helpful for researcher, student in field of biological science, Agricultural science and Seed technologist etc.

1. Course Seminar (SST-699)
On
Seed Senescence
Presented By: Advisor:
Abhishek Pati Tiwari Dr. C.B. Singh Gangwar
Ph.D. 2nd Year Assistant Professor/SRO
Id. No. CA-11332/19 Seed Science and Technology
Chandra Shekhar Azad University of Agriculture and Technology
Kanpur, (U.P.), India

2. Seed Senescence The word senescence means process
of deterioration with age. Senescence is biological
irreversible process.
Seed senescence is defined as deteriorative changes
occurring with time that increase the seed’s
vulnerability to external challenges and decreases the
ability of the seed to survive.
Seed senescence is an irreversible degenerative change
in the quality of a seed after it has reached its
maximum quality level. Generally, seeds reached its
maximum quality level at physiological maturity, and
beyond this point of time only degeneration occurs.

3. 1. Seed senescence is an inexorable process.
This means that seed senescence must be considered as an
unalterable fact. We cannot prevent senescence; we can,
however, influence or control its rate .
2. Seed senescence in seeds is an irreversible process.
Dead seeds cannot be brought back to life or more
realistically perhaps, dead portions or areas in seeds cannot
be rejuvenated or made whole again. If seed are allowed to
deteriorate in the field, or mechanically abused in
harvesting, the damage cannot be undone by subsequent
good storage, gentle handling or even seed treatment.

4. 3. Seed senescence is at its lowest level at the time of
physiological maturity.
By physiological maturity we mean the point in the
developmental history of a seed when it is capable of
developing into a highly vigorous seedling. Although
seeds usually reaches maturity long before normal
harvest and at relatively high moisture contents - 30 to
45%. Once the peak of maturity is attained, the seeds
having reached maximum dry weight, vigour and
viability and there is only one direction to go, downhill.
There can be considerable deterioration before harvest.

5. 4. Rate of seed senescence varies among the different
kinds of seed.
Cottonseed and soybeans have somewhat similar
chemical composition - they are both high in oil and
proteins with relatively little starch. Yet, cotton seed
will store or keep for 2 or even 3 years while soybeans
often deteriorate before the first planting season after
harvest. However Orthodox seeds shows slow rate of
senescence than recalcitrant seeds
5. Rate of deterioration varies among seed lots of the
same kind stored under the same conditions.
seed lots of the same kind and variety, of the same
chronological age and viability, and which even look
alike, are not necessarily of the same quality.

6. Changes in seed coat colour or embryo or endosperm
Delay of radicle emergence and seedling growth
Reduced total germination of seed population
Increase in the number of abnormal seedlings
Lower tolerance to adverse storage conditions
Loss of vigour
Slower rate of seedling growth and development
Decreased germination percentage
Stunting of radicle
Decreased resistance to environmental stress during germination and
early seedling growth
Reduced yield potential
The ultimate perform symptom is the complete loss of germinability
and death of the seed

9. MORPHOLOGICAL
CHANGES
ULTRA
STRUCTURAL
CHANGES
BIO CHEMICAL
CHANGES
GENETIC
CHANGES
PHYSIOLOGICAL
CHANGES

10. Change in seed coat colour
Examples: darkening of seed coat in deteriorating clover,
groundnut and soybean seed it is due to oxidative
reactions in seed coat, which are accelerated under high
temperature and high humidity .

11. Mitochondria: It become permanently swollen and loss their
natural swelling contracting ability and results in decrease in
the respiration rate of the seeds.
Ribosomes
Protein synthesis retarded
Nucleus
Develop a peculiar lobed condition in maize
Endoplasmic reticulum
Partially aged seeds have short ER
Completely degenerates

12. BIOCHEMICAL CHANGES
 LIPID PEROXIDATION It refers to oxidative degeneration of lipids. The free
radical steal the e- from the lipids in cell membranes, resulting in cell damage
Loss of membrane structures and increases in leakiness of o2 is able to
damage plant tissue and inhibiting chloroplast development.
 CHANGES IN CELL CHAMICALS CONSTITUENTS Some studies indicated
that oligosaccharide which has been associated in stabilizing membranes
decreased during storage. Verma et al. 2003 showed that carbohydrates
increased with decrease in protein content in deteriorated seeds.
 MEMBRANE DEGRADATION Loss in cellular membrane integrity,
permeability leads to increased leaching of seed constituents which results in
diminishing of normal cell function and energy production.
 LOSS OF ENZYMEACTIVITYThe activity of certain enzyme associated with
breakdown of food reserves or biosynthesis of new tissue during germination is
reduced. Enzymes that reduced are amylase, catalase, etc.

