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EFFECTS OF TEMPERATURE AND STORAGE ON THE GERMINATION OF CUCUMIS MELO L. AFrER

ACCELERATED AGEING

ElizabetliAnak. Ngitar@ Lugom

Bachelor of Science with Honours QI (Plant Resource Science and Management)661 2005E42 2005

,..... Pusat KhidnJv,M3 * at Akarieml1 UNIVERSITI MALAYSIA SARAWA¥

941(){) KOla Samarahan

P.KHIDMAT MAKLUMAT AKADEMIK UNIMAS

111111111" III 11111111111111 1000143821

EFFECTS OF TEMPERATURE AND STORAGE ON THE GERMINATION OF CUCUMIS MELD L. AFTER ACCELERATED AGEING

ELIZABETH ANAK NGITAR @ LUGOM

This project is submitted in partial fulfilment of the requirements for degree of Bachelor of Science with Honors

(Plant Resource Science and Management)

Faculty of Resource Science and Technology UNIVERSITI MALAYSIA SARA W AK

2005

I

Acknowledgement

Firstly, I'm grateful to God Almighty for the strength and wisdom that He has bestowed upon

me from the beginning until I have finally completed this study at the appropriate time. For

without Him, I am nothing and will cease to accomplish anything.

Secondly, I wish to express my deepest gratitude to my project supervisor, Dr. Petrus Bulan

for his continuous effort, guidance and encouragement that he has shown from the beginning

of this study until the time of completion. His invaluable words of wisdom and his enduring

patience towards the completion of this study will always be cherished. I am also utterly

grateful to Dr. Ismail for the times that he has sacrificed in order to lend a helping hand and

giving out advices.

I would also like to thank my parents and family for supporting me in prayer and financially.

My special thanks also goes to my beloved housemates; Anita ak Muda, Angela Ruran,

Darfrina Allnia, Farrah Raphael, Kristy Wong and Sweetie Munsing for their love and

encouragements during difficult moments. My sincere gratitude to Joshua Juan, for his

enduring patience in guiding and assisting me in the process of completing this study and

lastly, to my coursemates and friends who has continuously supported and contributed

valuable ideas to me the whole way.

II

TABLE OF CONTENTS

PAGE

Acknowledgement...... ....... ...... ....... .. ............... ................. .. ..... ... ... ... B

List of table................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... v

List of figures.................................................................. . ........... . .. VBl

Abstract.................. ...................................................................... x

Abstrak......................................................................................... x

CHAPTER ONE INTRODUCTION

1.1 Background............................. . ................ .

1.2 Problem Statement... ...... ...... ... ............... .... 5

1.3 Objectives.............................................. 6

CHAPTER TWO LITERA TURE REVIEW

2.1 Seed Storage........................................... 7

2.2 Viability of Seeds...................... .. ............. 8

2.3 Seed Germination............... ...... ................ 9

2.4 Seed Deterioration.................................... 9

2.5 Accelerated Ageing.............................. ...... 10

CHAPTER THREE MA TERIALS AND METHODS

3.1 Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 14

3.2 Methods

3.2.l Accelerated Ageing Test............. ........ 14

3.2.2 Seed Moisture Content Test................ 14

3.2.3 Seed Germination Test...... . .. ............. 15

3.2.4 Seed Storage Environment. . . . . . . . . . . . . . .... 15

3.2.5 Seedling Growth Test... ... . . .. ... . .... ..... 16

CHAPTER FOUR RESULTS AND DISCUSSIONS

4.l Seed Quality......... ............... ... ... ... .......... 17

iii

2 Seed Moisture Content.......................... ...... 17

4.3 Seed Gennination.............................. ........ 20

4.4 Seedling Growth.................. ...... .............. 22

4.5 Seed Detrimental Period............................. 27

CHAPTER FIVE CONCLUSION AND RECOMMENDATIONS... ..... 33

REFERENCES.............................................................................. 34

APPENDIX.. . . . . . .. . . . . . . . . . . . . .. . . . . .. . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . .. .... 37

iv

,..

