seed germination

1. Seed germination
The process by which a dormant embryo becomes
active, grows out of the seed coat and develops into a
seedling is called seed germination.
Seed germination is the process by which a plant
grows from a seed.

2. Seeds of most plants germinate when they are
provided with favourable environmental conditions
such as:-
1. Moisture
2. Air
3. Suitable temperature
4. Proper sequence of light and darkness
Types of seed germination
Seed germination can be classified into two types
based on the fate of the cotyledons:
1. Epigeal Germination
2. Hypogeal Germination
3. Viviparous germination

3. 1. Epigeal Germination
During epigeal, the cotyledon is pushed out of the soil.
This happens due to the rapid growth and elongation
of the hypocotyl. E.g., castor and bean.

4. 2. Hypogeal Germination
During hypogeal germination, cotyledons remain
below the soil due to the rapid elongation of
epicotyls. It mostly occurs in monocotyledonous
seeds.
E.g. Maize.

6. 3. Viviparous germination:-

7. Factors affecting seed germination

8. Orthodox and Recalcitrant seeds
All the seeds may be divided into two broad groups
depending on the maintenance of viability under
normal and specific environmental conditions.
(i) Orthodox seeds: Seeds belonging to this group
maintain viability for longer period when stored at
low moisture level. examples :- rice, wheat, maize,
groundnut and tomato etc. For storage vegetable
moisture contain 5-6% and field crops 8%.
(ii) Recalcitrant seeds: Seeds belonging to this group
maintain viability for longer period, when stored at
higher moisture level. e.g. lemon, grapes, apple,
jack fruit, litchi etc.