The document discusses the germination of seeds, detailing types such as epigeal, hypogeal, and viviparous germination, along with their respective examples. It also explores various biotic and abiotic factors affecting germination, including seed viability, dormancy, light, temperature, and water requirements. Understanding these factors is crucial as they influence the growth conditions and habits of different plant species.

1. GERMINATION OF SEED
Presented by
KADER MULLAH

2. INTRODUCTION
• Seed Germination in plants is the process by
which a dormant seed begins to sprout and
grow into a seedling under the right growing
conditions.

3. TYPES OF GERMINATION
1. EPIGEAL GERMINATION
2. HYPOGEAL GERMINATION
3. VIVIPAROUS GERMINATION

4. EPIGEAL GERMINATION

5. Cont..
 In this type of germination, the seed/ cotyledons emerge
out of the soil or above the soil.
 The cotyledons turn green( photosynthetic) and act as
first leaves of the plant.
 Energy for growth primarily derived from cotyledon.
 Some examples include- Bean, Castor etc.

6. HYPOGEAL GERMINATION

7. Cont.
• In this type of germination, the seed/cotyledons remains
inside the soil or below the soil.
• The cotyledon play no role in photosynthesis.
• The energy for growth primarily derived from endosperm.
• Examples- Pea, Maize, Cocconut.

8. VIVIPAROUS GERMINATION

9. Cont..
 In viviparous germination the seeds get germinated
being attached to the parent plant. The embryo grows
out of the seed and then out of the fruit and projects out
as a seedling with roots and hypocotyl.
 Example-mangrove.

10. GROWTH FACTOR AFFECTING
GERMINATION
 BIOTIC FACTOR:
1. VIABILITY OF SEED
2. DORMANCY PERIOD
 ABIOTIC FACTOR:
1. LIGHT
2. TEMPERATURE
3. OXYGEN
4. SOIL
5. WATER

11. BIOTIC FACTOR
 VIABILITY OF THE SEED:
After the seeds are produced they remain viable i.e.
they have potential to germinate up to certain period
that varies from plant to plant or seed to seed.

12. DORMANCY
 In some plants the embryo is not fully mature
at the time of seed shedding.
•Such seeds do not germinate till the embryo
attains maturity.
• The freshly shed seed in certain plants may not
have sufficient amounts of growth hormones
required for the growth of embryo.

13. Cont..
•These seeds require some interval of time during which the
hormones get synthesized.
•The seeds of almost all the plants remain viable or living for a
specific period of time.
•This viability period ranges from a few weeks to many years.
Seeds of Lotus have the maximum viability period of 1000 years.
Seeds germinate before the ending of their viability periods.

14. Cont..
•In many plants, the freshly shed seeds
become dormant due to various reasons like
the presence of hard, tough and impermeable
seed coats, presence of growth inhibitors and
the deficiency of sufficient amounts of food,
minerals and enzymes, etc.

15. ABIOTIC FACTOR
LIGHT OR DARKNESS:
•Light or darkness can be an environmental
trigger for germination and is a type of
physiological dormancy.
• Most seeds are not affected by light or
darkness, but many seeds, including species
found in forest settings, will not germinate until
an opening in the canopy allows sufficient light
for growth of the seedling.

16. Cont..
 Seeds of several other species germinate over
a wide range of temperatures. Many other
kinds of seeds germinate better when the
temperature fluctuates daily about 10°C
between maximum and minimum.

17. Cont…
 TEMPERATURE:
 The temperature influences strongly the percentage and
rate of seed germination, the optimum temperature
varying with the kind of seeds.
 In general, seeds of cool-season crops, such as lettuce,
celery, etc. germinate best at relatively low temperature
of 0 to 10°C, whereas seeds of warm-season crops like
pumpkin, bottle gourd, etc. require relatively high
temperature ranging from 20 to 30°C.

18. Cont..
 WATER:
 Water is required for germination. Mature
seeds are often extremely dry and need to
take in significant amounts of water, relative to
the dry weight of the seed, before cellular
metabolism and growth can resume.

19. Cont..
 Most seeds need enough water to moisten the seeds
but not enough to soak them.
 The uptake of water by seeds is called imbibition, which
leads to the swelling and the breaking of the seed coat.

20. Cont..
 When seeds are formed, most plants store a
food reserve with the seed, such as starch,
proteins, or oils.
 This food reserve provides nourishment to the
growing embryo.
 When the seed imbibes water, hydrolytic
enzymes are activated which break down
these stored food resources into metabolically
useful chemicals.

21. Cont..
 After the seedling emerges from the seed coat and
starts growing roots and leaves, the seedling's food
reserves are typically exhausted; at this point
photosynthesis provides the energy needed for
continued growth and the seedling now requires a
continuous supply of water, nutrients, and light.

22. THANK YOU