Tables PAGE

List of tables

1 The mean biomass (g) of seedlings following accelerated ageing and

storage in different environments........ . .............. . ........ . ...... .. ........... 24

2 Mean length of stem and shoots of e. melo seedlings following accelerated

3 Mean length of roots of e. melo seedlings following accelerated ageing and

9 Test of homogeneity of variances for moisture content (%) of seeds stored

10 Anova analysis for moisture content (%) of seeds stored in different

11 Test of homogeneity of variances for germination (%) of seeds stored in

12 ANOVA analysis for germination (%) of seeds stored in different

13 Model summary of regression analysis for germination of seeds stored in

ageing and storage in different environments........ .... ... ......... .............. 25

storage in different environments...................................... . ............. 26

4 Mean Moisture Content (%) of e. melo seeds..................................... 37

5 Mean Germination percentage (%) of e. melo seeds.............................. 37

6 Mean biomass of e. melo seeds (g)............................................ ....... 37

7 Mean length of stem and shoots ofe. melo seeds (cm)........................... 38

8 Mean length of roots ofe. melo seeds (cm)....................................... 38

in different environments..................... . ........................ .. ............. 38

environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......... 39

different environments.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

environments................................. . ................................... 41

ambient room (28-30°C)........................................................ ....... 42

I

v

Tables PAGE

14 ANOVA analysis for germination of seeds stored in ambient room (28

30°C).. . ............... .. . ............... . . ... . ... ... ........ . ......... . ........ . ........ 43



22 Model summary of regression analysis for germination of non-stored aged

25 Model summary of regression analysis for biomass of seedlings whereby

26 ANOVA analysis for biomass of seedlings whereby seeds was stored in

27 Coefficients for germination of biomass of seedlings whereby seeds was


15 Coefficients for germination of seeds stored in ambient room (28-30°C)..... 43

cold room (-12°C)..... . ....... ........... ........ ......................... . .. ......... 43

17 ANOV A analysis for germination of seeds stored in cold room (-l2°C).... .. 43

18 Coefficients for germination of seeds stored in cold room (-12°C)......... .. ... 44

refrigerator (3-5°C)... .......................... . ......................... . .... . .. ...... 44

20 ANOVA analysis for germination of seeds stored in refrigerator (3-5°C)...... 44

21 Coefficients for germination of seeds stored in refrigerator (3-5°C).. ....... ... 44

seeds........... . ............ .............. .. ........ ... ...... ... ... ......... ............. 44

23 ANOVA analysis for germination of non-stored aged seeds............ . ........ 45

24 Coefficients for germination of non-stored aged seeds................... ..... ... 45

seeds was stored in ambient room (28-30°C).......... .. ........ . ... . .. .. ... ......... 45

ambient room (28-30°C)...... . .... . ............................... . ... .... .......... ..... 45

stored in ambient room (28-30°C)... . . . .... .. .................. . ............. . .. .... 46

s eds was stored in cold room (-l2°C)... ..... ............. . . . ... . .. ..... . ...... ... 46

VI

.....

Tables PAGE

29 ANOVA analysis of biomass of seedlings whereby seeds was stored in cold

room (-12°C). . ...................................... .. ...... ... .. . ... . ... . ............. 46

30 Coefficients of biomass of seedlings whereby seeds was stored in cold room


32 ANOV A analysis for biomass of seedlings whereby seeds was stored in

33 Coefficients of regression analysis for biomass of seedlings whereby seeds

34 Model summary for of regression analysis for biomass of seedlings

35 ANOVA analysis for biomass seedlings whereby the aged seeds was not

36 Coefficients for biomass of seedlings whereby the aged seeds was not

(-12°C)............................... .... .. ......... .................................... 46

seeds was stored in refrigerator (3-5°C).... .. ....................... . .... ............ 47

refrigerator (3-5°C).................................................. . .. ................... 47

was stored in refrigerator (3-5°C).. . ..... .. ....................... .. ................ 47

whereby the aged seeds was not stored. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

stored............................................................................. ... .... . 48

stored......... ........ .. ...... . .......................................................... 48

