germination of seed with references

Answer 1

Germination is the process by which a seed starts to grow and develop into a new plant. It involves the activation of the seed's embryo and the emergence of a root and shoot system. Several factors are essential for successful seed germination, including moisture, oxygen, temperature, and sometimes light.

Below are the stages involved in seed germination:

1. Imbibition: Before germination can occur, a seed needs to absorb water. This process is known as imbibition. Water activates the enzymes needed for the next stages of germination.

2. Activation: Once the seed imbibes water, the embryo inside the seed is activated. This triggers the metabolic processes, including protein synthesis and enzyme activation, which are necessary for growth.

3. Respiration: After activation, respiration begins. The embryo starts to use stored carbohydrates, usually in the form of starch, as an energy source. Oxygen is required for this process.

4. Radicle emergence: The radicle is the embryonic root, which emerges first from the seed and helps to anchor the developing plant in the soil. The radicle grows downward, seeking water and nutrients.

5. Plumule emergence: The plumule is the embryonic shoot, which grows upward away from the seed. It eventually develops into leaves and a stem. Light is required for this stage, as it helps the shoot system to start photosynthesizing.

6. Seedling growth: Once the radicle and plumule have emerged, the seedling continues to grow. The root system elongates, allowing for water and nutrient uptake, while the shoot system develops leaves to capture sunlight for photosynthesis.

Some seeds may have specific germination requirements, such as exposure to cold temperatures (stratification) or fire (scarification) to break dormancy. Additionally, some seeds may also have specific light requirements for germination.

References:
1. Bewley JD, et al. (2013). Seeds: Physiology of Development, Germination and Dormancy (3rd ed.). Springer.
2. Nonogaki H, et al. (2017). Seed dormancy: from molecular genetics to geographic patterns. Wiley Interdisciplinary Reviews: Developmental Biology, 6(6).