This document discusses seed viability, dormancy, and storage. It defines seed viability as the ability of a seed to germinate and produce a normal seedling. Seed viability can be reduced by adverse weather during development or environmental conditions after maturity. Methods to test viability include tetrazolium tests, germination tests, and x-ray analysis. Seed dormancy is when viable seeds do not germinate under favorable conditions. Causes of dormancy include impermeable seed coats and immature embryos. Dormancy can be broken through mechanical or chemical scarification. Seed storage aims to maintain seed quality until planting by keeping seeds dry and cool in sealed containers or conditioned facilities.

2. ASSIGNMENT ON
SEED VIABILITY, DORMANCY AND
STORAGE
PRESENTING BY SUSHEEL KUMAR Id.NO-48008

3. SEED VIABILITY
SEED VIABILITY- “Seed viability refers to the capability of a seed to
germinate and produce a normal seedling.”
“The viability of the seed accession is a measure of how many seeds are
alive and could develop into plants which will reproduce themselves, when
given the appropriate conditions.”
(Copeland and Mc Donald, 1980)

4. VIABILITY OF SOME VEGETABLES SEED

5. SEED LOOSE VIABILITY DUE TO
 Seed loose viability due to adverse weather conditions during
seed development and maturation e.g. drought, excess water,
extreme temperature etc.
 Nutrient deficiencies and pesticides injury during seed
development and maturation.
 Environmental conditions after physiological maturity e.g.
during harvesting, drying, cleaning, storage and handling of
seeds.

6. SEED VIABILITY TESTS
 Tetrazolium test ( Tz )
 Germination test
 Cut test
 X-ray analysis
 Spectral imaging .
 Ferric Chloride Test for Mechanical Damage .
 Indoxyl Acetate Test for Seed Coat Damage.
 Noninvasive diagnosis of seed viability using infrared
thermography.

7. TETRAZOLIUM TEST
TETRAZOLIUM TEST (George Lakon in 1942) OBJECTIVE:
“Rapid assessment of viability.”
PRINCIPLE:
“A colorless tetrazolium solution is used as
an indicator producing in living cells a red,
stable and non-diffusible substance, named
Formazan.
Thus, it’s possible to distinguish the red colored living
tissues from the colorless dead ones and the seeds are
classified into viable and non viable seed classes.”

8. PRECONDITIONING OF SEED BEFORE
TETRAZOLIUM (Tz) TEST
 Preconditioing of seeds before Tetrazolium (Tz) test no
moistening or preparation required (small seeded legumes
with soft coats).
 Seeds directly placed in Tz solution in case of peas and
beans bisect longitudinally before placing in Tz solution.
 Eg: The seed coat may be removed e.g. cucurbits The
seed coat may be scratched above embryo e.g. lettuce

9. METHODOLOGY
SEED HYDRATION
 It is done by soaking seeds in water for a specific period of
time .
 This is done to active hydrolytic enzyme (dehydrogenase)
and stimulate respiration.
CUTTING OR PUNCTURING OF SEED
 This is done to allow the penetration of Tz solution into
internal tissues.

10. STAINING OF SEEDS
 Staining of seeds: It is done by soaking
seeds in Tz solution for a specific period
of time to allow staining of viable tissue
in the seed.
 Tz is used @ 0.1 or 1.0 % solution, at
30-35º C temperature for 24-48 hours
at pH of 6-8.

11. EVALUATION OF SEED
 Evaluation of seeds evaluated according to staining
pattern.

12. GERMINATION TEST
OBJECTIVE:
 To gain information about the field planting value of the seed lot.
GERMINATION :
 Germination in a laboratory test refer
to the emergence from the seed embryo
of those essential structures which for
the kind or seed being tested; indicate
its ability to develop into a normal plant
under favourable conditions.

13. PHASES OF GERMINATION
 Imbibition phase (Rapid uptake of water)
 Active metabolism (Major metabolic pathways affected
are respiration, protein synthesis, DNA replication, RNA
synthesis etc.)
 Cell expansion and seedling protrusion.