VII

I

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List of figures

Figures PAGE

Moisture content (%) of c. melD seeds stored in ambient room (28

30°C).............................. . ........ .... .. ... .. ... . .............................. 19

5 Germination of C. melD seeds before and after one week of storage in three

6 Biomass of C. melD seeds before and after one week of storage in three

7 Average length of stem and shoots (cm) of C. melD before and after one

8 Average length of roots of C. melD seeds before and after one week of

9 Detrimental period for germination of C. melD seeds following accelerated




2 Moisture content (%) of c. melo seeds stored in cold room (-12°C).. . ..... . ... 19

3 Moisture content (%) of c. melD seeds stored in refrigerator (3-5°C)........ . .. 19

4 Moisture content (%) for non-stored aged c. melD seeds......................... 19

different environments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

different environments. ....... . .................. ..................................... 24

week storage in three different environments....... . ........ ............ .. . ... . ... 25

storage in three different environments........................................... .. 26

ageing and storage in ambient room (28-30°C)................................... . 28

ageing and storage in cold room (-12°C)......................... ............ ...... ..... 28

ageing and storage in refrigerator (3-5°C) ....................................... ... 29

ageing but without storage................................... . ... ... .. . ... .. .... . ...... 29

Vlll

,...

Figures PAGE

13 Detrimental period for biomass of C. mela seedlings following accelerated

ageing and storage in ambient room (28-30°C)......... .............. ................ 30




ageing and storage in cold room (-12°C)............ ....... .. ............... .. ..... 31

ageing and storage in refrigerator (3-5°C)............................ . .......... ... 31

ageing but without storage.... . ................ . . . .... ............................ .... 32

17 Mean moisture content (%) of seeds stored in ambient room (28-30°C)..... .. 39

18 Mean moisture content (%) of seeds stored in cold room (-12°C)......... ...... .. .. 39

19 Mean moisture content (%) of seeds stored in refrigerator (3-5°C)............. 40

20 Mean moisture content (%) of non-stored aged seeds.. . .... .............. ... .... 40

21 Mean germination (%) of seeds stored in ambient room (28-30°C)... ......... 41

22 Mean germination (%) of seeds stored in cold room (-12°C)... ... ...... .......... 41

23 Mean germination (%) of seeds stored in refrigerator (3-5°C).............. . ... 42

24 Mean germination (%) of non-stored aged seeds..... .......... . .................. 42

ix

EFFECTS OF TEMPERATURE AND STORAGE ON THE GERMINATION OF CUCUMIS MEL0 L. AFTER ACCELERATED AGEING

Elizabeth ak Ngitar

Program of Plant Resource Science and Management Faculty of Resource Science and Technology

Universiti Malaysia Sarawak

ABSTRACT

A study was conducted to evaluate the effects of short period of accelerated ageing on storage and germination of Cucumis melo.L seeds. After seeds were placed in dessicators to age for 5 days at 40 - 42°C and 100% relative humidity, they were put in air - tight bottles, and stored in refrigerator (3-5°C), ambient room (28-30°C) and cold room (-12°C) for one week, and evaluated. Accelerated ageing caused a marked decreased in germination of C. melD seeds in 4 days and poor seedling growth after one week of storage. The detrimental period of germination for C. melD was at 1134.01 hours, which are 47 days and 6 hours after accelerated ageing and 619.77 hours (25 days and 19 hours) when seeds are stored following ageing. Hence, the ideal storage condition for storing C. melD was the refrigerator with 3-5°C and a cool environment of 40-50% relative humidity.

Keywords: Cucumis melo, desiccators, accelerated ageing, relative humidity, storage

A BSTRAK

Satu /cajian tela" dijalankan untuk meni/ai kesan penuaan buatan terhadap penyimpanan biji benih dan percambahan biji benih Cucumis melD L. Selepas biji benih diletakkan di dalam desikator untuk menjalani proses penuaan buatan selama 5 hari pada suhu 40 - 42°C dan /00% kelembapan bandingan, biji benih akan diletaklcan di dalam botol kedap udara dan disimpan di peti sejuk (3-5°C). suhu bilik (28-30°C) dan bilik sejuk (/2°C) selama seminggu. Penuaan buatan telah menyebabkan peratusan percambahan C. mela berkurangan dalam masa empat hari dan menunjukkan tumbesaran biji benih yang tidak bagus. Jangkamasa yang menunjukkan kesan memudaratk n akibat penuaan buatan pada percambahan biji benih C. melD ada/ah pada /134.01 jam (47 hari dan 6 jam) selepas menjalani proses penuaan buatan dan pada 6/9.77 jam (25 hari dan /9 jam) apabi/a bij; benih disimpan dalam tempat penyimpanan sejurus selepas mengalami proses penuaan buatan.. Kesimpulannya, tempat penyimpanan yang sesuai umtuk C. melo adalah peti sejuk dengan suhu 3-5°C dan 40-50% kelembapan bandingan.

