Germination of seed. List down and explain phases of germination and types of germination (epigeal and hypogeal)

Answer 1

Germination is the process by which a seed develops into a new plant. It involves several phases and can occur through two main types: epigeal germination and hypogeal germination. Let's explore each phase and type in more detail:

Phases of Germination:
1. Imbibition: The first phase of germination is known as imbibition, where the seed absorbs water through its coat. This uptake of water causes the seed to swell and become activated.

2. Activation: Once the seed absorbs water, it activates various enzymes and metabolic processes necessary for germination. These processes include the breakdown of stored nutrients such as starch, oils, and proteins.

3. Digestion of reserve food: During this phase, the stored food in the seed is broken down into simple substances that can be used by the developing embryo. These nutrients provide the initial energy and resources for the growth of the emerging plant.

4. Early Growth: As the embryo grows, it forms a primary root called the radicle. The radicle elongates and penetrates the soil, anchoring the seedling in place. Simultaneously, the shoot (plumule) emerges from the seed and starts growing towards the light.

5. Development of Seedling: Once the root and the shoot have established their respective systems, the seedling continues to grow and develop. The roots take up water and nutrients from the soil, while the shoot develops leaves for photosynthesis.

Types of Germination:

1. Epigeal Germination: In epigeal germination, the cotyledons (seed leaves) of the germinating seed emerge above the ground level. The cotyledons turn green and develop into the first leaves of the new plant. This type of germination is observed in plants like beans, peas, and sunflowers.

2. Hypogeal Germination: In hypogeal germination, the cotyledons stay below the ground and do not emerge. They remain in the seed and act as nutrient reserves for the developing seedling. Examples of plants that undergo hypogeal germination are maize, wheat, and rice.

Both types of germination, epigeal and hypogeal, are essential for the successful growth and establishment of different plant species. They provide the necessary mechanisms for seeds to transform into seedlings and eventually develop into mature plants.