Seed dormancy and Abscisic acid

Seed dormancy is a phenomenon in which the seed remains inactive even under favorable environmental conditions for germination. Abscisic acid (ABA) is a plant hormone that plays a vital role in inducing seed dormancy.

Role of ABA in seed dormancy:

1. Inhibition of germination: ABA inhibits seed germination by suppressing the action of gibberellins (GA), another plant hormone that promotes germination.

2. Induction of dormancy: ABA induces seed dormancy by inhibiting the synthesis of enzymes that break down starch into simple sugars, which are required for germination.

3. Regulation of water content: ABA regulates the water content in seeds by controlling the opening and closing of stomata. In dry conditions, ABA accumulates in the seed and promotes stomatal closure, preventing water loss and maintaining seed viability.

4. Stress response: ABA plays a role in the plant's stress response by inducing the expression of stress-responsive genes and protecting the seed from harsh environmental conditions.

Conclusion:

Therefore, it is clear that ABA is responsible for inducing seed dormancy by inhibiting germination, regulating water content, and promoting stress response. Hence, option B, i.e., Abscisic acid, is the correct answer.