Kata kunci: Cucumis melo, desikator, penuaan buatan, kelembapan bandingan, penyimpanan

x

CHAPTER ONE

INTRODUCTION

1.1 Background

Cucumis melD L. is a member of the Cucurbitaceae family of about 90 genera and 700 to 760

species (Porter, 1967). Its origin is traced back to Africa where it is found growing as wild

species. C. melo or also known as Rock Melon is a promising crop and one of the major non

seasonal fruits for export in Malaysia.

Melons are a diverse group of fresh, desert fruits which includes orange flesh cantaloupes,

green flesh honeydew, and mixed melon (Casaba, Crenshaw, Persian, Santa Claus, Juan

Canari). C. melD includes a wide range of cultivated plants. Although crosses outside the

species are sterile, intraspecific crosses are generally fertile, resulting in a confusing range of

variation (Purse glove, 1968).

C. melD is classified as a vine crop, mainly because they possess a prostrate or climbing

nature, and are characterized by tendrils. It is grown in bris and free-draining sedentary soils.

In Malaysia, melons are mostly cultivated in areas such as Rompin, Kuantan, Kota Baru, Kota

Tinggi, Semenyih and Tampin. The fruits vary in terms of colour, taste, and skin texture.

Some of these varieties included Sky Rocket, Milky Way and Red Queen, all of which are

disease resistance and high yielding (Sahadevan, 1987).

In 'he cultivation of melon, soil and water requirement is important. The crop should not be

grown uring dry season. It is beneficial to rotate the planting of crop as to avoid attack by

I

,...

pest and disease. C. melD is propagated by seed. Techniques used to cultivate C. melD are

usually direct seeding or transplant. Weeding is made after four to six weeks of planting to

control weeds. Pruning is done to ensure that sizes of the crops are uniform. A good crop

produces up to 12 tons per hectare of fruits (Sahadevan, 1987).

C. melD are grown for their sweet edible fruit walls. Seeds are also consumed and are high in

oil content which is about 12.5 - 39.1 % (Duke and Ayensu, 1985). Melons are also rich in

vitamins B and C (Allardice, 1993).The seed is antitussive, digestive, febrifuge and vermifuge

(Duke and Ayensu, 1985). The flesh of fruit can be dried, ground into a powder and used with

cereals for making bread and biscuits (Moerman, 1998). The fruits can be used as a cooling

light cleanser or moisturizer for the skin and are also used as a first aid treatment for burns

and abrasions (Allardice, 1993). Fresh fruits are normally sold for prices ranging between RM

8.00 - 10.00/ melon and RM 1.50 - 2.00 per kg in local markets.

In the production of vegetables and fruits, seed quality is especially important. The mass

marketing of vegetables and fruits requires size standards in the produce that can only be

achieved by specific plant spacings which in turn require high quality seed for uniformity in

crop establishment and seedling growth. Furthermore costly hybrid seed and modular

transplant production methods have created a demand from growers for consistently reliable

seed well above the minimum germination standards (Matthews, 1980).

In Malaysia, a majorjty of vegetables and fruits in the market are imported, and the seeds are

o ined from other countries like USA and Brazil. Through sufficient knowledge in proper

2

l

,.....

seed storage handling and preservation, in due time, local growers in Malaysia will be able to

harvest sufficient fru it and vegetable produce to supply local needs.

In genebanks, seeds are stored under optimal storage conditions which have normally low

temperature and low seed moisture content or relative humidity to prolong the seed viability.

