Question

Which plant hormone is mainly responsible for apical dominance?

• A. Cytokinin
• B. Gibberellin
• C. Abscisic acid
• D. Auxin

Hint:

Removal of the apical bud reduces auxin levels and allows lateral buds to grow.

Answer 1

The Correct Option is D

Step 1: Understanding apical dominance.
Apical dominance is a phenomenon in plants where the growth of lateral (side) buds is inhibited by the presence of the apical (terminal) bud. This ensures that the plant grows vertically rather than branching excessively.
Step 2: Role of plant hormones.
Plant hormones regulate growth and development. Different hormones control different physiological processes such as cell elongation, dormancy, and branching.
Step 3: Hormone responsible for apical dominance.
Auxin is produced in the apical bud and is transported downward through the stem. High concentrations of auxin suppress the growth of lateral buds, thereby maintaining apical dominance.
Step 4: Analyzing the options.
(A) Cytokinin: Cytokinins promote lateral bud growth and counteract apical dominance.
(B) Gibberellin: Gibberellins mainly promote stem elongation and seed germination.
(C) Abscisic acid: Abscisic acid is associated with dormancy and stress responses.
(D) Auxin: Correct — Auxin inhibits lateral bud growth and maintains apical dominance.
Step 5: Conclusion.
The plant hormone mainly responsible for apical dominance is auxin.