific radio energy using a leaky transmission line - 137 - 598 Field strength - 143 - 599 Growth and mass data parameters - 143 - 5910 Experimental analysis - 145 - 5911 Plants for observation purposes - 146 - 5912 Reasons for positive plant responses to RF fields - 149 -

510 PLANT RESPONSE REGARDING FLOWERING AND FRUITING WHEN APPLYING STIMULATION TO HYDROPONIC GROWN PLANTS - 150 -

5101 Flowering - 150 - 5102 Fruiting - 150 -

511 PLANT RESPONSE REGARDING PESTS AND DISEASES WHEN APPLYING STIMULATION TO PLANTS IN A HYDROPONIC SYSTEM - 152 -

5111 Pests - 152 - 5112 Bacterial and fungal diseases - 152 -

512 RF INTERFERENCE - 153 - 513 CONCLUSION - 153 -

CHAPTER 6 CONCLUSION - 155 - 61 INTRODUCTION - 155 - 62 SUMMARY OF RESEARCH - 156 -

621 The uniqueness of these research studies - 156 - 622 Purpose of research - 156 - 623 Facts about plant cells - 157 - 624 The practical issue of RF transmission - 157 - 625 Evaluating appropriate stimulus application points - 158 -

x

626 Plant response to the application of direct current (DC) to plants in a hydroponic system - 159 - 627 Plant response to the application of 16Hz square wave signals to plants in a hydroponic system - 160 - 628 Effect of frequency specific radio wave energy using a leaky transmission line on plants in a hydroponic system - 160 - 629 The effect of plant stimulation on neighbouring plants - 161 - 6210 Fruit production - 161 - 6211 Plant pest resistance - 162 -

63 CONCLUSIONS - 163 - 64 FACTORS THAT COULD HAVE HAD AN INFLUENCE ON RESEARCH OUTCOMES - 165 - 65 RECOMMENDATIONS AND FUTURE RESEARCH - 166 -

REFERENCES - 168 - GLOSSARY - 190 - APPENDIX A - 193 -

xi

LIST OF FIGURES FIGURE 21 PASSIVE HYDROPONICS LAYOUT [14] - 14 - FIGURE 22 FLOOD AND DRAIN OR EBB AND FLOW [15] - 14 - FIGURE 23 DRIP FEEDING [15] - 15 - FIGURE 24 NUTRIENT FILM TECHNIQUE (NFT) [16] - 15 - FIGURE 25 AEROPONICS SYSTEM) - 16 - FIGURE 26 NUTRIENT CONTAINERS - 17 - FIGURE 27 GROWTH TRAYS - 17 - FIGURE 28 WATER RESERVOIRS WITH WATER AND AIR PUMPS - 17 - FIGURE 29 APPLICATION RATE OF FERTILISER (GRAMS PER 1000L WATER) [22]

- 19 - FIGURE 210 THE EM SPECTRUM [27] - 21 - FIGURE 211 TYPES OF ELECTROMAGNETIC SIGNALS [ADAPTED FROM GYAWALI 2008]

[33] - 23 - FIGURE 212 POWER DENSITY VS RANGE [34] - 24 - FIGURE 213 PROCESS OF PHOTOSYNTHESIS [47] - 28 - FIGURE 214 TRANSMISSION LINE CHARACTERISTICS [52] - 29 - FIGURE 215 VOLTAGE AND CURRENT STANDING WAVES B AND C ARE MISMATCHED

LINES [53] - 30 - FIGURE 3-1 EXPERIMENTAL SETUP TO MEASURE POTENTIAL DISTRIBUTION NEAR THE

PLANT ROOT [54] - 35 - FIGURE 32 PLANTS VERSUS ANIMALS ndash BODY ARCHITECTURES [74] - 38 - FIGURE 33 APPARATUS FOR CHARGING FLUIDS (PATENT US 6055768) [102] - 41 - FIGURE 34 EXPERIMENTAL DESIGNS FOR APPLYING LOW ELECTRIC FIELDS [112] - 43 - FIGURE 35 ELECTRONIC BLOCK DIAGRAM OF A HIGH OUTPUT ELECTROMAGNETIC

GENERATION SYSTEM [116] - 44 - FIGURE 36 PYRAMID CONVERTER OF ELECTROSTATIC TO DC POWER [122] - 46 - FIGURE 37 EFFECT OF NEGATIVE AIR IONS ON BLOSSOMING OF PERSIAN VIOLETS

[124] - 47 - FIGURE 38 MODE STIRRING REVERBERATION CHAMBER - 48 - FIGURE 39 ACCUMULATION OF LEBZIP1 TRANSCRIPTS AFTER EMF-STIMULATION IN

THE NON-SHIELDED CULTURE CHAMBER - 49 - FIGURE 310 KARLSSON SIMPLIFIED SCHEMATIC SETUP - 50 - FIGURE 311 AN EXAMPLE OF THE TOOL AS DEVELOPED BY HUNT ET AL ADAPTED

FROM [144] - 53 - FIGURE 312 A PLUG-IN BASED SYSTEM ARCHITECTURE [154] - 54 - FIGURE 313 FLOWCHART OF IMPROVED GROWTH STIMULATION ALGORITHM [156] - 55

- FIGURE 314 OPTICAL PLANT GROWTH MEASUREMENTS SYSTEM [158]

- 56 - FIGURE 315 GROWTH BEHAVIOUR UNDER LED ILLUMINATION [158] - 57 - FIGURE 41 SUN RISE AND SET TIMES FOR 2630S280E [180] - 64 - FIGURE 42 CLIMATE AND TEMPERATURE JOHANNESBURG SA [186] - 66 - FIGURE 43 VARIOUS APPLICATION POINTS FOR STIMULI APPLICATION TO PLANTS - 72 - FIGURE 44 DECOUPLING POWER RAILS IN AN OP AMP [197] - 75 - FIGURE 4-5 HYDROPONICS SETUP ADAPTED FROM [206] - 80 - FIGURE 46 EARTH SPIKE [208] - 83 - FIGURE 51 INSTRUMENTATION AMPLIFIER [218] - 116 - FIGURE 52 CURRENT PROPAGATION IN A TWIN WIRE TRANSMISSION LINE - 137 - FIGURE 53 FIELD LINES IN A TWIN WIRE TRANSMISSION LINE - 139 - FIGURE 54 LINE IMPEDANCE MATCHING TECHNIQUES [229] - 140 - FIGURE 55 LINE IMPEDANCE CHARACTERISTICS FOR 15MM COPPER TUBING

TRANSMISSION LINE - 141 - FIGURE 56 DIFFERENT GROUNDING TECHNIQUES ADAPTED FROM [231]

- 142 - FIGURE 57 LOGARITHMIC COMPARISON PLOT SHOWING DIFFERENCE IN HEIGHT DATA

SETS - 147 -

xii

FIGURE 58 LOGARITHMIC COMPARISON PLOT SHOWING DIFFERENCE IN MASS DATA SETS - 148 -

FIGURE 59 CURRENT PROPAGATION IN A TWIN WIRE TRANSMISSION LINE - 149 -

FIGURE 61 SELECTION OF APPROPRIATE STIMULATION POINTS - 158 - FIGURE 62 GROWTH AND MASS OUTCOMES FROM STIMULATION BY DIRECT CURRENT

- 159 - FIGURE 63 GROWTH AND MASS OUTCOMES FROM STIMULATION BY 16HZ SQUARE

WAVE - 160 - FIGURE 64 GROWTH AND MASS OUTCOMES FROM STIMULATION BY 16HZ AM WAVE -

160 - FIGURE 65 FRUIT SIZE COMPARISON BETWEEN THE DIFFERENT STIMULATION

TECHNIQUES - 162 - FIGURE 66 PLANT YIELD - 162 - FIGURE 67 PLANT INSECT INFESTATION USING DIFFERENT STIMULATION

TECHNIQUES - 163 - FIGURE 68 GROWTH AND MASS COMPARISON USING DIFFERENT PLANT STIMULATION

TECHNIQUES - 164 - FIGURE 69 THE FOUR-WIRE PARALLEL TRANSMISSION LINE - 166 -

xiii

LIST OF TABLES TABLE 21 COMMON SYMPTOMS OF NUTRIENT DEFICIENCY IN AQUATIC PLANTS [23

24] - 20 - TABLE 31 RADIO FREQUENCY SPECTRUM [85] - 39 - TABLE 32 LIST OF MAIN CONCLUSIONS [142] - 52 - TABLE 41 EFFECT OF HUMIDITY LEVELS ON THE GROWTH OF TOMATO PLANTS [185]

- 65 - TABLE 42 JOHANNESBURG WATER QUALITY REPORT 2011 [194] - 70 - TABLE 43 STIMULATION DISTRIBUTION EXPERIMENT 1 - 84 - TABLE 44 EXPECTED PERFORMANCES EXPERIMENT 1 - 85 - TABLE 45 STIMULATION DISTRIBUTION EXPERIMENT 2 - 89 - TABLE 46 EXPECTED PERFORMANCES EXPERIMENT 2 - 90 - TABLE 47 STIMULATION DISTRIBUTION EXPERIMENT 3 - 92 - TABLE 48 EXPECTED PERFORMANCES EXPERIMENT 3 - 93 - TABLE 49 STIMULATION DISTRIBUTION EXPERIMENT 4 - 97 - TABLE 410 EXPECTED PERFORMANCES FOR EXPERIMENT 4 - 98 - TABLE 51 COMPOSITION OF NUTRIENT CONCENTRATES PER CONTAINER - 110 - TABLE 52 NUTRIENT DEFICIENCIES IN PLANTS [216] - 114 - TABLE 53 RESPONSES FOR EXPERIMENT 1 - 121 - TABLE 54 INITIAL AND FINAL MEASUREMENTS FOR EXPERIMENT 1 - 122 - TABLE 55 OBSERVATION MEASUREMENTS FOR EXPERIMENT 1 - 122 - TABLE 56 SUMMARY OF RESPONSES FOR EXPERIMENT 2 - 125 - TABLE 57 GROWTH OUTCOME WHEN APPLYING A DC TYPE OF STIMULUS - 126 - TABLE 58 PLANT MASS OUTCOME WHEN APPLYING A DC TYPE OF STIMULUS - 126 - TABLE 59 OBSERVATION MEASUREMENTS FOR EXPERIMENT 2 - 127 - TABLE 510 SUMMARY OF RESPONSES FOR EXPERIMENT 3 - 130 - TABLE 511 PLANT GROWTH OUTCOME WHEN APPLYING A 16HZ SQUARE WAVE

STIMULUS - 130 - TABLE 512 PLANT MASS OUTCOME WHEN APPLYING A 16HZ SQUARE WAVE

STIMULUS - 131 - TABLE 513 OBSERVATION MEASUREMENTS FOR EXPERIMENT 3 - 132 - TABLE 514 FIELD STRENGTH OUTPUTS FROM FREQUENCY GENERATORMODULATOR -

143 - TABLE 515 SUMMARY OF RESPONSES FOR EXPERIMENT 4 - 143 - TABLE 516 PLANT HEIGHT OUTCOME WHEN APPLYING A RF 16HZ MODULATED

FREQUENCY STIMULUS - 144 - TABLE 517 PLANT MASS OUTCOME WHEN APPLYING A RF 16HZ MODULATED

FREQUENCY STIMULUS - 144 - TABLE 518 OBSERVATION MEASUREMENTS FOR EXPERIMENT 4 - 146 - TABLE 519 FRUIT SIZES - 151 -

xiv

LIST OF PHOTOGRAPHS PICTURE 41 HALF A SECTION OF THE HYDROPONIC PLANT LAYOUT - 71 - PICTURE 51 SITE PREPARATION FOR HYDROPONIC PLANT - 102 - PICTURE 52 PLANTING - 103 - PICTURE 53 HYDROPONIC CONTROLLER AND NUTRIENT RESERVOIRS

- 105 - PICTURE 54 PROVISION FOR ADJUSTMENTS (OFFSET CONTROL) - 105 - PICTURE 55 PROBES ILLUSTRATED ARE PH TEMPERATURE AND EC PROBES - 106 - PICTURE 56 DRIP FEEDING TECHNIQUE AND THREE DIFFERENT SIZES OF CALIBRATED

DRIPPERS - 107 - PICTURE 57 HANNA HI 98130 ALONG WITH PH CALIBRATION SOLUTION AND PROBE

STORAGE SOLUTION - 111 - PICTURE 58 STAINLESS STEEL PROBES AND POLYWIREcopy FOR RELAYING SIGNALS TO

PLANTS - 120 - PICTURE 59 SHOWING THE 5V POWER SUPPLYSIGNAL GENERATOR THE PROBES IN

ACTION AND THE POLY-WIRE FOR SUPPORT AND RELAYING OF THE STIMULUS TO THE PLANT - 120 -

PICTURE 510 DC STIMULATED PLANTS (ON THE LEFT) APPEAR MORE COMPACT - 134 - PICTURE 511 BALUN TO MATCH TRANSMITTER WITH TRANSMISSION LINES WITH

SOME MISMATCHED TAPINGS - 142 - PICTURE 512 PLANT MASS DENSITIES AND SPREAD FOR RF STIMULATED (LEFT) AND

CONTROL PLANTS (RIGHT) - 145 - PICTURE 513 FRUITS WERE LIMITED TO 5 TOMATOES PER PLANT - 151 - PICTURE 514 VARIOUS FRUIT SIZES FOR EACH EXPERIMENT RANGING FROM LARGEST

TO SMALLEST - 152 - PICTURE 515 ALAN BROADBAND ZC 300 RF FIELD STRENGTH TESTER

- 153 -

PJJ van Zyl Chapter 1 Introduction

- 1 - Radio Frequency Energy for Bioelectric Stimulation of Plants

Chapter 1 Introduction

11 Background

The effects of using electrical energy to stimulate living matter are well-documented

and researched A typical example is the intracranial stimulation of heart tissue with

without which many patients would simply not be able to live Using electrical energy

to enhance plant growth is still somewhat unclear with not always positive results

documented What is known is the fact that plants flourish after environmental

stimulation for example new growth after a rainstorm dark green leaves after a

nitrogen application or vigorous growth after applying organic substances like

manure

According to the Food and Agriculture Organization (FAO) of the United Nations

(UN) [1 2] starvation affects more than one may think Some 6 million children die

every year directly or indirectly owing to food starvation The need to produce enough

food for every inhabitant is of major concern for any government Nearer to home we

have seen many countries in Africa where hunger is spreading leaving people

deprived of their most basic human rights In Maslowrsquos hierarchy of needs [3] the

physiological level forms the base of the pyramid he presented in 1943 In this

pyramid the physiological level indicates the need for water food and breathing

Without these life cannot exist

12 Problem Statement

To enhance the way in which food is produced the emphasis must be on improving

current methods or systems The reason is simple in that the only remaining fertile

land is either without water resources far away from civilisation or situated in forests

that we as humans animals and plants desperately need to exist For these reasons

farmers started years ago to farm hydroponically1 as fertile soil is not required and

1 Hydroponics (In Greek hydro= water and ponos= labour) Hydroponics is a method of growing plants in a controlled medium In this case controlled nutrient enriched water Soil is not used but an inert growth medium like sand sawdust stones or perlite is used to support the plant and cover the delicate roots



water usage is at a minimum It may sound ironic that farming with water actually

uses much less water than farming with soil

Travelling in South Africa one immediately notices that hydroponic farming is

becoming a favourite method to produce crops plants and flowers all year round

Because our country has vast areas of arid land ranging from semi-desert to desert as

well as places with only limited ground water farmers have no alternative but to

resort to high density crops where the minimum amount of water is used Hydroponic

farming is ideal in this case Preheated hydroponic tunnels also make all year food

production possible which is necessary for a continuous cash flow as food production

is labour-intensive and the salary bill is huge Although hydroponic farming is not

new some problems do still exist Large capital expenditure pest control and the high

level of expertise that is required are just a few [4]

It is a well-known fact that for agricultural products to obtain maximum profits your

input costs must be as low as possible and that your return from the plants must be

optimal or that the product must be of exceptional size or quality or colour It is on

achieving the latter four that this research will focus on

Research on plant stimulation is not new Douglas James [5] mentioned that Sir

Francis Bacon reported in 1627 about growing plants in soilless mediums while John

Woodward was the first to publish about spearmint grown in a water culture

According to Scott [6] the effect that electrical fields have on plants is well-known

and has been investigated for more than 180 years

Although research has proven the success of plant stimulation and the positive yields

that were achieved by applying electric fields the problem is that almost all

experiments were done on soil-planted mediums and in countries unlike South Africa

with our unique climate and abundance of sunshine Much of research was done

applying high voltages or creating high voltage fields to stimulate the plants This

method of course is not practical in hydroponics systems especially greenhouse

systems where space is limited and where high voltage fields cannot be established

due to the high humidity levels present in greenhouses



Very little research was done applying technology to stimulate plants in hydroponics

systems neither was a comparison outcome using different techniques performed nor

was there research using transmission lines as radiating antennas

The reason why transmission lines were decided upon is the practical usefulness

Applying for frequency bandwidth use from the authorities is not necessary as

radiation is only between the two lines and not into space or free air This also results

in the practical use of any frequency or range of frequencies

13 Objectives

First objective The aim of this dissertation will be to focus on practical and easily

implementable types of stimulation either fixed or transmitting devices which will

generate electric frequency pulsed frequency and or electromagnetic signalsfields to

treat plants for example although roots seeds or growth mediums can also be

stimulated The main purpose will be to create optimum nutrient uptake and to make

the plants produce high yield and quality fruit and vegetables

Although lots of time was spent by past researchers researching plant responses to

applying stimulation these were either not focussed on hydroponics systems or were

not practically implementable2 or were not using leaky transmission lines

To solve the problem of food production real practical solutions using technology

should be tabled The choice of choosing a hydroponic system is that it is easy with

pumps and controllers to control the concentration of nutrients for fast-growing plants

during stimulation unlike in soil where nutrient availability will be limited by the soil

nutrient content or the water level present in the soil Water stress in plants is also at a

minimum in hydroponic systems

Second objective This will be to find a preferred type or method(s) of stimulation

Signals for stimulation can be injected or applied via direct plant contact water or

nutrient medium antenna or by any other means for example conducting plates or 2 Practically implementable Under this we understood that it must be easy to install or connect to the plants not overcrowd the greenhouse with wiring or apparatus that takes up spaces not endangering workers maintaining or harvesting the plants grow (expand) in synchronism with the plants use of affordable systems simple design and maintenance



electrodes Frequency ranges can be from zero Hertz (DC) to 100MHz according to

the resonate frequency of what is to be accomplished

Also that said signal or pulse is applied for a minimum period of time or on a

continuous basis until the desired results are achieved Example If plants by means of

stimulation or nutrient formulation are only allowed to grow it would be to the

detriment of the main purpose which is of course to produce high yield and quality

fruit It is believed that the applied frequency should consist of pulses or modulated

pulses rather than single or fixed radio frequency To establish such pulses timing

devices may be utilised

A third aim would be to compare the effect of radio frequency stimulation with tested

methods of stimulation Using different plants to verify the research is also important

Certain plants are cultivated for their mass while other are used for fruit production

An example may be Barley grass and Solanum lycopersicum (tomato)

Fourthly a control system is established in which both the experimental results can be

compared The control will run alongside the experiment with the same nutrient

formulation environmental factors and light conditions

As a final aim plant response will be measured in two different ways The first aim

will be where observation and measurements are used to compare results of the

experiment to that of the control The second aim being plant outputs like fruit mass

quality and size Record-keeping for all positive and negative results will be

established

14 Scope of research

The experiment will be limited to 4 active hydroponic systems Two closed loop

systems3 along with two control systems for each of the mentioned types enabling the

3 Closed Loop System In a closed loop system the nutrients are circulated to the plants and the surplus water is collected after drainage This nutrient depleted water is then returned to the nutrient reservoir enriched with nutrients oxygenated and then pumped to the plants again This process is repeated for about 2 weeks before the nutrient is discarded to prevent an imbalance between nutrients



execution of more than one experiment at a time Each hydroponic system will be

equipped with an electronic control system that will automatically sample the nutrient

temperature and water levels at specific intervals and then automatically adjust these

factors to optimum levels

An electronic PH sampling system will ensure the PH of the nutrient medium is at

optimal levels as noncompliance with this will result in certain nutrients becoming

unavailable to the plant These measures will eliminate any possible errors due to

human negligence or detrimental effects as could occur over weekends

Once the setup is completed and plants established the plants may be stimulated using

electric frequency pulsed frequency andor electromagnetic signalsfields Range

include from 0Hz (DC) to about 100 Mhz Methods of application may include

antenna probes direct wiring and nutrient excitement4 Duration may be continuous

semi-continuous or at intervalsperiods of time Although many other forms of

stimulation like high frequency high voltage light electromagnetic laser and many

more exist it falls outside the scope of this research Stimulation of seeds and roots is

also possible but is not considered in this research More information on RF

stimulation of seeds can be found in Appendix A

15 Research Limits

As plants grow actively in cycles and typically from spring to late summer research

observations may exceed a single growing season if non-favourable conditions persist

to exist Financial constraints will have an impact on the size of the experiment and

the number of plants that can be accommodated As the university is closed for a long

period over December plants will have to be monitored before and after this period

meaning new plants will need to be planted after the break period

Pests and diseases may be a limiting factor although previous research suggests that

stimulation reduces the infestation of pests This is mainly because a healthy plant is

4 Nutrient excitement This is where the nutrient is charged electrically by circulating the nutrient inside a RF chamber with an RF electrode connected to frequency generating amplifier



strong and able to withstand pests Another concern is extremely high temperatures

winds and prolonged periods of rain or hailstorms that could ruin a plant in seconds

A prolonged power interruption or power load shedding is also a major concern

especially in experiments where backup generators are not normally part of the setup

Although hydroponics systems can be of either the open or the closed loop system

only closed loop systems will be used in this experiment The reason for this is the

saving in nutrient cost although the researcher is aware of the fact that should a virus

or bacterial infection develop it will affect all plants in the shared water system

16 Overview and Map

Figure 1 shows a hypothetical layout of the experiment This layout illustrates the

different components included in the experiment and shows an overview of what the

researcher wants to achieve


7 Radio Frequency Energy for Bioelectric Stimulation of Plants

Masterrsquos Dissertation Proposal Illustration

Data analysed Thesis

Stimulator Controllers

Measurements amp Data

Hydroponics Controllers

Plants

Hydroponics System

Data amp Observations

System Sensors

These include for example

Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF

Measurement circuitry

Controller data

Temperature

Nutrient and pH levels

Plant growth

Plant performance and appearance

Method and type of stimulation

Electronic circuitry to

Measure temp pH EC and

water level inputs and provide

outputs for EC pump pH pump

heaters fans aerator and GSM

copy [7]

copy [8]



17 Chapter overview

Chapter 2 highlights some background issues to the research Concepts of radio

frequency (RF) theory transmission lines electronics controllers and other

electronics fundamentals are discussed The basics fundamentals different types

nutrient formulations nutrient concentrations electrical conductivity measurements

and many more are discussed for hydroponics Another section covered in this chapter

is bio-stimulators and their effect as well as the measurement of bioelectrical signals

Plant requirements growth and pest control are also highlighted

Chapter 3 as the literature study concentrates on previous research their effects and

outcomes This chapter also gives an overview of the different types of stimulation

that were used in these studies Outcomes of these studies are reviewed

Chapter 4 is about the experimental design The construction setup operation and

functioning is discussed in detail Each method of stimulation is described in detail A

single solution to all design cases is not likely since every crop has different

requirements The goal will be to find the best possible technology according to the

desired performance parameters

Chapter 5 describes the setup and implementation of the four experiments

Hypothesises are verified and results are given Data is interpreted and outcomes are

analysed and discussed Other factors like fruiting pests and diseases are also

discussed

Chapter 6 is the concluding chapter that summarises the work by means of graphical

illustrations list shortcomings and indicates further research



18 Conclusion

It is a fact that plants generate bioelectrical signals (trans-membrane potentials) which

are responsible for intracellular movement of nutrients The opposite also applies

Plants may be stimulated with weak electrical signals to enhance the uptake of

nutrients in the plant

This is especially true if the plant is exposed to frequencies that excite the potassium

and calcium ions Plant metabolism is thus increased with a concurrent improved

response in the form of faster growth higher fruit count and improved fruit quality

Although soil-planted trials have proven the positive effects of plant stimulation

limited research was done on hydroponic systems which are the future method of

farming as plants can be grown in high density clusters with balanced pre-controlled

nutrients and extremely effective water usage South Africa is known as a land where

we have scarce water sources and vast areas of arid land that cannot be commercially

farmed in the traditional way

A positive outcome of this research may be to address the problem of land claims

where smaller pieces of land are required if farmers switch to high density

hydroponics farming Another is that electronics which are relatively cheap can be

employed to automate an entire process which can compensate for lack of skills by

new inexperienced farmers Of course the main goal remains and that is to find

practical applicable methods of technology according to the desired performance

parameters which are to enhance plant growth increase fruit sizeyield and to produce

high quality products

PJJ van Zyl Chapter 2 Background


Chapter 2 Background

21 Introduction

Plants like humans and animals are living things Like us they have certain needs but

they also provide certain yield(s) that can be put to good use Most of the species in

the family Plantae however are not as domesticated as we are and are able to grow

and survive in extreme growth conditions just like wild animals where the strongest

survive and the weaker animals become part of the food chain This implies that

plants can adapt to an environment and we as humans can exploit this to our

advantage We as humans were given the talent to breed modify and change the

growing conditions of plants and animals to ensure survival for us Ethically it is easy

and of no concern when experiments with plants are done

It is true that there is an increasing perception these days that we have to farm

scientifically and apply precise control to ensure optimum growing conditions for

plants This perception is backboned by the fact that food shortages with extreme

human suffering on our continent are witnessed weekly on television Then there are

also worrying conditions like global warming soils with depleted nutrients El Nino

weather conditions carbon content of the air due to the burning of fossil fuels pests

diseases and many more

Applying electrical stimulation techniques to enhance plant growth and production are

one method that we may use to solve a number of economic and socio-economic

problems relating to food security These techniques of stimulation have been known

for many years some with excellent results and other with not so promising

outcomes It was people like Karl Lemstroumlm - a professor at Helsinki University ndash

who started to carry out large scale experiments on crops [9] It was also in his time

that people started to use the word electroculture5 In Lemstroumlmrsquos experiments he

5 Electroculture stimulation of plant growth flowering or seeding by application of an electric or magnetic field Found on httpwwwelectropediaorgievievnsf



made use of high voltage electrostatic grids to produce 10kVm voltages This

stimulation yielded positive average surpluses of 45 compared to the control [10]

Since 1904 people like Krueger Bachman Melikov and many more have continued

to investigate plant stimulation and methods to increase crop production So the

production methods and farming practices have also changed over the years until a

point today where farming is a sophisticated hi-tech practice It thus makes common

sense to apply advanced technology to suit individual different farming practices

especially in relation to growth pest control production techniques fruit nutrient

content harvesting processes storage and marketing

This research however will concentrate on the production side by applying technology

to enhance the growth mass and an increased crop yield One of the topmost

technological practices farmers are using these days and which is also excellent for all

year round fresh crop produce is hydroponics farming Hydroponics is an ancient

concept and simply means lsquoworking water6rsquo

22 Overview

The purpose of hydroponic systems

Hydroponic methods

Open and closed loop hydroponic systems

The hydroponic setup

Electrical conductivity

PH control

Nutrient formulations

Symptoms of nutrient deficiencies

Electric fields

The Electromagnetic Spectrum

Experimentation with electromagnetic (EM) waves

Characteristics of EM waves

Types of electromagnetic signals

6 Latin meaning



Power density

Ionisation radiation

Non-ionisation radiation

Specific Absorption Rate (SAR)

Plant cell membranes

Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas

Transmission line radiation

Transmission line characteristic impedance

Standing wave ratio

Requirements for electronic hydroponic controllers

23 The purpose of hydroponics systems Plants absorb their nourishment in the form of ions that are actually dissolved

nutrients salts and minerals present in soil water Roots covered with tiny root hairs

are used to transport these nutrients and minerals along with water into the plant

where with the aid of light and atmospheric gases food and building blocks are

produced to make the plant grow and produce crops This means that only the

nutrients and minerals are absorbed and not the soil or other growing matter

It is because of this that one can grow plants in a water medium without soil Soil or

whatever growing medium only acts as an anchoring medium to house or hold the

delicate roots as well as giving stability so that a plant is not blown over by wind and

is able to grow upright Inert mediums like river sand stone chips coco fibre

vermiculite or any other is suitable to grow plants in

Hydroponics has a long history but it was two botanists Julius von Sachs and

Wilhelm Knop experimenting in the years 1859-1865 who developed the method or

technique of non-soil cultivation or solution culture [11]



This brings us to the question of lsquoWhat are the advantages when growing plants

hydroponically and why is soil not always the preferred medium [12 13]

Generally hydroponic grown plants are cleaner (less soil and dust) and need milder

washing which results in less damage to fragile crops

Weed control and soil preparation using high-powered machinery is not required

No need for specialised expensive cultivation implements

Less land area is required as crops are grown more densely and also vertically

Much more efficient water use as no water is lost in the soil No water stress

Very efficient use of nutrients as no nutrients remains in the soil

Optimum growth conditions can be simulated using greenhouse structures

Soil fumigation is not required and no crop rotation practices are needed

Crops can be grown on islands in desserts and in space

Plant specific requirements can be controlled

Although hydroponics farming has many advantages there are certain disadvantages such as

Artificial nutrients must be used which means that true organic growing is not

possible

Setting up a hydroponic system is initially very expensive

High levels of expertise are required although a short training course could solve this

problem

Because of high density crops pest and disease management are a problem

Daily attention is required unless technology is used to monitor the system

24 Hydroponic Methods In applying hydroponics different techniques are available These are not limited but there are

a few main ones which include Passive Hydroponics as can be seen in Figure 21 [14] In this

system the plants suck up water and nutrients by capillary action through the wick Plant roots

require oxygen to keep them healthy just as the leaves require carbon dioxide for

photosynthesis Air is bubbled through the water to provide oxygen to the roots and to keep

the water free from bacteria as oxygen has a sterilizing effect



Figure 21 Passive hydroponics layout [14]

In the second method of Flood and Drain water is pumped into the growth tray and

when the pump switches off water is drained back to the reservoir over a period of

time This draining process sucks in air (oxygen) into the root medium An air pump

is thus not required

Figure 22 Flood and Drain or Ebb and Flow [15]

In the Drip Feeding method oxygen-enriched water is circulated with the aid of a

pump through spaghetti pipes to plants via drippers The drippers provide a

continuous tickle of water nutrients and oxygen to the plants This process may be

continuous or the pump may run for certain periods of time using a timer



Figure 23 Drip feeding [15]

In the Nutrient Film Technique (NFT) the pump supplies oxygen-enriched water to a

growing tray (usually a tube or gutter) on a continuous base This thin layer of water

is just enough to wet the roots without drowning them No growth medium is required

which increases the harvesting and replanting time for smaller types of plants like

lettuce

Figure 24 Nutrient Film Technique (NFT) [16]

Aeroponics and Raft Cultivation Techniques are almost the same except that in

Aeroponics the roots are sprayed with a fine nutrient enriched water mist while in

Raft Cultivation the plants with their roots are floating on top of a nutrient rich but

also heavily oxygen-enriched bed of water



Figure 25 Aeroponics system [17]

25 Open and closed loop systems

The unused nutrient (after being applied to the plant or growing tray) can either be

recycled (closed system) or dumped (open system) In a closed system the recycling

method through a sawdust growing medium is however not recommended as the

sawdust will clog the drippers which then need to be cleaned with diluted acid

With closed [recycled] systems there will be a build-up of excess unused nutrients in

the recycled water which may make controlling the PH difficult This build-up may be

toxic to plants and can be controlled by changing the nutrient water in the reservoir

The frequency of changing the nutrient depends on the amount of dissolved solids An

alternative option to eliminate any guess is to include a wasting dripper What this

implies is that you use a low flow dripper on the pump circulation system that wastes

a small amount of water daily which then helps to control the build-up of any salts