The deterioration of the stored seed is a natural phenomenon and the seeds tend to loose

viability even under ideal storage conditions (Bhatti and Sato, 1997). The rate of seed

deterioration varies greatly from one species to another and even among varieties of the same

species. When large numbers of seed samples are preserved in genebank for longer periods, it

is recommended to monitor their vigour and viability at regular intervals.

High quality seeds produce highly vigourous plant and thus contribute to increased economic

value of the plant. The maintenance and preservation of superior quality seeds are important

for improved crop production, where 25% of increase in agricultural production depends on

seed quality (Heuver, 1981).

The purpose of seed storage is mainly to preserve planting stocks for the next planting season.

Proper storage of seeds is of great importance whereby the storage potential of seed lots is

initially related to their stage of deterioration or vigour status on entering storage. According

to Copeland and McDonald (1995), even the best storage conditions can only maintain the

quality of seeds in storage and seeds of low quality deteriorate more rapidly under conditioned

storage than high quality seeds.

3

In storing certain species it is important that the optimal storage environment is met as far as

possible. However, according to Schmidt (2002), even under the best storage conditions, some

species will only survive for a short time. He added that, deterioration may be delayed by

adopting the best possible storage conditions, but long term storage is not possible for such

species.

A large variation in storability is encountered between species. Seeds of recalcitrant species

maintain high moisture content at maturity which is often in the range of 30-50% and are

sensitive to desiccation below 12-30%, depending on species. They have a short storage

potential and rapidly lose viability under any kind of storage conditions (Schimdt, 2000).

Temperature and humidity are the most important factors in seed storage. Non-dormant seeds

may germinate if their moisture content is above 30%. Rapid deterioration by micro

organisms can occur if moisture content is 18-30%, and seeds with moisture content above

18-20% respire and metabolize actively. Metabolizing seeds may be damaged by

accumulation of toxic metabolites or heat if improperly ventilated. Certain seed insects are

active at a moisture content of less than 10%, and damage by fungi may occur down to 4-5%

(Bewley and Black 1994).

Accelerated agemg, a technique pioneered by Delouch.e (1965) was originally used for

treating seeds to determine the storability of seeds. This technique was to estimate the

longevity of seeds in commercial storage, but in the years that followed, it was used by other

re hers to test field emergence and stand establishment in many species. According to

4

McDonald (1977), the asset of accelerated ageing technique is that it is dynamic, universal for

all seeds and requires no specialized technical training.

In Accelerated ageing, seeds are exposed for short periods to two environmental variables

which are high temperatures (40-45°C) and high relative humidity (100%) for varying

periods. This will cause rapid seed deterioration and only high vigour seed can withstand

these extreme stress conditions and deteriorate at a slower rate compared to low vigour seeds.

After this period of stress, the aged seeds will be tested for its germination and the results will

be compared with germination of non-aged seeds (Delouche, 1965). Germination following

such treatments has been related to field emergence and seed longevity in storage. These

relationships not only provide the basis for a test of seed quality but also suggest that natural

ageing prior to testing and sowing is a major cause of quality differences (Matthews, 1980).

1.2 Problem Statement

Performance after storage is still dependent on the vigour status of the seed lot even if the

seeds are placed under controlled and suitable storage conditions. Poor storage conditions will

always accelerate vigour loss. Therefore, controlled storage will only reduce the rate of vigour

loss, but not prevent it (Hampton, 1991).

Through a clear understanding of storing and preservation of seeds, the capability to produce

and maintain high quality seeds is possible. Although there are a number of seed and

g nnplasm banks established in Malaysia, the amount and quality of seeds is insufficient to

a productive harvest that can sustain the needs of the country. Furthermore, collections

are small and are normally used for research purposes.

5

The purpose of this study is to help detennine the ideal storage period and temperature needed

to preserve C. melo seeds before they are planted in the field. Furthennore, there is lack of

infonnation on researches done to detennine the quality of the C. melD seeds using the

accelerated ageing technique.

1.3 Objectives

1. To evaluate the effects of short period of accelerated ageing on C. melD seeds.

2. To detennine the durations of ageing and storage periods which are detrimental

in preserving of C. melD seeds.

3. To detennine how long the C. melD seeds can surVIve In storage after

accelerated ageing.

