This document discusses seed storability and viability prediction in important oilseed crops. It covers several key topics:
1) Factors that affect seed viability and storability during storage like moisture content, temperature, packaging material and storage structure. Lower moisture content and temperature helps extend seed life.
2) Methods for predicting seed viability like accelerated aging tests, mathematical models and nomographs that relate viability to moisture content and temperature over time.
3) Biochemical changes that occur during storage like lipid peroxidation and accumulation of free radicals that can damage cell membranes and organelles leading to loss of viability over time.
4) The importance of understanding these factors and developing strategies to optimize seed storage conditions and predict viability
2. Speaker : Sangram Singh
Degree : Ph.D., Seed Sci. and Tech.
Reg. No. : 04-2188-2013
Major Guide : Dr. Sasidharan N.
Minor Guide : Dr. D. A. Patel
Course No. : SST 691
Date : 22/04/2015
Time : 16:00 hrs.
Seed Storability and Viability Prediction in
Important Oilseed Crops
4. India is world’s fourth largest country in vegetable oil
economy after USA, China & Brazil.
India is one of the major oilseeds grower and importer of
edible oils.
The diverse agro-ecological conditions in the country are
favourable for growing nine annual oilseed crops, which
include edible oilseeds and non-edible oilseeds.
Ninety per cent of oilseeds production is centred in nine
states viz. Madhya Pradesh, Rajasthan, Maharashtra,
Gujarat, Andhra Pradesh, Karnataka, Tamil Nadu, Uttar
Pradesh and Haryana.
Introduction
4
5. Seed viability and vigour are the serious problems.
Seed viability is affected by several factors (pre and post
harvest).
Oilseed are very sensitive, loose viability very fast due to
its fragile seed coat.
Maintenance of seed viability and vigour till sowing is
very critical.
Alternate strategy of off season for seed production is
not feasible due to low productivity.
Use of low physiological quality seeds is a common
practice leading to inadequate plant population.
5
6. Seed storage is to maintain the
seed in good physical and physiological
condition from the time they are
harvested until the time they are sown.
Objectives of seed storage
6
7. Harvest and Post harvest losses of oilseed at national level
0
2
4
6
8
10
12
Harvesting Threshing Drying Transporation Storage loss Overall loss
Groundnut Mustard Soybean Sunflower Safflower 7
8. Basic requirements for safe and scientific storage
Selection of site
Selection of storage structure
Cleaning and drying of oilseed
Cleaning of storage structures
Cleaning of bags
Separate storage of new and old
stock
Cleaning of vehicles
Proper aeration
Use of dunnage
Regular inspection 8
9. Types of storage requirements
Storage of Commercial seed (few days to eight months)
Storage of carryover seed (12–18 months): In this case storage requirements
consists of
Insulation of storage house with ventilation facility.
Storage of the seeds under dry conditions in moisture proof containers.
Storage of FS seed (1- several yrs):
Seed stored in cool and dry environment.
Well dried seed is packed in moisture proof containers in less than 15 0C
temperature.
Storage of germ-plasm (stored for very long period):
Storage environment should be less than 5 0C temp. and 20- 25% RH
Seed dried to the proper moisture level.
9
10. Natural Longevity of Oilseeds
Microbiotic: seed life span not exceeding 3 years
Macrobiotic: seed life span from 15 to over 100 years
Mesobiotic: seed life span from 3 to 15 years
Orthodox. Seeds which can be dried down to a low moisture
content (around 5% on wet basis) and successfully stored at
low or sub-freezing temperatures for long periods. e.g.
cereals, pulses and Oilseeds etc.
10
11. Rule of the thumb
For every decrease of 1% seed moisture content, the life of the
seed doubles. This rule is applicable when moisture content
(mc) is between 5 and 14%.
For every decrease of 5 C in storage temperature the life of the
seed doubles. This rule applies when temperature is between
0C to 50C.
Numerical rule of the thumb
Good seed storage is achieved when the RH(%) in storage
environment and the storage temperature in 0F add up to
hundred but the contribution from temperature should not
exceed 50F.
Thumb Rule (Harrington 1972)
11
12. 35-80% Moisture content of developing seed. Seed not mature enough
to harvest.
18-40% Physiologically mature seed, High respiratory rate,
susceptible to field deterioration, heating occurs if seed is
bulked without proper ventillation.