The size of the dripper can be selected to say replace a reservoir full of water over a

period of a week or longer if plant growth is slow

With open systems you need to regularly measure the electrical conductivity (EC) of

the remaining water in the growth medium (buffer water) to prevent plants going into

shock The electrical conductivity (EC) of this water will rise over time and when the

level rises to the required EC level plus 05 you need to flush the growth medium with

a diluted (say frac12 strength) nutrient mixture As soon as EC levels return to normal the



standard nutrient formulation may be resumed Good practice to keep the EC of buffer

water under control is to overwater (to have a runoff of) about 20 [18]

26 The hydroponic setup

To grow plants hydroponically you will need a growth tray with or without growth

medium a water reservoir water pump air pump and piping A structure is also

needed to support plants as well as nutrients and acid for PH control and good clean

water Additional equipment are (but not limited to) drippers measuring jugs

weighing scales minmax thermometer planting bags and sterilization chemicals

Figure 26 Nutrient containers

Figure 27 Growth trays or channels

Figure 28 Water reservoirs with water and aerator pumps

27 Electrical Conductivity (EC)

Plants require 17 different nutrients to grow (refer to Chapter 4 for more detail)

Electrical conductivity indicates the total dissolved salts (TDS) of the nutrient

solution and is measured with an EC meter EC is measured at 250C and the unit is

Nutrients1 Nutrients2

Water Pump

Air

Heaters (optional)

Acid



micro Siemenscm (1microScm = 1 micromhocm) (This micromho is from the term mhos which

describes the inverse relationship between resistance and conductivity) One mS or

1000microS with relation to hydroponics can be defined as a current of one milli-amp that

will flow when a potential of 1 Volt is applied to the edges of a square 1cm block of

nutrient solution An EC of 1000 microScm thus corresponds to an EC of 1

A limitation of EC as defined in hydroponics systems is that it indicates only the total

concentration of the solution and not the individual nutrient components A typical

EC range for cucumbers grown hydroponically is between 15 and 25mS but for

tomatoes this is 25 to 3mS [19] Higher EC will prevent nutrient absorption due to

osmotic pressure and lower EC severely affects plant health and yield Note that the

PH must be corrected before any EC measurements are taken

28 PH control

PH is a unit of measure in chemical engineering to describe acidity or basicity in

terms of a decimal logarithm ranging in units from 0 to 14 A PH of 7 is considered

neutral while less than 7 relates to acidity (acid) and above 7 as basicity (alkaline) In

pure water the hydrogen (H+) and hydroxyl (OH-) ions are in balance which results in

a neutral PH In hydroponic systems the ideal PH is slightly acidic to enhance nutrient

absorption and typically ranges from 55 to 65 (more detail in Chapter 4) [20]

Different plants generally require different PH levels because they require different

nutrients which again are more freely available at different PH levels An example is

iron which will not be available (precipitated out of solution) at a PH of 8 while

calcium would be very available [21]

The reason for PH to drift is due to the fact that plants remove positive ions such as

calcium (Ca 2+) from the nutrient solution as they grow while negative hydrogen ions

are then released by the roots to ensure equalisation This results in an increase of the

PH of the solution PH is measured with a PH meter that requires a special probe



29 Nutrient formulations

It is essential that nutrients be applied correctly as specified by the chemical

manufactures As will be noticed from the following chart (source Ocean Agriculture

Fertilisers) [22] the composition of these fertilisers is so that minimum experience is

required to make use of them

It will be noticed that calcium as a macro-nutrient cannot be included with the other

macro-nutrients because calcium and phosphate from the Hydrogrocopy for example

will precipitate as bonemeal which will be inaccessible to the plant Once in a

hydroponic nutrient solution the combination is of no concern because these elements

are now in a much diluted solution preventing them from combining In the

Hydrogrocopy however some elements like iron also need to be in the chelated7 form

Figure 29 Application rate of fertiliser (grams per 1000L water) [22]

210 Common symptoms of nutrient deficiencies in plants

If a hydroponic system is well managed nutrient deficiencies should rarely occur

However certain crops grown solely in such a system might induce some deficiencies

of certain elements The following table serves as a guide to quickly identify

shortages and their effects (symptoms) that may be experienced [23 24]

7 A chemical compound in the form of a heterocyclic ring containing a metal ion attached by coordinate bonds to at least two non-metal ions Source httpwwwthefreedictionarycomchelate

CROP HYDROGRO HORTICULTURAL CALCIUM NITRATE

POTASSIUM SULPHATE

(Hort Grade)

EC at 25oC in distilled

water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm

TOMATOES 1 To flowering of third Truss 2 After third

Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE

amp LEAF CROPS 1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm



COMMON SYMPTOMS OF NUTRIENT DEFICIENCY IN AQUATIC PLANTS

Element Leaves to first show deficiency Symptom

Nitrogen Old Leaves turn yellowish ()

Phosphorus Old Premature leaf fall-off Similar to nitrogen deficiency

Calcium New Damage and die off of growing tips Yellowish leaf edges

Magnesium Old Yellow spots ()

Potassium Old Yellow areas then withering of leaf edges and tips

Sulphur New Similar to nitrogen deficiency

Iron New Leaves turn yellow Greenish nerves enclosing yellow leaf tissue First seen in fast growing plants

Manganese () Dead yellowish tissue between leaf nerves

Copper () Dead leaf tips and withered edges

Zinc Old Yellowish areas between nerves Starting at leaf tip and edges

Boron New Dead shoot tips new side shoots also die

Molybdenum Old Yellow spots between leaf nerves then brownish areas along edges Inhibited flowering

() The plants may also become reddish from the presence of the red pigment anthocyanin () Although Jacobsen does not differentiate between new and old leaves David Whittacker reports from a hydroponics book that boron calcium copper iron manganese and sulphur are immobile elements and whose deficiencies affect new leaves

Table 21 Common symptoms of nutrient deficiency in aquatic plants [23 24]

211 Electric Fields Everyone is familiar that it was Michael Faraday who introduced the world to the existence of electric fields These fields are the electrical force between two charges The equation for electric force comes from the gravitational force formula (Isaac

Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)

Q = electric force of one object (C) q = electric force of the other object (C) and d = distance between the two objects (m) The electric fields for Q and q can now be formulated as

Electric field (E) for Q 2E KQ d Electric field for q 2E Kq d

From this one can now prove that the force divided by the charge will equal electric

force (E) [25]

2 2

F KQq KQ Eq d q d



212 The Electromagnetic (EM) Spectrum

The electromagnetic spectrum (EM) is a band of frequencies due to electromagnetic

radiation Known wave spectrums are visible light radio waves infrared ultra-violet

X-rays and gamma rays X-and gamma rays are situated at the higher order

frequencies while infrared is at the lower range

Any EM can be described in terms of three properties which are frequency

wavelength and photon energy [26] The wavelength is inversely proportional to the

frequency This implies that gamma rays for example have very short wavelengths

while the lower than infrared frequencies have wavelengths thousands of kilometres

long Visual applications of EM are depicted in the following illustration [27]

Figure 210 The EM Spectrum [27]

213 Experimentation with electromagnetic waves

Experimenting with electromagnetic waves on plants has the advantage that there are

no ethics involved Sunlight for example has a luminous efficacy of about 117

lumens per watt for solar elevation attitudes greater than 250 and reducing to 90

lumens at 750 [28] As long as the frequency duration and intensity are controlled



without destroying plant tissue then one may use electromagnetic energy waves to

your advantage as they are free

EM radiation also has some disadvantages Studies especially those relating to

communication devices like cell phones with more than 41 billion users worldwide

are controversial [29] Some claim memory loss and other carcinogenic8 effects

Some researchers claim little to no effect while others report that static fields may

lead to an increase in blood pressure but according to Andrauml as long as field strength

is below 2T no adverse effects were detected [30] In a conference in 2006 even the

degree of dangers to induced currents to human bodies from low voltage appliances

was highlighted Luckily it was found that these low voltage fields cause no transient

effects on human health [31]

214 Characteristics of the EM wave

An EM wave carries energy and consists of an electric field E and a magnetic field H

These two components are in phase but perpendicular to one another as well as

perpendicular to the direction of propagation in which they are travelling The energy

contained can be given by

34 2 (6626068 10 m kg s)E hf whereE Electric field h plank const and f frequency

The relationship between frequency and wavelength is

Maxwell and later confirmed by Hertz revealed the wavelike structure of electric and

magnetic fields Maxwell also concluded that what we perceive as light is indeed

itself an EM wave [32]

8 Any substance or agent that tends to produce a cancer From httpdictionaryreferencecombrowsecarcinogen

8310 ( )

c wheref

c m s and defined as the phase speed of light or EM speed in a vacuum space



215 Types of Electromagnetic Signals

Electromagnetic signals may have many different forms They may either be static

(DC) sinusoidal triangular saw tooth square frequency varying time varying

pulsed pulsed damped or combination [33]

Figure 211 Types of Electromagnetic Signals [Adapted from Gyawali 2008] [33]

216 Power Density

In an electric field the radio frequency (RF) strength of the power present is known as

the power density or the power flux density Power emitted by a transmitting isotropic

(all directions) radiator (antenna) will have uniform power delivered in all directions

At a distance from such radiator the power density can be determined as

24PtPd or Pfd whered

Pt is the power transmitted

d is the distance in meter from the antenna

Depending on Pt Pd will either be a peak or average power

An antenna also has gain and gain is defined as

Maximum radiation intensity of specific antennaGtMaximum radiation intensity of an isotropic antenna

This implies that the power density now becomes

24PtGtPfd where

d Gt is the gain transmitted



Further to this all power transmitted is not effectively used due to losses This results

in what is known as the Effective Isotropic Radiated Power (EIRP)

Pt GtEIRP orLbo Lbf

EIRP Pt Gt Lbo Lbf if expressed in dBwhere

Lbo is the back off losses9 and

Lbf is the combined branching and feeder losses

The capture area for a receiving antenna is constant regardless of how far the transmitter is The received signal power decreases by 6 dB when the distance doubles The following figure illustrates this concept [34]

Figure 212 Power density vs range [34]

217 Ionising radiation

When energy is released from a source of electromagnetic radiation like radio

frequency (RF) infrared light (IR) visible light (VL) ultra-violet light (UV) or x-rays

and gamma rays it is referred to as radiation of energy Although all listed forms of

radiation carry energy it is only the high frequency portion of electromagnetic

radiation (above 3x108Hz or 300GHz) [35] like x-rays and gamma rays that carry

enough energy to cause ionisation

9 The input back-off is the difference in decibels between the carrier input at the operating point and saturation input that would be required for single carrier operation



Radiation may be ionising or non-ionising In the case of ionising radiation the

radiation carries plenty of energy along This energy is so powerful that when

colliding with an atom of another particle it can bounce electrons off the

aforementioned particle In such a case the mentioned atom will losegain electrons

due to the collision and this atom will now become ionised

Further to this ionising radiation may occur in two forms namely wave or particle

Wave types like visible light and radio waves carries wave packets of photons while

in particle type there are atomic particles that contain huge quantities of kinetic

energy [36]

218 Non-ionizing radiation

Non-ionizing radiation is similar to ionising radiation as it also contains the

electromagnetic spectrum of light but now more towards a different set of frequency

ranges like ultraviolet (UV) visible light infrared (IR) microwave (MW) radio

frequency (RF) and extremely low frequency (ELF)

The problem with non-ionizing radiation is that it still poses health risks because it

can interact with the biological systems of workers and the public if not properly

controlled [37]

219 Specific Absorption Rate (SAR)

When an object or a sample of an object is subjected to radio frequency (RF) then

such sample will absorb some of this applied energy This energy referred to may

only be labelled as non-ionising energy when the energy does not cause ionisation to

samples of living matter (plant animal or human tissue)

Should ionising energy be applied to mentioned matter it will cause a heating effect in

such sample which would be detrimental to the sample of living matter

Generally SAR can be defined as the power absorbed per certain mass of matter with

a unit labelled as Wkg [38]

Different factors determine the SAR Generally a SAR of 4 Wkg tissues will

normally bring about a change in temperature of 10C [39]

To calculate SAR [40]



2

2ESAR where

-is the electrical conductivity of the sample (Sm)

E -is the intensity if the electric field (NC or Newton Coulomb) and

-is the density of the tissue or matter in the sample (kgm3)

220 Plant cell membranes

Membrane potential or trans-membrane potential is the [Vinside ndash Voudside] potential that

exists in a cell This potential is due to the insideoutside fluid difference of a cell The

cell fluid again consists of high levels of different ions and the ions are a result of ion

lsquopumpsrsquo embedded in the membrane of a cell [41]

When there is no ion flow across the membrane it is said that the trans-membrane

voltage exactly opposes the force of diffusion of the ion This is known as the lsquoresting

potentialrsquo and may be calculated using the Nernst equation [42 43]

[ ]ln[ ]eq K

i

KRTE wherezF K

EeqK+ is the equilibrium potential for potassium measured in volts

R is the universal gas constant equal to 8314 joulesmiddotKminus1middotmolminus1

T is the absolute temperature measured in Kelvin (= K = degrees Celsius + 27315)

z is the number of elementary charges of the ion in question that is involved in the reaction

F is the Faraday constant equal to 96485 Coulombsmiddotmolminus1 or JmiddotVminus1middotmolminus1

[K+]o is the extracellular concentration of potassium measured in molmiddotmminus3 or mmolmiddotlminus1

[K+]i is the intracellular concentration of potassium

The significance of this potential is that there is actually a small battery present in

each and every cell due to the voltage created by the ions present These intercellular

batteries were described in 1952 by the 1963 Nobel Prize winners Hodgkin and

Huxley (also known as the Hodgkin - Huxley Model) [44]

It is important to notice that although plants primarily use potential to transport

nutrients they may also may also use electric signals to defend themselves or to catch

live prey like the Dionaea Muscipula Ellis (Venus Flytrap plant) This form of action

potential was first observed in 1873 in a plant which Burdon-Sanderson described to



the British Royal Society When an insect comes in contact and disturbs certain

sensory hairs on the central part of either lobe the lobes swiftly snap together to trap

the prey [45]

221 Bioelectric effects

Every living cell or organism is emitting but are also influenced by electrical

magnetic or electromagnetic fields The most basic evidence of this is the electrical

potential present on the membrane of any living cell [46]

Because higher frequencies and higher intensity fields increase the SAR and could

possible harm living matter SAR needs to be tightly monitored especially in

experimental phases When field intensities are limited one may compensate for the

loss by applying different types of electromagnetic waves or altering the duration of

such application Further to this one might also change the orientation of fields

applied or change the way in which such a field is connected to some living structure

222 Photosynthesis

Along with mineral nutrients plants also need organic sugars to grow The process of

converting carbon dioxide and water with sunlight (or artificial sources of light) into

chemical energy for the plant to be used is known as photosynthesis This is not a

very efficient process and for this reason many experiments were done to find ways to

harvest solar energy with solar panels and then applying the harvested energy directly

to plants [47] During photosynthesis with the aid of sunlight mainly sugars and

oxygen are manufactured from carbon dioxide and water This process is therefore

referred to as carbon fixation



Figure 213 Process of photosynthesis [47]

223 Bio-stimulation

The word lsquobiorsquo a combining form meaning lsquolifersquo occurs in loanwords from Greek for

example biography in this model it is used in the formation of compound words such

as bio-stimulation [48] Bio-stimulation in relation to plants thus involves the altering

of the environment conditions or needs to stimulate plants to enhance nutrient uptake

increase photosynthesis or change ion concentration in cells

224 Quad antennas

From linear frac12 waves or appropriate frac12 wave dipoles one may add together loops of

antenna into directive arrays As a loop array or known as a Quad antenna this

antenna is very effective but relative easy to design In a Quad antenna which consists

of a driven and reflection loop the loops are electronically equal to one wavelength in

circumference The Quad antenna was designed in 1941 and patented in 1947 by

Moore [49 50] to compete with the then popular Yagi antenna

According to Hall [51] the quad covers a wider area in the vertical because of a

broader H-plane pattern that is emitted Hall also mentions that for any parasitic

element used as a reflector the loop length should be 3 longer than that of the

resonance frequency element Alternatively if used as a director it should be 3

shorter than that of the resonance frequency element These considerations in design

will simplify tuning and efficiency of a Quad antenna From these the loop lengths

may be calculated as follows



306324Driving element ( )( )

313944Reflector( )

29718Director( )

m tolal loop lengthf Mhz

mf Mhz

mf Mhz

Final tuning of the antenna may be done with a tuning stub tuning capacitor or

tuning inductor

225 Transmission line radiation

To limit the losses from a transmission line one must ensure that the electromagnetic

field is zero This implies that the one line must be balanced by the inverse field from

the other line so that no radiation takes place Also important is that conductor

separation should be kept as small as possible otherwise the line will start to radiate

226 Transmission line characteristic impedance

The characteristic impedance of a transmission line consists of numbers of

capacitances and inductances along the entire length of the transmission line

Figure 214 Transmission line characteristics [52]

In a transmission line energy is transferred (absorbed) from one section to the next

Should the conductor diameter increase this would lead to a decrease in inductance

The same will happen to the capacitance as the capacitance will decrease if the line

spacing increases Should a line be terminated with a pure resistance that matches that

of the line then the line would be matched ie all energy transferred from section to

section will be fully dissipated in the final section (the load) [52]

If the above is not the case then some of the power will be reflected back to the input

and the more the mismatch the more the reflected coefficient



where p is the reflection coefficient

Er is the reflected voltage and

Ef is the forward voltage

227 Standing wave ratio

The line ratio of maximum versus minimum voltage is known as voltage standing

wave ratio (SWR) where SWR =E (max)E (min) [53] This is however not only

limited to the voltage but also applies to the current Should the reactance not be

included then

Figure 215 Voltage and current standing waves B and C are mismatched lines [53]

ErpEf

R ZoSWR or where R is lessZo R



228 Requirements for an electronic controller

Running a hydroponic system does not have to be time-consuming should one utilise

an electronic nutrient controller The basic requirements for such a controller (with

optional functions indicated in brackets) are provision for in-and outputs insulation of

inoutputs and battery backup in case of a power supply or mains failure When

frequent water failure is an issue then an emergency water backup system should also

be included In such a case water is supplied via a gravity feed system to the nutrient

reservoir system or directly to the plants via a separate watering line system This type

of backup is essential should plants be grown using nutrient film flow techniques

Regarding power failures a mains sensor device is used to switch on a 12 DC solenoid

type water valve that will then supply plain tap water to the plants preventing water

stress in the plants In analysing the controller the following inoutputs also need to be

provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing

GSM module (if controller is remotely controlled)

Outputs for

Heater(s)

Fans

Water pumpcontroller

Nutrient pump

Acid pump

Nutrient adjustment

Aerator

Growing lights (if required)

GSM unit (if controller is remotely controlled)



229 Conclusion

Designing a hydroponics system requires a solid knowledge about plants hydroponic

systems and hydroponic controllers This is especially true when conducting research

as for example a badly designed controller could affect the outcome of an experiment

Should one add the concept of plant stimulation then the researcher also needs to

understand plant metabolism and nutrient functioning In plant research there are no

shortcuts as plant growth and performance are connected to thousands of variables

Past research is also contradictive regarding electromagnetic radiation on plants and

its effect on plants

A solid knowledge of electronics electromagnetic waves and application media like

antennas and transmission lines is also required Apparatus used to convey signals to

plants makes use of very tiny signals and measuring these signals requires specialised

equipment like differential probes Then there is also the problem of interference

when using such tiny signals that one needs to be aware of and be able to take care of

PJJ van Zyl Chapter 3 Literature survey


Chapter 3 Literature Survey

31 Introduction

Well-documented research exists about the effect that light soil nutrient temperature

soil salinity moisture content and humidity have on the growth performance of crops

These research studies are covered in detail and expand from the physical plant down

to plant cell molecular level Research also indicates the positive and negative effects

that electromagnetic fields have on plants Little research about the effects of these

electromagnetic fields on plants in hydroponic systems especially enhancing crop

production exists

However what is evident from analysing research publications is that low intensity

electromagnetic fields have a greater influence than high intensity fields These lower

intensity fields are not only limited to manmade ones but also include static

magnetism and gravitation fields of the earth

An aspect of concern is the reason why the use of electricity to enhance plant growth

has not really caught on ie why is it not practised full scale on current crops but only

documented in research and experimental publications Surely there were plenty of

positive results applying electrical signals and voltages to enhance seed germination

boost plant growth and improve crop yield

As it is impossible to document all past and present research on the effect of

electromagnetic fields on plants only the major and applicable ones are briefly

outlined

32 Overview

This chapter is considering the following topics

Electrochemical potential around the plant root

Calcium as a plant growth regulator

Electricity in horticulture



Calcium homeostasis in plant cell nuclei

Weak microwaves to overcome salt stress

Plant responses to electrical stimuli

o The effects of radio frequency electromagnetic fields

o Oxidative stress regarding root growth

o Effect of frequency exposure to weeds

o Effects of pulsed frequencies on plant growth

Process of enhancing plant growth

o Electroculture in greenhouses

o Electro-charging of growth medium fluid

o Treating plants with high frequency sound waves

o Stimulating plant growth using a helical coil

o Sound waves for aiding in osmosis processes

o Electrical control of plant morphogenesis

o Eradication of weevils using high power frequency

o Digital agriculture

o Medicinal plants for alleviating poverty

o The concept of primary perception in plants

o The pyramid electrical generator

o Crop enhancement by air ions

o Moderate electro-thermal treatments

Plant signalling

o Microwave irradiation

Bioelectric signalling

o Non-random bioelectric signals in plant tissue

o Biological effects of weak electromagnetic fields

Plant growth algorithms

o Evaluation of experimental designs and computational methods

o A modern tool for plant growth analysis

o Plant stimulation algorithm of linear antenna arrays

o Plant framework for modelling plant growth

o Distribution network simulation algorithm

Plant growth statistical interferometry



o Dynamic range of statistical interferometry

Other uses of energy fields

o Curing diseases with energy fields

33 Electrochemical potential around the plant root

According to Takamura one should control the chemistry around the plant root if you

want to boost plant growth [54] In an experiment conducted he used a micro-

electrode to measure specific ion potential distribution near the plant root He

specifically mentions that neither ionic concentration nor time dependence of root

potential has been studied in relation to plant growth He also hypothesizes that it is

not only chemical concentration that affects plant growth but also the electrochemical

potential spreading present in ATP10 cycles He concludes that the electrochemistry

that exists in plants is a mechanism of plant survival

Figure 3-1 Experimental setup to measure potential distribution near the plant root [54]

In 1988 Ezaki et al reported [55] that according to Toko the current flow around the

roots of plants is related to plant growth Miwa and Kushihashi a few years later

reported about H+ ions in the growing section of the root [56] and how these affect

plant growth

10 The ATP-ADP is about the storage and use of energy in living things Energy is defined as the ability to do work There are two types of energy Potential Energy and Kinetic Energy (free energy) Available from httpwwwindepthinfocombiologyatp-adp-cycleshtml



In 1994 Mizuguchi et al set up a culturing bath to stimulate plant roots with DC and

square waves [57] In the same year Taeuchi et al found a large well of negative

voltage near the growth tip of roots [58] and in 2003 Bibikova and Gilroy mentioned

that one should keep in mind that there is also a relationship between the growth rate

of plants and the surface area of their roots [59]

34 Calcium as a plant growth regulator

Calcium concentrations in plants are quite high and proof of this and the fact that

calcium is a growth regulator is not hard to find [60 61 and 62] A review of the

origin of calcium as a second order cellular messenger is well explained by Hepler

[63] According to him the plant cell wall requires calcium in the order 10M to

10mM In the cell wall the Ca2+ is responsible for coupling acid like pectin debris and

in the cellular membrane lower levels of Ca2+ will make the cell membrane more

porous

The effect of this was recorded by Bennet-Clark and Tagawa and Sonner [64 65]

which clearly indicate that a lowering of positive calcium ions and specifically on the

membrane will intensify cell and tissue growth In this research study one of the aims

was to electrically reduce the Ca2+ concentration on the cell membrane By doing this

it is understood that by opening the cell more nutrients will move into the cell

enhancing plant growth

35 Electricity in horticulture

Electricity has many applications where one of them is to enhance the growing

process of plants This may include soil heating to enhance germination of seeds air

heating to allow plants to be grown in winter high intensity illumination to enhance

photosynthesis or soil sterilization [66] A main concern was always the interaction

and effects on electrical method plant and horticultural worker Brown et al describe

in lsquoThe application of electricity to horticulturersquo a practical method of using wires

carrying a low voltage to heat soil He also describes different arrangements of these

wire layouts



36 Calcium homeostasis in plant cell nuclei

Mazars et al [67] describe plant stimuli as responses on which plants react to ensure

survival These signals to which they respond are known as calcium signalling

pathways To start this process a stimulus received will eventually result in a specific

outcome for the plant known as ldquocell signallingrdquo Bush Sanders et al Hetherington

and Hepler [68 69 70 and 71] all agree that calcium has a high affinity for negative

ions As rising calcium levels are needed to start specific cell responses free calcium

needs to be regulated inside the plant cell otherwise the plant cell will become stocked

with solid like calcium phosphate

37 Weak Microwaves to overcome salt stress in seedlings

Salinity of soils is increasing worldwide [72] According to Flowers this may affect

up to 50 of all irrigated land Salinity affects both crop yield and growth (Chen et

al) This is because salt causes oxidative stress in plants [73] Cheng pre-treated

wheat seeds with low levels of microwave energy to increase the seedlingsrsquo tolerance

of salt He reported increases in both root and shoot lengths with 10 to 15 second

treatments regarded as the optimum

38 Plant responses to electrical stimuli

In applying stimuli to plants one surely can expect a response as plants are living

things As there are manmade stimuli as well as natural cosmic stimuli one needs to

consider both when analysing plant responses However to understand some of the

manmade stimuli one needs to investigate some of the work done on these topics

Vian et al [74] makes an interesting statement ldquoAs an example 1 cm3 of animal

tissue has a surface area of 6 cm2 while for the same volume a 05 mm thick leaf

would have a 41 cm2 surface area ie almost seven times as muchrdquo This makes the

use of plants for electromagnetic studies extraordinary because of the mentioned

advantage and secondly there is no ethics involved in experimenting with plants



Figure 32 Plants versus animals ndash body architectures [74]

381 The effects of radio frequency electromagnetic fields

It is believed that the average person is familiar with the fact that radio frequencies

have an effect on their health What is referred to for example are the dangers of

high levels as well as long duration exposure to for example cell phone

transmissions These effects include areas from cell proliferation to enzyme changes

[75-79] Relating to plant studies Tkalec et al investigated the effects of

radiofrequency fields (400 and 900MHz) on seed germination and initial rooting [80]

Seeds were exposed for a period of 2 or 4 hours at intensities of 1023 23 41 and

120Vm-1 They found that that RF testing did not enhance seed germination nor did it

prevent initial root growth However they did notice some defects in root tips under

certain situations

382 Oxidative stress limiting root growth due to mobile phone radiation

When Sharma et al studied the effect of mobile phone radiation (855W cm-2

900MHz) on mung beans they found that a very noticeable reduction in germination

occurred [81] However of major concern was the oxidation stress as well as the

damage to cells that occurred during this experiment In contrast Kursevich et al



Rochalska et al and Atak et al (2007) found positive results relating to induced stress

when seeds were exposed to low frequency magnetic fields of 16 Hz [82 83 84]

383 Effect of radiofrequency exposure on duckweed

The radio frequency band stretches from 30 kHz to 300GHz This electrical energy is

used to carry information and data all over the world

Frequency Band

10 kHz to 30 kHz Very Low Frequency (VLF)

30 kHz to 300 kHz Low Frequency (LF)

300 kHz to 3 MHz Medium Frequency (MF)

3 MHz to 30 MHz High Frequency (HF)

30 MHz to 144 MHz 144 MHz to 174 MHz 174 MHz to 3286 MHz

Very High Frequency (VHF)

3286 MHz to 450 MHz 450 MHz to 470 MHz 470 MHz to 806 MHz 806 MHz to 960 MHz 960 MHz to 23 GHz 23 GHz to 29 GHz

Ultra High Frequency (UHF)

29 GHz to 30 GHz Super High Frequency (SHF)

30 GHz and above Extremely High Frequency (EHF)

Table 31 Radio frequency spectrum [85]

Tkalec et al [86] showed that radio frequency causes stress but noted that the relative

parameters of time type of modulation and the strength of the field are very important

as they determine the amount of stress They contribute most of the damage to

increase in temperature that was caused by absorption of energy by the biological

tissue of the plant

As can be observed from this and similar studies one needs to apply special caution to

energy levels when experimenting with biological tissue The main problem in these

cases being the generation of heat which will literally lsquocookrsquo the tissue



384 Effects of pulsed frequencies on plant growth

Selga et al showed that reduced germination of seeds occurs at high levels of

electromagnetic exposure (27 to 55 versus 100 when low exposure was applied)

[87] This corresponds to Balodis et alrsquos finding that electromagnetic fields decreases

tree year ring width [88]

39 Processes for enhancing plant growth

In 1904 Lemstroumlm noted that plants are stimulated when a charge was placed above

seedlings These were based on experiments done in the 1800s Because Lemstroumlm

was a professor at Helsinki he was the ideal person to capture the information in book

form [89] From 1923 to 1924 controlled studies were undertaken by Blackman which

proved maximum seedling growth stimulation at 50x10-12 or 50pA He also showed

that growth is not only active during the application but also for hours afterwards [90

91]

Although numerous positive results were achieved there were also failures Collins et

al could not manage to obtain positive results in the 1920s This was confirmed by

Briggs and his co-personnel in greenhouse as well as field trials [92 93 and 94]

In the 60s experiments highlighted again when Andriese experimented with positive

and negative ions When Fuller indicated that it was the indole acetic acid levels that

were changed by the electric fields Krueger et al did not agree [95 96 and 97] As

research on grain continued it was however found that electric fields do have an effect

on the uptake of calcium and magnesium [98 99] This continued in the 70s where

the use of direct current (DC) was investigated Positive results of linear growth were

reported by a number of people [100]

391 Electroculture in hydroponics greenhouses

A journal paper by Yamaguchi was the initiation of this kind of research During their

research Yamaguchi et al investigated the effect of high voltage ionisation on

seedlings [101] A standard greenhouse of approximate 40x8x3m was set up

according to standard hydroponics systems and equipped with a negative ion

generator Flux density was kept at levels 82 x 103 to 69 x 103 per cm2 measured at a



height of 20cm above the plants Application of stimulation was initially 24 hours a

day but later reduced to daytime only With an experimental and control group results

after 18 days indicated that the experimental group outperformed the control group by

50 to 75 in plant height What is of note is that in the initial phase after transplanting

there was no significant difference between plants in the control and experimental

sections

392 Electro-charging of growth medium fluid

US Patent 6055768 of May-2 2000 presents an invention that can electrically charge

the fluid in for example a hydroponics system An isolated antenna is used inside a

concealed cylinder to effectively apply radionic or loptic signals to the water by

means of frequency energy [102] This energised water was then used to water

seedlings The main advantage of this patent at the time was that the energy contained

in the medium was not lost when the water was removed from the energising system

and applied to the plants This design overcomes a major shortcoming of previous

experiments like Us Patents 5464456 5077934 or 4680889 [103]

Figure 33 Apparatus for charging fluids (patent US 6055768) [102]

393 Treating plants with high frequency sound waves

Carlson in 1987 found very promising results over a growth period of two years when

plants were treated with sound waves in the order of 47 to 53 kHz and at levels of

120dB Plants responses were positive especially when the frequency was varied

within the band range Application duration is preferably from 30 seconds to 20

minutes once a month [104]



394 Stimulating plant growth using a helical coil

One does not need to use expensive equipment and apparatus to see the benefits of

electrical plant stimulation Zucker [105] used a helical coil which he placed around

the stem of a living plant Low currents at 60 Hz were circulated in the coils and a

25 increase in height as well as a more dense plant compared to the non-stimulated

plants was observed

395 Sound waves to open cell walls aiding in the osmoses process

A process for treating plants with sound waves is described by Carlson [106] In this

1987 experiment the process of osmosis for promoting growth was analysed Sound at

120dB levels and at frequencies ranging from 47 kHz to 53 kHz were used With

duration from 30 seconds to 20 minutes some plants grew over 300 meters during the

experiment that lasted two years

396 Electrical control of plant morphogenesis

A common problem that tickled early researchers for many years was how to

optimally increase the rate and tempo of plant renewal What was known was that low

intensity signals but especially pulsed signals had positive effects Also known was

that plant roots are an excellent starting point to study due to the electric patterns

created in and around them [107 108 and 109]

