The process of germination occurs when a seed develops into a new plant. There are several distinct phases of germination, each with its own characteristics and requirements. Additionally, germination can be categorized into two types: epigeal germination and hypogeal germination.
Phases of Germination:
1. Imbibition: This is the initial phase of germination, where the seed absorbs water from the environment. This causes the seed to swell and become metabolically active.
2. Activation of Enzymes: Water absorption triggers the release of enzymes within the seed, which break down stored nutrients such as starches and proteins into simpler substances that are used by the growing embryo.
3. Respiration: During this phase, the stored nutrients are converted into energy through a process called respiration. This energy is crucial for the growth and development of the embryo.
4. Radical Emergence: The embryo develops a root called a radicle, which grows downward into the soil to establish anchorage and absorb water and nutrients.
5. Shoot Emergence: As the radicle continues to grow, the embryonic shoot, or plumule, emerges from the seed. This shoot eventually develops into the stem and leaves of the new plant.
6. Expansion and Growth: After shoot emergence, the cotyledons (seed leaves) unfold and begin photosynthesis, producing carbohydrates that fuel the further growth of the plant.
7. Establishment of Seedling: The roots continue to grow, anchoring the seedling firmly in the soil. The shoot elongates, and true leaves develop, allowing the plant to start photosynthesizing independently.
Types of Germination:
1. Epigeal Germination: In this type of germination, the cotyledons emerge above the soil surface along with the plumule. The epicotyl (portion of the shoot above the cotyledons) extends rapidly, lifting the leaves and cotyledons into the air. Examples of plants with epigeal germination include beans and peas.
2. Hypogeal Germination: In hypogeal germination, the cotyledons remain below the soil surface while the rest of the plant develops. The epicotyl elongates, pushing the plumule and leaves upward while the cotyledons remain in the soil, serving as a source of stored nutrients. Examples of plants with hypogeal germination include corn and wheat.
Both types of germination are adaptations that allow plants to optimize their growth and survival in different environments. Epigeal germination helps plants grow quickly in nutrient-rich environments, as the above-ground cotyledons can photosynthesize immediately. Hypogeal germination, on the other hand, provides extra protection for the delicate cotyledons and allows plants to grow in challenging conditions, such as in dry or cold soils.
assignment; list down and explain phases of germination and types of germination (epigeal and hypogeal)
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