13-18% Respiratory rate still high, mold and insects can be damaging
and seed resistant to mechanical damage.
10-13% Seed stored well for 6-8 months in open storage in temperate
climates.
8-10% Seed sufficiently dry for 1-3 years under open storage in
temperate climates. Very little insect activity.
Role of moisture on oilseed viability and storability
12
13. Stages of Oilseed Storage
1 Post maturation/ Pre harvest
segment
Period from physiological maturity to
harvest (seed in field).
2 Bulk seed segment Period from harvest to packaging
(bulk seed in aeration drying bins,
surge bins, etc.).
3 Packaged seed segment Period from packaging to distribution
(seed in packages in warehouse).
4 Distribution /Marketing
Segment
Period during distributing and
marketing (packaged seed in transit
and/or retailer’s storehouse).
5 On-farm segment Period from purchase to planting of
seed (seed in on-farm storage).
13
14. Store well mature seeds.
Store normal coloured seeds.
Seeds should be free from mechanical injury.
Seeds should not have met with adverse conditions
during maturation.
Seeds should be dried to optimum moisture content.
Seeds should be treated with fungicides before storage.
Suitable packaging materials should be used for packing.
Seed selection for extended storability
14
15. Factors affecting oilseed longevity in storage
A. Biotic factors
Factors related to seed
Kind/variety of seed
Initial seed quality
Seed moisture content
Provenance
Activity of organisms associated with seeds in storage i.e. Seed health
B. Abiotic factors
Temperature & Relative humidity.
Good (Ideal) storage : RH (%) + Temp (0F ) = 100
Gaseous atmosphere
Storage in extreme condition like cold, hot, and over dried
Other factors (Packaging material, type of godowns seed store,
sanitation,seed treatment fumigation, and period of storage in transit)
15
16. Approximate moisture content of oilseed crop in
equilibrium air at different relative humidity
Crops
Relative humidity (RH) in percentage
15 30 45 60 75 90
Soybean 4.3 6.5 7.4 9.3 13.8 18.8
Groundnut 4.6 5.2 6.6 7.2 9.8 13.0
Mustard 6.0 7.7 8.5 12.2 14.8 20.6
Source: SST, Copeland and McDonald 16
17. Seed storability prediction
Predicting the actual seed quality of oilseed during natural aging by
applying the accelerated aging test, the main factors being the time of
natural aging duration and degree of seed deterioration.
The prediction of oilseed seed quality depends on understanding the
relationships between three factors i.e. seed moisture content, storage
temperature, and storage time.
In oilseeds the quality losses mainly due to poor storage of seeds is
very high.
Moisture content ranging from five to seven percent is the most
suitable for storage of oilseed.
Seed rich in lipids has limited longevity due to its chemical
composition.
17
18. The environmental conditions that exist during the growth and harvest
affects the seed quality and storability.
Seed is hygroscopic in nature, viability and vigour of seeds are
known to be regulated by physiochemical and variations in storage
containers, storage period, initial seed quality, and packaging
conditions factors, etc.
Oilseed has short life and looses viability quickly under ambient
condition. Several factors affect the self life of the seed; among them
infections by seed borne fungi is one of the factors for quick loss of
viability of a seed.
For better storage, the seeds can be stored in moisture proof containers like
gunny bags with polythene. Hence, there is a need to assess the suitability of
different containers for enhancing the storability of summer groundnut seeds.
18
19. STORAGE STRUCTURES
Conventional storage structures
Examples: Bamboo structures, Mud and earthen structures, Wooden
structures, brick structures, and underground structures
Community storage structures (village level)
Examples: Concrete/cement silos, Metal or Plastic drums
and metal Silos etc.
19
20. Improved rural - level storage structures
Coal tar drum, Hapur bin, Udaipur bin, Stone bin, Bamboo bin, PKV bin,
Pusa bin, Pusa Cubicle, Pusa Kothar, Metal bins
Long term storage ( germplasm ) technology
Seed storage in Cryopreservation
Svalbard Seed Bank
20
21. Seed storage in Cryopreservation
It is also called cryogenic
storage. It is the technique of
germplasm conservation (storage
of cells, tissues, embryo or seeds)
by ultra low temperature in liquid
nitrogen at – 196 0 C. It is not
practical for commercial seed
storage, but is useful to store the
valuable germplasm.