This knowledge empowered them to apply electricity to single root calluses using

stainless steel probes and research was taken to a fairly advanced level by [110 111

112 and 113] In these experiments a probe was inserted in the nutrient reservoir

while another one was directly inserted into the callus Increases up to 70 in callus

growth were obtained with the positive electrode connected to the nutrient medium



Figure 34 Experimental designs for applying low electric fields [112]

Cogalniceanu stated that low intensity low frequency long duration electric fields

have huge potential for the use of biotechnological applications in especially

enhancing the rate and speed at which plant reproduction and growth occur [114]

ldquoWhatever type and level of external electric field is used in stimulating experiments

interference between exogenous and endogenous electric fields occurs with

consequences on the simultaneous or subsequent developmental processesrdquo

(Cogalniceanu 2006 p 410)

Important to note is that one does not require sophisticated signal sources A simple

50 Hz 01 to 50A sinusoidal wave will also increase shoot regeneration by 300

[115]

397 Eradication of red palm weevils using high power frequencies

A high frequency source can be successfully used to kill palm weevils and stem

borers This is type of radiation is in contrast to low power radiation used to promote

plant growth as high energy levels produces thermal energy and thereby killing the

weevils and stem borers Caution in this case is of uttermost importance and

precautions like stopping watering a few days before application keeping

temperatures below 60 degrees are just some of them [116]



Figure 35 Electronic block diagram of a high output electromagnetic generation system [116]

In these kinds of setup frequencies in the universal scientific industrial and medicine

range are used and comprise 1356 2712 and 4068 MHz of which the latter is

according to Yousef the most effective

398 Digital agriculture

The search for alternative fuels has resulted in many new patents and procedures

Although not new to the field the ldquoCrop Growth Simulation Modelrdquo [117] from the

National Centre for Supercomputing Applications (NCSA) is something to take note

of In this model a number of researcher variable parameters can be set up before

running the model Outputs in terms of visual graphs or tables are easy for researchers

or students to use to compile documents or reports for their research

399 Medical plants for alleviating poverty

In this 2006 released paper a method is described in which meditational plants are

cultivated and used as a tool to alleviate poverty in the Amatola11 region in South

Africa The paper also shows how such cultivation could be used to protect

indigenous and scarce plant species [118] Wiersum et al describes how a project like

11 ldquoThe Amatolas stretch into the hinterland just north of Grahamstown and west of Stutterheim their slopes covered in dense natural forests of white stinkwoods yellowwoods Cape chestnuts and a myriad other indigenous treesrdquo[ Amatola Eastern Cape [online] (1999-2010) [Accessed 16 May 2010] Available from httpwwwsa-venuescomattractionsecamatola-regionhtm]



this could also be used to change peoplersquos outlook to preserve biodiversity rather than

to destroy One can understand this when realising that more than 700 000 tonnes of

plant material is collected annually by traditional African herbalists or their relatives

[119]

3910 The concept of primary perception and the evidence thereof in plants

Backster who can be described as a self-trained expert in bio-communication [120]

conducted several experiments attaching electrodes to plant leaves to study the

relationship between humans (or animal) and plants relating to methods of

communication As described in the International Journal of Parapsychology

experimental results indicated the existence of primary perception even over distance

From this ldquothe author hypothesizes that this perception facility may be part of a

primary sensory system capable of functioning at cell levelrdquo [121]

3911 Pyramid Electrical Generator

A method of harvesting energy is described in this invention In this case energy is

drawn or tapped from a DC electrostatic field This phenomenon was observed by

Feynman [122] who found that a 400 000V potential exists in the earthrsquos voltage

field According to Grandics the typical layout of such a harvesting unit will consist

of the following [123]

A pyramid type of capacitor

A coil on top of the capacitor

A coil attached to a bridge rectifier

A battery or capacitor storage device connected to the rectifier

In this case DC electrostatic energy is responsible for generating an alternate current

in the coil which is then rectified and stored Capacitor shape in this invention is

important as this determines the amount of current captured The following illustrates

the capturing device



Figure 36 Pyramid converter of electrostatic to DC power [122]

As described by Grandics a typical production plant would have a floor span (base) of

about 40 000m2 with measurements 200m x 200m and 150m high (capacitor cone)

3912 Crop enhancement by air ions

Pohl et al experimented with air ions by applying it to commercial produced

blossoming plants During experiments with a uni-polar negative ion generator [124]

they recorded a blossom increase between 4 and 7 times per plant On top of these

results there was an increase in plant height (and stem length) and blossoming was

speeded up by about 20 days



Figure 37 Effect of negative air ions on blossoming of Persian Violets [124]

3913 Moderate Electro-thermal treatments (MET)

Although it is not the intention of the current research to employ MET on plants it

surely can be used to solve plant related problems such as sterilization Should MET

of plants be an option it will have to be at extreme low levels as MET will result in an

increased permeability of the cell wall which would change the ratio at which

nutrients enter the cell The use of MET however has other advantages such as drying

of fruitvegetables extraction of plant constituents and enhancingcontrolling

fermentation [125]

310 Plant Signalling

3101 Microwave irradiation

Non-ionizing radiations a factor not normally considered by researchers in the past

are currently becoming a factor of major concern if one studies current research being



carried out in relation to RF and especially cell phone radiation Vian et al noticed

this ever-increasing high frequency radiation and conducted an experiment to

investigate the effects of non-ionisation radiation on plants Because plants are very

sensitive to environmental signals they are excellent specimens to conduct research

on There is far less emotional concern about this research [126 127 and 128]

Vian et al set up an experiment using Lycopersicon esculentum (tomato) plants

where the plants were concealed in a Faraday cage equipped with a 900MHz signal

synthesizer a log periodic antenna and a rotating signal distributor as can be seen in

the following layout [129]

Figure 38 Mode stirring reverberation chamber

(A) A large room with metal walls (dark lines) to exclude external EMF an antenna

(lower left) to emit tuneable EMF a rotary stirrer to make the EMF homogeneous

(right side) and a plant culture chamber placed within the working volume (grey

area) (B) Schematic representation of EMF types

(B) Also shown are a non-polarized (isotropic) and homogeneous field where the field

components align in all possible directions and the field has the same amplitude at

all points and b a polarized nonhomogeneous field where the field components

align in a single direction while the amplitude varies (heterogeneity) [129]



From this experiment at an application rate of 5Vm and an effective 39Vm inside

the growth chamber it was concluded that a 3 to 5 times stress component was

experienced by the plants

Figure 39 Accumulation of LebZIP1 transcripts after EMF-stimulation in the non-

shielded culture chamber Plant shows either an immediate response (white bars) or a 5

min delayed response (black bars) Plants stimulated in the shielded culture chamber

(grey bars) Each value is expressed relative to the non-exposed control (C) and

normalized to the actin mRNA and is the average of at least 3 independent repetitions plusmn

the standard error [129]

311 Bioelectric Signalling

3111 Non-random bioelectric signals in plant tissue

Just as important as plants are so important are the instruments that the researcher

chooses for an experiment These instruments are required as the existence of trans-

membrane potentials is well-known [130 131]

High impedance voltmeters are of course a necessity for accuracy For obtaining the

trans-membrane potential one may use the Nernst Equation



Where Eio is the trans-membrane voltage R the gas constant T as absolute temperature z the change

in ions F is Faradayrsquos constant and Ci Co are the cell outerinner ion concentrations respectively

[132]

Karlsson made his observations with low bias current amplifiers and found that well-

defined bursts are given off by the plant These pulsating bursts are in the order of 05

to 30 minutes at a rate of 05 to 200 pulses per minute and at a peak to peak amplitude

of 10 to 200μV [133]

Figure 310 Karlsson simplified schematic setup [133]

In this setup the amplifier is used as a differential amplifier to eliminate the

amplification of common mode signals Electrodes should not be subject to

electrolysis Gold or stainless steel can act as suitable electrodes

3112 Biological effects of weak electromagnetic fields

According to Goldsworthy electromagnetic fields may be a topic that is not fully

disclosed by the major contributors of these fields According to him [134] the effects

of these fields are

lnRT CoEiozF Ci



EM fields dislodge calcium ions from their membranes causing cells to

become porous

Fertility of sperm cells is reduced because DNAase (enzymes

destructive to DNA) is leaked from damaged cells

As calcium enters the cell due to EM damage it causes an increase in

not only growth but also unwanted tumours

Should calcium enter high level cells like brain cells neuron pulses are

generated that actually numb these cells making them less responsive

to low level stimulus

Pulsed and especially weak type fields are the most destructive

312 Plant Growth Algorithms

3121 Evaluation of experimental design and computational methods

To be able to measure the growth performance of plants experimentally one may

make use of a well-defined and proven growth algorithm

In the nineteen twenties Blackman developed a method for determining plant growth

rate (classical approach) known as lsquorelative growth ratersquo (RGR) [135 136] In this

approach the difference in plant mass between two harvests are divided by time that

elapsed between the two harvests This gives an indication of how active the plants

were growing This approach is similar to lsquonet assimilation ratersquo (NAR) where an

increment in leaf weight over time is measured as reported by Evans [137]

With the arrival of computers new algorithms were developed But this so called

lsquopolynomial approachrsquo also experiences shortcomings [138 139 and 140] Wickens et

al combines the classical approach with a bent to create the lsquocombined approachrsquo

[141]

Poorter et al evaluated various experimental designs and also investigated the

accuracy of lsquorelative growth ratesrsquo They also evaluated three computational methods

to measure dry weight yield [142] The following table summarises their findings



Table 32 List of main conclusions [142]

3122 A modern tool for plant growth analysis

From the authors Hunt et al a paper that describes an integrated plant growth

approach appeared in Annals of Botany Volume 90 in 2002 In this approach the

calculations and analysis were based on a mathematical model proposed by Venus et

al [143]

The free software tool developed by Hunt et al runs on Microsoftcopy Excel 2000 or

higher Variables include Inputs Outputs and Units Limitations apply as only two

harvests can be included in the input There needs to be at least a minimum of 2 plants

per collection a minimum of 5 plants for both collections Calculations are based on

the classical approach and are specifically developed for people using this approach

[144] The relation by whom the parameters are defined in this paper is as follows

Where RGR is lsquorelative growth ratersquo ULR is lsquounit leaf ratersquo SLA is lsquospecific leaf arearsquo and LWF is the

lsquoleaf weight fractionrsquo

1 1( )( ) ( )( ) WA

A W

LLdW dW x xW dt L dt L W

RGR ULR SLA LWF



Figure 311 An example of the tool as developed by Hunt et al Adapted from [144]

3123 Plant simulation algorithm of linear antenna arrays

Different antenna pattern nulling techniques are in existence The reason for this is

electromagnetic pollution To combat such pollution one would project nulls at a

specific and strategic direction to a point in the far field [145 146 and 147]

Analysing nulling techniques of the different patterns one may summarise them as

Control of amplitude only [148 149] In this case the amplitude is controlled

by tuning attenuators

Control of the phase only [150 151] Phase control is popular because the

phase of the signals only is changed to effectively radiate more power in a

certain direction

Control of the position only [152] Mechanical means are used in this case to

adjust the arrays to emit in a specific direction

Dataset Date

t1 t2

Root Non-leaf Leaf week 1 week 2

1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372

Indirect Rbar 1780775

Indirect of direct 1126

Input Output

Weights

Mean Relative Growth Rate

Time Leaf Area

Tool for classical plant growth analysis v11 Help and FAQs

Root-Shoot Allometry

Check on assumptions

Experiment 24 van Zyl 1-Apr-11

Mean Unit Leaf Rate

Mean Leaf Area Ratio

Mean Leaf Weight Fraction

Mean Specific Leaf Area

week mmsup2g week g mmsup2



According to Gunet et al the lsquophase only null synthesisingrsquo is less complex because

no extra means of controlling is required However problems with this method do

exist In the paper lsquoA plant growth simulation algorithm for Pattern nulling of linear

antenna arrays by amplitude controlrsquo the authors describe a different method known

as the Alternative Plant Growth Stimulation Algorithm (PGSA) PGSA will stimulate

a plant node from which a new branch will grow However this new growth will only

be from a node with the best cost function [153]

where F0 () is the PGSA pattern and and Fd () the wanted pattern W() is the null depth

According to PGSA certain plant growth laws exist and the nulling can be achieved

by controlling the amplitude of the arrays only With PGSA the amplitudes are

controlled specifically to give a main beam with closed spaced side lobes and broad

nulls into the noise source

3124 Plug-in framework for modeling plant growth

A software tool is described by Shenglian et al in a conference paper delivered in

2010 One of the major things that led to the development of this tool is the concerns

of interoperability and recyclability

In this plug-in framework software is used to present a visible and synergistic method

to imitate plant growth with a main aim to integrate the models from various past

developed research models [154]

Figure 312 A plug-in based system architecture [154]

0

0

90

90

( ) ( ) ( )o dg W F F



3125 Distribution network simulation algorithm

The way in which a plant grows can be defined as the growth kinetics minus the

growth restraint A value higher than zero would thus indicate growth while a value

less than zero would mean death [155]

Zhe et al developed a plant growth algorithm that works on a distribution network

method In this model the algorithm continuously changes the rate of plant growth to

minimise the lsquolook for timersquo This results in a more accurate answer and in less time

[156]

Figure 313 Flowchart of improved growth stimulation algorithm [156]



313 Plant Growth Statistical Interferometry

3131 Dynamic range of statistical interferometry to sample plant growth

A study by Kadono et al used an optical system in 2007 to do extremely accurate

measurements of short-term plant growth [157] A shortcoming however was the less

than one wavelength displacement that limited the dynamic measurement range

Figure 314 Optical plant growth measurements system [158]

In 2009 Kadono proposed a new optical technique known as ldquostatistical

interferometryrdquo to overcome the limitations of the previous algorithm This algorithm

is excellent for sampling plant growth in the ultra-short term aimed at taking

environmental concerns into consideration Short-term measurements in this case

relate to measurements as short as a second (mmsec) [158] The main growth

parameters considered were ozone and light using Light Emitting Diodes (LED)



Figure 315 Growth behaviour under LED illumination [158]

314 Other uses for energy fields

3141 Energy fields for curing diseases

As for plants electrical stimulation applied to human beings could also be beneficial

Throughout the years mankind has been constantly plagued by bacteria viruses and

diseases Some diseases like bird flu and AIDS are so detrimental that if not

controlled could pose some serious risk to human beings Thomas Valone delivered a

good summary at a healing congress in 2003 In his report he highlights multiple bio-

electromagnetics (BEMs) innovations throughout the years [159]

Some of the greatest scientists were experimenting with energy fields To name them

all is impossible but some of the greatest contributors were Nikola Tesla Alexander

Gurvich Georges Lakhovsky Royal Raymond Rife Antoine Priore Robert Becker

and Abraham Liboff

Various experiments by Nickola Tesla in the 1800 have showed positive results using

high frequencies In 1898 Tesla presented a paper at the eighth annual meeting of the

American Electro-Therapeutic Association The title was lsquoHigh Frequency Oscillators

for Electro-Therapeutic and Other Purposesrsquo [160] One of the observations he made

using a 3 feet diameter coil was the fact that the application did not cause pain to the

human body and was harmless to body tissue His motto for these experiments was



the fact that the human body tissue can be represented by tiny capacitors The body

tissue also exhibits excellent dielectric properties due to the high trans-membrane

potential cellular that exists in cellular tissue [161]

315 Conclusion

Today frequencies light pulses and laser are frequently used in medical therapeutic

and cosmetic centres as an alternative to for example operations However using

electricity to enhance plant growth dwindled because researchers are more occupied

in harvesting carbon dioxide as there is currently lots of money available for carbon

credits 12[162]

As customers demand more high quality nutrient stacked fruit and vegetables it may

be worthwhile for researchers to spend more time on this topic Recent research by

Dannehl et al (2011) on the issue of using electro-culture to treat plants and fruits

during post harvesting proved to be very successful In an experiment done in 2010

they showed that the antioxidant activity and lycopene content could be increased by

applying a low ampere DC signal to the harvested tomatoes [163]

12 A carbon credit is a generic term for any tradable certificate or permit representing the right to emit one tonne of carbon or carbon dioxide equivalent (tCO2e)

PJJ van Zyl Chapter 4 Experimental design


Chapter 4 Experimental Design

41 Introduction

Plants have to cope with an ever-changing environment due to more and more

pollution in the air and soil Soils are becoming nutrient depleted and acid-loaded due

to poor farming practices and limited crop rotation Water resources are limited and

polluted The carbon content of soils is very low and on top of this a plant has to cope

with heat damage as well as heat stress due to global warming [164165 166 167

168 and 169]

To survive plants have adapted through the ages with respect to growth shape and

survival techniques But it is not only the plants that have changed due to changing

environments but also due to human involvement Good examples are genetically

modified seed to improve cultivars or crop yield hybrid seeds that are cross-

pollinated and that are only usable once to seed

Then there are improved farming practices like grafting where a plant with an

excellent rooting system can be used to grow a hybrid cultivar with not so good a

rooting system by grafting it onto the rootstock Another is hydroponic farming where

the producer can control temperature humidity optimum nutrient levels and prevent

the plant from experiencing any water stress

A fourth element is the deliberate attempt to change the way in which plants grow and

produce This element is by intentional stimulation of the plant where electrical

signals (or other) are used to alter the growth and production in a favourable manner

Although nutrient stimulation is also an option to accomplish this it is not the focus

of this thesis

This research study shows practical ways in which to increase the growth and

maturity rate to grow larger fruit and to increase plant mass It is generally

understood that we require scientific methods to sustain growth and stability in the

ways and methods we use to produce food Labour issues in South Africa are



becoming a major obstacle and this might just be the final motivator for the producer

to move rapidly towards using technology in all farming facets to help produce more

and more efficiently

With relation to plants there are three main applications of electricity to control the

growth of a plant

It may be applied to control the growing process for example heated tunnels

heated soils or additional lighting

A second application is for auxiliary purposes like irrigation soil sterilization

and ventilation

The third application is to use electricity to enhance the intercellular processes

to increase nutrient uptake Bibikova et al (2003) [170] suggest controlling

the environment around the roots may be a key factor for optimum plant

growth

When applying technology in the form of plant stimulation it is important to keep in

mind a few important factors

The setup and application should not add additional stress to the producer and

hisher environment

It is safe to work with as some producers and their workers are only emerging

farmersfarm workers who are not even familiar with electricity and the safety

aspects of it

It benefits the economy in relation to installation cost maintenance cost and

ease and energy consumption

It must be reliable and work satisfactorily

The process is practically implementable quick to install and to remove

The system is robust and little affected by chemicals and humidity

42 Overview

This chapter describes the methods and tools to be used to achieve plant stimulation

The chapter is divided into the following sections



Inside the plant o This section explains what cell potential is as well as the significance

of it It is important to know about cell potential as it is this delicate variable that is going to be influenced during electrical stimulation

Plant communication o Plants make use of stimuli which are known as messengers The

function of these messengers is explained Plant growth factors

o In this section typical plant parameters like light and humidity requirements are discussed and analysed

Plant response signals o These are the type of signals as well as the magnitude that one may

expect during the experimental phase Nutrient composition

o A detailed analysis was done on fertiliser ingredients and composition This is very important should someone else need to simulate the experiments contained in this thesis Specific experimental formulations are also given

pH Control o Before one can measure and control nutrient levels the pH must first be

optimised This is what this section is about Structure design

o A structure supporting hydroponic plants needs to be able to carry many kilograms of growing medium as well as giving adequate support to the plants

Methods of stimulation application o Various methods can be used to apply the electrical stimulus This

section gives a brief graphical overview Constraints

o General constraints which are not experiment specific are considered Measurements

o Overview of non-specific measurements and cautions Frequency effects

o This section discusses important information when working with frequencies

Types of plants to be used o To limit the experiment only certain plants and specific cultivars would

be experimented with Growth dynamics

o This section explains the way that plants respond to EMF and also what happens inside the plant when EMF is applied

Experiments o Evaluation of appropriate points of application of stimuli



o The effect of DC stimuli on plants in a hydroponic system o The effect of 16Hz square waves on plants in a hydroponic system o The effect of radio frequency through leaky transmission lines on

plants in a hydroponic system Conclusion

43 Inside the Plant

To understand the concept of electronic stimulation one needs to study the plant cell

and especially the membrane that surrounds each cell It is this membrane that allows

nutrients to move into the cell mainly by diffusion [171]

For proper function this cell membrane has a potential across it This implies that

there is a potential difference between the exterior and interior of the cell which is

mainly due to a concentration of ions Along with the cell membrane with its highly

negative voltage each cell now acts like a tiny battery with millions of them together

in a single plant Luumlttge et al has found voltages in the order of -350mV in freshwater

algae [172 173]

The voltage of a cell is also known when the plant is in the standby stage ie with no

stimulation or stress the lsquostandby or restingrsquo potential exists This voltage varies from

plant to plant for example Anholt et al (2009) [173] report -70mV Luumlttge et al

(2009) [172] report as high as -400mV and Blinks (1955) measured -10 to -200mV

[174] According to Blinks (1949) the internal cell voltage is negative with respect to

the external cell ion potential [175]

How does cell membrane voltage relate to this research Kerz [176] uses a patent to

describe an electronic stimulation effect where a square wave generator is used to

stimulate the active membrane transport systems in plants In this patent the nutrient

uptake of the cells is influenced favourably to increase growth rate and to extend the

shelf-life of harvested flowers

44 Plant Communication

To understand plant growth one needs to know how a plant operates One of the

factors that one needs to consider is the communication within itself as well as with

the environment within which it is growing Plants make use of stimuli in the form of



messengers to control internal growth operations as well as for protection and

survival These messengers each have specific names for example the hydraulic signal

which is a messenger in wound-induced plants [177]

In Kholodova et al [178] the authors describe that when a plant experiences drought

the root sensors will generate a stress signal which will change cell metabolism in the

upper parts of the plant to put defensive mechanisms in place They describe this drop

in hydraulic pressure to be a messenger signal for the plant This then generates a

primary water deficit signal which occurs to the plant as an excessive salinity or no

water message Because of this the plant can now respond and protect itself by closing

some stomata

František (2009) refers to plants as truly intelligent dynamic highly sensitive

organisms that even like to be territorial They are able to find and survive on few

resources They can control and eliminate environmental threads and show good

behaviour to the environment in which they are present [179]

45 Plant Growth Factors

451 Light factor

Light is important because without light no photosynthesis can take place With too

little light growth would be hindered and the experimental results may not be a true

reflection of growth obtainable As the research location in South Africa lies at about

260 south the plants received more than 12 hours of light a day This is considered as

sufficient in relation to other plant stimulation models done in the past Artificial

lights were not considered as an option



Figure 41 Sunrise and sunset times for 2630S280E [180]

452 Temperature and Humidity

Temperature is a signal used by plants to awaken after winter and induce flowering It

is also sometimes used along with day length by horticulturists to influence the

flowering time of plants This is helpful as one can ensure flowers and fruit at

different times of a season Too high temperatures are also not good as energy that

was produced by photosynthesis will be lost Low temperatures required for bud

breaking are not considered in this experiment as active growing plant seedlings will

be used [181 182]

It was proven by research [183 184] that atmospheric levels of humidity do have an

effect on plant growth Plants tend to withhold their growth in times of very low

humidity It is thus necessary during experimentation to keep record of extreme

temperature and humidity conditions as these may have an effect on the experimental

results The effect of different humidity levels are well-documented by Swalls and

OrsquoLeary [185]



Table 1 Fresh weight (gplant) of plants grown under three humidity levels

Relative Leaf Stems amp Shoots Roots Total Shootroot

humidity blades petioles plant ratio

35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42

Table 2 Dry weight (gplant) of plants grown under three humidity levels


humidity blades petiolesrsquo plant ratio

35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66

Table 41 Effect of humidity levels on the growth of tomato plants [185] Climate conditions for Johannesburg (SA) are moderate as can be seen in Figure 42

The average temperature in Johannesburg South Africa is 162 degC (61 degF)

The average temperature range is 10 degC

The highest monthly average maximum temperature is 26 degC (79 degF) in

January and December

The lowest monthly average minimum temperature is 4 degC (39 degF) in June and

July

Johannesburgs climate receives an average of 849 mm (334 in) of rainfall per

year or 71 mm (28 in) per month

On average there are 96 days per year with more than 01 mm (0004 in) of

rainfall (precipitation) or 8 days with a quantity of rain sleet snow etc per

month

The driest weather is in June when an average of 7 mm (03 in) of rainfall

(precipitation) occurs during 1 day

The wettest weather is in January when an average of 150 mm (59 in) of

rainfall (precipitation) occurs across 15 days

The average annual relative humidity is 592 and average monthly relative

humidity ranges from 47 in August September to 71 in February

Average sunlight hours in Johannesburg range between 74 hours per day in

March and 97 hours per day in August



There is an average of 3182 hours of sunlight per year with an average of 87

hours of sunlight per day

There is an average of 8 days per year with frost in Johannesburg and in July

there is an average of 3 days with frost

Figure 42 Climate and temperature in Johannesburg SA [186]

46 Plant Response Signals

461 Awareness of responses expected

One needs to remember that due to cellular potential any plant seems to work like an

ordinary electronic device but is still remains a live object with an awareness of its

surroundings It is thus likely that during experimentation the equipment and

apparatus used may provide electrical mechanical or chemical response which may

interfere or alter results expected from experimental stimuli

Electrical signals from plants have shown through research to be less complex than

those in humans



This can be seen with the multiple inputs required when an ECG machine is used to

record cardio responses from a human or animalrsquos heart Karlsson 1971 [187] wrote

that in all physical instances where measurements are to be taken there will always be

two signals present namely

o The wanted biological signal and

o The unwanted interference signal

He also mentioned that the unwanted is mainly due to electromagneticmagnetic

induction It makes thus commonsense to employ differential amplifiers when

measuring these signals These amplifiers have high levels of common mode

rejection ratio (CMRR)13 to get rid of interference The second option is to use power

supplies with high power supply rejection ratios

462 Levels of responses expected

When capturing responses from an experiment the data capturer needs to be familiar

with the magnitudelevel of responses to be expected so as to select sensitive enough

equipment These responses of cause will be typically in the pico (1x10-9) to mili

(1x10-3) range These ranges apply to voltages currents and nutrient concentrations

[188] Appropriate sensitive enough small signal equipment needs to be used

47 Nutrient and Water Composition

471 Individual nutrient data

Nutrients for use in hydroponic systems are quite complex because different

chemicals cannot simply be mixed together Some elements therefore need to be

chelated and others simply kept apart in their concentrated state The nutrients that

were used in these experiments were purchased as a tri-pack chemical An acid as a

fourth element to control and correct pH imbalances in the nutrient water was also

used Nutrient specification datasheets are available from Ocean Agriculture [189]

13 Common Mode Rejection Ratio is the ability of an amplifier to only amplify the differential (real or true) signal and not any common signals like noise and interference



Nutrient Data Horticultural Calcium Nitrate

195 gkg Ca 155 gkg N Fertilizer Group 1 Reg No K 5710 Act 361947 Source HORTICHEM DIVISION of OCEAN AGRICULTURE Ltd [189]

Hydrogrow

Water Soluble Hydroponic Fertilizer Mix N 65 gkg P 45 gkg K 240 gkg Mg 30 gkg S 60 gkg

Fe 1680 mgkg14 Mn 400 mgkg B 500 mgkg Zn 200 mgkg Cu 30 mgkg Mo 50 mgkg Fertilizer Group 1 Reg No K3945 Act 361947 Source HORTICHEM DIVISION of OCEAN AGRICULTURE (Pty) Ltd

Hydrogrow potassium sulphate

Water Soluble Potassium Sulphate 420 gkg K 180 gkg S Fertilizer Group 1 Reg No K5405 Act No 36 of 1947 Approximate Formula K2SO4 Approximate Molecular Weight 174 Potassium oxide 5025 Typical (50 Min) Potassium 417 Typical (415 Min) Chloride mm 08 Typical (13 Max) Sodium mm 08 Typical (12 Max) Calcium mm 09 Typical (15 Max) Sulphate 545Typical (335 Min) Sulphur 181 Typical (112 Min) Source HORTICHEM DIVISION of OCEAN AGRICULTURE Ltd [189]

Nitric acid (58)

HNO3 Weight 6302 gmol

Nitrogen mm 124 (min) Density 1345gcm3 200C Fertilizer Group 2

Reg No K5227 Act 361947 Source HORTICHEM DIVISION of OCEAN AGRICULTURE Ltd [189]

14 ChelatedChelating A chemical compound in the form of a heterocyclic ring containing a metal ion attached by coordinate bonds to at least two non-metal ions The Free Dictionary [online] (2010) [Accessed 3 September 2010] Available from lthttpwwwthefreedictionarycomchelatedgt



472 Nutrient composition for experiment

Per 1000L (with conductivity lt15mSm3) pure tap water 1000g Hydrogrow 650g Calcium nitrate 0-150g Hydrogrow Potassium sulphate 1ml of 10 Agricultural nitric acid per 1L water (This is only an initial dose and needs to be fine-tuned with a pH meter and more 10 acid

Different plants require different levels of calcium For example cucumbers require about

1000g1000L water or tomatoes require only 650g1000L water If more than one type of plant is

grown together 750g 1000L water can be used as an average [189]

Extra potassium is required as the plant matures as well as a plant hardener during the cold winter

months Because the experiments were done on young immature plants to fully matured plants the

potassium addition was accordingly adjusted and 0 to 150g potassium was added

Agricultural nitric acid strength is 58 by volume To make a 10 agricultural strength solution

from this would equate to diluting 100ml acid into 1000ml pure water Please note that this dilution is

for simplicity and ease of use as the nitric acid per volume would only be 58 This dilution is

required because nitric acid is extremely dangerous but when diluted down to 10 it is fairly safe to

work with even by an inexperienced farmer Storage of nitric acid at concentrations higher than this

10 strength is not recommended because the acid will simply dissolve plastic PVC or PET

containers Glass would not be a problem for the acid but it is far too dangerous to store acid in

breakable glass containers

473 Water compliance

To grow healthy plants the water quality is important so as to prevent for example

heavy metal accumulation in the cultivated plants or fruits Being aware of factors like

harmful dissolved mineral content and salinity is also important as they will impair

plant growth performance although the latter is not true for all plants according to

Mishra et al [190 191 192 and 193] For the experiments it was found that the water

quality exceeded agricultural standards



Table 42 Johannesburg Water Quality Report 2011 [194]



48 PH Control

Proper pH control is important as it will jeopardise the nutrient formulation and

concentration if not properly adjusted and controlled Plants remove positive nutrient

ions from the water causing the pH to drift The roots now release hydrogen (H+) or

hydroxyl (OH-) ions to compensate When plants however are growing actively the

ion balance becomes unbalanced and the pH rises sharply For optimum growth the

pH needs to be maintained at 56 to 62 [195]

To return the pH to ideal an acid is used This acid may be nitric phosphoric citric or

any other suitable acid Due to unwanted chemicals being introduced into the nutrient

solution it is preferred to stick to plant friendly types of acids These acids are nitric or

phosphoric acid If the latter however is used the phosphorus in the nutrient solution

should be lowered which will not always be possible due to the fact that this nutrient

comes combined with the other chemical elements

49 Structure Design

A structure supporting two sets of 20 individual plants in two 6m PVC gutters was

accommodated with adequate underneath support The structure was set up to

incorporate a slope of 50 to make water run-off to the reservoir possible This was

necessary as a water recirculation process was used An overhead 15m steel

(Polycarp-isolated) support was installed to support experimental signal connections

as well as for plant support

Picture 41 Half a section of the hydroponic plant layout



410 Various Application points for plant stimuli

Before commencing with the various experiments it was necessary to establish so-

called lsquobest points of applicationrsquo to apply stimulus to plants The following options

were considered

Figure 43 Various application points for stimuli application to plants



411 Constraints

A few but important limitations are highlighted These may have a negative outcome

on the experiments or may prevent the researcher from exploring all possibilities