14. GENERAL REQUIREMENT FOR GERMINATION
SUBSTRATUM
 Suitable substratum : Paper, sand or soil .
 Adequate moisture/ water : pH 6-7.5,.
 Favourable temperature : as per crop .
 Light : Required for germination in some of the crops like lettuce etc.
 Chemicals : KNO 3 , GA 3 , Ethephon as prescribed by ISTA.
 Prechilling : Also called stratification and it is exposing of imbibed seeds to cool
temperature usually between 5-10 º C for a period of time (days, week or months)
 Duration of germination tests : Number of days to first and final count .
Germination Methods in the laboratory:
 Between the paper(BP method)
 Top of the paper (TP)
 Sand

15. PROCEDURE
 From working sample take 400 seed at random.
 Method Between Paper/ Top Paper / sand
 Plant seed as 100×4R, 50×8R, 25×16R
 Provide temperature or light and humidity as recommended.
 Germination count(1st and final as per specie)

16. THE CUT TEST
 The cut test is simple and easily executed.
 Viability is determined by cutting the seed open and
examining the contents.
 In particular, the seed embryo must appear intact and healthy
if the seed is to go on and germinate.
 In addition, the endosperm must appear clean and firm.

17. X-RAY ANALYSIS
 X-ray radiography is a valuable tool to supplement
laboratory tests , provide additional information about
the seed lot quality along with the internal
detail/structure of the seed.
 X-ray analysis can be a very efficient and non-destructive
method of assessing seed quality.
 A good x-ray image will reveal details of seed fill, insect
infestation and also size or absence of the embryo.

19. SEED DORMANCY

20. SEED DORMANCY
Failure of fully developed & mature viable seed to
germinate under favorable conditions of moisture &
temperature.
- This condition called as resting stage, period or
dormancy.
- This seed called as dormant seed.

21. TYPES OF DORMANCY
Primary dormancy-
Due to internal causes even favorable environmental
conditions are available for germination.
Secondary dormancy-
They germinate immediately after present the
favorable conditions, but the dormancy is induced in
the seeds if there is kept under certain conditions.
Eg. Mustard seed – is kept in higher concentration with
CO2 due to respiration.

22. Special dormancy-
Some species are germinated , but the primary roots fail to develop
that’s why epicotyls is stopped.
Organic dormancy-
Seed remains hard after the expiry of germination period and don’t
germinate, when the moisture reduced below 4%.

23. CAUSES OF DORMANCY
1. Impermeability of seed coat to water-
Seed coat become hard (family- Leguminosae,
Solanaceae, Malvaceae, Convolvulaceae,
Chenopodiaceae.) the seed contain external waxy coating
made up off Lignin, Suberin or Cutin which is
impermeable to water.
- These seed remain dormant until seed coat is removed
by microbial activity of alteration of temperature.

24. 2. Impermeability of seed coat to oxygen-
Germination is inhibit due to impermeability of the
seed coat to oxygen.
Eg. Fruit of Oats and Xanthium-
These contains two seed (upper & lower) lower is
germinate under soil and upper seed doesn’t
germinate until seed coat is punctured or removed by
the high concentration of oxygen.

25. 3. Growth of embryo-
Mustard & Amaranthus- seed are easily permeable in
oxygen and water, but the seed coat doesn’t rupture.
4. Immaturity of embryo-
The development of other parts of seed completed except
embryo.
5. Temperature requirement-
Apple , Peach require low temperature to germinate further
more require high temperature to germinate.

26. 6. Light requirement-
Carrot, tobacco require absolute requirement of light, while
Datura exposure to light is inhibitory for germination.
7.Germination Inhibitors-
Tomato fail to germinate due to presences cirulic acid found
in the sap of fruits.
These chemical present the husk in Rice and Oats seed .