6

CHAPTER TWO

LITERATURE REVIEW

Seed storage

preservation and storage of high quality seeds is an important factor in field planting.

is to ensure high quality yield plants and potentially marketable. Seeds of high quality

result in a rapid germination, shoot and root growth and emergence during the early

. tag4es of growth. Failure to maintain the quality of seeds during storage period will decrease

vigour of seeds. According to Prange et at. (1995), quality of seeds declined (increased

berc:ent unmarketable) with increasing shelf temperature and storing time.

on a study conducted by Hampton (1991) using Trifolium patense L. seed lots, results

. lIllovvea that if a high germinating seed lot is placed in a temperature storage environment

~~nelre ambient air temperature ranges from 5°C to 25°C and the seeds moisture content does

increase or decrease beyond 8 to 14%, then the seed lot would be expected to maintain it's

to germinate for at least 12 months, and probably several years.

Hampton (2000) added that, the germination percentage before storage does not

reflect the storage ability as high germinating seed lots, because it may perform

differently after storage even under the same conditions. This is due to the differences in

ofcuitivar, certification class and chronological age.

ttegordinlg to Harrington (1973), for each 1 % decrease in seed moisture content and each

rease in storage temperature, the storage life of the seed is doubled. Similarly,

7

""""hl~r & Agpaoa (1976) stated that viability of many seeds is maintained longer if the seeds

stored at constant rather than fluctuating temperatures.

Viability of seeds

~~OODr<1m~ to Copeland (1995), the capability of seeds to produce normal seedling is termed as

Seed viability is at its optimum when seeds are at physiological maturity and

. VlilDlllllY will gradually decrease after reaching the physiological maturity.

viability of seeds in storage depends on temperature and moisture during storage.

, temperature and moisture influence the enzymatic and biological activities in seeds

and thus increases the rate of damage. According to Schimdt (2002), seed lots that rapidly lose

their viability under accelerated ageing, are believed to have a generally shorter viability

under normal storage conditions.

of viability and vigour can be seen at biochemical level whereby changes can be

imeasured in terms of decline in metabolic activity upon germination (Ferguson et aI., 1990),

dumges (in most cases a decrease) in enzymatic activities (Gangali and Sen-Mandi, 1993),

and a decline in protein and nucleic acid biosynthesis (Bray and Chow, 1976).

In a recent research on C me/o, Pesis and Ng (1984) have observed that in five cultivars of

~lIltlfici.a1I) aged muskmelon that they had used, the seeds differed in their viability and vigour

determined by germination tests. This means that the degree of effects varies for each

8

Seed Gennination

" W UrultlOlll of seeds is characterized by the emergence and development from the seed

....Ihn'n of those essential structures which, for the kind of seed being tested, indicate the

-'-lit" to develop into a nonnal plant under favorable condition in the soil (AOSA 1991).

gennination test is simply used to detennine the viability of seeds. Although it has several

. ruultlons, it is regarded as a universal method to test the quality of seeds. Seeds undergo

sequences in gennination. The major events are imbibition, enzyme activation,

of embryo growth, rupture of the seed coat, and the emergence of seedling

-.Ao'~.'Q.lIU and McDonald, 1995).

percentage and rate of gennination are markedly reduced when seeds undergo accelerated

. mg. Based on a study conducted by Tekrony, et al. (1980), which evaluates the vigour of

~turc:~ soy beans after accelerated ageing, the results showed that accelerated ageing

. murultlon declined more rapidly than in standard gennination

Seed deterioration

common feature of seed deterioration is the loss of integrity of cell membranes. As ageing

",1UJ1I.."." membrane integrity within the seed at imbibition declined followed by the increase

of sugars and electrolytes (Villers, 1973). This increase in cellular membrane

in seed as ageing progresses is due to seed impainnent and is the first indication

. ''''Ith,l decline (Abdul-Baki and Baker, 1973).

9

deterioration is a major problem in agricultural production. According to Salunkhe et al.

985), over US$ 800 million is lost annually due to deterioration and as consequences of

m:alKa~te and microorganism spoilage during production, storage and shipping of seeds.

