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

To answer the question about which plant hormone is mainly responsible for apical dominance, we need to explore the role of each hormone provided in the options.

1. Cytokinin:
   • Cytokinins are plant hormones that promote cell division and growth, and they have a part in delaying leaf senescence. They often work in opposition to auxins.
   • One of their key roles is to promote lateral bud growth, which is opposite to apical dominance.
2. Gibberellin:
   • Gibberellins are involved in promoting stem elongation, seed germination, and flowering.
   • They do not have a primary role in apical dominance.
3. Abscisic acid:
   • Abscisic acid is often associated with stress responses in plants and helps in closing stomata and seed dormancy.
   • It does not contribute to apical dominance.
4. Auxin:
   • Auxins are crucial in maintaining apical dominance, where the terminal bud suppresses the growth of lateral buds.
   • The presence of a high concentration of auxin in the apex inhibits the growth of lateral buds, maintaining focus on elongation of the main stem.

From the explanations above, it is clear that Auxin is the correct answer as it plays a critical role in apical dominance by suppressing lateral bud growth while promoting elongation of the main shoot.