13. IT ISOF TWO POSSIBILITIES
DNA is somewhat degraded and fails to produce
mRNA (transcription fails) that results in no enzyme
formation causing a reduction in germination
DNA functional, formation of functional stored mRNA.
During storage, stored mRNA may be degraded. Impaired
transcription causing incomplete or faulty enzyme synthesis
leads to slower seedling growth
Production of free radicals (unstable molecules that can
damage the cells)

14. DECREASEDTOLERANCE TO ADVERSE
ENVIRONMENTALCONDITION WITH RESPECTTO
GERMINATION
REDUCED SEEDLING GROWTH
INCREASE INABNORMAL SEEDLING
DELAYED GERMINATION

15. factorsassociatedwith
seed
kind/variety of
seed
Genotypic
factor
Initial seed
quality
Provenance
Toxic substance
Abioticfactors
Temperature
Moisture content
Fluctuating
environmental
condition
Oxygen pressure
Bioticfactors
Bacteria and
fungi
Insects and
mites
Factors

16. Effect of temprature:
High temperature hastened the rate of biochemical
processes like respiration etc. triggering more rapid
deterioration that resulted in rapid losses in seed having
high moisture content (Shelar et al., 2008). Seeds sensitivity
to high temperatures is strongly dependent on their water
content, loss of viability being quicker with increasing
moisture content (Kibinza et al., 2006).
Temperature is important because it influences the amount
of moisture and also enhances the rate of deteriorative
reactions occurring in seeds as temperature increases
Effect of oxygen pressure
If the oxygen pressure increases, the viability of seed will
decreases.

17. Effect of Moisture contents of seeds
Seed stored at high moisture content demonstrate increased
respiration, heating, and fungal invasion resulting in
reduced seed vigour and viability. After physiological
maturity the rate of seed quality loss depends on the degree
of unfavorable environmental conditions surrounding the
seed. Environmental moisture, predominantly intermittent
or prolonged rainfall, during the post maturation and pre-
harvest period, is quite detrimental to seed quality and
cause rapid deterioration.
Effect of fluctuating environmental condition
Fluctuating environmental conditions are harmful for
seed viability. Rapid changes in seed moisture content
and temperature cause deleterious effect

18. Bacteria & Fangi
There are several factors which favour infection of
bacteria & fungi and promote their infestation such as
moisture content of seed, relative humidity, temperature,
pre storage infection and storage pest. Most of the
bacteria needs atleast 90 % RH while fungi needs
almost 75% RH for their development. Mostly storage
fungi belongs to Penicillium and Aspergillus.
Insect and Mites
The optimum temperature for insect activity on storage
ranges from 28 to 38°c. the temperature below 17 to
20ºc and below 8% moisture content are considered
unsafe for insect activity.

19. Kind or Variety of Seed
The seed storability is considerably determined by the
kind or variety of seeds. Some seeds are naturally
short-lived, e.g., onion, soybeans, peanuts, etc.,
whereas some seeds like tall fescue and annual rye
grass appear very similar but differ in storability.
Genetic make-up of varieties also influences
storability.
Genotypic factors
Some types of seeds are inherently long lived; others
are short lived, while others have an intermediate life
span owing to their differences on genetic makeup

20. Initial Seed Quality
 High initial viability of seeds maintains their
quality in storage longer than those with less initial
viability.
 Vigorous and undeteriorated seeds can store longer
than deteriorated seeds. Seeds that have been broken,
cracked, or bruised due to handling deteriorate more
rapidly in storage than undamaged seeds.
 Cracks in seeds serve as entrance to pathogens
causing consequent deterioration.
 Seeds that have been developed under environmental
stress conditions (such as drought, nutrient deficiency
and high temperatures) become more susceptible to
rapid deterioration.