21
22. :
Storage of seed for enhancing longevity.
Establishment of germplasm bank.
Exchange of germplasm and information at International level.
To ensure the availability of useful germplasm for use in future.
Some seeds can not be preserved by conventional method which
can be preserved.
We can preserve the plant species, which loose the viability of
seeds when it is dried at certain water content or exposed to low
temperature.
ADVANTAGES OF CRYOPRESERVATION
OBJECTIVES OF CRYOPRESERVATION
22
23. Svalbard global seed vault
The seeds are stored in
four-ply sealed envelopes, then
placed into plastic tote containers
on metal shelving racks. The
storage rooms are kept at −18 °C.
The low temperature and limited
access to oxygen will ensure low
metabolic activity and delayed seed
aging. The permafrost surrounding
the facility will help maintain the
low temperature of the seeds,
should the electricity supply fail.
23
24. 24
Storage containers
Seed are packaged in containers varying in size from
packets holding one gram of seed to bulk bins holding tons of
oilseed. In determining the kinds of container, the following
points are to be considered.
The quantity of seed desired in each package
The protection desired
The cost of the package
The value of the seed
The storage conditions in which the container is to be
placed
24
25. Classification of containers
These container allow the entry
of water in the form of vapour
and liquid.
These are suited for short term
storage.
The seed in these containers
will attain seed equilibrium
moisture with the surrounding
atmosphere.
e.g. Cloth bag , gunny bag,
paper bag etc.
1. Moisture and vapour pervious
containers
25
26. 2. Moisture impervious but vapour pervious
containers
The containers allow
the entry of water in
the form of vapour
and not in liquid.
The seed in the
containers can’t be
carried over for long
period in hot and
humid conditions.
e.g. polythene bag of
300 gauge.
26
27. 3. Moisture and vapour proof containers
These containers will
not allow the entry of
moisture in the form
of liquid or vapour.
These are used for
long term storage
even in hot and
humid conditions if
the seeds are sealed
at optimum moisture
content.
e.g. Polythene bag of
700gauge thickness,
aluminium foil
pouches, rigid plastics
etc.
27
28. Seed Viability Predictions
Seed viability prediction of oilseed lots in
relation to storage duration might save money
and time, allowing the early sale of low
storability seed lots.
28
SEED VIABILITY
29. A viable seed is one which is capable of germination under
suitable conditions. The definition includes dormant
but viable seeds, in which case the dormancy must be
broken before viability can be measured by germination.
Seed viability test is a rapid estimate to determine whether
the seed is alive or dead, i.e. the embryo is potentially active
or inactive.
Though germination is the final expression of viability, a
potentially active embryo with very low vigour or a dormant
viable embryo will not germinate normally.
SEED VIABILITY
29
30. Physical method:
Radiographic test
Cut test
Spectral imaging
Physiological method:
USAP test (Urine Sugar Analysis Paper test)
EE test (Embryo Excision Test)
SLC test (Seed Leachate test)
LC test (Leachate Colour Test)
SC test (Seed Crushing Test)
Biochemical method:
TZ test (Tetrazolium test)
IC Test (Indigo Carmine)
FC test (Ferric chloride test)
GADA test (Glutamic Acid Decarboxylase Activity test)
Noninvasive diagnosis of seed viability using infrared
thermography
Methods For Viability Prediction
30
31. Viability loss during storage
Lipid peroxidation (LP) is oxidative damage of cell membranes,
lipoproteins and other molecules containing lipids, caused by
oxidative stress. Once initiated, reaction of LP continues auto-
catalytically and progressively leads structural and functional
substrate changes.
Seed deterioration during storage was due to the damage in cell
membrane and other chemical changes in the seed.
Some biochemical changes strongly influencing the quality and
viability of seed take place inside the oilseed during aging.
The qualitative loss of seed can be attributed to biochemical
changes in protein, carbohydrates, fatty acids and vitamins. 31
32. Lipid auto oxidation and increase of free fatty acid content during
storage are the most often mentioned reasons for accelerated damage of
seed of oil plant species.
Accumulation of active oxygen species and free radicals has often been
considered as one of the most important factors of seed ageing.