-""'UIUjl". to McDonald and Nelson (1986), it is estimated that 25% (approximately US$ 500

.-&6•••..,..., of seed sales in 1984, was lost due to poor seed quality.

capability to predict seed deterioration would be extremely valuable to seed companies

gennplasm repositories since the loss of seed quality could be anticipated and seed stocks

replenished (Copeland and McDonald, 1995). Hence, the use of poor quality seeds due to

stock or poor storage conditions can be avoided following accelerated ageing technique.

Accelerated Ageing

accelerated ageing is by far the most accurate testing of seeds intended for storage before

as a planting material. According to Tekrony (1995), the accelerated ageing test is

M:kl11O'~leclQ(:d as one of the most employed tests to evaluate the physiological potential of

species of seeds, providing information of high degree of consistency on the quality of

purpose of this test is not to provide an absolute value, but an indication of whether a high

Lmninatulg seed lot may have performance problems if subjected to environmental stresses in

field or during storage. The use of accelerated ageing in predicting storage life for seeds is

applicable where the processes that cause ageing under accelerated ageing are the

_:uw~nsthat caused the loss of viability during storage (Hampton, 2000).

10

of vigour and viability during dry storage includes a wide range of degenerative events

accumulate over time, causing the loss of viability. The losses can be grouped as

WSI.Olo1glcal and biochemical. Among the physiological changes that occur as a result of

are; decreased rates of gennination and seedling growth (Heydecker, 1972), increased

of morphologically abnonnal seedlings (Mackay, 1972), decreased ability to emerge

sown under stressful conditions (Mackay, 1972), increased metabolite and ion leakiness

and Ellis, 1982), and also greater susceptibility of seedlings to pathogens

i3Jrislens(m, 1972).

seeds with reduced vigour genninate slowly, produce small or abnormal seedlings and

little resistance to stress (Schmidt, 2002). As ageing process progresses, the seed losses

capability to germinate altogether. According to Bulan (1984), the influence of temperature

relative humidity on seed deterioration is exerted right from the beginning of storage

the development of seedlings and mature plants. Schmidt (2002), highlighted that

mperalture and humidity are the most important factors in seed storage. Non-donnant seeds

germinate if their moisture content is above 30%. Rapid deterioration by microorganisms

occur if moisture content is between 18% and 30% and seeds with moisture content above

and 20010 respire and metabolize actively.

a study conducted by Jatoi et at. (2001) on the seed deterioration behaviour in pea, using

~Iera:tea ageing techniques, seeds were subjected to different temperatures (25, 35 and

and storage durations (48, 72 and 96 hours). The study revealed that gennination rate

speed of germination were significantly affected by different temperatures and storage

'-1OrJ1S. They also found that the rate of seed deterioration increased with the increase in

11

temperature and storage period. The results revealed significant varietal differences in

deterioration were observed and the rate of deterioration and some of the varieties were

and Filho, (2003) has conducted a study to compare different procedures of accelerated

test to evaluate the physiological quality of melon seeds (C mela). Their results

that, exposure period of 72 and 96 hours at 38°C or 41 °C can present enough

_ ...,n,n'nl for the physiological potential evaluation of melon seeds. In general, the 41°C

IIlPrnlture showed a greater reduction in the germination than 38°C, especially for seed lots

UlCtttp1"Pi1 as having lower physiological potential.

(1993) has conducted a study on the effects of short periods of accelerated ageing on

Irmiinatlon performance of soybean (Glycine max L.). Results showed that the benefits of

~I,erateo ageing on gennination perfonnance were very brief and became negative when

aged seeds were stored for longer period.

(2002) conducted a similar study with the same approach but, with a different species

is Capsicum annum L. She mentioned that the percentage of germination increased

a short period of ageing which enabled better perfonnance in ageing and decreased with

mcrement in period of ageing and storage. The main purpose of these studies concerned

suitable and appropriate preservation period and storage conditions to maintain high

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inn.orgtllrp

this study is conducted to evaluate the quality of C. melD seeds and to detennine

detrimental effects of short period of accelerated ageing on C. melD seeds in terms of

and storage condition when the seeds are stored in different environmental

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effects of temperature and storage on the … of temperature and storage on the... · effects of...

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