Question

Hormone which breaks seed dormancy is
A) Auxin
B) Gibberellin
C) Ethylene
D) Cytokinin

Answer 1

Hint:The evolutionary adaptation of seeds that prevents them from growing in unfavourable conditions that cannot ensure seed survival is known as seed dormancy.


Complete answer:
Let us look at each option one by one.
Auxin is a plant hormone known to play its role in the maintenance of seed dormancy by the stimulation of Abscisic acid, the main hormone responsible for induction of seed dormancy. Auxin does not break seed dormancy. Therefore, this option is incorrect.

Gibberellin biosynthesis is shown to be induced in the presence of light. Gibberellin primarily affects the seed cotyledons where it stimulates the synthesis of certain enzymes which leads to the breakdown of seed dormancy. Therefore, this is the correct option.

Ethylene is shown to counteract the effects of abscisic acid and help in the breakdown of seed dormancy and aid in seed germination but it is not the primary enzyme responsible for the breakage of seed dormancy. Therefore, this option is incorrect.

Cytokinin is known to regulate several plant growth and developmental processes by regulating cell proliferation and differentiation and it is known to contribute towards breakage of seed dormancy and induction of germination but it is not the primary enzyme responsible for breaking seed dormancy. Therefore, this option is incorrect.

Thus, the correct answer to this question is option (B) Gibberellin.

Note:Seed dormancy is of three types
i) Innate dormancy- seeds are incapable of germination even in suitable conditions
ii) Enforced dormancy- seeds are incapable of germination due to environmental restraints.
iii) Induced dormancy- seeds are incapable of germination due to imbibed water which does not allow them to germinate even when the conditions are favourable.