Individual experimental constraints are listed under each experimental design

Governmentrsquos Department of Communications via its subsidiary the

Independent Communications Authority of South Africa (ICASA) governs

frequency use in South Africa This may imply that usable frequencies suited

to the level thereof to optimise plant growth may not be available to the

public

Long-term water interruption Although provision is made for water

interruptions these emergency measures are only designed to protect the

experiment for 24 hours

Power failures lasting more than an hour Battery backup and an emergency

watering system are provided to water both experimental and control plants in

the case of power failures To make this system practically implementable so

that it may also apply to large scale farming practices where no emergency

backup generatorspower sources are available the system will only provide

the plants with clean water Depending on the duration of the power failure

means that the plants will during this period receive no nutrients which surely

will impair growth and fruit production It may also imply that the affected

dayrsquos pollinated flowers may be aborted or that cracking scarification or

blossom end rot may occur

It may be that through stimulation too much energy is applied that will impair

growth or cause cellular damage

Due to the location of one of the experiments it may be that overhead power

cables may cause interference with the results although this is unlikely

because of being low voltage cabling

Wind factor Although for experimental purposes plants are not expected to

grow to great heights the wind around buildings in a city may have a serious

impact on maintaining plants upright and may cause damage to such plants



412 Measurements

Due to the minute nature of signals only equipment providing very high input

impedance (1x1010) Ohms or more should be considered All measuring instruments

should be connected by buffering and or instrumentation type operational amplifiers

to provide isolation and prevent interference with adjacent measurements Amplifiers

shall employ series current feedback (Trans-conductance Amplifiers) as to obtain the

required impedances

One needs to keep in mind that trans-conductance is a function of the differential

input voltage which of cause is temperature sensitive (ie varies with changes in

temperature) [196] Also very important is that the output does not depend on the load

impedance

( ) where Vin Vin VdifferentialIo gm Vin Vin

However this is only true if we apply the following conditions

Do not exceed the amplifier output parameter current

Stay within the saturation voltage of the amplifier

Attention to temperature compensation input offset voltages (vio) input offset

currents (iio) and Common Mode Rejection Ratio15 (CMRR) is of outmost

importance

Offset voltages and currents will cause DC offsets at the outputs and low CMRR

values will not ensure complete rejection of interference The CMRR can be

determined from

20log AdCMRR dB whereAc

Ad is the differential mode gain and Ac is the common mode gain

15 Common-mode rejection ratio (CMRR) refers to the ability of an amplifier (or other device) to

reject common input signals These are signals that appear on both input leads and hence the name

common signals Contrary to this the amplifier will provide a high gain to the differential or difference

(real signal) CMRR is measures in decibels and should ideally be infinitive but a value less than

100dB is normally considered as a poor design



One practical way to describe the operation of how a differential amplifier works is

that it does not lsquoseersquo (no voltage difference) any common voltages but only the true

difference voltage which is applied and then this voltage is amplified by the current

source

Another important factor is the power supply rejection ratio (PSRR) PSRR is a

measure of how much the power supplyrsquos ripple affects the output voltage and is

measured by limiting the gain to unity while setting the inputs to zero volts Simply

speaking it means that should the supply voltage change the output should remain

constant A good op amp should have

cc

out

VPSRRV

where a large value would be best (normally in dBs)

Because PSRR is frequency dependant the op amp power supplies should be well

decoupled Tutorial MT043 describes a practical way to do this [197]

Figure 44 Decoupling power rails in an op amp [197]

413 Frequency Effects

In stimulating live matter especially plants as in this case it is important to note the

following (more detail in Chapter 5)

Lower frequency will penetrate deeper than high frequency This is due to the

longer wavelength associated with lower frequencies

The energy levels present in frequency need to be low otherwise the radiation

makes the stimulation device a microwave that will lsquocookrsquo the plants



If the wavelength is too long it will not be fully absorbed by the plant In

stimulating the plant the plant needs to appear as a receiving antenna This

means the plant length (height) needs to conform to basic antenna principles

414 Types of Plants

Lund (1931) [198] discovered that potential distribution (gradients) in large plants is

more complex than in small plants For this reason mainly large types of plants will be

used in the experiments This includes Solanum Lycopersicum (tomato) and

Ageratina adenophora (sticky snakeroot)

415 Growth Dynamics

According to Goldsworthy [199] growth dynamics may be defined as

The cell membrane is negative with respect to the ions around it This implies that it will always attract high charge positive calcium ions to it

Plants respond to EMF because eddy currents are produced within the plants when electrically stimulated This means that the kinetic energy of the ions rises

When applying enough energy these calcium ions can be dislodged This then causes an imbalance of the ion concentrations in and outside the cell

The eddy currents now replace the bonded calcium ions (around the cell membrane) with potassium ions This makes the density less ie these causes the cell to become more porous According to Goldsworthy this is especially true when the potassium ions are at resonance (32 Hertz)

There is however a problem and that is that (depending on the type of stimulation) during the oppositereverseoff cycle the calcium ions would return to the cell membrane

This implies that one needs to practise special electrical stimulation techniques to

move the calcium ions far away so that lower charge ions fill their position and they

will not have enough time to return to the cell membrane before the next stimulation

pulse arrives

416 Preferred experimental system

There are two reasons for using hydroponic systems



Lemstroumlm (1904) [200] reported that stimulation was inhibitory when plants

experienced dry conditions This of course would not be a problem in a

hydroponic system

According to [201] growth kinetics minus growing resistance is equal to net

growing In hydroponic systems with optimum nutrient levels we can ensure

that growth resistance is minimal

417 Experimental exclusions

Various research studies were done in the past to prove that the nutritional value of

plants and fruits are minimally or not at all influenced if growth stimulators or

growth regulators are used on plants Some studies however mentioned changes in

taste and appearance [202 203 204 and 205]

Nutritional value and analysis is thus not considered or investigated

418 Evaluating appropriate points for stimulus application on plants in a hydroponics system ndash Experiment 1

4181 Objective

The purpose of this experiment was to find which stimulation application is most

effective according to methods illustrated in Figure 43 This experiment is a pre-run

for all other experiments as it will indicate the most appropriate stimulus points on a

plant

4182 Hypothesis

Stimulating plants electrically in the inter root zone or from plant tip to root position

both have the same effect

4183 Range

In this experiment direct stimulation of DC voltages 5-15Volt and square wave

signals 16Hz was considered for application according to the following node

connections



Root and root Plant tip and root Root and water

4184 Equipment and materials

This experimental setup consisted of the following equipment and materials

1x fully electronically controlled hydroponic setup o System with closed loop water control Nutrient reuse at a rate of

9625 (3L nutrient replaced each day with an automatic wasting control)

2x ACDC power supplies 30V 5 Amp Switched mode type o Electro Magnetic Compatibility (EMC16)

Conforms to Class A o Voltage and current specifications

Fine tuning available Current limitation

o Line regulation Maximum of 001 across operating range

o Load regulation Maximum of 001 for a step load change from 0 to 100

load o Ripple and noise

Maximum of 50mV o Temperature stability

Maximum of 002 C0 1x Oscilloscope

o Bandwidth Not less than 20MHz o Number of channels 2 o Vertical resolution 8 bits o Accuracy of not less than plusmn5 o Input ranges (full scale) plusmn1V to plusmn20 V in 8 ranges o Input impedance 1 MΩ in parallel with 15-20 pF o Input type Single-ended BNC connector o Overload protection o Maximum sampling rate not less than 500Ms o Time base ranges minimum 002 microsdiv to 05 sdiv o Delay Time Range 02 to 10X delay timediv settings of 20 ns to 05 s

16 EMC means nothing more than an electronic or electrical product shall work as intended in its environment The electronic or electrical product shall not generate electromagnetic disturbances which may influence other products Available from httpwwwemtestcomwhat_isemv-emc-basicsphp



o Time base accuracy 50 ppm o Common-mode rejection ratio at least 20 dB at 20 MHz o Humidity Min of 72 hours at 95 relative humidity

2x Digital multimeters o Voltage DC Minimum Voltage 600V (03 accuracy) o Voltage AC Minimum Voltage 600V (2 accuracy) o Minimum Resolution 1 mV o Current DC Minimum Current 10 A o Minimum Resolution 001 mA o Current AC Minimum Current 10 A o Minimum Resolution 001 mA o Resistance Minimum Resistance 20MΩ (005 accuracy) o Minimum Resolution 01 Ω o Environmental Specifications

Operating Temperature 0degC to +50degC Humidity (Without Condensation) 0 - 90 (0degC - 35degC) Overvoltage 1000V CAT II Shock amp Vibration Class III

1x Temperature meter o MinMax indication with a hold function

Resolution 10C Error 010C

1x EC pH TDS and temperature combination meter o Compliance to

Waterproof floating casing Replaceable pH electrode cartridge Dual-level LCD battery power indicator Stability indicator Automatic Temperature Compensation Adjustable TDS ratio Automatic calibration

o Technical specifications pH Range 000 to 1400 Temp Range 00 to 600 degC or 320 to 1400 degF pH Accuracy plusmn005 Temp Accuracy plusmn05 degC or plusmn1 degF pH Resolution 01 Temp Resolution 01 degC or 01 degF EC Range 0 to 3999 microScm TDS Range 0 to 2000 ppm EC amp TDS Accuracy plusmn2 FS EC Resolution microScm TDS 1ppm



Typical EMC Dev plusmn2 FS ECTDS plusmn002 pH plusmn1 degC or plusmn1 degF

pH Calibration 1 or 2 points with 2 sets of memorized buffers ECTDS Calibration Automatic 1 point ECTDS Conversion factor Adjustable from 045 to 100 Temp Compensation for EC BETA (szlig) = adjustable from 00

to 24 per degC in increments of 01 ECTDS Temp Compensation for pH Automatic for pH Environmental requirements 0 to 50degC (32 to 122degF) RH

100 1x Function generator

20MHz dial set function generator 02Hz to 20MHz frequency range Sine square and triangle waveforms plus dc 10mV to 20V peak-peak from 50 Ohms DC offset control with zero detent

4185 Procedure

Hydroponic setup

Figure 45 Hydroponics setup Adapted from [206]

A hydroponic system with continuous drip irrigation was decided on (Chapter 2 item

23) An electronic injection system was used to control the nutrient levels in the

hydroponic system to an EC level of 18mS to 2mS (plusmn01) The same applied to

control the pH at 62 to 64 (plusmn01) An important fact to remember is that the pH



system must come into operation and correct the pH before the EC control corrects

the nutrient level

A nearby (plusmn 1m) permanent water supply with emergency shut off tap as well as

multiple 220 volt mains power sockets were required and installed

A floor with white PVC as to aid in light reflection towards the plants was needed

Gutter stands to accommodate PVC gutters were assembled and filled with 4L plant

bags prefilled with washed river sand at space intervals of 400mm Any open spaces

between plant bags had to be covered with PVC lining to prevent algae growth

For irrigation an electric water pump with multiple drippers to every plant bag was

needed and installed

The water reservoir to the system had to have a 50 to 100L capacity A permanent

water supply with an automatic fill valve kept the water level at maximum in the

reservoir An overflow hole had to prevent damage to the probes in case of an

overflow

Gutter ends need to be adjusted to ensure a proper return flow of nutrients back to the

waternutrient reservoir

EC sensing electrodes had to be constructed and installed This also applied to

temperature compensation thermistors and pH probes into the water reservoir all

connected to their respective controller circuits

Finally the water reservoirs had to be filled and the pH and nutrient levels adjusted

Leaks had to be checked for and fixed

Nutrient solution

Nutrient solutions were prepared as follows Refer to section 471 for nutrient

analysis



Nutrient composition per 1000L water o 13825 mol17 N o 6138 mol K o 1453 mol P o 3649 mol Ca o 1234 mol Mg o 1871 mol S o 30082 mmol Fe o 7282 mmol Mn o 46249 mmol B o 3059 mmol Zn o 0472 mmol Cu o 0521 mmol Mo

Common ground

It is required that a common return path (ground platform) be created for the

experiments The nutrient solution will form part of this grounding system The

control circuit and measuring electrodes for the pH and EC measurements must thus

be supplied from an isolated power supply to prevent shorting of the electrodes If

grounding is not available then earth spikes should be used The spike length depends

on distance and layout Preferably a 1 to 10 ratio should be adhered to This implies

that if the length of the unit is 10m then one would require a 1m earth spike or for

20m this relates to 2x 1m earth spikes spaced evenly [207]

Wires should be properly secured with proper clamps to spike and earth mat inside

reservoir Due to electrochemical processes the use of undesirable conducting metals

like aluminium or zinc should be avoided in the nutrient reservoir All metal used

should also be from the same metal ie copper mat copper wire copper clamps

17 The mole is a unit of measurement for the amount of substance or chemical amount It is a base unit contained in the International System of Units The unit symbol is ldquomolrdquo International Bureau of Weights and Measures (2006) The International System of Units (SI) (8th ed) pp 114ndash15



Figure 46 Earth spike [208]

Plant preparation

Propagate plants from seeds or acquire seedlings When seedlings are 5-10cm high

plant them into the hydroponic system Plant plants at a rate of one plant per bag

Allow the plants to settle (acclimatise) for 5 to 14 days

Stimulation

Electrodes were connected as illustrated in section 410 The negative electrode was

connected to the top of the plant (where applicable) For this experiment the plants

were divided into 6 groups consisting of 5 plants each Between each group of 5

plants one plant was paced to investigate the effect of how stimulation affects

adjacent plants (see 4186 for detail) The electrodes were connected to 5v DC and

applied to plants in batches 1 to 3 The same was done to batches 4-6 but 16 Hertz 5V

square wave signal was applied The connections to the plants were done in the

following manner




Group 1 - DC stimulation

Connection

Batch 1 Root and root Plants 1-5

Batch 2 Tip and root Plants 6-10

Batch 3 Root and water Plants 11-15

Group 2 - Square wave stimulation

Connection




Group 3 - Control

Batch 7 Connection None Plants 31-35

Table 43 Stimulation distribution experiment 1

Factors for recording purposes

Data were collected for

Extreme temperature variation Extreme weather condition Nutrient EC Nutrient pH Bioelectric response Plant appearance Plant height Pest and diseases Hydroponic system condition and appearance

4186 Effect on nearby neighbouring plants

It is important that the researcher is familiar with what the effect of stimulation on nearby plants is To investigate the effect of stimulation on nearby plants the following additions to the setup need to be incorporated

Insert into the hydroponic system amongst each group of 5 plants a lsquodummyrsquo plant This plant should not be connected to any stimulation configuration but only used for observation

Record from this plant the following o Initial placement date o Initial height o Initial appearance o After experiment height o After experiment appearance



o After experiment pest and disease infections

4187 Expected Results

The following plant performances were expected Reasons for decisions are highlighted


Connection

Response expected Reason

Batch 1 Root and root Plants 1-5 Highly positive Large root to root potential difference present

Batch 2 Tip and root Plants 6-10 Highly positive Large root to root potential difference present

Batch 3 Root and water Plants 11-15 Just positive Low current present due to high impedance path


Connection





Table 44 Expected performances experiment 1

4188 Management

Daily management of the following are of utmost importance

Hydroponic setup Check and record

Voltage and signal levels Ph EC temperature max temperature min and weather condition

Stimulation connections and plant health Pest or disease presence

Measuring equipment and accuracy

Check and record settings of voltage and frequency Calibrate EC meters Calibrate pH meters Check that bias currents do not exceed 100pA if DC balances differential

amplifiers Check that all screening of cables is grounded Check and measure common ground in system



Measurement strategies

Day and night temperatures will vary the temperature characteristics of the electrodes and sensors Measurements must therefore be taken at specific temperature ranges

All probes and electrodes for measurement (stimulation excluded) should be applied with AC to prevent polarization of the electrodesprobes

A pH lower than neutral will cause electrodesprobes to corrode over time These electrodesprobes should thus be made from lessnon-corrosive volatile materials like tungsten gold platinum brass or stainless steel

Experimental equipment

Record stimulation voltages frequencies and wave shape Inspect plant connection attachment probes Inspect cabling and measure continuity Reduce or stop stimulation during periods of cold weather and reduce during

periods of continuous rain

Maintenance

Check BNC connectors and clips for oxidation Renew nutrient solution every 4 weeks (system includes automatic wasting of

375 per day) Clean drippers every 4 weeks with a 10 diluted hydrochloric acid Rinse river sand in used plant bags to recycle Disinfect with hydrogen

peroxide 50 at a rate of 20ml per litre (1 solution) o To calculate the amount of H2O2 required use the following equation

2 22 2 2 2

Final volume required Required new H O strenthAmount of H O required per final volume = H O Stock strenth

Uncertainties and concerns

Although one will always try to create optimum conditions for plant growth

there are always some aspects that one cannot control However it is expected

that both control and experimental groups may be influenced in the same

manner A few to mention are

o Electromagnetic interference by other apparatus used in building for example the hundreds of computers and laboratory equipment

o Extreme weather conditions like hail and wind o Equipment failure o Plant stress due to the stimulation



o Because a closed loop circulation system is used it may cause an unwanted build-up of certain minerals used less frequently by plants As a nutrient waste system is incorporated it is not to say that the amount of nutrient wastage is sufficient It is thus suggested that all nutrient be dumped every two weeks and that the system be flushed with clean water before every new experiment is undertaken

419 Plant response to the application of direct current (DC) to plants in a hydroponic system ndash Experiment 2

4191 Objective

Allowing low current and voltage to flow by a process of stimulation in living matter

such as Plantae it is expected that this stimulation will cause ionic voltage changes in

the plantsrsquo main nutrient salts These energised ionic salts are now expected to

penetrate the cell membrane with ease allowing the plant to grow faster produce

bigger and better quality fruits

4192 Hypothesis

Stimulating plants with direct current (DC) will cause the plant to grow faster to produce heavier and more plant material

4193 Range

In this experiment direct current was applied in the range 5 to 15 Volt and currents 10A to 15mA were applied

Application of the various stimuli was done according to the following node connections as was found in experiment one

Root and root - select as per experiment 1 in 418 Plant tip and root

4194 Equipment and Materials

Experimental setup consisted of the following equipment and materials

1x fully electronically controlled hydroponic setup o See description in 4184

2x ACDC power supplies 30V 5 Amp Switched mode type o See description in 4184

1x Oscilloscope



o See description in 4184 2x Digital multimeters

o See description in 4184 1x Temperature meter

o See description in 4184 1x EC pH TDS and temperature combination meter

o See description in 4184 1x 220V to 220V 440VA isolation transformer 1x 220V to 6V 12VA transformer

o The abovementioned 220V and 6V transformers were connected together to create a double insulated transformer All joints and wires were sealed and screened and each transformer was properly grounded

4195 Procedure

Hydroponic and nutrient setup

The experimental setup as in 4185 was followed

Common ground

Similar grounding connections and procedure as in 4185 were followed

Plant preparation

Insect-free tomato plants and Ageratina Adenophora (sticky snakeroot) plants each

weighing about 20g propagated in a separate hydroponic system were used As

tomato seedlings are slow to grow initially cuttings were rooted in a separate

hydroponic system Seedlings and cuttings at a height of 5-10cm were planted into the

hydroponic system Plants were planted at a rate of one plant per bag The plants were

allowed to settle (acclimatise) for a minimum period of five days

Stimulation



were again divided into groups of 3 consisting of 8 plants each Between each group

of 8 plants one plant was placed to investigate the effect of how stimulation affects




applied to plants in batches 1 to 2 The connections to the plants were done in the

following manner

Root and root (as was found in experiment 1 in 418) Plant tip and root

Group 1 - DC stimulation Connection

Batch 1 Batch 2

Root and root Tip and root

Plants 1-8 Plants 9-16

Group 2 - Control Connection

Batch 5

None Plants 17-24


Factors for record-keeping purposes


Extreme temperature variations Extreme weather conditions Nutrient EC Nutrient pH Bioelectric response Plant appearance Plant height Pest and diseases Hydroponic system condition and appearance


It is important that the researcher is familiar what the effect of stimulation on nearby plants is To investigate the effect of stimulation on nearby plants the following additions to the setup need to be incorporated

Insert into the hydroponic system in-between each group of 8 plants a lsquodummyrsquo plant This plant should not be connected to any stimulation configuration but only used for observation

Record from this plant the following o Initial placement date o Initial height o Initial appearance o After experiment height o After experiment appearance o After experiment pest and disease infections






Connection




Group 3- Control

Batch 5 Not connected Plants 17-24


4198 Management

Daily management was very important The same procedure as in 4188 regarding setup measurements and maintenance was followed

420 Plant response to the application of 16Hz square wave signals to plants in a hydroponic system ndash Experiment 3

4201 Objective






4202 Hypothesis

Stimulating plants with a square wave 16Hz AC signal will improve their growth and mass performance



4203 Range

In this experiment a square wave 16Hz signal with amplitude of 5 volt was applied Currents were limited to a maximum of 20mA The 16 Hertz were obtained from a signal generator isolated through a double isolation transformer


Root and root (as selected as per experiment 1 in 418) Plant tip and root





1x Oscilloscope o See description in 4184

2x Digital multimeters o See description in 4184

1x Temperature meter o See description in 4184

1x EC pH TDS and temperature combination meter o See description in 4184

1x 220V to 220V 440VA isolation transformer 1x function generator

o 20MHz dial set type function generator o 02Hz to 20MHz frequency range o Sine square and triangle waveforms plus dc o 10mV to 20V peak-peak from 50 Ohms o DC offset control with zero detent

1x 220V to 6V 12VA transformer o The mentioned 220V and 6V transformers were connected together to

create a double insulated transformer All joints and wires were sealed and boxed and each transformer was properly grounded



4205 Procedure

Hydroponic setup and nutrient solution


Common ground


Plant preparation

Insect free tomato and Ageratina Adenophora plants each weighing about 20g

propagated in a separate hydroponic system were used As tomato seedlings are slow

to grow initially cuttings were rooted in a separate hydroponic system Seedlings and

cuttings at a height of 5-10cm were planted into the hydroponic system Plants were

planted at a rate of one plant per bag The plants were allowed to settle (acclimatise)

for a minimum period of five days

Stimulation





adjacent plants (see 4196 for detail) A 16 Hertz 5V square wave signal was applied

The connections to the plants were done in the following manner

Root and root Plant tip and root

Group 1 - AC stimulation Connection Batch 3 Root and root Plants 25-32 Batch 4 Tip and root Plants 33-40


Batch 5

None Plants 17-24






Extreme temperature variation Extreme weather condition Nutrient EC and pH Bioelectric response Plant appearance Plant height Pest and diseases Hydroponic system condition and appearance


To investigate the effect of stimulation on nearby plants the following additions to the setup needs to be incorporated

Insert into the hydroponic system in-between each group of 8 plants a lsquodummyrsquo plant This plant should not be connected to any stimulation configuration but be only used for observation




Group 1 ndash AC Square wave stimulation

Connection


Batch 3 Root and root Plants 25-32 Very highly positive Large root to root potential difference present

Batch 4 Tip and root Plants 33-40 Very highly positive Large root to root potential difference present

Group 2- Control





4208 Management

The same procedure as in 4188 regarding setup measurements and maintenance were followed

421 Effect of frequency specific radio wave energy using a leaky transmission line on plants in a hydroponic system ndash

Experiment 4

4211 Objective



the plants main nutrient salts These energised ionic salts are now expected to



4212 Hypothesis

Applying electromagnetic fields in the form of an amplitude modulated signal to plants exciting the potassium ions will shake loose the highly positive calcium ions from the cell membrane causing the membrane to become porous to plant nutrients This will allow higher nutrient uptake with and increased growth performance

4213 Range

In this experiment a 16 Hz signal was amplitude modulated onto a 1-50MHz carrier Field strength was limited to a maximum of 5T although studies have found that the average magnetic field pollution in domestic homes is in the order of 007 to 011T [209 210]


Transmission lines in line with roots (as per experiment 1 in 418) Transmission lines in line with tip and root of plant








2x Digital multi-meters o See description in 4184



1x Function generator o Low-Sine Wave Distortion less than 05 o Temperature Stability 20ppmdegC o Sweep Range 20001 o Low-Supply Sensitivity not more than 001V o Linear Amplitude Modulation o TTL Compatible FSK Controls o Supply Range 10V to 26V o Adjustable Duty Cycle 1 TO 99

1x AMFM modulator o Sine Square 001Hz to 16 MHz o Triangle Ramp Pulse 001Hz to 100 kHz o Noise (Gaussian) Maximum 8 MHz bandwidth o Repetition rate 001 Hz to 16 MHz o Resolution 7 digits o Accuracy 50 ppm o Amplitude (into 50) 50 mVp-p to 10 Vp-p o Accuracy plusmn (1 of setting + 5 mV) at 1 kHz no offset o Flatness (at 1 V amplitude relative to 1 kHz) lt100 kHz plusmn1

Up to 100 kHz plusmn1 100 kHz to 1 MHz plusmn15 1 MHz to 16 MHz plusmn3

1x RF Impedance Analyser o Compliance to

Measurement of impedance Z Measurement of R L and C in rectangular format Measurement of R L and C in Polar format Measurement of VSWR Measurement of Reflection coefficient Measurement of Return loss Battery and power options Software compatible to windows RS232 or USB port



o Technical specifications Frequency range 05-150 MHz Frequency resolution 10kHz steps Impedance measurement range at any angle 1Ω to 10k Ω Measurement display updated every 500 milliseconds Typical accuracy of measurement at 50 Ohm magnitude plusmn1

angle plusmn10 SWR measurement range Greater than 1001

4215 Procedure

Hydroponic and nutrient solution setup


Common ground


Plant preparation

Insect-free tomato plants each weighing about 20g propagated in a separate

hydroponic system were used As tomato seedlings are slow to grow initially cuttings

were rooted in a separate hydroponic system Seedlings and cuttings at a height of 5-

10cm were planted into the hydroponic system Plants were planted at a rate of one

plant per bag The plants were allowed to settle (acclimatise) for a minimum period of

five days

Stimulation

Electrodes in this experiment were a leaky transmission line consisting of 2 x 15mm

copper tubes separated 900 mm and suspended in line or above the plants For this

experiment the plants were divided but kept as a single group The modulated signal

was connected to the transmission line that acted as the antenna To investigate the

effect of stimulation on nearby plants a plant was placed at either end of the

transmission lines The alignments to the plants were done in the following manner

Transmission lines in line with roots Transmission lines in line with plant tip and the root of the plant



Group 1 ndash 16Hz AM Modulated Applied to Batch 1 + 2 Plants 1-16

Group 2 - Control Not connected

Batch 6

Plants 33-40






It is important that the researcher is familiar with what the effect of stimulation on nearby (which may or not may have an influence on the plants in the control group) plants are To investigate the effect of stimulation on nearby plants the following additions to the setup needs to be incorporated

Insert into the hydroponic system in-between each group of 8 plants a lsquodummyrsquo plant This plant should not be connected to any stimulation configuration but should be only used for observation






Group 1 ndash 16Hz AM modulated

Connection


Batch 1 Antenna Plants 1-8 Very highly positive Eddy currents to cause cell to be more permeable


Group 2- Control


Table 410 Expected performances for experiment 4

4218 Management


422 Conclusion

Calcium ions are there to give structure to fragile cell membranes Unfortunately they

also control the in-and out-going of elements into and from the cell By removing

them it may be detrimental to the health of a cell as cancerous cells may start to grow

inside the cell [211] However if the cells are in a growing state it may also lead to a

growth phase as non-calcium elements are now able to enter the cell

There is clearly a need where useful electrical stimulation of living matter especially

plants needs to be investigated As is evident in medical advances into the effect of

electromagnetic fields on humans as observed by Bawin et al [212] it is clear that

when applying these fields calcium is released from cells This is especially true for

weak and low frequency types of electromagnetic fields In plants however this effect

can be used to our advantage to increase plant nutrient uptake which will cause

accelerated plant growth and production

Jokela et al and Sage et al [213 214] found that levels as low as 1 Tesla can give

biological effects If we can apply electromagnetic fields to our advantage it will

ensure sustainable food production This of course will not only be to the benefit of

large commercial farmers but also to small private entrepreneurs as well as home

gardeners

PJJ van Zyl Chapter 5 Experimental results and discussion


Chapter 5 Experimental Results Analysis and Discussion

51 Introduction

General growth parameters for plants are well-documented Growing plants in

hydroponics systems however have different parameters Some of these are

Different growth medium

Continuous wet growth medium

Electromagnetic effects on plants due to fairly good nutrient (salts) conduction

properties

Electrical interferenceeffects due to power sources from electrical

conductivity (EC) and acidalkalinity (pH) measuring and control circuits

Utilising a continuous wet growth medium also has major advantages in that it is

possible to apply and study the various effects that electromagnetic fields have on

plants This is especially important as one is be able to control the various variables

like plant nutrition and alkalinity

As revealed by the literature study in Chapter 3 the use of electricelectromagnetic

fields have a major impact on the growth performance and appearance of plants Also

noted are that some of these effects can be detrimental to living plants in that their

appearance production and growth rate are changed Also revealed is that these

electromagnetic fields may possess positive or beneficial effects for plants This latter

mentioned aspect is especially true at applying low intensity electromagnetic fields

(as discussed in Chapter 3)

In this research the primary objective would be to find an appropriate method to

electrically enhance the nutrient uptake of plants specifically in hydroponic systems

that will enhance plant growth performance but will not change the standard

characteristics layout or setup of any current hydroponic system as used by

commercial farmers Neither should such a system be a nuisance to unpack and apply

nor interfere with harvesting and general plant maintenance



52 Overview

This chapter describes the actual experiments as well as the results of such

experiments The chapter is divided into the following sections

Construction of the setup

o This section explains site preparation installation testing calibration

and the construction of the hydroponic setup

o Design of hydroponic controllers

o Measurement probe design

o Hydroponic technique followed

o Nutrient preparation and control

o Test equipment and their calibration

Experimental plants

o Cultivars used plant health symptoms of nutrient deficiency

identification of pests and diseases

o Electrical potential measurements on plants

Selection of stimulus methods

o Various types of stimulation methods discussed

Evaluation of stimulus application points

o Electromagnetic fields and their uses

o The way in which plants utilise electromagnetic fields

o Experiment 1 to select appropriate points for applying electrical stimuli

o Experimental outcomes analysis and discussion

Plant response to the application of direct current

o Aim hypothesis range and method

o Experimental results of plant growth and mass accumulation

performance analysis and discussion

Plant response to the application of 16Hz square wave energy signals




Plant response to the application of frequency specific radio wave energy

using leaky transmission lines



o Effects of frequency and pulses harmonics modulation and

transmission line radiation


o Transmission line design impedance and field strength for the

experiment



o Response of plants to exposed RF fields

Plant response regarding fruiting and flowering

o Delays in flowering and fruit yield comparison of the different

experiments

Plant response to pests and diseases

o Effects of funguses bacteria and pests on experimental plants

Conclusion

53 Layout and setup

531 The setup

A fully functional hydroponic setup with automatic nutrient and pH control was

designed During September 2010 measuring instruments were acquired and

appropriate differential amplifiers constructed for the measurement of plant responses

In the beginning of October 2010 a water supply mains power supply and

construction frame was set up in Doornfontein Johannesburg South Africa at the

coordinates S 26deg 11 33 E 28deg 3 2304 By mid-October construction on the

hydroponic controllers and electrical installation started and by end of October 2010

the first test runs were started



Picture 51 Site preparation for hydroponic plant

532 The structure

The base structure 14m long by 18 m wide and 25m high consisted of 12mm square

steel frames capable of carrying 110mm standard square PVC gutters Gutters were

glue joined together and provided with end caps and outflow pipes An overhead

isolated steel structure to support the plants was installed On top of the base structure

the following was also put in place

Installation of water supply

Electrical installation

Construction of growing frame and support for plants

Construction of antenna (transmission lines) support

Signal delivery system to the plants

Installation of nutrient reservoirs

Installation of pipes drippers and placing of plant bags

Installation of hydroponic controllers battery backup pumps and aerators

Testing phase of

o Water circulation system

o Nutrient level concentration control It took 24 hours for the nutrient

levels to stabilise After this over a 72 hour test period variation was



clamped by the controller to 106 variation in electrical conductivity

and 065 variation in the pH

o pH functioning and control

Priming of setup with nutrient rich water and dripper tests to ensure constant

supply to all plants

Testing and calibration of measuring instruments

Planting

Picture 52 Planting in progress

533 The hydroponic controller

Electrical Conductivity

Electrical conductivity (EC) is an indication of how saline a sample is ie how

conducive the medium is to conduct electric current It also refers to Total Dissolved

Salts or TDS in a sample Typical EC applications are hydroponic EC meters

moisture metersindicators oil change indicators in the automotive industry distilled

water analysers fuel moisture contaminator meters etc

It is represented by the symbol σ (sigma) or sometimes κ or γ The SI unit is Siemens

per meter (Sm-1) and

Where ρ is the electrical resistivity

1



EC is the inverse of resistance (Ohms) One may define EC as the conduction that

exists between two probes that are inserted 10mm apart in a container This is further

related in that 1 EC is equal to 1 m Siemens or roughly 500 to 700 Parts per Million

