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Thursday, September 2, 2010

Germination

Germination
The process in which dormant or sleeping embryo awakes up renews its life and develops into a seeding is called as Germination.

OR
The breaking of dormancy of seed to produce seedling is called Germination.
Kinds of Germination
Seed can germinate into three ways i.e.
1. Epigeal Germination
2. Hypogeal Germination
3. Viviparous Germination
1. Epigeal Germination
Epi => above, geo => earth
The kind of germination in which cotyledons came above the soil due to rapid growth of hypocotyl is called Epigeal Germination.
Example
Caster oil seed, tomato, cotton etc.
2. Hypogeal Germination
Hypo => below, geo => earth
The kind of germination in which cotyledons remain under the soil due to rapid growth of epicotyl is called Hypogeal Germination.
Example
Maize-grain, Pea-gram etc.
3. Viviparous Germination
The special of germination in which seed germinates within fruit is called Viviparous Germination.
Process
The fruit is still attached to parent plant. Redicle comes out of the fruit which becomes swollen and heavy due to increasing weight the seedling gets detached and falls vertically into the soft mud gets embeded and starts growing.
Example
Rhizophora, coconut, date palm etc.
Seed
Seed may be defined as
A ripened ovule or a part of a plant body in which embryo lives in dormant condition is called Seed.
Structure of Seed
Structure of seed can be divided into two parts
1. External Structure
2. Internal Structure
1. External Structure
Externally seed consists of following parts
Seed Coat
  • The seed is covered from outside by a coat called Seed Coat.
  • The seed coat is formed by integuments. It is made up of two layers.
Testa
  • The outer thicker layer is called Testa.
Tegmen
  • The inner thin layer is called Tegmen.

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