By

Shehzad Ahmad Kang

Ph.D - Plant Breeding & Genetics

Corresponding email ID: shehzadpbg@gmail.com

Breeding for Salinity Tolerance in

Hydroponic Systems of Crop plants

Hydroponics, the ‘water culture’ of plants, has been used in both research and commercial contexts since the 18th century.

plants needs only less dose of inorganic elements e.g. water, oxygen and sunlight, to grow.

• It was later realized that plants can grew better hydroponically if the solutions would be aerated.

Overview

It permit to easily observe the effects of elemental deficiencies and toxicities and to study other aspects of plant development under more controlled conditions i.e. temperature, control light and specific dose of nutrients for experiments.

The growing of plants in a solution of nutrients necessary for plant growth, rather than directly in soil.

What is Hydroponic?

What is needed for a plant to survive? Water Sunlight Air Nutrients Anchorage

PLANT REQUIREMENTS

Salt Tolerant Experiments.

To produce disease free crops like wheat, Barely,

lettuce, tomato and others etc.

To grow transgenic plants for screening after genetic

transformation.

Why We Use Hydroponics?

Hydroponic Systems

Wheat

Vegetables

Passive systems (no moving parts) are great for beginning hydroponics gardeners because they are inexpensive, portable, and simple to set up.

Active systems employ pumps and other devices to deliver nutrient solutions to plant roots.

Passive vs Active

The capillary or wick system do not use pumps or timers. Water and nutrients are drawn up to the roots by capillary action. These systems may be important when designing a system to operate in a space station where gravity is nonexistent.

Capillary System (passive)

Most versatile. Each time the water floods from the lower reservoir into the upper growing tray, the roots are bathed in the fresh nutrients. When the nutrient drains back to the reservoir, fresh air is drawn through the root system refreshing oxygen to the roots.

Flood and Drain System (active)

The NFT systems provide a constant film of water and nutrients along the bottom of a channel. In effect, part of the roots grow down in the water/ nutrients and parts of the roots above the water line getting fresh air and oxygen

Nutrient Film Technique (NFT)

USE OF GREEN HOUSE FOR HYDROPONICS

Salinity stress is a limitation to the productivity of agricultural crops worldwide.

It has been estimated that almost 80 million hectares of arable lands worldwide is currently affected by salinity.

This issue showed big losses in crop yield and this problem can minimize by the development of salt tolerant varieties of crops for

• good seed germination• Plant vegetative and reproduction growth• And plant biomass and grain yield

Breeding for Salt Tolerance

The soil solution of saline soil is composed of a range of dissolved salts i.e. NaCl, Na2SO4, MgSO4, CaSO4, MgCl2, KCl and Na2CO3, each of which contribute to salinity stress whereas NaCl is the most prevalent salt and has been the focus of much of the work on salinity to date.

Because high concentrations of NaCl in soils may ultimately help to improve yield on saline lands.

Salinity tolerance is a difficult trait to score in the field and is often genetically complex.

Hence, identification of salinity tolerance loci/genes and their selection using molecular markers is needed to assist in the breeding of salt-tolerant crops like SSR,RAPD,RFLP,AFLP etc.

Quantitative trait loci (QTL) have been identified for germination, plant growth and reproduction process and other various growth parameters measured in saline hydroponic culture i.e. wheat, Barely etc.

Results of a study by Gorham et al. (1990) also suggested that barley chromosomes 6H and 7H could enhance Na+ exclusion or K+/Na+ ratios in a wheat background.

Hexaploid wheat genome (AABBDD) accumulates less Na+ in the shoot relative to K+ and this trait has been attributed mainly to the Kna1 gene on chromosome 4D.

Good seed germination. Plant height. Plant biomass/grain yield. Long root length. Good vegetative and reproduction growth. High shoot length/weight.

Breeding Objectives

1- Conventional breeding approacheso Introduction of germplasms.o Screening of line for salt tolerance.o Selection of genotypes for salt tolerance.o Hybridization with desire genotype.• Evaluation of salt tolerant lines through screening and

then hybridize with high yielded line to incorporate salt tolerant genes by back crossing method.

• This technique is very time consuming and costly and breeders in modern globe now approach the Biotechnological breeding approaches salt tolerant breeding.

Breeding Approaches

Conventional breeding strategy for salt tolerance is not much successful due to reproductive barrier, transformation of other undesirable traits. So to avoid this problem, biotechnological strategy is more preferred, as it only deals with the specific gene(s) transferred i.e.

Molecular markers (SSR,RAPD,RFLP,AFLP etc.) Used to identify the desirable gene. Recombinant DNA method for gene transformation Tissue culture- Technique used to growth the

transgenic plant material.

2-Biotechnological approaches.

Growing in Any Condition and Season-

Systems may be constructed and used in any location

from space to under water exploration.

Smaller Growing Area

More control of the growing environment of plant

Year-round supply

Advantages

Faster Growth-

Hydroponics works by automatically getting the

complete nutrient mixture and water to the roots

without drowning the plant. Plants get everything

they need all the time, so they do not waste growing

a lot of roots or searching for nutrients.

No Weeds or Pests-

Gardening without soil eliminates the weeds do you do

not need weed sprays. Also, because there are no

weeds, there will be no backache from a hoe or

rototiller. Since most pests live and breed in the soil,

you do not need to use pesticides or other toxic

chemicals.

Great Plant Quality and Taste-

Since the plants get everything it needs, all the time, it

will reward you with great taste, strong and fast

growth, and overall plant quality.

Cost of initial investment on hydroponic systems is high.

Hydroponic production is management, capital and labor

intensive.

A high level of expertise is required.

Daily attention is necessary.

Disadvantages

Specially formulated, soluble nutrients must always be

used.

Pests and diseases remain a big risk.

Some water born diseases can spread rapidly in

recirculation system.

THANKS