Question

Explain different types of seed germination with suitable examples.

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Answer 1

AnsWer :

Seed Germination:

• The process by which dormant embryo of the seed resumes metabolic activities and grows to produce a seedling is called seed germination.

• It is the first step in plant growth and occurs when the dormancy period is either over or broken under favourable conditions.

Types of germination:

Three types of seed germination are given below:

Epigeal Germination (epi = above, geo = soil):

• Cotyledons come above the soil surface.
• Hypocotyl shows faster and active growth and thus, elongates considerably.
• Epicotyl shows slow growth and remains short during germination.
• Radicle comes out first and grows into the soil to form primary root.
• Plumule comes up above soil to form primary shoot.
• Cotyledons become flat and green, they function as embryonic leaves till the development of foliage leaves. e.g. Tamarind, Cucumber, Cotton, Castor, Papaya, Onion.

Hypogeal germination (hypo = below, geo = soil):

• The cotyledons remain below soil surface.
• Hypocotyl shows slow growth and thus remain short.
• Epicotyl shows faster and active growth and thus elongates considerably to push the plumule above soil surface.
• Radicle comes out first and grows into the soil to form primary root.
• Plumule comes up above soil and forms young shoot. e.g. Pea, Gram, Groundnut, Mango, Maize, Jowar.

Vivipary germination:

• When the seeds germinate within the fruit before the dispersal of fruits from parent plant, it is called viviparous germination.
• It is found in mangrove plants like Rhizophora. In such plants, the seed dormancy is absent.
• During this type of germination, the hypocotyl elongates and pushes the radicle out of the seed and fruit.
• The hypocotyl grows more vigorously and becomes club-like.
• The young seedling comes out of the fruit showing the long hypocotyl and radicle.
• When the seedling gains weight, it gets detached from the fruit, and falls down vertically like a dart.
• Now, the radicle penetrates into the mud and grows continuously to form a plant. e.g. Rhizophora, Sonneratia, etc.

Answer 2

Explaination :

The process of germination ends with the formation of seedling.

A seedling is the stage where the plant has just developed from the seeds and partly dependent on its stored food.

The newly formed root system absorbs water and minerals from the soil and the shoot system develops leaves which in turn prepare food for the plant which matures and flowers and seeds.