(PPM) depending on the type of solids dissolved in the solution In measuring

conductance one cannot make use of ordinary measuring instruments DC in these

cases will polarize the electrodes and destroy them as this would result in a process

similar to electroplating Current in a case like this has to be kept to a minimum

534 EC and PH controller

A hydroponic controller was designed with inputs for electrical conductivity (EC)

alkalinity (pH) water level power failure and nutrient water temperature Outputs

provided for were nutrient pumps acid pumps water circulation pumps emergency

watering control and display The principle of operation is as follows

An Oscillator generating a preferred frequency of 10 - 100 kHz Too low a

frequency would cause DC polarization of the probes and too high would

increase parasitic capacitances changing signal to noise ratios

A low impedance input stage As the EC probes are connected to this stage

and the probes are submersed in a nutrient solution with a typical EC of 2μS it

implies that this amplifier should be of parallel current feedback or commonly

known as a current amplifier In such an amplifier the low input impedance

matches the low impedance of the nutrient solution (about 500Ω ) The output

however provides high impedance for differential amplifiers to follow

The third stage would be a pure voltage gain stage

The fourth stage is responsible for rectification as to produce an output voltage

that may be connected to a digital display or via a voltage follower to an

analogue display

Stage five serves as an interrupter stage to allow the correction of pH before

nutrient adjustment is done This is important as EC measurement will vary at

different pH This stage functions with immediate effect when the controller

senses a difference of more than 5 in the nutrient concentrations from the

said reference



Sampling and comparing with a pre-set reference this sixth stage determines

when nutrient adjustment needs to be done Standard offset was set at 5

Stage 7 and 8 are the nutrient and pH control sections that act as driving stages

to switch on the pH and nutrient pumps These pumps would then via

feedback adjust the pH and nutrient levels to the pre-set levels

In order to compensate for temperature variations stage 9 is responsible to

automatically offset the measurement circuits so as to adjust for temperature

off 200C the probe calibration temperature

Picture 53 Hydroponic controller and nutrient reservoirs

Specific care was taken to combat internal voltage offsets Each operational amplifier

used was equipped with an offset trimmer potentiometer to ensure that offsets were

not carried throughout the highly precise EC controller

Picture 54 Provision for adjustments (offset control)



535 Probe design

Conductivity is affected by temperature This implies that measuring an EC of 2 at

200C would probably measure 32 at 300C For this reason a temperature

compensation probe was included in the design This probe consisted of a 10k Ohm

NTC thermistor connected series with the probe to create a potential dividing effect

Care was given as with any voltage dividing network the input voltage had to be

doubled (2x gain) to provide for the loss in the dividing circuitry

To conserve the probes the controller was run using a timer and comparator to sense

variation in the nutrient At regular intervals of 15 minutes the comparator would

detect when 5 of the preset nutrient concentration level was exceeded and would

then activate and switch on the controller After this the pH and EC adjustment would

be executed by the controller

Picture 55 Probes Illustrated are pH Temperature and EC probes

536 Nutrient and air pumps

Pumps were isolated from the mains by firstly using an isolating transformer

Secondly the nutrient pumps were double isolated because air and not fluid pumps

were used For the water nutrient pumps situated in the water triple insulation was

ensured by use of the isolation transformer using double isolated pump casings with

inductive driving impellers and by running the pump through a 30mA trip type earth

leakage



537 Hydroponic technique

Type For this research it was decided to utilise the drip technique This technique is

simple to operate and does not require much maintenance The only work that needed

to be done was the cleaning of drippers once a season with hydrochloric acid to

remove calcium scale The pump is used to deliver a continuous trickle of nutrient

rich oxygenated water to the growth medium The drippers are set to run for 24 hours

Since the dippers are very accurate in delivering specific quantities of liquid it was

ensured that each plant receives the same amount of nutrient water A dripper rate of

8L per minute was used

Picture 56 Drip feeding technique and three different sizes of calibrated drippers

For economic reasons it was decided to use a closed loop circulation system In this

system nutrient rich water is circulated to the plants via the drippers and upon return

to the reservoir the partially depleted ion rich water is topped up with nutrients by

means of the hydroponic controller At the same time pH correction was also done

538 Preparation of the nutrient solution

Nutrient water reservoir

It is possible for hydroponic growers to formulate their own fertilizer mixtures but

owing to affordable premixed fertilisers there is no need mixing it yourself People

who mix it themselves may run in trouble An example is the use of urea which is a

highly soluble nitrogen fertiliser but the plants will not be able to utilise it as it will



not break down into ionic form and microorganisms are usually not present in

hydroponic systems

Some fertilizers will react with one another to produce insoluble precipitations

Although most fertilisers salts may be combined (although some need to be chelated)

this is not true for calcium salts Calcium needs to be kept separately and added

separately at high concentrations During mixing with water there is no problem as the

calcium salts are fairly diluted

The nutrient reservoir was filled with (conductivity lt15mSm3) pure tap water and

nutrients were prepared by combining per 1000L

1000g Hydrogrowcopy

650g Calcium nitrate

0-150g Water-soluble Potassium sulphate

1000 ml of 58 Agricultural nitric acid per 1L water (This is only an initial

dose and needs to be fine-tuned with a pH meter and more 10 acid

Extra potassium is required as the plant mature as well as a plant hardener during the cold

winter months Because the experiments were done on young immature plants to fully matured

plants the potassium addition was accordingly adjusted and 0 to 150g potassium was added

Agricultural nitric acid strength is 58 by volume To make a 10 agricultural strength

solution from this would equate to 100ml acid into 1000ml pure water Please note that this

dilution is for simplicity and ease of use as the nitric acid per volume would only be 58

This dilution is required because nitric acid is extremely dangerous but when diluted down to

58 (10 of the original) it is fairly safe to work with even by an inexperienced farmer

Storage of nitric acid at concentrations higher than this 10 strength is not recommended

because the acid will simply dissolve plastic PVC or PET containers Glass would not be a

problem for the acid but it is far too dangerous to store acid in breakable glass containers



Nutrient storage tanks

To operate the hydroponic controller nutrient reservoirs were installed and filled with

concentrated nutrient solution Three 15L each nutrient reservoirs were used18

Container 1

o Hydrogrowcopy concentrate at a rate of 1500g salts per container Salts

were premixed with about 10L water and then poured into the

container The container was then topped up with water to its full mark

(15L) Potassium was added according to season and growth stage

Container 2

o Calcium Nitrate concentrate at a rate of 975g salts per container Salts



(15L)

Container 3

o A 10 nitric acid concentrate was prepared as described in Chapter

472 This prepared acid was added at a rate of 150ml to the

container The container was half-filled with water after which the acid

was added The container was then topped up with water to its full

mark (15L)

It was found by the researcher that should lower acid concentrations

be used like in this instance where 150 ml of acid was used per

container the outflow from container 3 matched the outflow from the

other two containers This implied that all three containers could be

filled (topped up) simultaneously without the possibility of

overlooking an empty container

18 NOTE Do not exceed 100g salts Litre of water in your concentrated solution otherwise the salts

will combine and become insoluble (Example 100g Hydro grow 1L water is maximum concentration

strength) And do not exceed a higher than 58 nitric acid ratio otherwise the PVC container will

disintegrate



Summary Container 1 Container

2

Container 3

Season Hydro-grow Calcium

Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L

Winter 1500g + 0-15g

Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L

Table 51 Composition of nutrient concentrates per container

539 Nutrient injection

Nutrient injection was administered during the daytime with more frequent injections

during cooler times (0500 to 1100 and 1500 to 1800) and less during the warm

time (1100 to 1500) None was applied during night-time (1800 to 0500) as

reducing the EC enhances water uptake and with this more calcium can be taken up

and transported within the plant to developing tissue Calcium uptake is enhanced at

night-time when the xylem sap pressure drives water and calcium into the low or non-

transpiring tissues such as young and still enclosed leaf tips as well as fruits and

vegetables

5310 Plant nutrient control

pH Adjustment pH affects nutrient availability If the pH is too high iron availability

is hampered Too low and the absorption of calcium and magnesium cannot take

place pH adjustment was done every time that the nutrient injection cycle was

started During the first three minutes of the cycle the EC control was disabled and

only the pH control was allowed to make pH corrections EC Adjustment After the

initial three minute stage the EC controller was allowed three minutes to sample and

make EC corrections



5311 Test equipment and calibration

To calibrate the EC and pH controller a Hanna HI 98130 Combo pH and EC

waterproof meter with automatic temperature compensation was used

Picture 57 Hanna HI 98130 along with pH calibration solution and probe storage solution

To calibrate the HI 98130 three sets of calibration solution was used The following

calibration protocol was followed on the fifth day of every week during the

experimentation phase

pH calibration

Low pH calibration was done with HIL 7004500 solution from Hanna Instruments

(available from Hanna SA 6 Vernon Rd Morninghill Bedfordview Johannesburg)

High pH calibration was done with HIL 7007500 solution from Hanna instruments

EC calibration

EC calibration was done using HIL 7030500 calibration solution from Hanna

instruments

Temperature calibration

As the instrument was new and under guarantee there was no need to refer the

instrument to Hanna for temperature calibration

For measuring electronic signals differential probes were built as in the experimental

setup it is impossible to properly earth plants



5312 Probe storage and cleaning

As the Hanna has a built in storage facility for its pH probe all that was required was

to top up the reservoir weekly with Hannarsquos probe storage solution HI 70300L The

EC probe required no storage precautions except regular rinsing after each use Once

a month the probes were cleaned for 30 minutes using Hanna HI 7061L cleansing

solution

54 Experimental plants

541 Cultivars

Seeds of tomato Alboran (Lycopersicon Lycopersicum (L)) were obtained from Rijk

Zwaan Seeds They were seeded in moistened Gromix Greencopy and allowed to

germinate An automatic irrigation and environmental control unit was built to house

the seedlings and grow them according to the seed providers operational instructions

After 4 weeks the seedlings were divided randomly into the different groups as set out

in Chapter 4 This type of plant was used because it is a popular plant cultivated in

hydroponic systems For some experiments conducted well into the growing season

tomato cuttings were rooted to speed up the process

As a second experiment plant cuttings plusmn 200mm in length of Ageratina Adenophora

(sticky snakeroot or Mexican devil weed) or alternative name Eupatorium

Adenophorum (a family member of Asteraceae) was used This plant has opposite

leaves and has clusters of white flowers and grows up to 2 m tall Stems are purple

with sticky hairs on them [215] This plant originates from Central America and is

considered a pest but was chosen as current research requires fresh plant material to

study mechanisms of controlling this plant This plant was selected to continue the

experiments during the cooler months (autumn and spring) as tomatoes are tropical

plants



The plants were rooted in a separate hydroponic system using butyric acid rooting

hormones and the water was pre-heated to 200C After three weeks the plants were

ready for transplant This plant was selected as it is a plant that not only has excellent

growth dynamics but also is a plant capable of rapidly gaining plant mass

For experiment one the plants were divided into

Batch 1 plants 1-5 batch 2 plants 6-10 batch 3 plants 11-15 batch 4

plants 16-20 batch 5 plants 21-25 batch 6 plants 26-30 and batch 7

plants 31-35

The layout for experiment two and three was


plants 33-40 and batch 5 plants 17-24 Batch 5 acted as control for both

experiments

The layout for experiment four was

Batch 1 plants 1-8 batch 2 plants 9-16 and batch 3 for the control plants

33-40

During planting accurate records were kept about plant height stem diameter weight

leaf size and plant health status

542 Plant health

Nutrient deficiency is generally not a concern in well-managed hydroponics systems

However the following was used as a guide to pick up any problems in time



COMMON SYMPTOMS OF NUTRIENT DEFICIENCY

Element

Leaves to

first

show

deficiency

Symptom

Nitrogen Old Leaves turn yellowish () After this the entire plant turn yellow Stunted growth

Phosphorus Old

Premature leaf fall-off Plant stays dark green but does not grow

Some plants may show purple colour and stripes on underside of leaf

Similar to nitrogen deficiency

Calcium New

Damage and die off of growing points Smaller leaves Distorted leaves Bending forward

curlingrolling or twisting of the leaf White to yellow edges in new growth Severe shortage

entire leaf turns white

Magnesium Old Yellow spots () Main vein stays green Three-in-one tinting of PurpleOrangeRed

Potassium Old Purple-brown then yellow areas then withering of leaf edges and tips No main green vein Plant

has a dark dead-green look


Iron New

Leaves turn yellow

Greenish nerves enclosing yellow leaf tissue

First seen in fast-growing plants

Manganese New Dead yellowish tissue between leaf nerves

Copper New Dead leaf tips and withered edges


Boron New Dead shoot tips new side shoots also die Cracks in stem Hollow stem Crown rot Brown rings

around the leaf edge indicate boron toxicity

Molybdenum Old Yellow spots between leaf nerves then brownish areas along edges

Inhibited flowering

() The plants may also become reddish from the presence of the red pigment anthocyanin

() Although Jacobsen does not differentiate between new and old leaves David Whittacker reports from a hydroponics book

that boron calcium copper iron manganese and sulphur are immobile elements and whose deficiencies affect new leaves

Table 52 Nutrient deficiencies in plants [216]



543 Identifying common funguses and pests

Pest and funguses affects the growth performance of plants It is thus essential that the

researcher has a basic understanding of these to manage the experimental setup

Downy Mildew This fungus appears as yellow spots (black underneath)

when plants are allowed to stay wet for long periods Increased ventilation

could prevent this problem

Powdery Mildew This fungus is represented as white to grey spots spreading

all over the leaves surface

Pythium In this disease the fruits and roots of the plant are attacked Wilting

is a sign of this disease

Botrytis This is a fungus due to wet conditions You can identify this as a

grey fungus on stems or fruits

Thrips These are tiny brown insects that are attracted to the flowers of the

plant Except for the damage they cause they also carry diseases from one

plant to another

White Fly A small white fly found underneath the leaf spreads viruses It is

important to control the young nymphs as the adult flies are coated with a

waxy layer preventing insecticides from destroying them

Red Spider Small almost invisible red spiders Look out for their webs

Aphids These secrete sugars that allow funguses to grow on

544 Plant production issues

Although plant growth analysis can be used as a method to determine how successful

plant stimulation will be one has to remember (according to Blackman) that

The weight of the seed will determine the size of the seedlings which again

determine how quick the production of plant mass begins

The rate of new plant material as some plants grow much quicker than others

The time of planting It is obvious that spring is more suitable than autumn

To double the leaf area requires a stem twice the weight to provide enough

strength to the plant [217]



545 Electrical potential measurements

After planting in the experimental setup plants were allowed to acclimatise for two

weeks or until about eight leaves had developed From this time onwards regular

weekly measurements were taken

Plant stimulus was applied as set out in Chapter 4 and is described in 55 onwards

Measuring signals and signal levels was complicated by the fact that plants in

hydroponic systems are not evenly earthed over the spectrum The same is true when

using Operational Amplifiers (OP AMP) as there is no physical ground pin This

problem was overcome with the use of differential probes on the measuring

instruments as well as the use of high common mode rejection ratio (CMRR)

amplifiers

A concept utilized by Karlsson [218] was adapted and applied to ensure that the

correct level of signal is applied to the plants

Figure 51 Instrumentation amplifier [218]

The amplifier in Figure 51 IC 1 and 2 acts as voltage followers and buffers the inputs

from the plants and the measuring instrument This is necessary as any loading effect

caused on the plants will result in a change in voltage In a buffer amplifier the

inverting inputs are not earthed and this can be observed in the above drawing by the

lsquoopenrsquo connection to the coax cable screen Although only one terminal is available



from this setup is compensated by the fact that another terminal is available from the

second IC

To obtain a voltage output (potential difference) the two input probes needs to be

combined by the differential amplifier IC 3 IC 3 produces an output equal to the

difference V2 ndashV1 As OP AMPrsquos are precision devices they still have shortcomings

especially due to internal offsets For this reason pins 2 and 3 need to be grounded on

IC 3 and the offset pins 1 and 5 need to be adjusted by applying a negative supply

voltage to set the output equal to zero After final testing the drift experienced

between day (max 330C) and night (min 50C) was less than 1mV and the p-p noise

was less than 10μV per 5m length of cables

High impedance field effect type TL081 op amps were used To keep signal to noise

ratios down on the longer as normal measuring leads required screened RG6 coaxial

cables proved to be the solution This is especially important as a hydroponic setup is

not very instrument friendly if kept in mind the moisture and humidity present

55 Possible types of stimulation applications to plants in hydroponic systems

Although the methods used in this thesis is outlined in Chapter 4 it needs to be

mentioned that the methods listed in Chapter 4 are not the only possible ones

Possible methodstypes of stimuli can be any of the following ndash no specific order

Applying DC directly 3 to 15μA and 15V maximum

50 to 60 Hz through a coil connected to the stem of a plant (01 to 50μA)

50 to 100Hz in underground loops

Oscillations in sine square or triangular format ranging from 8 to 1kHz

applying low intensity waves of lt1Vcm

Applying any method of stimulus with or without plant recovery off times

Stimulation at various resonance frequencies for sufficient periods of time

ranging from 0 to 18 Mhz

Using high electrostatic voltages 01nA to 01μA and voltages up to 40kV

Antenna radiation at about 1mAm2

Various modulated signals of low frequencies on high carrier frequencies



Emitting radio waves sound or light or AM modulation of these frequencies

Pulsed waves square or other types gate modulated or not

56 Evaluating appropriate points for stimulus application on plants in a hydroponics system

561 Introduction

According to Goldsworthy several studies have shown that electromagnetic field

causes a biological effect on plants These include but are not limited to [219]

Weak electromagnetic fields dislodge calcium ions around the two molecule

thick plant cell making the cells to become open

This energy allows calcium to move into the cell acting as a stimulant for

growth

Weak fields are more potent than strong ones

Magnetic portions (current flow gradient) of a field penetrates the plants

easier but may also cause more harm due to its penetrating properties

562 Electromagnetic fields

The reason why electromagnetic fields produce plant growth benefits is because they

cause eddy currents to flow around the plant cells We know that calcium with its 2x

positive charge is attracted to the negatively charged cell membrane A changing

electromagnetic field will pull away the positive calcium ions during the negative part

of the energy cycle and restore them to their original position during the positive

energy cycle

It is important that to understand that potassium ions exists in their thousands they

also carry a positive charge and will also be dislodged by the positive energy cycle

This of course would be undesirable and for this reason it is important that only weak

electromagnetic fields should be applied to cause only the highly positive ions to

move away from the plant cell and not the potassium ions (the potassium ions have to

take the place of the removed calcium ions)



563 How plants utilize non-changing electromagnetic fields

According to Brownian motion19 living cells can cause their own time variation in an

electromagnetic field For this reason it is possible that even direct current (DC) can

cause field orientation in a cell to change [220]

564 Aim hypothesis and range

The purpose of the first experiment was to find which stimulation application

position is most effective according to methods illustrated in paragraph 49

During this experiment the way forward in which all other experiments would

be conducted was determined

Applying stimulus to plants electrically in the inter-root zone or from plant tip

to root position both have the same effect

During this experiment direct stimulation of DC voltages 5 (plusmn01V) and square

wave signals 16Hz (5V amplitude) were applied according to the following

node connections

o Root and root

o Plant tip and root

o Root and water

565 Uniform measurements

It is important to note that to obtain uniform measurements all measurements were

taken from the rim of the base gutter This is why the initial plant height rater reflects

heights in the 250 to 350 mm region than the initial plant height of about 10cm

566 Evaluating appropriate stimulus application points

Plants seedlings were selected and cultivated as described in 54 and 53 respectively

Once they reached a height of about 10cm they were planted in 4L plant bags

containing plain river sand particles ranging in size from about 500 microns (5mm) to

19 The random movement of microscopic particles suspended in a liquid or gas caused by collisions with molecules of the surrounding medium Also called Brownian movement From httpwwwanswerscomtopicbrownian-movementixzz1Y7vWhI00



about 4 millimetres The sand was washed 5 times and then disinfected for 12 hours

using a 1 hydrogen peroxide solution

To apply the signals probes were constructed using 10cm pieces of solid 304304L

stainless steel wire (1mm2) which is approved for corrosive liquids process

equipment chemical food and pharmaceutical industries Digitechcopy audio wire

15mm2 was used to relay the signals from the source to the plants For connections to

the plant itself Polywirecopy available from Alnetcopy was used Polywire is a polyurethane

rope with 6 strains of wire woven into the rope and is generally used for controlling

animals using high voltage in temporary rotational grazing camps

Picture 58 Stainless steel probes and polywirecopy for relaying signals to plants

Signals were applied using instruments described in Chapter 4 after an acclimatizing

period of 14 days Electrodes were connected as illustrated in section 410 The

negative electrode was connected to the top of the plant (where applicable)

Picture 59 showing the 5V power supplysignal generator the probes in action and the Polywire for support and relaying of the stimulus to the plant



For this experiment the plants were divided into groups of 6 consisting of 5 plants

each Between each group of 5 plants one plant was placed to investigate the effect of

how stimulation affects adjacent plants (see 4186 for detail) The electrodes were

connected to 5v DC and applied to plants in batches 1 to 3 The same was done to

batches 4 to 6 but a 16 Hertz 5V square wave signal was applied

Summary of response outcome Group 1 - DC stimulation

Connection

Response Notes

Batch 1 Root and root Plants 1-5 Almost very high

positive

Large root to root potential difference present

Batch 2 Tip and root Plants 6-10 Very high positive Large tip to root potential difference present



Connection

Response Notes




Table 53 Responses for experiment 1



The experimental outcome is summarised in table54

Table 54 Initial and final measurements for experiment 1

567 Plants for observation purposes

Five plants were placed between the different batches of plants for growth observation

status only The results are shown in Table 55

Plant 1 Plant 2 Plant 3 Plant 4 Plant 5 Plant parameter measured Plant growth

Between batch 1 and 2 Between batch 2 and 3 Between batch 3 and 4 Between batch 4 and 5 Between batch 5 and 6 113 increase 14 increase 126 increase 142 increase 118 increase

Table 55 Observation measurements for experiment 1

568 Experimental analysis

Applying stimulus to plants electrically in the inter root zone or from plant tip to root

position did indeed have positive effects As can be noted from Table 54 direct

PJJ van Zyl 2011 Data collection sheets Date 04-Mar-11 Key

Experiment One RampR [Root to Root]

Experiment type END TampR [Tip and Root]

Scope To find appropriate points of application RampW [Root and Water (nutrient solution)]

Signal type DC 5V and Sq wave signal 5Vp-p

EC (mS) 18 pH 641

Batch Plant Height (mm) Signal type Signal level Plant cond Electrode cond Growth (mm) Return in Start height Analysis

B1 P1 380 DC - RampR 501 V positive 91 315 289 B1 3058

P2 390 DC - RampR 501 V electrodes 95 322 295 B2 3324

P3 425 DC - RampR 501 V slightly 104 324 321 B3 2592

P4 393 DC - RampR 501 V corroded 89 293 304 B4 373

P5 403 DC - RampR 501 V not healthy for all 87 275 316 B5 3526

B2 P6 298 DC - TampR 501 V plants 70 307 228 B6 275

P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316

P9 398 DC - TampR 501 V flowers 111 387 287

P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307

P14 389 DC - RampW 501 V flowers 78 251 311


B4 P16 423 SQ - RampR 1598-1601 Hz All electrodes 106 334 317

P17 409 SQ - RampR 1598-1601 Hz unchanged 106 35 303

P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314

P23 499 SQ -TampR 1598-1601 Hz flowers 135 371 364

P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311

P28 326 SQ - RampW 1598-1601 Hz flowers 71 278 255

P29 402 SQ - RampW 1598-1601 Hz not healthy 84 264 318


Control

B7 P31 302 none not healthy 29 106 273

P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243



stimulation with DC voltages 5Volt and square wave signals at 16Hz when applied to

plants during the experiment achieved positive results compared to plants in the

control group The results from batch 1 where a DC signal 5V (plusmn001V) was applied

returned a positive growth performance of 3058 (start to end of experiment) For

batch 2 the return was higher at 3324 and for batch 3 lower at only 2592

For plants where the 16Hz square wave [0 to +5V (plusmn002Hz)] was applied growth

performance exceeded that of the DC stimulated ones For batch 4 it was 373

Batch 5 at 3526 with batch 6 lower at 275

For batch 7 the control group increase in growth was a mere 1336

569 Discussion

What is evident from the results is that there was a clear correlation between batch 1

and 4 (both extremely positive results for root to root stimulus application) batch 2

and 5 (tip and root application) and batch 3 and 6 (root and water application)

Performance from applying a square wave did however exceeded that of the DC

method of application

Applying DC had a slight disadvantage in that the positive stainless steel electrodes

were slightly corroded Although not significant this method would increase

production cost as electrodes will need to be replaced at regular intervals The reason

for the corrosion is understandable as electrolysis takes place between the electrodes

though the nutrient salts in the water A factor that assists the process is the fact that

the water is slightly acidic (pH 62)

Studying these results it was decided to proceed using only these two possible

application points for further experiments These were root - root and tip - root

The hypothesis proved workable in that applying stimulus to plants electrically in the

inter root zone or from plant tip to root will both have similar effects on the growth

performance of the plant



57 Plant response to the application of direct current (DC) to plants in a hydroponic system

571 Introduction

In certain plants it does not matter in which direction the voltage is applied In these

plants growth will be to the anode or cathode [221] In other plant species voltage

sources cause greater effects than current sources [222] However what is known is

that in all experiments done the field and currents are of a very low magnitude

572 Aim hypothesis range and method

Allowing low current and voltage to flow by a process of stimulation in living

matter such as Plantae it is expected that this stimulation will cause ionic

voltage changes in the plantsrsquo main nutrient salts that will induce growth

Stimulating plants with direct current (DC) will cause the plant to grow faster

produce heavier and more plant material

In this experiment direct current was applied in the range 4999 to 5001 Volt

and currents 100A to 10mA were applied depending on the method of

application

Application of the DC voltage stimuli was done according to the following

node connections (These were according to the findings in experiment 1 in

Chapter 565)

o Root and root


573 Effect of direct current (DC) on plants in hydroponic systems


Once planted the same procedures as in experiment 1 was followed

Plants were divided into 3 batches using the abovementioned plants Electrodes were

connected as described in section 410 The negative electrode was connected to the

top of the plant (where applicable) For this experiment the plants were divided into

groups of 3 consisting of 8 plants each Between each group of 8 plants one plant was

placed to investigate the effect of how stimulation affects adjacent plants (see section



4196 for detail) The electrodes were connected to a 5v DC source and power was

applied to plants in batches 1 to 3

For batch 2 half the plants were provided with a positive supply at the top (tip) of the

plant (Batch B2A) while the rest (Batch B2B) were provided with a negative voltage

at the tip of the plant

Summary of response outcome Plant growth performance DC stimulation

Connection

Response Remark

Batch 1 Root and root Plants 1-8 Very Highly positive Healthy plants

Batch 2A Tip and root Plants 9-12 Ultra Highly positive Healthy plants Batch 2B Tip and root Plants 13-16 Very Highly positive Healthy plants

Group 3- Control

Batch 5 Not connected Plants 17-24 Positive Healthy plants

Plant mass performance DC stimulation

Connection

Response Remark



Group 3- Control


Table 56 Summary of responses for experiment 2 For this experiment height as well as mass accumulation were sampled Results are shown in Table 57 and Table 58 ndash overleaf



Table 57 Growth outcome when applying a DC type of stimulus

Table 58 Plant mass outcome when applying a DC type of stimulus

PJJ van Zyl 2011 Data collection sheets Date 24-Jun-11

Experiment 2 Height

Experiment type END

Scope Effect of DC Stimulation

Signal type DC 5V

EC (mS) 18 pH 641

Batch Plant Height (mm) Signal type Signal level Plant cond Electrode cond Growth (mm) Return in Start height Ave Growth

B1 P1 857 DC 5V rootroot Healthy Pos rusted 479 1267 378 B1 1501

P2 984 DC 5V rootroot Healthy but fine 616 1674 368 B2A 16935

P3 908 DC 5V rootroot Healthy for all 557 1587 351 B2B 15095

P4 878 DC 5V rootroot Healthy 525 1487 353 B3 12468

P5 902 DC 5V rootroot Healthy 587 1863 315




B2 A P9 958 DC 5V roottip +DC Healthy 100 614 1785 344

P10 927 DC 5V roottip +DC Healthy 100 579 1664 348



B2B P13 945 DC 5V roottip -DC Healthy 100 577 1568 368

P14 967 DC 5V roottip -DC Healthy 100 577 1479 390



B3 P17 792 None Control Healthy NA 394 99 398

P18 857 None Control Healthy NA 494 1361 363








Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641

Batch Plant Weight (g) Signal type Signal level Plant cond Electrode cond Growth (g) Return in Start weight Ave Weight




























With the application of direct current (DC) plants were expected to grow faster

produce heavier and more plant material as was evident from the outcomes achieved

in experiment 1 Table 56 indicates clearly that plants where the positive DC voltage

was applied to the top of the plant growth slightly outperformed plants where it was

applied to the root by a ratio of 11221(1122) This may not always be the case and

depends on the type of plants as discovered by Peng et al [221] Root to root gave

almost the same results as root to tip where the negative of the supply was connected

to the top of the plant The stimulated plants outperformed the control group by

13581 (1358)

The results for plant weight followed a similar trend For plants where the positive

DC voltage was applied to the top of the plant the plant mass significantly

outperformed plants where it was applied to the root by a ratio of 13441 (1344)

Compared to the control group the gain caused by DC stimulation was better by a

ratio of 18871 (1887)


Five plants were placed between the different batches of plants for observation status

only The results were as follows

Plant 1 Plant 2 Plant 3 Parameter measured Plant growth

Between batch 1 and 2A Between batch 2A and 2B Between batch 2B and3 115 increase 148 increase 131 increase


576 Discussion

As was expected the massgrowth ratio was correct in that the plants gained more

weight than height Group B2A (+ DC connected to top of plant) performed as

expected and just like in experiment one performed much better in both height and

mass accumulation One problem with DC stimulation did however emerge and that

was the slight corrosion (especially the positive) electrode The corrosion was much

more evident in the root to root application than in the tip to root application



Although previous research (literature study) indicated that direct current does have

positive effects on plant growth performance experiment 2 was necessary because

the results are needed to serve as a comparison to experiment 4 (effect of RF energy)

The application of direct current (DC) had a major advantage in producing a mass

gain of 1311 (131) when compared to the plants in the alternating (16Hz) field

The hypothesis was proved to be correct in that stimulating plants with direct current

(DC) in a hydroponic system will cause the plant to grow faster produce heavier and

more plant material

58 Plant response to the application of 16Hz square wave signals to plants in a hydroponic system

581 Introduction

A common factor between plants and electricity is that there is a correlation between

electrical potential and the movement of nutrients through the membrane of a plant

cell Another fact is that off-time (resting) potentials exist between the interior

(negative) and exterior (positive) of a cell which is typically 10 to 200mV It is this

that causes nutrients to move into the cell [223]

Should a signal possess time or time and amplitude-varying electromagnetic

properties then it will hasten the effect of creating current densities in plant tissue

This is even truer should pulses or square wave be used [224] As we have seen

before the resonating frequencies of potassium and calcium are quite low This

implies that to create these current effects the frequencies applied should also be low

especially close to potassium and calcium




Stimulating plants with a square wave 16Hz AC signal will improve their

growth performance Further should there be a DC offset this will change the

plant heightweight parameters

In this experiment a square wave 16Hz signal with amplitude of 5 volt was

applied Currents were limited to a maximum of 20mA The 16 hertz were

obtained from a signal generator through a double isolation transformer

Application of the various stimuli was done according to the following node

connections as was found in experiment one (Chapter 565)

o Root and root


583 Effect of 16Hz wave energy on plants in a hydroponic system

Plants seedlings were selected and cultivated as described in 54 but this time only

rooted plant cuttings were used Once planted the same procedures as in experiment 1

was followed

Electrodes were connected as described in section 410 The negative electrode was





The summary of response outcome is to be seen in Table 510 Table 511 and Table 512 - on the next page



