Question

What is apical dominance?

Answer 1

Hint: The phenomenon in which the apical bud suppresses the growth of lateral growth into branches is known as apical dominance. Auxin promotes the phenomenon of apical dominance whereas cytokinin inhibits the phenomenon of apical dominance. These two hormones act antagonistically.

Complete answer:

(•) Apical dominance: It is the phenomenon by which the presence of apical buds does not allow the nearby lateral or axillary buds to grow.
(•) Apical bud secretes auxin which inhibits the growth of lateral buds.
(•) If the apical bud is removed (Decapitation), the lateral buds sprout i.e., start growing.
(•) However, if a paste containing auxin is applied on the cut portion of the decapitated shoot, the lateral buds remain inhibited in the similar way when apical bud is present.
(•)The removal of apical bud is done for the preparation of hedges and bushy growth in certain plants. For example, when the apical bud of tea plants is removed, the lateral buds start developing into branches. It is done to produce a greater number of leaves so that yield can be increased.
(•) In this phenomenon the central branch is dominant over the side branches.
(•) It is the phenomenon in which control is exerted by apical portions of shoot towards the outgrowth of lateral buds.

Note: Auxin hormones maintain apical dominance, they increase the growth of shoot and inhibit the growth of lateral buds. When lateral bud present in the axil of the leaves does not grow to form branches it is known as apical dominance. It is caused due to apical bud.