Such degenerative changes result in complete disorganization of
membranes and cell organelles and ultimately causing death of the seed
and loss of viability.
32
Lipase is the enzyme which is produced abundantly in oil seeds during
storage which breaks down the lipid into free fatty acid and glycerol.
Oilseed is usually harvested and stored dry in different storage facilities,
traditional and modern. Being an oil seed, it losses its viability within a
short period due to the irreversible phenomena of ageing. 32
33. Basic Viability Equations
The viability equations are mathematical models that
have been developed to predict seed storage life in
different environments.
33
34. Viability equations are useful in designing and managing
seed banks
Estimate the final viability of a species stored under known
environmental conditions for a specified period of time.
Estimate the likely storage life of a species stored under known
environmental conditions.
Estimate how long it will take to lose a certain amount of viability
under known environmental conditions.
Estimate the storage temperature required to achieve a particular
level of viability after a period of storage at a specified moisture
content.
To estimate the equilibrium moisture content, the seed lot needs to
be dried in order to achieve a specified viability after a period of
storage under known temperature conditions.
34
35. .
Prediction of Seed Viability by Nomographs
Nomo graphs are helpful in predicting the
retention of seed viability in defined storage
environment for a particular period or to determine
combinations of temperature and moisture content
which will ensure the retention of a desired level of seed
viability for specific period.
35
37. Table 1: Influence of seed pelleting on germination (%) of Niger Cv.No.71
during storage
Koppalkar and Deshpande, 2006Dharwad 37
One Month Five months
40. Table 4: Effect of packaging material for storage of
groundnut produced during rabi or summer season on seed
germination.
Gowda and Reddy, 2007Raichur
Treatment
Seed germination
Months after storage
2 5 8
C1: Gunny bag 85 77 63
C2: PLGB 87 81 67
C3: HDPB 86 77 58
C4: PLGB + Silica gel 87 81 72
C5: PLGB + CaCl2 87 81 71
C6: HDPB +Silica gel 87 81 68
C7: HDPB + CaCl2 86 81 68
CD at 5 % 4.23 8.32 3.31
40
PLGB- poly line gunny bag, HDPB- High density poly bag
42. Figure 1: Change in Lipid content, starch,α-amylase and β-amylase in cotyledons of
germinating soybean seed during storage .
Sharma, et al. 2007Ludhiana 42
46. Figure -2: Changes in seed germination of sunflower and soybean genotypes
under different storage conditions and duration measured after 6 and 12
months of storage
(FS-fresh seed; CC-controlled conditions and CS-conventional storage
Balesevic et al. 201046Republic of Serbia
47. Figure 3: Prediction of seed germination during natural aging of sunflower and
soybean seed based on accelerated aging test
(CS12-conventional storage after 12 months; AA3-accelerated aging test for 3 days;
AA5- accelerated aging test for 5 days)
Balesevic et al. 201047Republic of Serbia
48. Figure -4 : Moisture content of mustard seed stored in different containers
Days Tithi, et al. 2010Bangladesh 48
49. 52
Figure - 5: Germination percentage of mustard seed stored in different containers
DaysBangladesh Tithi, et al. 2010 49
53. 53
Table 12: Observed and predicted seed viability value of groundnut by
equation
Brazil Usberti and Gomes, 1998
54. Oilseed behave differently under storage as reflected by their
sensitivity to germination and accumulation or depletion of bio-
molecules in the cell.
Low temperature and relative humidity (RH) can retain better
seed vigour.
The efficiency of packaging material for different oilseed crops
will vary according to the nature of crops. i.e. polythene bag+
Aluminium foil (soybean), polyline gunny bag+silica gel
(groundnut), Airtight containers (mustard) etc.
Soybean seed treated with Deltamethrin @40 mg/kg of seed
recorded significantly higher germination%, root length, shoot
length and seed vigour index.
Conclusion
55. Urgent need to develop area specific seed storage protocol
for different seeds.
Need for innovative seed storage techniques for various
oilseed crops to improve the seed storability.
Development of low cost eco-friendly seed storage with
micro-sensors to monitor seed quality in storage for warding
off pests and pathogen.
Development of storage technologies, such as vacuum
packaging containers for high volume low value seeds.
Development of national seed grid with modern seed storage
technology as a contingent planning measure during natural
calamities.
Future Thrust