Plant growth performance Group 1 ndash AC Square wave stimulation

Connection

Response Remark

Batch 3 Root and root Plants 25-32 Very highly positive Healthy plants

Batch 4 Tip and root Plants 33-40 Very highly positive Healthy plants

Group 2- Control


Plant mass performance Group 1 ndash AC Square wave stimulation

Connection

Response Remark

Batch 3 Root and root Plants 25-32 Very highly positive Healthy plants Batch 4 Tip and root Plants 33-40 Very highly positive Healthy plants

Group 2- Control


Table 510 Summary of responses for experiment 3 Height gain

Table 511 Plant growth outcome when applying a 16Hz square wave stimulus


Experiment 3 Height

Experiment type END

Scope Effect of AC Stimulation

Signal type 1598 to 1601 Hz Square wave signal

EC (mS) 18 pH 641

Batch Plant Height (mm) Signal type Signal level Plant condElectrode cond Growth (mm) Return in Start height Ave Growth

B1 P25 857 Square 16Hz root to root 5 Volt Healthy Pos rusted fine 513 1491 344 B1 1586

P26 984 Square 16Hz root to root 5 Volt Healthy Pos rusted fine 582 1448 402 B2 16775


P28 878 Square 16Hz root to root 5 Volt Healthy Pos rusted fine 507 1367 371





B2 P33 958 Square 16Hz tip to root 5 Volt Healthy 100 605 1714 353

P34 927 Square 16Hz tip to root 5 Volt Healthy 100 561 1533 366

















Mass gain

Table 512 Plant mass outcome when applying a 16Hz square wave stimulus


For experiment 3 plants were subjected to square wave energy which was applied root

to root as well as tip to root Again tip to root plants outperformed the root to root

connections by 10581 (1058) compared to the control The 16Hz stimulated plants

outperformed the control by 13451 (1345) regarding gain in growth parameters

(Table 511)

Plant mass when stimulated by a square wave yielded similar results compared to

plant height for both root to root and tip to root applications Again the tip to root

application outperformed the root to root Tip to root ratio was 10591 (1059)

compared to root to root mass gain However the best performance yielded a ratio of

14411 (1441 gain) comparing the stimulated plants to the control group (Table

512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641

Batch Plant Weight (g) Signal type Signal level Plant condElectrode cond Growth (g) Return in Start weight Ave Weight






























Plant 1 Plant 2 Parameter measured Plant growth

Between batch 1 and 2 Between batch 2 and 3 128 increase 120 increase


586 Discussion

Because data differs statistically significant no specific statistical test method had to

be used The Kolmogorov-Smirnov test (KS-test) was used to obtain statistical

parameters This is an easy test to evaluate the hypothesis especially as data

distribution has no effect on this test [225]

Data set for the control Mean = 4216 Standard Deviation = 451 Highest

growth = 494 Lowest growth = 335 Median = 4210 Average Absolute

Deviation from Median = 296

From this the KS test finds the data is consistent with a normal distribution P

= 069 where the normal distribution has mean = 4226 and sdev = 5951

KS finds the data is consistent with a log normal distribution P = 058 where

the log normal distribution has geometric mean = 4197 and multiplicative

sdev = 1160

Data set for growth parameters root to root stimulation

Mean = 5561 Standard Deviation = 451 Highest growth = 623 Lowest

growth = 504 Median = 5560 Average Absolute Deviation from Median =

361 Median = 5560

KS finds the data is consistent with a normal distribution P = 090 where the

normal distribution has mean = 5585 and sdev = 5166





sdev = 1097

Data set for the KS test of the growth parameters (tip to root)



195





sdev = 1053

The outcomes for the control and treatment plants are significantly different The

maximum difference between the cumulative distributions D is 10000 with a

corresponding P of 0000 As values are so small the null hypothesis can be rejected

indicating that applying 16Hz square waves does cause a significant change (D) in

growth

The application of 16Hz square wave energy to plants had shown that the growth rate

was slightly higher by 10411 (104) compared to similar to plants where direct

current was applied

However plants stimulated by DC appeared more compact in appearance while the

16Hz stimulated plants started to flower 7 days later than those in the DC and control

groups The hypothesis proved to be correct in that stimulating plants with varying

pulsed energy in a hydroponic system will cause the plant to grow faster produce

heavier and more plant material



Picture 510 DC stimulated plants (on the left) appear more compact

59 Effect of frequency specific radio wave energy using a leaky transmission line on plants in a hydroponic system

591 Introduction

In plant cells the positively charged potassium ions exist in their thousands (10 000 to

1) next to the highly positive charged calcium ions These thousands of potassium

ions are much easier to excite which will in turn cause the calcium ions to become

dislodged from the cell wall This of cause causes cell breakdown if time is not

allowed for the calcium ion to return to its original position Using a window during

which no energy is applied will allow for such return An electromagnetic wave

suitable for such an action is the amplitude modulated wave especially if it is

modulated near the cyclotron resonance frequency of potassium (16Hz)

592 Effects of frequencies and pulses

Low frequencies work best because they allow sufficient time for the calcium ion to

be removed from the plant cell and because the fields are not so strong that the

positive potassium ions could now take their place Pulsed energy is better than

smooth energy fields because it rapidly increases the field strength to allow the



calcium ions to become dislodged and then in the decaying magnetic field there is just

enough energy to keep them away from the cell wall for a few milliseconds [226]

593 Harmonics

When utilising the cyclotron resonance frequency of potassium it is understood that

similar effects could also be obtained at the even harmonics being 32Hz 64Hz etc

Interestingly 32Hz is the cyclotron resonance frequency of calcium The reason why

odd harmonics of potassium are not useful (actually they inhibit growth) can be found

in a document compiled by Blackman (1990) [227] According to Blackman this is

because for a calcium ion the mass is twice that of the potassium ion making the

fundamental harmonic of calcium equal to the first harmonic of potassium (32Hz)

594 Modulated signals and their effects

When applying a modulated wave the energy from the carrier will normally be very

low However the energy in the lower modulated frequency and if such that this

frequency is the same as the vibration frequency of the ions surrounding the plant cell

(cell wall) then these ions will surely acquire some energy from the electrical wave

This is because the low frequency signal allows enough time for the slow speed

diffusion process

Surely it is understood that this should be a controlled process because if too many

calcium ions are released it would cause plant stress and may cause plant breakdown

This could be appreciated from the fact that calcium gives structure to the plant and

controls ion entry in and out of the cell This also confirms the studies highlighted in

Chapter 3 which all indicates that low level radiation is much more beneficial to

living matter such as plants

595 Transmission lines as radiating antennas

5951 Frequency allocations

Frequency allocations in South Africa are regulated by the Independent

Communications Authority of South Africa (ICASA) It is illegal for someone to just



assign a pair of frequencies for a specific application and use it Applying for the use

of specific frequencies would also be troublesome and could cost a lot of money For

this study a set of transmission lines was used to act as radiating antennas Because

radiation is only between the two leaking lines no outward radiation took place and no

frequency interference was caused There was no need to apply and use allocated

frequencies

5952 Transmission lines

Transmission lines are there to carry or guide information from one point to another

Causing a transmission line to leak and operate like an antenna is not simply

removing its ideal characteristics Radiation from an open wire can take place when

the line is terminated in its characteristic impedance Zo

Where D is the distance between the two conductors and d is

the diameter of the conductors (same units)

Should a line be properly terminated the power radiated (Pr) as well as the power

radiation resistance (Rr) will increase should the frequency increase

It is also easy to find the radiation losses as one can measure the input power (P= I2

R) to the line as well as the power received in an unmatched terminating resistance

The difference is the power lost (radiated) or Pr =Pin ndash Pzl


To apply radio waves to make the layers of citations along the cell membrane

to move along with the applied AM envelope of low frequency This will

lsquoopenrsquo the cell and allow for an increase in the absorption of nutrient ions by

the cell

Applying electromagnetic fields in the form of an amplitude modulated signal

to plants will tear away calcium ions from the cell membrane causing the

membrane to become porous to plant nutrients This will allow higher nutrient

uptake with and increased growth performance

In this experiment a 16 Hz signal was amplitude modulated onto a 1-50MHz

carrier Field strength was limited to a maximum of 5T

02120ln[ ]DZd





o Root and root


597 Frequency specific radio energy using a leaky transmission line

5971 Plants

Plants seedlings were selected and cultivated as described in 54 Once planted the

same procedures as in experiment 1 were followed

Electrodes in the form of an antenna were suspended in line with the plants The

antenna in this case was a leaky transmission line For this experiment the plants

were again divided into 2 batches consisting of 8 plants each At the end of the two

groups two plants were placed to investigate the effect of how stimulation affects

adjacent plants (see section 4196 for detail) A 48468MHz carrier modulated with

16Hz square wave signal was applied to the transmission lines

5972 Transmission line design

Since λ =cf and should a tunnel be of length 30m (typical length) then this will result

in a carrier of 10MHz Utilizing such a frequency is within limits of most inexpensive

signal generatorsmodulators and would not be problematic as the field at maximum

amplitude will radiate between the two lines and not into space This will limit any

interference in the region extending as far as the diameter between the two

conductors The following drawing sketches such a scenario

Figure 52 Current propagation in a twin wire transmission line



For physical electrical wavelength in a transmission line one should consider the losses as well In this instance where VF is the velocity factor of the specific line used

Using mentioned formula the practical wavelength at 10MHz is 2908 m for a velocity

factor of 0967 This is still fine as the walking path in any practical setup also takes

up some space

For the experimental setup the distance was limited to 6m

With the 55m transmission line as well as the 05m transmission line connecting the

so-called antenna to the transmitter this 6m setup results in a frequency of

48486MHz which is still within the limits of inexpensive generatormodulators

5973 Transmission line impedance

For this experiment the traditional design parameters designing transmission lines

was of no use as this transmission line had to be leaky and had to radiate Voltage

Standing Wave Ratio (VSWR) was also encouraged in this experiment due to the

mismatch using an open-ended transmission line

29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M



Figure 53 Field lines in a twin wire transmission line Figure 53 shows how current travels along one line while an opposite current flows

in the second parallel line This second current is of course in an opposite direction

Plants are located in a position where the two H fields intercept one another Because

the transmission lines are carrying RF energy and the lines are in proximity of the

plants (conducting medium) the magnetic field lines penetrate the plants causing

small voltages which in turn creates tiny eddy currents with their own magnetic fields

that penetrate the plant cells As current travels in these lines and change direction so

will the magnetic fields also change its direction

To obtain the inductance of the loop (L) as well as the differential impedance (Zdiff)

the following formulas apply [228]

Where s is the distance between the conductors r is the radius of the conductor and Ln is the length of

the conductors

dk is the material specific dielectric constant

291016 10 ln 1

2 2s sL x x xLnr r

2120 ln 12 2s sZdiff xr rdk



Termination of the line into its characteristic impedance was not a requirement as

energy was expected to return on the lines However to transfer energy from the

transmitter an impedance matching technique had to be used This impedance

matching circuit or technique also had to provide protection to the transmitter in case

of reflections due to standing waves

The following options solve the issue of line impedance matching

Figure 54 Line impedance matching techniques [229]

Figure B shows a conventional two wire transmission line while in Figure C a 4 line

parallel layout is shown to reduce the typical high characteristic impedance of an open

wire transmission line Figure E is another method using twin wire to obtain a 41

balun The coils are to improve the frequency range [15] In Figures F and G

alternative methods are shown

A Tomcocopy TE1000 RF vector impedance analyzer was available to determine line

characteristic impedance but to assist with transmission line design an impedance

calculator (available from httpvk1odnetcalctltwllchtm) was first used



Figure 55 Line impedance characteristics for 15mm copper tubing transmission line [230] ldquoModelling losses R is the series resistance in the conductors and is subject to skin effect and proximity

effect The model assumes that the conductor is homogeneous to a couple of times the skin depth That

assumption may not be valid at very low frequencies for plated conductors (tinned copper copper-

plated steel) laminated or clad conductors (copper-clad aluminium copper-weld) A proximity

resistance correction is calculated using an algorithm from the program line_zinpas by Reg Edwards

(G4FGQ) and G is the shunt admittance and is usually considered to be a result of loss in the dielectric

material It is calculated from the Loss Tangent inputrdquo [230]

For practical reasons and to minimize obstruction in a typical hydroponic

environment the last option was utilized to match the transmittersrsquo 50Ω impedance

with that of the line which is around 550Ω (558Ω according to vector analyzer)



Picture 511 Handmade Balun to match the transmitter with the transmission lines (two mismatched tapings included)

Overlap windings were used according to Where R2 is the secondary and R1 the primary impedance Grounding the setup the following illustration serves as applicable methods

Figure 56 Different grounding techniques Adapted from [231] A common ground was provided should ground connections prove difficult for

example like in a hydroponic setup Normally option 2 would be prone to static

build-up but due to the plants and the humid environment created by the plants it was

found that no static existed

22 11

RN NR



598 Field strength

Field strength was initially designed to be in the order of 15Vm The transmitter with

pre-set outputs however only allowed for an output of 157Vm

Frequency F 48468 MHz

Modulation F 16 (m = 03) Hz

Received power Pr 13 dBm

Electric field strength E 157 Vm

Magnetic field strength H 00042 Am

Power density S 00065 Wm2

Table 514 Field strength outputs from frequency generatormodulator

599 Growth and mass data parameters

Summary of response outcomes Plant growth performance Group 1 ndash 16Hz AM modulated

Connection

Response Reason



Group 2- Control


Plant mass performance Group 1 ndash 16Hz AM modulated

Connection

Response Reason



Group 2- Control


Table 515 Summary of responses for experiment 4

For this experiment height as well as mass accumulation was sampled Results are

shown overleaf



Height results

Table 516 Plant height outcome when applying a RF 16Hz modulated frequency stimulus

Mass gain

Table 517 Plant mass outcome when applying a RF 16Hz modulated frequency stimulus

PJJ van Zyl 2011 Data collection sheets Date 23-Nov-11

Experiment 4 Height

Experiment type END

Scope Effect of RF Stimulation

Signal type 48468MHz with 16Hz AM modulated

EC (mS) 2 pH 622


B1 P1 795 16Hz AM 13dBm Healthy NA 620 3543 175 B1 34904

P2 799 16Hz AM 13dBm Healthy NA 617 339 182 B2 35639


P4 880 16Hz AM 13dBm Healthy NA 690 3632 190





B2 P9 974 16Hz AM 13dBm Healthy NA 771 3798 203








B6 P33 682 None None Healthy NA 494 2628 188

P34 633 None None Healthy NA 426 2058 207








Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622

Batch Plant Weight (g) Signal type Signal level Plant cond Electrode cond Weight ret (g) Return in Start weight Ave Weight




























During the subjection of plants to a low energy amplitude modulated electromagnetic

field one noted very distinctly the vigour and healthy status of the stimulated plants in

comparison with the control plants just a few meters away The experimental plants

were purely from a point of interest divided into a set of plants close to the startend

of the transmission line and another set close to the centre of the transmission line

Plants near the end of the transmission line outperformed the control by a ratio of

10871

In height the experimental plants grew 1542 (1542) times faster than the control

and in plant mass the stimulated plants yielded a greater mass of 5241 (524)

Picture 512 Plant mass densities and spread for RF stimulated (left ndash average at 1150mm) and control (right at 510mm) plants




Three plants were between the different batches of plants for observation status only

The results were as follows


Before batch 1 Between batch 1 and 2 After batch 2

347 increase 352 increase 353


Although the data between the experiment and the control differs significantly the

Kolmogorov Smirnov test (KS) was used to obtain statistical values The KS test

shows that the maximum difference between the cumulative distributions D is

10000 with a corresponding P of 0000

Control ndash plant height

Mean = 4536 95 confidence interval for actual Mean 4377 through 4695

Standard Deviation = 223 Highest growth = 494 Lowest growth = 422

Median = 4540 and average Absolute Deviation from Median = 168





sdev = 1061

Growth parameters ndash experiment 4



Median = 6810 and Average Absolute Deviation from Median = 308







sdev = 1074

Figure 57 Logarithmic comparison plot showing difference in height data sets [225]

Control ndash plant mass

The maximum difference between the cumulative distributions D is 10000 with a

corresponding P of 0000


Standard Deviation = 920 Highest mass gain = 475 Lowest mass gain = 193

Third Quartile = 403 First Quartile = 288 Median = 3420 and Average

Absolute Deviation from Median = 644





sdev = 1485



Mass accumulation parameters ndash experiment 4


Standard Deviation = 112 Third Quartile = 1757E+03 First Quartile =

1596E+03 Median = 1652 and Average Absolute Deviation from Median =

842

Highest plant mass gain = 1876E+03 Lowest plant mass gain = 1485E+03


normal distribution has a mean = 1682 and sdev= 1264



sdev = 1078

Figure 58 Logarithmic comparison plot showing difference in mass data sets [225]

Again the test shows that the growth and mass accumulation of the control and

treatment plants are significantly different The maximum difference between the

cumulative distributions D is 10000 with a corresponding P of 0000 As values

are so small the null hypothesis can be rejected indicating that applying 16Hz

Amplitude Modulated signals via an un-terminated transmission line square does

cause standing waves that in turn are absorbed by the plants This captured energy

does cause a significant change (D) in growth and mass



The hypothesis proved to be correct in that stimulating plants with varying pulsed

energy in a hydroponic system will cause the plant to grow faster produce heavier

and more plant material

5912 Reasons for positive plant responses to RF fields

The leaky transmission line

Working with antennas is problematic as they may cause undesired levels of

radiation A second problem is the acquiring of a frequency licence One would

also be very limited to usable frequencies as the allocated frequencies are

regulated by the authorities Using leaky transmission lines this problem was

overcome During the experiment it was discovered that plants near both the ends

of the transmission line obtained slightly higher plant mass than the more centre

position plants by a ratio of 10321 (1032) Growth height for the centre placed

plants were 1021 (102) more than for the plants near the end of the line


To find a reason one has to look at characteristic impedance The energy at the end of

the line cannot just disappear into space If this were be possible there would not be a

need to use antennas What happens is that the energy is either lsquoreflected back to the

sourcersquo or it is lsquoabsorbed by a loadrsquo To be fully absorbed the line impedance must

match the load impedance

In this research the line was left open as an un-terminated line (Figure 59) However

the plants placed in the field in between the transmission lines acted as load to the

line Because the plants did not 100 represent the transmission line impedance

some of the energy followed the path of reflection back to the source Along the way



more and more plants absorbed some of the power but never all of it due to the

impedance mismatch

Because one cannot have two voltages at the same time at a specific point on the line

the forward movement of the original and the reverse of the reflected wave will add

and subtract For an open terminated line the reflection will be in phase with the

original or forward signal This implies that the signals superimpose onto one another

and double the original wave to be 2x the voltage if there are no losses However the

output of the transmitter is only the forward power minus the reflected power in the

transmission line Should the transmitter power be say 1 watt and for example 06

watt is reflected back then the total transmitter output is 1 watt but the forward power

on the line will be 16W

510 Plant response regarding flowering and fruiting when applying stimulation to hydroponic grown plants

5101 Flowering

Plants stimulated by DC or 16Hz AC square waves and those under the leaky

transmission lines all behaved similarly For DC stimulated plants flowering was

delayed on average for 4 days For both the square wave and the RF transmission

lines the delay was on average 7 days

5102 Fruiting

Fruits were harvested in the second week of January 2012 when the third tomato truss

was showing the first signs of decolouring Trusses were earlier clipped to contain

only 5 tomatoes each From the first and second truss the four heaviest tomatoes were

selected The tomatoes harvested from some of the experimental plants were allowed

a week to mature as the RF treated tomatoes which started to flower one week later

were not fully deep red in colour



Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None

Largest tomato 169g 187g 286g 168g

Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g

Smallest tomato 100g 132g 154g 80g

Largest diameter 72mm 81mm 99mm 70mm

Smallest diameter 65mm 62mm 71mm 52mm

Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g

Average tomato size 140g 160g 200g 128g

Comment Most fruit per tree

but smaller

Heaviest fruit per

tree

Table 519 Fruit sizes

There was no noticeable difference in taste or colour between tomatoes from the

control plant and those from the experimental plants This of course does not mean

that there are no differences but this did not form part of the scope and was excluded

Picture 513 Fruits were limited to 5 tomatoes per truss



Picture 514 various fruit sizes for each experiment ranging from largest to smallest

511 Plant response regarding pests and diseases when applying stimulation to plants in a hydroponic system

5111 Pests

On plants using DC stimulation 3 types of pests were identified Thrips

(Thysanoptera) per cluster of flowers were on average 21 when shaken out on a sheet

of white paper Aphids (Family Aphidoidea ) were 12 insects and larvae (for worst

infected leaf) Regarding White Flies (family Aleyrodidae) infestation was 16 adult

and visible larvae This compared similarly to the control plants where Thrips were

22 Aphids 11 and White Flies 16

For the 16Hz pulsated plants only White Flies (7 averages) and Thrips where 2 insects

were on average collected from the two trusses of flowers Plants under the RF

transmission lines had zero pests although some winged thrips were often seen on top

of a leaf but they all disappeared when the plant was inspected 15 minutes later

5112 Bacterial and fungal diseases

No bacterial diseases were detected during any of the experiments However plants

used for control and those where DC was applied both suffered from early blight

(Alternaria solani) in a very light degree Infected leaves were continuously removed

Powdery mildew (Erysiphales) appeared during prolonged wet periods on both the

control and DC stimulated plants Plants connected to 16Hz pulsed energy and those

under the RF transmission lines were less susceptible to fungal attacks with almost no

visible traces of fungus



512 RF interference

An Alan Broadband ZC 300 RF field strength tester was used to detect RF radiation

on the outside of the transmission lines At a distance of two meters away from the

leaky lines RF signals were down to 30 (compared to that in between the two

transmission lines) and at 25m zero signal was detected

Picture 515 Alan Broadband ZC 300 RF field strength tester

513 Conclusion

This research showed that signals for stimulation can be injected or applied via direct

plant contact water or nutrient medium antenna or by any other means for example

conducting plates or electrodes Finding and developing a practical implementable

type of plant stimulation either fixed or transmitting using frequency andor

electromagnetic signalsfields is not planned and developed in a month or two Then

the issue of controlling the nutrient strength was also a major challenge especially

when optimum levels are required to give reliable experimental results

A common factor that exists between plants and electricity is the correlation between


cell Plant cells experience resting potentials between the negative interior and

positive exterior of the cell in a range of 10 to 200mV It is this potential that that

causes nutrients to move into the cell [223] Should a signal possess time or



timeamplitude-varying electromagnetic properties then it will hasten the effect of

creating these current densities in plant tissue This effect is even more potent when

pulses or square waves are being used [224] This is because pulses with sharp rising

edges rapidly increase the field strength breaking ionic bonds As the resonating

frequencies of potassium are quite low at 16Hz it makes sense to use this frequency to

bounce off the tightly packed positive calcium ions on the plant cell wall However to

prevent plant structural damage one needs to momentarily return the calcium ions and

it is for this reason that an amplitude modulated wave was used to modulate the 16 Hz

square wave

In the past lots of time was spent by researchers about plant stimulation but none were

really practically implementable or were not utilising leaky transmission lines The

biggest obstacle that was hindering farmers and researchers from using radio

frequencies was the troublesome application for frequency bandwidth use and

availability of suitable frequencies from the relevant authorities For this study the use

of leaky transmission lines was investigated and proved suitable to carry radio signals

to the plant Although this research used proper transmission lines the farmer in a

practical setup will use ordinary galvanised wires or simply the support wires that

exist naturally in a hydroponic setup This research shows that utilising radio signals

via a radiating medium is not an obstacle anymore because radiation is only between

the two transmission lines and not into space close air or free air This now for the

first time opened the practical use of any frequency or range of frequencies for plant

stimulation

The concept of using transmission lines arises from the fact that these lines are there

to carry or guide information from one point to another Altering a transmission line

to leak and operate like an antenna instead of relaying a signal is what was achieved

in this research This can be appreciated when the reader recalls that radiation from an

open wire can take place when the wire is terminated in its characteristic impedance

PJJ van Zyl Chapter 6 Conclusion


Chapter 6 Conclusion

61 Introduction

There are numerous methods to stimulate plant growth These so called bio-

stimulators like electric and magnetic fields sound light and radio frequencies allows

for a low current and voltage to flow It is believed that this stimulation cause ionic

voltage changes in the plantsrsquo main nutrient salts There are also ionic changes in the

cell wall which regulates the movement of nutrients into the cell Using energised

ionic salts it is relatively easy for them to penetrate the cell membrane allowing the

plant to grow faster produce more plant mass with an increase in fruit production

Additionally using electrical stimulation may produce fruit with a longer shelf life

Plants may also pose higher pest resistance and less bacterial and fungal growth

Finding points of application and the implementation thereof is complicated by the

fact that plant growth induced by electrical voltages does not always correspond to the

sign of the applied voltage [232 233] Sometimes the effects of voltages and currents

are resulting in different outcomes ie stimuli are not always voltage dependant [234]

Research also indicates that both magnetic as well as electric fields are effective but

there is a definite favour for low frequencies by plants [235 236] This of cause

makes perfect sense as this effect of using low frequencies was found beneficial by

this research study

In this chapter various outcomes from the different experiments are analysed and it is

expected that this contribution could add valuable information not only to enhance

and make production more affordable but also to ensure stable food production for

future generations



62 Summary of research

621 The uniqueness of these research studies

This research focuses firstly on the stimulation of plants in hydroponic systems

Although research was done previously on plants these were mainly focused on plants

planted in a soil medium Research about using radio waves as stimulation for plants

in a hydroponic system is very limited or non-existent

Conducting a research study where one of the outcomes is to find a practically

implementable method is the second factor that makes this study unique Many

researchers make use of plant growth algorithms simulation models and software

where the actual implementation phase is never part of the research Others make use

of laboratory experiments using artificial lights and Faraday cages

Thirdly is that the actual results of the preferred stimulation model were compared to

existing methods and proved to outperform these methods

622 Purpose of research

The first purpose of this study was to find out if plants respond positively when radio

energy when was applied to them when grown in a hydroponic system When plants

are planted in a soil medium various inhibitory plant growth conditions occur

Examples are retarded growth and production output when the plant experience

periods of dryness or nutrient deficiency This is not the case with hydroponic systems

and is why growing plants hydroponically is so popular

A second purpose was to find and implement a practical method to accomplish the

said preferred stimulation

The third purpose was to compare the preferred model to existing methods of

stimulation to test its effectiveness



623 Facts about plant cells

To understand plant growth one needs to be familiar with the following facts

Plant cell membranes are negative with respect to the ions around it

Plant cells firmly attract positive ions creating a barrier around the membrane

especially the very positive calcium ions

Plant cells gain kinetic energy from EMF stimulation

Potassium ions exist in their thousands around the membrane and which if

excited at their resonance frequency (32Hz) will bounce against the very

tightly packed positive calcium ions removing their dense barrier around the

cell membrane

With the calcium ion removed and replaced by the less positive potassium

ions more nutrients are able to rush into the cell causing an acceleration in

growth

However removing calcium ions for prolonged periods will cause structural

collapse of the cells as well as the plant and for this reason time must be

allowed for these ions to return

A suitable compromise is to make use of amplitude modulation where the

period of low energy will accomplish the return of the calcium ions

624 The practical issue of RF transmission

For transferring radio energy from a source to the plants one requires an antenna

However regarding the issue of a practically implementable stimulation system one

has to remember that frequencies are regulated by The Independent Communication

Authority of South Africa (ICASA) Using radio frequencies to aid in the stimulation

of plants is therefore problematic as the frequencies available in the public domain are

not the preferred frequencies for plant stimulation

To overcome the frequency related problem this research study used a unique method

of leaky transmission lines This is in contrast with previous research where quad

antennas (quads fit the hydroponic layout) were used As plants are planted in rows

next to one another the transmission line actually fits the hydroponics layout better



than any type of antenna and could simultaneously become part of the trailing

structure in a hydroponics setup


When applying stimulus to plants one needs a way to evaluate how the plant

responds This enables the researcher to establish if maximum absorption from the

stimulus occurred in the plant

As previous research pointed out appropriate signal levels and duration times

when applying stimulus this study did not focus on either of them However the

purpose of the first experiment was to find which stimulation application position

is most effective according to methods illustrated in section 410 During this

experiment direct stimulation of DC voltages 5Volt (plusmn01V) and square wave

signals 16Hz (5V amplitude) was applied according to the following connections

o Root and root


o Root and water

It was found that the positive electrodes were slightly corroded and can be blamed on

electrolysis in the highly conductive nutrient solution

Figure 61 Selection of appropriate stimulation points

Using DC the tiproot combinations yielded maximum growth at 3324 while

applying 16Hz the rootroot combinations yielded the highest growth From this it is

clear that the tiproot and rootroot are the most favourable types of application points

(Chapter 5 Table 53)




Applying a DC current where the top (tip) part of the plant was connected to a

positive potential definitely favoured plant growth and mass accumulation

performance The performance was 484 more for the mass when compared to

plants where the negative was connected to the tip part In relation to growth when the

positive potential applied to the top resulted in 147 more growth compared to

plants where the negative was at the tip

From this one can conclude that DC stimulation is exceptionally suited for use on

plants where mass accumulation rather than growth height is preferred This may

include low growing plants like grass herbs and fodder

Figure 62 Growth and mass outcomes from stimulation by direct current




Applying a 16Hz square wave signal (DC amplitude +5V) yielded a similar response for

growth as when direct current was applied

Figure 63 Growth and mass outcomes from stimulation by 16Hz square wave

However the mass accumulation was much lower at 1441 when comparing it to DC

stimulation where it was 1887 (446 difference) Again the root to tip application

proved to be the most beneficial


When 16Hz amplitude modulated (AM) signal was used plant growth appeared to be

the highest from all three kinds of stimulation used The result was a difference of

184 compared to plants in the direct current stimulated experiment This is 542

more than the growth of the control plants

Figure 64 Growth and mass outcomes from stimulation by 16Hz AM wave

The mass accumulation however was an astonishing 5238 of that of the control

This was 3351 more than the return from any other experiment Plants at the ends



of the transmission line utilised the spilled energy to their advantage to produce

163 more mass than plants in the centre of the transmission line Interestingly the

growth was little effected between centre and end plants

Fruits weighed in at an average of 2003g per 10 tomatoes (2 trusses of 5 each)

Compared to the control this was 719g heavier Fruit weight was also more than those

obtained from the other two stimulation experiments

629 The effect of plant stimulation on neighbouring plants

For the DC stimulated experiment observation plants number two and three had a

positive correlation meaning that energy must have been transferred to these

observation plants This was probably due to the fact that these plants (where a

voltage was connected to the tip) touched adjacent stimulated plants

For the 16Hz experiment there was no evidence of stimulation Plant 1 was slightly

positive while plant 2 slightly negative with respect to the control For RF there was a

clear transfer of stimulation energy to the observation plants as they were also placed

inside the RF field Interestingly Plant 1 responded worse as it was about 10cm

outside the transmission line end

6210 Fruit production

Although fruit appearance size and volume as well as pest resistance was not a direct

objective of this study it is important that it should be included for comparison and

reference analysis

Fruit mass varied significantly between the different types of stimulation with the RF

stimulated plants bearing the heaviest fruits Interestingly this higher mass

corresponds to higher plant volume as well as higher mass of these plants It can thus

be concluded that the RF stimulated plants produce more as well as heavier fruits The

diameter of these fruits is also greater Except for a delay (7days) the fruit appearance

and taste was similar to that of the control plants The following graphs illustrate the

various fruit size and fruit mass



Figure 65 Fruit size comparison between the different stimulation techniques

Figure 66 Plant yield

6211 Plant pest resistance

Insect infestation was much less for plants stimulated by 16Hz square wave and there

were almost no pests on the plants stimulated by RF energy However none of the

stimulation techniques used prevented fungal attacks on plants



Figure 67 Plant insect infestation using different stimulation techniques

63 Conclusions

Past research mainly focused on radiation from high voltage transmission lines and

their effect on plants nearby This study is about utilising low energy signals from RF

transmission lines for the benefit of plant growth and production The use of radiating

transmission lines eliminates common problems like radiation interference and

licence application protocols when ordinary antennas are utilised



what is clear is that there is a significant increase in plant and fruit mass by as much

as 523 and 56 respectively On top of these insects generally infected the plants

stimulated with RF less Stimulated plants also had a more intense and healthier

appearance

It was also confirmed that ordinary practised stimulation techniques like direct current

and square wave signals proved to positively enhance plant growth and production

when applied to plants in a hydroponic system

Results can be summarised as follows

Stimulating plants in the root to root and tip to root regions produced better

results than when plants were stimulated in the root to water zone

Tip to root application is superior to root to root application



Applying a positive voltage to the plant tip is preferred over a negative voltage

at the tip This is true for both an increase in growth and for mass

accumulation

RF stimulation using a leaky transmission line is preferred over direct current

stimulation

RF stimulation using a leaky transmission line is preferred over 16Hz square

wave stimulation

Using leaking transmission lines does not cause RF disturbances as zero RF

energy was detected 24m away from the transmission lines Observation

plants placed 10cm outside the line also confirmed this quick decaying

radiation field

Applying RF energy as stimulation causes a plant to increase its mass by as

much as 500 over non-stimulated plants and 335 if other forms of

stimulation are used

Stimulating plants with a 16Hz amplitude modulated RF energy causes a plant

to produce fruit with an average weight of 200g compared to a non-stimulated

plant where the average mass is only 128g

RF stimulated plants are less susceptible to attract insects

Figure 68 Growth and mass comparison using different plant stimulation techniques