27. METHODS OF BREAKING DORMANCY
1.Mechanical treatment of seeds-
The dormancy can be removed by mechanically to
weakening the seed coat called as Scarification.
1) Filing (using sand)
2) Chipping (using knife)
3) Piercing (using needle)
4) Chilling (using temperature)
5) Pre-drying (using temperature)
6) Pre-washing (using water)
7) Pre-soaking (using warm water)

28. 2. Chemical treatment-
Seed are dipped in mineral acid (HCL, H2SO4) or
organic solvent (Alcohol, Acetone) to cause degrading of
seed coat and dissolving of waxy coating.
3. Use of growth regulator-
Germination can be influence by using growth
hormones (GA3, IBA, IAA, NAA, 2,4-D)

29. ADVANTAGES OF DORMANCY
 Seed survive in adverse conditions.
 Seed stored till next season, transport to another place
without loosing its viability.
 Seed use in research such as gene pool.
 Some seed kept in cold condition to get best price when
there is off season.
 Due to dormancy species are saved from wipeout in case of
natural calamity.
 Seed germinate itself.

30. DIS-ADVANTAGES OF DORMANCY
 The seed can not sown immediately after maturity, will have
to wait for the expiry of dormant period.
 Seed remain naked during dormant period they get shabby
look.
 Germination of the seeds is poor and growth of buds is slow
and irregular even under favorable condition.
 Noxious weed seed lie dormant for many years in soil and
thus growing year after year becomes eradication
impossible.

31. PURPOSE OF SEED STORAGE
 The purpose of seed storage is to maintain the seed in good physical
and physiological condition from the time they are harvested until the
time they are planted .

32. GENERAL PRINCIPLES OF SEED STORAGE
 Seed storage conditions should be dry and cool .
 Effective storage pest control .
 Proper sanitation in seed stores .
 Before placing seed into storage they should be dried to safe moisture limits,
appropriate for the storage system .

 Storing of high quality seed only i.e well cleaned , treated as well as of high
germination with vigour and good pre-storage period .

33. SEED LONGEVITY IN STORAGE IS A FUNCTION OF:
 Type of species
 Initial seed quality (production and conditioning)
 Storage environment

34. SPECIES CAN DISPLAY ORTHODOX AND
RECALCITRANT BEHAVIOUR
ORTHODOX SEED:
Orthodox seeds tolerate maturation drying and can remain
viable for years.
Medium-lived seeds (3 – 15 years). Long-lived seeds (> 15
years).
RECALCITRANT SEED:
Recalcitrant seeds do not tolerate maturation drying and
are short-lived seeds. Species can display orthodox or
recalcitrant seed behavior

35. RELATIVE STORABILITY INDEX
Crop Category 1
(1 to 2 yr.)
Category 2
(3 to 5 yr.)
Category 3
( >5 yr.)
VEGETABLES Green bean
Broccoli &
cabbage
Beet
Lettuce
Sweet corn
Tomato
Onion
Cucumber
Pepper Pea

36. STORAGE CONDITIONS
 Seed longevity is improved by storing seeds at low temperature
and low moisture content.
Rule of thumb for seed storage
Seeds lose half their storage life:
1.For each 1% increase in seed moisture between 5 and 14%.
2.For each 5ºC increase in storage temperature between 0 and
50ºC.

37. TYPES OF STORAGE
 Sealed containers
 Open storage
 Conditioned storage

38. SEALED CONTAINERS:
Used to keep out moisture
Types include:
 Aluminum or plastic cans
 Aluminum pouches

39. CONTI……
 Plastic bottles
 Waxed boxes
 Laminated paper bags

40. OPEN STORAGE
Does not have temperature or relative humidity control.
Cheapest type of storage.
 Needs basic protection from water,
contaminating agents (herbicides), and rodents.

41. CONDITIONED STORAGE
 Conditioned storage as temperature control.
 Commercial storage facilities held at <10ºC.
 Humidity may be controlled below 50% RH
or seeds stored in sealed containers.
 Conditioned storage is used for high value seeds.

42. Thank you