21. TOXIC SUBSTANCES
Loss in seed viability is due to the accumulation of
toxic metabolites is one of the most attractive
explanation of seed deterioration
Bio chemicals suggested to be the cause of loss in seed
viability are Indole derivatives and some Phenolics
Example: Coumarin, Ferulic acid, Abscisic acid etc.,

22. There is no direct method for estimating seed senescence.
However, by assessing seed viability, vigour and enzyme
activity seed senescence is measured.
Methods Involved
GERMINATION TEST
TETRAZOLIUM (TZ) TEST
ELECTRICAL CONDUCTIVITY TEST
VITAL COLOURING TEST
ENZYME ACTIVITY TEST
X-RAY PHOTOGRAPHY
FERRIC CHLORIDE TEST
FAST GREEN TEST

24. 2,3,5 –Triphenyl
tetrazolium chloride
TZ TEST IN
BARLEY

25. Electrical conductivity test
As seed deterioration progresses, the cell
membranes become less rigid and become more
water permeable.
It allows the cell contents to leakage into solution
with the water and increasing electrical conductivity.
It provides a rapid indication of seed viability for
seed lots.
Enzyme activity test
These methods measure enzyme activity (such as
lipase, amylase, diastase, catalase, peroxidase and
dehydrogenase) of imbibed seeds as an indication of
their viability.

26. X-Ray photography for viability
It is generally used to test the viability in forest seeds.
PRINCIPLE:
BaCl2 penetrate into the dead cells , but do not penetrate
into living cells because of their semi-permeability.
Thus dead parts of the embryo and endosperm show up
clearly as contrast areas on X- ray photographs.
PROCEDURE:
Seeds soaked in water for 16 hrs
Drain excess water
soak in 20-30% BaCl2 for an hour
After drying, seeds are radiographed using soft X-rays

27. FERRIC CHLORIDE TEST FOR MECHANICAL
DAMAGE
Mechanically injured areas of legume seeds turn black
when placed in a solution of ferric chloride . A solution
of 20% ferric chloride (FeCl3 ) is prepared by adding
four parts water to one part FeCl3.
Two 100-seed replicates in dishes or saucers are
completely immersed in the FeCl3 solution. After 5
minutes, the black staining seeds exhibiting
mechanical damage are separated from those
remaining seeds.

28. Fast Green Test
 The fast green test reveals physical fractures in the seed
coat of light colored seeds and is often used in corn.
 Seeds are soaked in a 0.1% solution of fast green for
10 minutes. During this period, the vital stain
penetrates into areas of the seed that have lost their
physical integrity and stains them green.
 After soaking, the seeds are washed and any
deformations are clearly identified by green markings

30. Conclusion
Seed senescence is natural process it can not be stopped
but it’s rate can be slow down by several management
practices.
e.g. Harvesting at proper stage, proper threshing, Proper
storage and seed treatments with several means etc.

31. References
 C P Malik and Jyoti (2013) Seed Deterioration: a review I. J. of Life
Sciences and Pharma Research.
 Copeland and McDonald (2001) Principles of Seed Science and
Technology. Kluwer Academic Publishers Boston.
 D. Khare and M.S. Bhale (2016) Seed Technology. Scientific publishers
(India).
 J. D. Bewley· M. Black (1982) Physiology and Biochemistry of Seeds.
(Volume – 2) Springer - Verlag Berlin Heidelberg New York.
 Kibinza, Serge; Vinel, Dominique; Come, Daniel; Bailly, Chistophe
(2006) Sunflower seed deterioration as related to moisture content
during aging, energy metabolism and active oxygen species
scavenging. Physiologia Plantarum 128(3):496 - 506
 Shelar, V. R., Shaikh, R. S. and Nikam, A. S. 2008. Soybean seed
quality during storage: A review, Agricultural Review, 29: 125-131.
 Sen subir and Nabinananda Ghosh.2014.Seed science and technology.
Kalyani publishers.New Delhi.
 Verma S.; S, Tomer R. P. S. and Verma U. (2003), “Loss of viability
and vigor in Indian mustard seeds stored under Ambient conditions”,
Seed Research. 31(1) 98-101.