64 Factors that could have had an influence on research outcomes

As with any practical research study there are always practical factors that could

influence results unlike when simulation models are used In this study optimum

conditions that could have had a positive impact on the experimental performance

included

The sophisticated built electronic dosage controller that kept nutrient levels at

optimal levels This would be more difficult in large scale operations

The transmission lines were large diameter low permittivity copper

conductors that may not be possible in a typical hydroponic setup due to the

cost factor and possible chance of theft

In a typical hydroponic setup plants are allowed to only grow vertically with

very little to no side shoots In such a case only the extra mass from the fruit

and not the plant itself would be to the advantage of the grower

High precision laboratory modulators were used during the experiments while

a typical hydroponic setup will rather use cheaper industrial types

Conducting experiments from mid-spring to mid-summer could have been an

advantage as slow kick off (early spring) and slow maturing (late autumn) was

bypassed

Negative growth parameters that could have affected the results included

Pre-trial experimentation on modulation depth

During mid-summer the plants were partially shaded for about an hour due to

the position of the experimental platform and the position of the sun

The presence of steel reinforcing in concrete structures in close proximity of

the plants could have had a limited effect on available RF energy



65 Recommendations and future research

As it is impossible to study all variables in a single study future research may provide

more clarity on plant mass versus plant growth ratios when fruit production is of

importance From the results of this study it is unclear if the orientation of the

transmission lines might have had an effect on the growth versus height parameters

Some recommendations are

Use different nutrient strengths

Combine with other methods of stimulation like light or ultra sound

Conduct the study over a longer period of time

Use different plants to conduct the experiment

Expand transmission line research to field-grown crops

Perform the study over a full season

Increase the sample of plants used

Perform the study at different places

Try out different field strengths

Experiment with the position of the leaky transmission lines ie vertical

horizontal or diagonal

Replace the two wire transmission line conductors with say parallel lines ie

use 4 lines to have better growth as well as mass distribution

Figure 69 the four-wire parallel transmission line

where 2

2 2138log1 ( 2 1)

LZod L L



Construct the setup with different materials to relay the RF signals

Replace the transmission lines with antennas and screen the setup (wire mesh

screen inside a tunnel)

PJJ van Zyl References


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[146] Akdagli A Guney K and Karaboga D (2002) Pattern nulling of linear

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[147] Akdagli A and Guney K (2004) Null steering of linear antenna arrays by

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[148] Guney K and Akdagli A (2001) Null steering of linear antenna arrays

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375-383

[150] Mouhamadou M Vaudon P and Rammal M (2006) Smart antenna

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[151] Mouhamadou M Armand P Vaudon P and Rammal M (2006)

Interference suppression of the linear antenna arrays controlled by phase

with use of SQP algorithm Progress In Electromagnetics Research PIER

59 pp 251-265





[153] Guney K Durmus A and Basbug S (2009) A plant growth simulation

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[154] Shenglian Lu Xinyu GuoWeiliang Wen Teng Miao Boxiang Xiao

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[155] Luo Wei-qiangYu Jian-tao and Huang Jia-dong (2008) Bionic

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[156] Zhe Yu Yong et al (2009) Reconfiguration of distribution network based

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[157] Rathnayake AP Kadono H Toyooka S and Miwa M (2008) A novel

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[158] Kadono H and Kobayashi K (2010) Improvement of dynamic range of

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[159] Valone TF (2003) Bioelectromagnetic healing its history and a rationale

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[160] Tesla N (1898) High frequency oscillators for electro-therapeutic and

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477

[161] Polk C and Postow E (1986) Handbook of biological effects of

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[162] Collins English dictionary Complete amp unabridged 10th ed Carbon credit

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[163] Dannehl D Huyskens-keil S Eichholz I Ulrichs C and Schmidt U

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[164] Bruyn LD Scheirs J and Verhagen Ron (Feb 2002) Nutrient stress

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[165] Huberty AF and Denno RF (May 2004) Plant water stress and its

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[166] Jonak C Kiegerl S Ligterink W Barker PJ Huskisson NS and Hirt

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vol 93 pp 11274-11279

[167] Lam-Son Phan Tran Urao T Qin F Maruyama K Kakimoto T

Shinozaki K and Yamaguchi-Shinozaki K (2007) Functional analysis

of AHK1ATHK1 and cytokinin receptor histidine kinases in response to

Abscisic Acid drought and salt stress in Arabidopsis Proc Natl Acad

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[168] Sakuma Y Maruyama K Qin F Osakabe Y Shinozaki K and

Yamaguchi-Shinozaki K (2006) Dual function of an Arabidopsis

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18822-18827

[169] Shepherd T and Griffiths DW (2006) The effects of stress on plant

cuticular waxes New Phytol vol 171 pp 469-499


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[171] Mengel K Kirkby EA Kosegarten H and Appel T (eds) (2001)

Principles of plant nutrition Dordrecht Kluwer Academic Publishers pp

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[172] Luumlttge UE Beyschlag W and Buumldel B (eds) (2009) Progress in

botany vol 71 Heidelberg Springer pp 176-177

[173] Anholt RRH and Mackay TFC (eds) (2009) Principles of behavioral

genetics USA Academic Press pp 24-30

[174] Blinks LR (1955) Some electrical properties of large plant cells In T

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John Wiley amp Sons pp 187-212

[175] Blinks LR (1949) The source of the bioelectric potentials in large plant

cells Proc Natl Acad Sci 35 pp 566-575

[176] Kertz MG Electronic stimulation of plants U S Patent 5464456

November 7 1995

[177] Malone M (1994) Wound-induced hydraulic signals and stimulus

transmission in Mimosa pudica L New Phytol vol 128 pp 49-56



[178] Kholodova VP Meshcheryakov AB Rakitin VY Karyagin VV and

Kuznetsov VV (2006) Hydraulic signal as a ldquoprimary messenger of water

deficitrdquo under salt stress in plants Biomedical and Life Sciences vol 407

number 1 pp 155-157 [online] [Accessed 24 August 2010] Available

from lthttp0-

wwwspringerlinkcomujlinkujaczacontentr0n11600433584u1fulltextp

dfgt

[179] František B (ed) (2009) Plant-environment interactions Heidelberg

Springer pp 9-10

[180] Sun Rise and Set Times (2004) [online] [Accessed 23 August 2010]

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[182] Went FW (1953) The effect of temperature on plant growth Annual

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2023gt

[183] Ford MA and Thorne GN (1973) Effects of atmospheric humidity on

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[184] Brown BT (2006) A new screening procedure for detecting plant growth

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[186] Climate and temperature South Africa Johannesburg (2008-2010)

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[187] Karlsson L (1972) Instrumentation for measuring bioelectrical signals in

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ieeexploreieeeorgujlinkujaczasearchsearchresultjspnewsearch=truegt

[188] Lautner S Grams TEE Matyssek R and Fromm J (2005)

Characteristics of electrical signals in poplar and responses in

photosynthesis Plant Physiology Whole Plant and Ecophysiology 138


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[189] Water soluble fertilisers (2010) [online] [Accessed 4 September 2010]

Available from lthttpwwwoceanagcozaindexphpid=11gt

[190] Houle G Morel L Reynolds CE and Sieacutegel J (2001)The effect of

salinity on different developmental stages of an endemic annual plant Aster

laurentianus (Asteraceae) Am J Bot vol 88 pp 62-67

[191] Howard RJ and Mendelssohn IA (1999) Salinity as a constraint on

growth of Oligohaline Marsh Macrophytes II Salt Pulses and Recovery

Potential Am J Bot vol 86 pp 795-806

[192] Sanan-Mishra N Pham XH Sopory SK Tuteja N and Swaminathan

MS (2005) Pea DNA Helicase 45 overexpression in tobacco confers high

salinity tolerance without affecting yield Proc Natl Acad Sci U S A

vol 102 pp 509-514

[193] Zandt PAV and Mopper S (2002) Delayed and carryover effects of

salinity on flowering in Iris hexagona (Iridaceae) Am J Bot vol 89 pp

1847-1851

[194] Johannesburg Metro water quality report (2009) [online] [Accessed 18

January 2011] Available from

lthttpwwwreservoircozalocal_authorities12_month_

averagejohannesburg_12monthpdfgt

[195] Peckenpaugh D (2004) Hydroponic solutions vol 1 Hydroponic

growing tips 1st ed Corvallis New Moon Publishing Inc p105



[196] Maheshwari LKandAnand MMS (eds) (2006) Analog electronics

New Delhi Prentice Hall pp 113-121

[197] Op amp power supply rejection ratio (PSRR) and supply voltages [online]

[Accessed 8 September 2010] Available from

lthttpwwwanalogcomstaticimported-filestutorialsMT-043pdfgt

[198] Lund EJ (1931) Electric correlation between living cells in cortex and

wood in the Douglas Fir Plant Physiology pp631-652 [online] [Accessed

3 September 2010] Available from lthttp0-



plants and related topics In Volkov AG (ed) Plant electrophysiology

theory and methods Heidelberg Springer pp 247-267

[200] Lemstroumlm K (ed) (1904) Electricity in agriculture and horticulture

London Electrician Publications pp 12-33

[201] Luo Wei- qiangYu Jian- tao and Huang Jia- dong (2008) Bionic


Engineering and Applications 44 pp 57- 59

[202] Muchtar FB (2008) Effect of some plant growth regulators on the growth

and nutritional value of Hibiscus sabdariffa L (Red sorrel) International

Journal of Pure and Applied Sciences pp 70-75 [online] [Accessed 2

August 2010] Available from

lthttpwwwijpascomarticleviewFile29852186gt

[203] Martiacutenez LS Verde S J Maiti RK Oranday AGaona H Aranda

E and Rojas M (1999) Effect of an algae extract and several plant growth

regulators on the nutritional value of potato (Solanum tuberosum L var

gigant) Arch Latinoam Nutr 49(2) pp 166-170 [online] [Accessed 2


lthttpwwwncbinlmnihgovpubmed10488397gt

[204] Wheeler RM Mackowiak CL Sager JC Knott WM and Berry

WL (1996) Proximate composition of CELSS crops grown in NASAs

Biomass Production Chamber Adv Space Res 18(4-5) [online]



[Accessed 2 August 2010 Available from


[205] Akman Z (2009) Effects of plant growth regulators on nutrient content of

young wheat and barley plants under saline conditions Journal of Animal

and Veterinary Advances vol 8 Issue 10 pp 2018-2021 [online]

[Accessed 1 August 2010] Available from

lthttpwwwmedwelljournalscomfulltextdoi=javaa200920182021gt

[206] Swart Prof PH (2005) Hydromaster hydroponics manual Schematic At

Pretoria 0506181

[207] Heathcote M and Reeves EA (eds) (2003) Newnes electrical pocket

book 3rd ed Great Britain George Newnes pp 255-259

[208] Earth spike kit (2010) [online] [Accessed 14 September 2010] Available

from

lthttpwwwgooglecozaimgresimgurl=httpwwwcanfordcoukimage

sitemimageslarge3138-01jpggt

[209] Electromagnetic fields and public health Fact Sheet No 322 World Health

Organization (2007) [online] [Accessed 21 September 2010] Available

from lthttpwwwwhointmediacentrefactsheetsfs322enindexhtmlgt

[210] Electric and magnetic fields associated with the use of power (PDF)

National Institute of Environmental Health Sciences (2002) [online]


lthttpwwwniehsnihgovhealthdocsemf-02pdfgt

[211] Wilson BW Stevens RG and Anderson LE (eds) (1990) Extremely

low frequency electromagnetic fields The question of cancer Columbus

Ohio Battelle Press pp 362-363

[212] Bawin SM Kaczmarek KL and Adey WR (1975) Effects of

modulated VHF fields on the central nervous system Ann NY Acad Sci

247 pp 74‐81

[213] Jokela K Puranen L and Sihvonen A‐P (2004) Assessment of the

magnetic field exposure due to the battery current of digital mobile phones

Health Physics 86 pp 56‐66

[214] Sage C Johansson O and Sage SA (2007) Personal digital assistant

(PDA) cell phone units produce elevated extremely low frequency



electromagnetic field emissions [online] [Accessed 21 September 2010]

Bioelectromagnetics DOI 101002bem20315 Published online in Wiley

InterScience (wwwintersciencewileycom)

[215] Henderson L (2001) Invasive alien plants in South Africa [online]


lthttpwwwsabonetorgzaaliensaliens_part3_asteraceaehtmgt

[216] Frank N (1999) Nutrient deficiency symptoms [online] [Accessed 15

July 2011] Available from

lthttpwwwthekribcomPlantsFertilizernutrient-deficiencyhtmlgt

[217] Blackman VH (1919) The compound interest law and plant growth

Annals of Botany 33 pp 353-360 [online] [Accessed 26 August 2010]

Available from lthttpaoboxfordjournalsorgcgireprintos-

333353maxtoshow=gt


plants Physiol Plant 43 pp 458ndash463


fields [online] [Accessed 15 March 2011]

httpwwwradiationresearchorggoldsworthy_bio_weak_em_07pdf

[220] Lavenda Bernard H (1985) Nonequilibrium statistical thermodynamics

John Wiley amp Sons Inc p 20

[221] Peng HB and Jaffe LF (1976) Polarization of fucoid eggs by steady

electrical fields Dev Biol 53 pp 277ndash284

[222] Novaacutek B and Bentrup FW (1973) Orientation of Fucus egg polarity by

electric ac and dc fields Biophysik 9 pp 253ndash260

[223] Blinks LR (1955) Some electrical properties of large plant cells In

Shedlovsky T (ed) Electrochemistry in biology and medicine Chapman

and Hall pp 187-212

[224] Adey WR (1990) Electromagnetic fields cell membrane amplification

and cancer promotion In Wilson BW Stevens RG and Anderson LE

(eds) Extremely low frequency electromagnetic fields The question of

cancer Columbus Ohio Battelle Press pp 211ndash249

[225] Kolmogorov Smirnov Test (2011) [online] [Accessed 5 December 2011]

Available from lthttpwwwphysicscsbsjuedustatsKS-testhtmlgt





Theory amp methods Berlin Heidelberg Springer‐Verlag pp 247‐267

[227] Blackman CF (1990) ELF effects on calcium homeostasis In Wilson

BW Stevens RG and Anderson LE (eds) Extremely low frequency

electromagnetic fields The question of cancer Columbus Ohio Battelle

Press pp 189-208

[228] Simonovichs B (2011) Twin-rod and rod-over-plane transmission line

geometries [online] [Accessed 15 October 2011] Available from

lthttpbloglamsimenterprisescom20110301twin-rod-and-rod-over-

plane-transmission-line-geometriesgt



[230] Duffy O (2011) RF two wire transmission line loss calculator [online]


lthttpvk1odnetcalctltwllchtmgt

[231] Bryant J Bowers B and Patch N (2003) DXinginfo A second look at

fabricating impedance transformers for receiving antennas


electrical fields Dev Biol pp 277-284

[233] Mycielska ME and Djamgoz MBA (2004) Cellular mechanisms of

direct-current electric fields effects Galvanotaxis and metastatic disease J

Cell Sci pp 1631-1639


electric ac and dc fields Biophysik pp 253-260

[235] Jaffe LF and Nuccitelli R (1977) Electrical controls of development

Annu Rev Biophys Bioeng pp 445-476




cancer Columbus Ohio pp 211-249

PJJ van Zyl Glossary


Glossary Attenuation A loss of signal strength in a light wave electrical or radio signal usually related to the distance the signal must travel Electrical attenuation is caused by the resistance of the conductor poor (corroded) connections poor shielding induction RFI etc Radio signal attenuation may be due to atmospheric conditions sun spots antenna design positioning obstacles etc Decibels (dB) Quantification of the gain for an antenna in comparison with the gain of a dipole dBi The dB power relative to an isotropic source dBm A measure of power based upon the decibel scale but referenced to the milliWatt ie 1 dBm = 001 Watt dBm is often used to describe absolute power level where the point of reference is 1 milliWatt In high power applications the dBW is often used with a reference of 1 Watt dBW The ratio of the power to 1 Watt expressed in decibels dc ground An antenna which is a dead short to a DC current and has a shunt-fed design To RF it is not seen as a short Dipole An antenna - usually a half wavelength long - split at the exact center for connection to a feed line Also called a lsquodoubletrsquo Directional Antenna An antenna having the property of radiating or receiving electromagnetic waves more effectively in some directions than others Directivity The theoretical characteristic of an antenna to concentrate power in only one direction whether transmitting or receiving Efficiency The ratio of useful output to input power determined in antenna systems by losses in the system including losses in nearby objects Electromagnetic Interference (EMI) Any electromagnetic disturbance that interrupts obstructs or otherwise degrades or limits the effective performance of electronicselectrical equipment It can be induced intentionally as in some forms of electronic warfare or unintentionally as a result of spurious emissions and responses intermodulation products and the like EMI is also an engineering term used to designate interference in a piece of electronic equipment caused by another piece of electronic or other equipment EMI sometimes refers to interference caused by nuclear explosion Synonym radio frequency interference E-Plane and H-Plane Antenna measurements in general and radiation patterns in particular must be performed with polarization in mind Since polarization is defined as having the same orientation as an antennaacutes electric field vector it is common practice to refer to measurements aligned with either the electric vector ( E-plane) or magnetic vector (H-plane)



ERP Effective Radiated Power Field Strength An absolute measure in one direction of the electromagnetic wave field generated by an antenna at some distance away from the antenna Field Tunable Antennas identified as Field Tunable are shipped with a cut chart the installer uses to select a desired operating frequency by tuning the antenna to resonance Cut charts should be used as guidelines and are adequately accurate for many applications However Larsen recommends using appropriate RF measurement devices whenever possible for more accurate tuning Frequency The number of cycles per second of a sound wave Front-to-Back Radio Ratio of radiated power off the front to the back of a directive antenna Gain The practical value of the directivity of an antenna Gigahertz (GHz) One billion cycles per second Ground Plane A man-made system of conductors placed below an antenna to serve as an earth ground Hertz (Hz) A unit of frequency equal to one cycle per second H-Plane See E-Plane Impedance The Ohmic value of an antenna feed point matching section or transmission line at a radio frequency An impedance may contain a reactance as well as a resistance component Load The electrical entity to which power is delivered The antenna system is a load for a transmitter Mbps Megabits per second or millions of bits per second a measure of bandwidth Megahertz (MHz) 1 million cycles per second Noise Any unwanted and un-modulated energy that is present to some extent within any signal Omnidirectional An antenna providing a 360-degree transmission pattern This type of antenna is used when coverage in all directions is required PCB Printed Circuit Board Radiation Pattern The graphical representation of the relative field strength radiated from an antenna in a given plane plotted against the angular distance from a given reference



Radiator A discrete conductor radiating RF energy in an antenna system Receiver (Rx) An electronic device which enables a particular signal to be separated from all and converts the signal format into a format for video voice or data Relative Antenna Power Gain The ratio of the average radiation intensity of the test antenna to the average radiation of a reference antenna with all other conditions remaining equal Standard Impedance The nominal impedance associated with the transmission line and test equipment Standing Wave Ratio (SWR) See VSWR Transmission Line The connecting link allowing the radio frequency energy generated by the radio to be delivered to the antenna (Coaxial cable microstrip or coplanar lines in our industry) Transmitter An electronic device consisting of oscillator modulator and other circuits which produce a radio electromagnetic wave signal for radiation into the atmosphere by an antenna Voltage Standing Wave Ratio (VSWR) VSWR of the antenna is the ratio of the maximum to minimum values of voltage in the standing wave pattern appearing along a lossless 50 Ohms transmission line with an antenna as the load WAN Wide Area Network A network connecting computers within every large areas such as states countries and the world Wave Length See Basic Antenna Concepts

PJJ van Zyl Appendix A


Appendix A

Source Velizarov S Raskmark P and Kwee S (1999) The effects of radiofrequency fields on cell proliferation are non-thermal Bioelectrochem Bioenerg pp 177ndash180

ii

ACKNOWLEDGEMENTS

This research work was made possible through the help and support of family friends

and faculty colleagues at the University of Johannesburg

I owe great gratitude to my promoter Prof Mike Case for his support and for

providing direction when most needed Thank you for sharing years and years of RF

experience (and wisdom) in the most understandable way Surely prior to retirement

he had to have been a formidable favourite professor for any young student

Many thanks go to Glynne Case and Melanie Steyn for proofreading and editing the

document

A special thanks to Vikash Rameshar for the construction of the hydroponic

controller It was a privilege to guide him as a student in the design and construction

of this controller as his final B-Tech project Also thank you for helping with the

installation of the hydroponic plant

I am also very grateful for all the academic support and guidance from Hennie van der

Walt Pieter Hansen Johann Fouche and Meera Joseph

Thanks are also due to the Staff Qualifications Project Team namely Pia Lamberti

Tinyiko Shilenge and Dr Riёtte de Lange for all the training and administration

support

I also would like to thank colleagues like Brett Daniel Pat Andrew Phillip Hannes

Eugene and Nico for their interest in the study

Unending appreciation goes to my wife Ohna and children Christopher Grant and

Michael for always having to cope with an occupied study full of journal papers and

loose experimental datasheets

Thanks also go to my father Pieter for love and support throughout this study

iii

ABSTRACT




























and production

iv







stimulated plants


v

FOREWORD







Nutrient strengths



Carrier frequencies

Radiation intensity




Line termination



vi

TABLE OF CONTENTS






vii














viii













ix
















x




xi














SETS - 147 -

xii










xiii









xiv











- 153 -




11 Background








manure

























































13 Objectives









































established
























15 Research Limits




















16 Overview and Map











Plants

Hydroponics System


System Sensors


Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF


Controller data

Temperature


Plant growth








copy [7]

copy [8]



17 Chapter overview



















discussed





18 Conclusion

























21 Introduction









































22 Overview


Hydroponic methods




PH control



Electric fields





6 Latin meaning



Power density





Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas



Standing wave ratio

































possible



problem




























lettuce














































Water Pump

Air

Heaters (optional)

Acid














28 PH control




































POTASSIUM SULPHATE

(Hort Grade)


water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm


Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE


1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm




















Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)




force (E) [25]

2 2

F KQq KQ Eq d q d











































8310 ( )

c wheref









216 Power Density












24PtGtPfd where






Pt GtEIRP orLbo Lbf
























energy [36]








controlled [37]















2

2ESAR where












[ ]ln[ ]eq K

i

KRTE wherezF K




















the prey [45]











222 Photosynthesis












223 Bio-stimulation






224 Quad antennas

















313944Reflector( )

29718Director( )


mf Mhz

mf Mhz


tuning inductor



























included then


ErpEf
















provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing


Outputs for

Heater(s)

Fans


Nutrient pump

Acid pump

Nutrient adjustment

Aerator





229 Conclusion

















31 Introduction







production exists












outlined

32 Overview




























Plant signalling






























plant growth
















porous















wire layouts










































certain situations













Frequency Band
















tissue of the plant


















91]
























sections
























plants was observed






























[115]
































[119]












































fermentation [125]















































[132]




of 10 to 200μV [133]








of these fields are

lnRT CoEiozF Ci




become porous






















[141]











al [143]









1 1( )( ) ( )( ) WA

A W


RGR ULR SLA LWF













certain direction



Dataset Date

t1 t2


1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372



Input Output

Weights


Time Leaf Area





Mean Unit Leaf Rate



























0

0

90

90

( ) ( ) ( )o dg W F F










[156]






























and Abraham Liboff












315 Conclusion





credits 12[162]











41 Introduction






168 and 169]















of this thesis











growth of a plant




and ventilation




growth




hisher environment



aspects of it






42 Overview





























43 Inside the Plant









algae [172 173]



























some stomata






451 Light factor

















be used [181 182]






OrsquoLeary [185]






35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42




35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66







July





month
























those in humans

































Hydrogrow





Nitric acid (58)



































48 PH Control













49 Structure Design













were considered




411 Constraints








public
























412 Measurements






required impedances




impedance







importance



determined from













source






cc

out

VPSRRV

















414 Types of Plants





415 Growth Dynamics










pulse arrives







hydroponic system











4181 Objective




plant

4182 Hypothesis



4183 Range



connections



































4185 Procedure

Hydroponic setup









the nutrient level












overflow








Nutrient solution


analysis




Common ground

















Plant preparation




Stimulation








following manner





Connection





Connection




Group 3 - Control
















Connection






Connection






4188 Management

















Maintenance




2 22 2 2 2













4191 Objective






4192 Hypothesis


4193 Range








1x Oscilloscope








4195 Procedure



Common ground


Plant preparation







Stimulation









following manner



Batch 1 Batch 2




Batch 5

None Plants 17-24














Connection




Group 3- Control



4198 Management



4201 Objective






4202 Hypothesis




4203 Range


















4205 Procedure



Common ground


Plant preparation







Stimulation










Batch 5

None Plants 17-24














Connection




Group 2- Control





4208 Management



Experiment 4

4211 Objective






4212 Hypothesis


4213 Range























4215 Procedure



Common ground


Plant preparation






five days

Stimulation












Batch 6

Plants 33-40














Connection




Group 2- Control



4218 Management


422 Conclusion

















gardeners




51 Introduction






properties






















52 Overview











Experimental plants



























experiment






experiments



Conclusion

53 Layout and setup

531 The setup












532 The structure














Testing phase of












Planting












1



























analogue display





said reference


















535 Probe design



















leakage


























hydroponic systems








1000g Hydrogrowcopy





















Container 1





Container 2




(15L)

Container 3





mark (15L)










disintegrate




2

Container 3


Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L


Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L










vegetables








make EC corrections










pH calibration




EC calibration


instruments













solution


541 Cultivars

















plants










plants 31-35




experiments



33-40



542 Plant health






Element

Leaves to

first

show

deficiency

Symptom


Phosphorus Old




Calcium New








Iron New

Leaves turn yellow









Inhibited flowering





















plant to another



























amplifiers












second IC

































561 Introduction






growth










energy cycle






















node connections

o Root and root


o Root and water


































Connection

Response Notes


positive





Connection

Response Notes























EC (mS) 18 pH 641








P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316


P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307





P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314


P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311




Control


P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243












569 Discussion




















571 Introduction













application



Chapter 565)

o Root and root


















Connection

Response Remark



Group 3- Control



Connection

Response Remark



Group 3- Control








Experiment 2 Height

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641



























Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641





































13581 (1358)





ratio of 18871 (1887)







576 Discussion
















more plant material


581 Introduction























o Root and root





was followed










Connection

Response Remark



Group 2- Control



Connection

Response Remark


Group 2- Control





Experiment 3 Height

Experiment type END



EC (mS) 18 pH 641




























Mass gain







(Table 511)






512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641


































586 Discussion












sdev = 1160




361 Median = 5560







sdev = 1097




195





sdev = 1053





growth



current was applied










591 Introduction


















593 Harmonics














diffusion process


















frequencies

















the cell







02120ln[ ]DZd





o Root and root



5971 Plants






















up some space










29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M














the conductors


291016 10 ln 1

2 2s sL x x xLnr r







































22 11

RN NR



598 Field strength












Connection

Response Reason



Group 2- Control



Connection

Response Reason



Group 2- Control




shown overleaf



Height results


Mass gain



Experiment 4 Height

Experiment type END



EC (mS) 2 pH 622



























Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622



































10871

























sdev = 1061











sdev = 1074













sdev = 1485







842






sdev = 1078





































impedance mismatch











5101 Flowering





5102 Fruiting









Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None


Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g




Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g



but smaller

Heaviest fruit per

tree










5111 Pests





















512 RF interference






513 Conclusion























square wave













stimulation









61 Introduction

















this research study




future generations






































cell membrane



growth































o Root and root


o Root and water



























































reference analysis



















63 Conclusions











appearance












accumulation


stimulation


wave stimulation




radiation field















included













bypassed





























where 2

2 2138log1 ( 2 1)

LZod L L








References















from


02205gt










247-267







Press pp 326-327







Press pp 61 174



wickgt




Issue February 18
















opdfgt





deficiencyhtmlgt







Newnes p 241


















Missouri-Columbia








Available from










pp 639-642









































Rep (C) pp 216-221








Regul pp 383-415














284ndash291



207ndash212








261- 274



122








pp1ndash4








dfgt















231



pp 245ndash253





76-81


































14 pp 240-257


pp 38 585




Wiley and Sons












207 pp 1177-1178











6055768 May 2 2000




1987


October 13 1998


1987



Physiol pp 614-619



485-487










































and Medicine 51 (10) pp 1505-1515



pp 47-55













December









1134[PubMed]









[PubMed]





















pp 200-207





571-581



pp 297-307







244







633-638








375-383
















375-383








59 pp 251-265






































477


















pp 1383-1398






vol 93 pp 11274-11279





Sci U S A vol 104 pp 20623-20628





18822-18827







64-67











November 7 1995









from lthttp0-


dfgt


Springer pp 9-10






plantshtmlgt





2023gt







































vol 102 pp 509-514



1847-1851


















































Pretoria 0506181




from















247 pp 74‐81




















333353maxtoshow=gt














and Hall pp 187-212















Press pp 189-208




































Appendix A


iii

ABSTRACT




























and production

iv







stimulated plants


v

FOREWORD







Nutrient strengths



Carrier frequencies

Radiation intensity




Line termination



vi

TABLE OF CONTENTS






vii














viii













ix
















x




xi














SETS - 147 -

xii










xiii









xiv











- 153 -




11 Background








manure

























































13 Objectives









































established
























15 Research Limits




















16 Overview and Map











Plants

Hydroponics System


System Sensors


Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF


Controller data

Temperature


Plant growth








copy [7]

copy [8]



17 Chapter overview



















discussed





18 Conclusion

























21 Introduction









































22 Overview


Hydroponic methods




PH control



Electric fields





6 Latin meaning



Power density





Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas



Standing wave ratio

































possible



problem




























lettuce














































Water Pump

Air

Heaters (optional)

Acid














28 PH control




































POTASSIUM SULPHATE

(Hort Grade)


water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm


Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE


1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm




















Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)




force (E) [25]

2 2

F KQq KQ Eq d q d











































8310 ( )

c wheref









216 Power Density












24PtGtPfd where






Pt GtEIRP orLbo Lbf
























energy [36]








controlled [37]















2

2ESAR where












[ ]ln[ ]eq K

i

KRTE wherezF K




















the prey [45]











222 Photosynthesis












223 Bio-stimulation






224 Quad antennas

















313944Reflector( )

29718Director( )


mf Mhz

mf Mhz


tuning inductor



























included then


ErpEf
















provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing


Outputs for

Heater(s)

Fans


Nutrient pump

Acid pump

Nutrient adjustment

Aerator





229 Conclusion

















31 Introduction







production exists












outlined

32 Overview




























Plant signalling






























plant growth
















porous















wire layouts










































certain situations













Frequency Band
















tissue of the plant


















91]
























sections
























plants was observed






























[115]
































[119]












































fermentation [125]















































[132]




of 10 to 200μV [133]








of these fields are

lnRT CoEiozF Ci




become porous






















[141]











al [143]









1 1( )( ) ( )( ) WA

A W


RGR ULR SLA LWF













certain direction



Dataset Date

t1 t2


1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372



Input Output

Weights


Time Leaf Area





Mean Unit Leaf Rate



























0

0

90

90

( ) ( ) ( )o dg W F F










[156]






























and Abraham Liboff












315 Conclusion





credits 12[162]











