### Theory:

The process of development of a new plant from the seed is known as germination.
Germination of seed

It is a slow biological process. Hence, the seeds in a dry state are alive, but remain dormant.

Conditions necessary for germination:
• Water
• Air (oxygen)
• Favourable temperature
Role of water in seed germination:
• It helps in softening by of the seed by rupturing the seed coat.
• Allows the plumule and radicle to emerge out of the seed coat.
• Converts the stored food into soluble material.
• Transports the soluble food from the storage tissue to the embryo.

Role of oxygen in seed germination:
• It provides energy required for the process of germination.
• It facilitates aerobic respiration to liberate energy.
• Increases the rate of respiration.
• Oxidation of food takes place with the help of oxygen.
Role of temperature in seed germination:
• As different biological processes takes place during the process of respiration an optimum temperature is required.
• Hence, maintenance of an optimum temperature ranging from $$25 to 35°C$$ is required,
Types of germination:
Germination of seeds occurs in two ways:
• Hypogeal
• Epigeal
Different types of germination

Hypogeal germination in seed:

In the term hypogeal 'hypo' refers to below and 'geo' refers to earth.

Epigeal germination
• During this type of germination the seeds swell due to the absorption of water leading to the bursting of testa.
• The radicle emerges and grows downwards and forms the root.
• The plumule grows upwards and forms the shoot.
Epigeal germination of the seed:

In the term epigeal 'epi' refers to above and 'geo' means earth.

Hypogeal germination
• During this type of germination the seeds swell due to the absorption of water.
• The radicle emerges and grows downwards and forms the root.
• Hypocotyl forms an arch and grows above  the soil, and brings the cotyledons above the soil.
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