41 Introduction






168 and 169]















of this thesis











growth of a plant




and ventilation




growth




hisher environment



aspects of it






42 Overview





























43 Inside the Plant









algae [172 173]



























some stomata






451 Light factor

















be used [181 182]






OrsquoLeary [185]






35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42




35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66







July





month
























those in humans

































Hydrogrow





Nitric acid (58)



































48 PH Control













49 Structure Design













were considered




411 Constraints








public
























412 Measurements






required impedances




impedance







importance



determined from













source






cc

out

VPSRRV

















414 Types of Plants





415 Growth Dynamics










pulse arrives







hydroponic system











4181 Objective




plant

4182 Hypothesis



4183 Range



connections



































4185 Procedure

Hydroponic setup









the nutrient level












overflow








Nutrient solution


analysis




Common ground

















Plant preparation




Stimulation








following manner





Connection





Connection




Group 3 - Control
















Connection






Connection






4188 Management

















Maintenance




2 22 2 2 2













4191 Objective






4192 Hypothesis


4193 Range








1x Oscilloscope








4195 Procedure



Common ground


Plant preparation







Stimulation









following manner



Batch 1 Batch 2




Batch 5

None Plants 17-24














Connection




Group 3- Control



4198 Management



4201 Objective






4202 Hypothesis




4203 Range


















4205 Procedure



Common ground


Plant preparation







Stimulation










Batch 5

None Plants 17-24














Connection




Group 2- Control





4208 Management



Experiment 4

4211 Objective






4212 Hypothesis


4213 Range























4215 Procedure



Common ground


Plant preparation






five days

Stimulation












Batch 6

Plants 33-40














Connection




Group 2- Control



4218 Management


422 Conclusion

















gardeners




51 Introduction






properties






















52 Overview











Experimental plants



























experiment






experiments



Conclusion

53 Layout and setup

531 The setup












532 The structure














Testing phase of












Planting












1



























analogue display





said reference


















535 Probe design



















leakage


























hydroponic systems








1000g Hydrogrowcopy





















Container 1





Container 2




(15L)

Container 3





mark (15L)










disintegrate




2

Container 3


Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L


Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L










vegetables








make EC corrections










pH calibration




EC calibration


instruments













solution


541 Cultivars

















plants










plants 31-35




experiments



33-40



542 Plant health






Element

Leaves to

first

show

deficiency

Symptom


Phosphorus Old




Calcium New








Iron New

Leaves turn yellow









Inhibited flowering





















plant to another



























amplifiers












second IC

































561 Introduction






growth










energy cycle






















node connections

o Root and root


o Root and water


































Connection

Response Notes


positive





Connection

Response Notes























EC (mS) 18 pH 641








P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316


P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307





P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314


P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311




Control


P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243












569 Discussion




















571 Introduction













application



Chapter 565)

o Root and root


















Connection

Response Remark



Group 3- Control



Connection

Response Remark



Group 3- Control








Experiment 2 Height

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641



























Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641





































13581 (1358)





ratio of 18871 (1887)







576 Discussion
















more plant material


581 Introduction























o Root and root





was followed










Connection

Response Remark



Group 2- Control



Connection

Response Remark


Group 2- Control





Experiment 3 Height

Experiment type END



EC (mS) 18 pH 641




























Mass gain







(Table 511)






512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641


































586 Discussion












sdev = 1160




361 Median = 5560







sdev = 1097




195





sdev = 1053





growth



current was applied










591 Introduction


















593 Harmonics














diffusion process


















frequencies

















the cell







02120ln[ ]DZd





o Root and root



5971 Plants






















up some space










29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M














the conductors


291016 10 ln 1

2 2s sL x x xLnr r







































22 11

RN NR



598 Field strength












Connection

Response Reason



Group 2- Control



Connection

Response Reason



Group 2- Control




shown overleaf



Height results


Mass gain



Experiment 4 Height

Experiment type END



EC (mS) 2 pH 622



























Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622



































10871

























sdev = 1061











sdev = 1074













sdev = 1485







842






sdev = 1078





































impedance mismatch











5101 Flowering





5102 Fruiting









Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None


Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g




Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g



but smaller

Heaviest fruit per

tree










5111 Pests





















512 RF interference






513 Conclusion























square wave













stimulation









61 Introduction

















this research study




future generations






































cell membrane



growth































o Root and root


o Root and water



























































reference analysis



















63 Conclusions











appearance












accumulation


stimulation


wave stimulation




radiation field















included













bypassed





























where 2

2 2138log1 ( 2 1)

LZod L L








References















from


02205gt










247-267







Press pp 326-327







Press pp 61 174



wickgt




Issue February 18
















opdfgt





deficiencyhtmlgt







Newnes p 241


















Missouri-Columbia








Available from










pp 639-642









































Rep (C) pp 216-221








Regul pp 383-415














284ndash291



207ndash212








261- 274



122








pp1ndash4








dfgt















231



pp 245ndash253





76-81


































14 pp 240-257


pp 38 585




Wiley and Sons












207 pp 1177-1178











6055768 May 2 2000




1987


October 13 1998


1987



Physiol pp 614-619



485-487










































and Medicine 51 (10) pp 1505-1515



pp 47-55













December









1134[PubMed]









[PubMed]





















pp 200-207





571-581



pp 297-307







244







633-638








375-383
















375-383








59 pp 251-265






































477


















pp 1383-1398






vol 93 pp 11274-11279





Sci U S A vol 104 pp 20623-20628





18822-18827







64-67











November 7 1995









from lthttp0-


dfgt


Springer pp 9-10






plantshtmlgt





2023gt







































vol 102 pp 509-514



1847-1851


















































Pretoria 0506181




from















247 pp 74‐81




















333353maxtoshow=gt














and Hall pp 187-212















Press pp 189-208




































Appendix A


iv







stimulated plants


v

FOREWORD







Nutrient strengths



Carrier frequencies

Radiation intensity




Line termination



vi

TABLE OF CONTENTS






vii














viii













ix
















x




xi














SETS - 147 -

xii










xiii









xiv











- 153 -




11 Background








manure

























































13 Objectives









































established
























15 Research Limits




















16 Overview and Map











Plants

Hydroponics System


System Sensors


Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF


Controller data

Temperature


Plant growth








copy [7]

copy [8]



17 Chapter overview



















discussed





18 Conclusion

























21 Introduction









































22 Overview


Hydroponic methods




PH control



Electric fields





6 Latin meaning



Power density





Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas



Standing wave ratio

































possible



problem




























lettuce














































Water Pump

Air

Heaters (optional)

Acid














28 PH control




































POTASSIUM SULPHATE

(Hort Grade)


water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm


Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE


1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm




















Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)




force (E) [25]

2 2

F KQq KQ Eq d q d











































8310 ( )

c wheref









216 Power Density












24PtGtPfd where






Pt GtEIRP orLbo Lbf
























energy [36]








controlled [37]















2

2ESAR where












[ ]ln[ ]eq K

i

KRTE wherezF K




















the prey [45]











222 Photosynthesis












223 Bio-stimulation






224 Quad antennas

















313944Reflector( )

29718Director( )


mf Mhz

mf Mhz


tuning inductor



























included then


ErpEf
















provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing


Outputs for

Heater(s)

Fans


Nutrient pump

Acid pump

Nutrient adjustment

Aerator





229 Conclusion

















31 Introduction







production exists












outlined

32 Overview




























Plant signalling






























plant growth
















porous















wire layouts










































certain situations













Frequency Band
















tissue of the plant


















91]
























sections
























plants was observed






























[115]
































[119]












































fermentation [125]















































[132]




of 10 to 200μV [133]








of these fields are

lnRT CoEiozF Ci




become porous






















[141]











al [143]









1 1( )( ) ( )( ) WA

A W


RGR ULR SLA LWF













certain direction



Dataset Date

t1 t2


1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372



Input Output

Weights


Time Leaf Area





Mean Unit Leaf Rate



























0

0

90

90

( ) ( ) ( )o dg W F F










[156]






























and Abraham Liboff












315 Conclusion





credits 12[162]











41 Introduction






168 and 169]















of this thesis











growth of a plant




and ventilation




growth




hisher environment



aspects of it






42 Overview





























43 Inside the Plant









algae [172 173]



























some stomata






451 Light factor

















be used [181 182]






OrsquoLeary [185]






35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42




35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66







July





month
























those in humans

































Hydrogrow





Nitric acid (58)



































48 PH Control













49 Structure Design













were considered




411 Constraints








public
























412 Measurements






required impedances




impedance







importance



determined from













source






cc

out

VPSRRV

















414 Types of Plants





415 Growth Dynamics










pulse arrives







hydroponic system











4181 Objective




plant

4182 Hypothesis



4183 Range



connections



































4185 Procedure

Hydroponic setup









the nutrient level












overflow








Nutrient solution


analysis




Common ground

















Plant preparation




Stimulation








following manner





Connection





Connection




Group 3 - Control
















Connection






Connection






4188 Management

















Maintenance




2 22 2 2 2













4191 Objective






4192 Hypothesis


4193 Range








1x Oscilloscope








4195 Procedure



Common ground


Plant preparation







Stimulation









following manner



Batch 1 Batch 2




Batch 5

None Plants 17-24














Connection




Group 3- Control



4198 Management



4201 Objective






4202 Hypothesis




4203 Range


















4205 Procedure



Common ground


Plant preparation







Stimulation










Batch 5

None Plants 17-24














Connection




Group 2- Control





4208 Management



Experiment 4

4211 Objective






4212 Hypothesis


4213 Range























4215 Procedure



Common ground


Plant preparation






five days

Stimulation












Batch 6

Plants 33-40














Connection




Group 2- Control



4218 Management


422 Conclusion

















gardeners




51 Introduction






properties






















52 Overview











Experimental plants



























experiment






experiments



Conclusion

53 Layout and setup

531 The setup












532 The structure














Testing phase of












Planting












1



























analogue display





said reference


















535 Probe design



















leakage


























hydroponic systems








1000g Hydrogrowcopy





















Container 1





Container 2




(15L)

Container 3





mark (15L)










disintegrate




2

Container 3


Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L


Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L










vegetables








make EC corrections










pH calibration




EC calibration


instruments













solution


541 Cultivars

















plants










plants 31-35




experiments



33-40



542 Plant health






Element

Leaves to

first

show

deficiency

Symptom


Phosphorus Old




Calcium New








Iron New

Leaves turn yellow









Inhibited flowering





















plant to another



























amplifiers












second IC

































561 Introduction






growth










energy cycle






















node connections

o Root and root


o Root and water


































Connection

Response Notes


positive





Connection

Response Notes























EC (mS) 18 pH 641








P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316


P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307





P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314


P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311




Control


P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243












569 Discussion




















571 Introduction













application



Chapter 565)

o Root and root


















Connection

Response Remark



Group 3- Control



Connection

Response Remark



Group 3- Control








Experiment 2 Height

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641



























Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641





































13581 (1358)





ratio of 18871 (1887)







576 Discussion
















more plant material


581 Introduction























o Root and root





was followed










Connection

Response Remark



Group 2- Control



Connection

Response Remark


Group 2- Control





Experiment 3 Height

Experiment type END



EC (mS) 18 pH 641




























Mass gain







(Table 511)






512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641


































586 Discussion












sdev = 1160




361 Median = 5560







sdev = 1097




195





sdev = 1053





growth



current was applied










591 Introduction


















593 Harmonics














diffusion process


















frequencies

















the cell







02120ln[ ]DZd





o Root and root



5971 Plants






















up some space










29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M














the conductors


291016 10 ln 1

2 2s sL x x xLnr r







































22 11

RN NR



598 Field strength












Connection

Response Reason



Group 2- Control



Connection

Response Reason



Group 2- Control




shown overleaf



Height results


Mass gain



Experiment 4 Height

Experiment type END



EC (mS) 2 pH 622



























Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622



































10871

























sdev = 1061











sdev = 1074













sdev = 1485







842






sdev = 1078





































impedance mismatch











5101 Flowering





5102 Fruiting









Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None


Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g




Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g



but smaller

Heaviest fruit per

tree










5111 Pests





















512 RF interference






513 Conclusion























square wave













stimulation









61 Introduction

















this research study




future generations






































cell membrane



growth































o Root and root


o Root and water



























































reference analysis



















63 Conclusions











appearance












accumulation


stimulation


wave stimulation




radiation field















included













bypassed





























where 2

2 2138log1 ( 2 1)

LZod L L








References















from


02205gt










247-267







Press pp 326-327







Press pp 61 174



wickgt




Issue February 18
















opdfgt





deficiencyhtmlgt







Newnes p 241


















Missouri-Columbia








Available from










pp 639-642









































Rep (C) pp 216-221








Regul pp 383-415














284ndash291



207ndash212








261- 274



122








pp1ndash4








dfgt















231



pp 245ndash253





76-81


































14 pp 240-257


pp 38 585




Wiley and Sons












207 pp 1177-1178











6055768 May 2 2000




1987


October 13 1998


1987



Physiol pp 614-619



485-487










































and Medicine 51 (10) pp 1505-1515



pp 47-55













December









1134[PubMed]









[PubMed]





















pp 200-207





571-581



pp 297-307







244







633-638








375-383
















375-383








59 pp 251-265






































477


















pp 1383-1398






vol 93 pp 11274-11279





Sci U S A vol 104 pp 20623-20628





18822-18827







64-67











November 7 1995









from lthttp0-


dfgt


Springer pp 9-10






plantshtmlgt





2023gt







































vol 102 pp 509-514



1847-1851


















































Pretoria 0506181




from















247 pp 74‐81




















333353maxtoshow=gt














and Hall pp 187-212















Press pp 189-208




































Appendix A


v

FOREWORD







Nutrient strengths



Carrier frequencies

Radiation intensity




Line termination



vi

TABLE OF CONTENTS






vii














viii













ix
















x




xi














SETS - 147 -

xii










xiii









xiv











- 153 -




11 Background








manure

























































13 Objectives









































established
























15 Research Limits




















16 Overview and Map











Plants

Hydroponics System


System Sensors


Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF


Controller data

Temperature


Plant growth








copy [7]

copy [8]



17 Chapter overview



















discussed





18 Conclusion

























21 Introduction









































22 Overview


Hydroponic methods




PH control



Electric fields





6 Latin meaning



Power density





Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas



Standing wave ratio

































possible



problem




























lettuce














































Water Pump

Air

Heaters (optional)

Acid














28 PH control




































POTASSIUM SULPHATE

(Hort Grade)


water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm


Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE


1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm




















Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)




force (E) [25]

2 2

F KQq KQ Eq d q d











































8310 ( )

c wheref









216 Power Density












24PtGtPfd where






Pt GtEIRP orLbo Lbf
























energy [36]








controlled [37]















2

2ESAR where












[ ]ln[ ]eq K

i

KRTE wherezF K




















the prey [45]











222 Photosynthesis












223 Bio-stimulation






224 Quad antennas

















313944Reflector( )

29718Director( )


mf Mhz

mf Mhz


tuning inductor



























included then


ErpEf
















provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing


Outputs for

Heater(s)

Fans


Nutrient pump

Acid pump

Nutrient adjustment

Aerator





229 Conclusion

















31 Introduction







production exists












outlined

32 Overview




























Plant signalling






























plant growth
















porous















wire layouts










































certain situations













Frequency Band
















tissue of the plant


















91]
























sections
























plants was observed






























[115]
































[119]












































fermentation [125]















































[132]




of 10 to 200μV [133]








of these fields are

lnRT CoEiozF Ci




become porous






















[141]











al [143]









1 1( )( ) ( )( ) WA

A W


RGR ULR SLA LWF













certain direction



Dataset Date

t1 t2


1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372



Input Output

Weights


Time Leaf Area





Mean Unit Leaf Rate



























0

0

90

90

( ) ( ) ( )o dg W F F










[156]






























and Abraham Liboff












315 Conclusion





credits 12[162]











41 Introduction






168 and 169]















of this thesis











growth of a plant




and ventilation




growth




hisher environment



aspects of it






42 Overview





























43 Inside the Plant









algae [172 173]



























some stomata






451 Light factor

















be used [181 182]






OrsquoLeary [185]






35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42




35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66







July





month
























those in humans

































Hydrogrow





Nitric acid (58)



































48 PH Control













49 Structure Design













were considered




411 Constraints








public
























412 Measurements






required impedances




impedance







importance



determined from













source






cc

out

VPSRRV

















414 Types of Plants





415 Growth Dynamics










pulse arrives







hydroponic system











4181 Objective




plant

4182 Hypothesis



4183 Range



connections



































4185 Procedure

Hydroponic setup









the nutrient level












overflow








Nutrient solution


analysis




Common ground

















Plant preparation




Stimulation








following manner





Connection





Connection




Group 3 - Control
















Connection






Connection






4188 Management

















Maintenance




2 22 2 2 2













4191 Objective






4192 Hypothesis


4193 Range








1x Oscilloscope








4195 Procedure



Common ground


Plant preparation







Stimulation









following manner



Batch 1 Batch 2




Batch 5

None Plants 17-24














Connection




Group 3- Control



4198 Management



4201 Objective






4202 Hypothesis




4203 Range


















4205 Procedure



Common ground


Plant preparation







Stimulation










Batch 5

None Plants 17-24














Connection




Group 2- Control





4208 Management



Experiment 4

4211 Objective






4212 Hypothesis


4213 Range























4215 Procedure



Common ground


Plant preparation






five days

Stimulation












Batch 6

Plants 33-40














Connection




Group 2- Control



4218 Management


422 Conclusion

















gardeners




51 Introduction






properties






















52 Overview











Experimental plants



























experiment






experiments



Conclusion

53 Layout and setup

531 The setup












532 The structure














Testing phase of












Planting












1



























analogue display





said reference


















535 Probe design



















leakage


























hydroponic systems








1000g Hydrogrowcopy





















Container 1





Container 2




(15L)

Container 3





mark (15L)










disintegrate




2

Container 3


Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L


Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L










vegetables








make EC corrections










pH calibration




EC calibration


instruments













solution


541 Cultivars

















plants










plants 31-35




experiments



33-40



542 Plant health






Element

Leaves to

first

show

deficiency

Symptom


Phosphorus Old




Calcium New








Iron New

Leaves turn yellow









Inhibited flowering





















plant to another



























amplifiers












second IC

































561 Introduction






growth










energy cycle






















node connections

o Root and root


o Root and water


































Connection

Response Notes


positive





Connection

Response Notes























EC (mS) 18 pH 641








P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316


P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307





P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314


P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311




Control


P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243












569 Discussion




















571 Introduction













application



Chapter 565)

o Root and root


















Connection

Response Remark



Group 3- Control



Connection

Response Remark



Group 3- Control








Experiment 2 Height

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641



























Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641





































13581 (1358)





ratio of 18871 (1887)







576 Discussion
















more plant material


581 Introduction























o Root and root





was followed










Connection

Response Remark



Group 2- Control



Connection

Response Remark


Group 2- Control





Experiment 3 Height

Experiment type END



EC (mS) 18 pH 641




























Mass gain







(Table 511)






512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641


































586 Discussion












sdev = 1160




361 Median = 5560







sdev = 1097




195





sdev = 1053





growth



current was applied










591 Introduction


















593 Harmonics














diffusion process


















frequencies

















the cell







02120ln[ ]DZd





o Root and root



5971 Plants






















up some space










29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M














the conductors


291016 10 ln 1

2 2s sL x x xLnr r







































22 11

RN NR



598 Field strength












Connection

Response Reason



Group 2- Control



Connection

Response Reason



Group 2- Control




shown overleaf



Height results


Mass gain



Experiment 4 Height

Experiment type END



EC (mS) 2 pH 622



























Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622



































10871

























sdev = 1061











sdev = 1074













sdev = 1485







842






sdev = 1078





































impedance mismatch











5101 Flowering





5102 Fruiting









Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None


Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g




Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g



but smaller

Heaviest fruit per

tree










5111 Pests





















512 RF interference






513 Conclusion























square wave













stimulation









61 Introduction

















this research study




future generations






































cell membrane



growth































o Root and root


o Root and water



























































reference analysis



















63 Conclusions











appearance












accumulation


stimulation


wave stimulation




radiation field















included













bypassed





























where 2

2 2138log1 ( 2 1)

LZod L L








References















from


02205gt










247-267







Press pp 326-327







Press pp 61 174



wickgt




Issue February 18
















opdfgt





deficiencyhtmlgt







Newnes p 241


















Missouri-Columbia








Available from










pp 639-642









































Rep (C) pp 216-221








Regul pp 383-415














284ndash291



207ndash212








261- 274



122








pp1ndash4








dfgt















231



pp 245ndash253





76-81


































14 pp 240-257


pp 38 585




Wiley and Sons












207 pp 1177-1178











6055768 May 2 2000




1987


October 13 1998


1987



Physiol pp 614-619



485-487










































and Medicine 51 (10) pp 1505-1515



pp 47-55













December









1134[PubMed]









[PubMed]





















pp 200-207





571-581



pp 297-307







244







633-638








375-383
















375-383








59 pp 251-265






































477


















pp 1383-1398






vol 93 pp 11274-11279





Sci U S A vol 104 pp 20623-20628





18822-18827







64-67











November 7 1995









from lthttp0-


dfgt


Springer pp 9-10






plantshtmlgt





2023gt







































vol 102 pp 509-514



1847-1851


















































Pretoria 0506181




from















247 pp 74‐81




















333353maxtoshow=gt














and Hall pp 187-212















Press pp 189-208




































Appendix A


vi

TABLE OF CONTENTS






vii














viii













ix
















x




xi














SETS - 147 -

xii










xiii









xiv











- 153 -




11 Background








manure

























































13 Objectives









































established
























15 Research Limits




















16 Overview and Map











Plants

Hydroponics System


System Sensors


Direct current

Alternating current

Pulsed signals

Frequency

Modulated EMF


Controller data

Temperature


Plant growth








copy [7]

copy [8]



17 Chapter overview



















discussed





18 Conclusion

























21 Introduction









































22 Overview


Hydroponic methods




PH control



Electric fields





6 Latin meaning



Power density





Bioelectric effects

Photosynthesis

Bio-stimulation

Quad antennas



Standing wave ratio

































possible



problem




























lettuce














































Water Pump

Air

Heaters (optional)

Acid














28 PH control




































POTASSIUM SULPHATE

(Hort Grade)


water CUCUMBERS

1 Summer 2 Winter

1000 1000

1000 900

-

150

19 mScm 22 mScm


Truss flowering

1000

1000

640

640

-

250

18 mScm

21 mScm

CELERY LETTUCE


1000 1000

740 640

-

150

19 mScm 20 mScm

FLOWER CROPS

1 Summer 2 Winter

1000 1000

740 640

-

150

19 mScm 20 mScm




















Newton) and is 2

QqF Kd

where 9 2

2

90 10x NmKC

(a constant)




force (E) [25]

2 2

F KQq KQ Eq d q d











































8310 ( )

c wheref









216 Power Density












24PtGtPfd where






Pt GtEIRP orLbo Lbf
























energy [36]








controlled [37]















2

2ESAR where












[ ]ln[ ]eq K

i

KRTE wherezF K




















the prey [45]











222 Photosynthesis












223 Bio-stimulation






224 Quad antennas

















313944Reflector( )

29718Director( )


mf Mhz

mf Mhz


tuning inductor



























included then


ErpEf
















provided for

Inputs for

Temperature sensing

AC power

DC power

Nutrient sensing

PH sensing

Water level sensing


Outputs for

Heater(s)

Fans


Nutrient pump

Acid pump

Nutrient adjustment

Aerator





229 Conclusion

















31 Introduction







production exists












outlined

32 Overview




























Plant signalling






























plant growth
















porous















wire layouts










































certain situations













Frequency Band
















tissue of the plant


















91]
























sections
























plants was observed






























[115]
































[119]












































fermentation [125]















































[132]




of 10 to 200μV [133]








of these fields are

lnRT CoEiozF Ci




become porous






















[141]











al [143]









1 1( )( ) ( )( ) WA

A W


RGR ULR SLA LWF













certain direction



Dataset Date

t1 t2


1 11 21 111 1234

1 134 2 115 1320 week

1 15 23 114 1156 Rbar SE 95 CL

2 377 127 392 2870 1581247 0115672 0321105

2 366 1433 4 2865

2 44 151 499 3009

g mmsup2 week

Ebar SE 95 CL

0009067 0001041 0002891

mmsup2 g

Fbar SE 95 CL

2016975 2356756 6542353

g g (dimensionless)

Pbar SE 95 CL

0220926 0018408 0051101

mmsup2 g

Qbar SE 95 CL

8890272 7651153 212396

Coeffic SE 95 CL

0643845 0153468 0660372



Input Output

Weights


Time Leaf Area





Mean Unit Leaf Rate



























0

0

90

90

( ) ( ) ( )o dg W F F










[156]






























and Abraham Liboff












315 Conclusion





credits 12[162]











41 Introduction






168 and 169]















of this thesis











growth of a plant




and ventilation




growth




hisher environment



aspects of it






42 Overview





























43 Inside the Plant









algae [172 173]



























some stomata






451 Light factor

















be used [181 182]






OrsquoLeary [185]






35-40 526 618 1143 346 1489 33

80-85 712 811 1523 426 1959 36

95-100 922 1588 251 601 3108 42




35-40 8 479 1279 204 1482 63

80-85 925 556 1481 231 1712 64

95-100 102 863 1883 286 217 66







July





month
























those in humans

































Hydrogrow





Nitric acid (58)



































48 PH Control













49 Structure Design













were considered




411 Constraints








public
























412 Measurements






required impedances




impedance







importance



determined from













source






cc

out

VPSRRV

















414 Types of Plants





415 Growth Dynamics










pulse arrives







hydroponic system











4181 Objective




plant

4182 Hypothesis



4183 Range



connections



































4185 Procedure

Hydroponic setup









the nutrient level












overflow








Nutrient solution


analysis




Common ground

















Plant preparation




Stimulation








following manner





Connection





Connection




Group 3 - Control
















Connection






Connection






4188 Management

















Maintenance




2 22 2 2 2













4191 Objective






4192 Hypothesis


4193 Range








1x Oscilloscope








4195 Procedure



Common ground


Plant preparation







Stimulation









following manner



Batch 1 Batch 2




Batch 5

None Plants 17-24














Connection




Group 3- Control



4198 Management



4201 Objective






4202 Hypothesis




4203 Range


















4205 Procedure



Common ground


Plant preparation







Stimulation










Batch 5

None Plants 17-24














Connection




Group 2- Control





4208 Management



Experiment 4

4211 Objective






4212 Hypothesis


4213 Range























4215 Procedure



Common ground


Plant preparation






five days

Stimulation












Batch 6

Plants 33-40














Connection




Group 2- Control



4218 Management


422 Conclusion

















gardeners




51 Introduction






properties






















52 Overview











Experimental plants



























experiment






experiments



Conclusion

53 Layout and setup

531 The setup












532 The structure














Testing phase of












Planting












1



























analogue display





said reference


















535 Probe design



















leakage


























hydroponic systems








1000g Hydrogrowcopy





















Container 1





Container 2




(15L)

Container 3





mark (15L)










disintegrate




2

Container 3


Nitrate

Nitric Acid Total

concentrate

Summer 1500g + 0-5g

Potassium

975g

(65gL)

150ml of 10

acid by Volume

3X 15L


Potassium

900g

(60gL)

150ml of 10

acid by Volume

3X 15L










vegetables








make EC corrections










pH calibration




EC calibration


instruments













solution


541 Cultivars

















plants










plants 31-35




experiments



33-40



542 Plant health






Element

Leaves to

first

show

deficiency

Symptom


Phosphorus Old




Calcium New








Iron New

Leaves turn yellow









Inhibited flowering





















plant to another



























amplifiers












second IC

































561 Introduction






growth










energy cycle






















node connections

o Root and root


o Root and water


































Connection

Response Notes


positive





Connection

Response Notes























EC (mS) 18 pH 641








P7 388 DC - TampR 501 V 104 366 284 B7 1336

P8 408 DC - TampR 501 V 92 291 316


P10 430 DC - TampR 501 V 102 311 328

B3 P11 317 DC - RampW 501 V 62 243 255

P12 303 DC - RampW 501 V 69 295 234

P13 381 DC - RampW 501 V 74 241 307





P18 351 SQ - RampR 1598-1601 Hz 98 387 253

P19 433 SQ - RampR 1598-1601 Hz 126 41 307

P20 371 SQ - RampR 1598-1601 Hz 103 384 268

B5 P21 467 SQ -TampR 1598-1601 Hz 126 37 341

P22 429 SQ -TampR 1598-1601 Hz 115 366 314


P24 461 SQ -TampR 1598-1601 Hz 109 31 352


B6 P26 354 SQ - RampW 1598-1601 Hz 79 287 275

P27 393 SQ - RampW 1598-1601 Hz 82 264 311




Control


P32 251 none 32 146 219

P33 271 none 30 124 241

P34 269 none 33 14 236

P35 280 none 37 152 243












569 Discussion




















571 Introduction













application



Chapter 565)

o Root and root


















Connection

Response Remark



Group 3- Control



Connection

Response Remark



Group 3- Control








Experiment 2 Height

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641



























Experiment 2 Weight

Experiment type END


Signal type DC 5V

EC (mS) 18 pH 641





































13581 (1358)





ratio of 18871 (1887)







576 Discussion
















more plant material


581 Introduction























o Root and root





was followed










Connection

Response Remark



Group 2- Control



Connection

Response Remark


Group 2- Control





Experiment 3 Height

Experiment type END



EC (mS) 18 pH 641




























Mass gain







(Table 511)






512)


Experiment 3 Weight

Experiment type END



EC (mS) 18 pH 641


































586 Discussion












sdev = 1160




361 Median = 5560







sdev = 1097




195





sdev = 1053





growth



current was applied










591 Introduction


















593 Harmonics














diffusion process


















frequencies

















the cell







02120ln[ ]DZd





o Root and root



5971 Plants






















up some space










29981( )HZ

x VFf M

29986 097( )

48468HZ

HZ

m xf M

F M














the conductors


291016 10 ln 1

2 2s sL x x xLnr r







































22 11

RN NR



598 Field strength












Connection

Response Reason



Group 2- Control



Connection

Response Reason



Group 2- Control




shown overleaf



Height results


Mass gain



Experiment 4 Height

Experiment type END



EC (mS) 2 pH 622



























Experiment 4 Weight

Experiment type END



EC (mS) 2 pH 622



































10871

























sdev = 1061











sdev = 1074













sdev = 1485







842






sdev = 1078





































impedance mismatch











5101 Flowering





5102 Fruiting









Experiment 2

DC Stimulation

Experiment 3

16Hz Square wave

Experiment 4

RF AM modulated

Control

None


Tomato 3 158g 160g 216g 137g

Tomato 2 142g 157g 178g 124g




Average plant yield

(gplant selected

from 2 trusses 5

tomatoes each)

1395g 1603g 2003g 1284g



but smaller

Heaviest fruit per

tree










5111 Pests





















512 RF interference






513 Conclusion























square wave













stimulation









61 Introduction

















this research study




future generations






































cell membrane



growth































o Root and root


o Root and water



























































reference analysis



















63 Conclusions











appearance












accumulation


stimulation


wave stimulation




radiation field















included













bypassed





























where 2

2 2138log1 ( 2 1)

LZod L L








References















from


02205gt










247-267







Press pp 326-327







Press pp 61 174



wickgt




Issue February 18
















opdfgt





deficiencyhtmlgt







Newnes p 241


















Missouri-Columbia








Available from










pp 639-642









































Rep (C) pp 216-221








Regul pp 383-415














284ndash291



207ndash212








261- 274



122








pp1ndash4








dfgt















231



pp 245ndash253





76-81


































14 pp 240-257


pp 38 585




Wiley and Sons












207 pp 1177-1178











6055768 May 2 2000




1987


October 13 1998


1987



Physiol pp 614-619



485-487










































and Medicine 51 (10) pp 1505-1515



pp 47-55













December









1134[PubMed]









[PubMed]





















pp 200-207





571-581



pp 297-307







244







633-638








375-383
















375-383








59 pp 251-265






































477


















pp 1383-1398






vol 93 pp 11274-11279





Sci U S A vol 104 pp 20623-20628





18822-18827







64-67











November 7 1995









from lthttp0-


dfgt


Springer pp 9-10






plantshtmlgt





2023gt







































vol 102 pp 509-514



1847-1851


















































Pretoria 0506181




from















247 pp 74‐81




















333353maxtoshow=gt














and Hall pp 187-212















Press pp 189-208




































Appendix A


radio frequency energy for bioelectric stimulation of plants

Documents