Question

How does pruning help in making the hedge dense?
A. The apical shoot grows faster after pruning.
B. It releases wound hormones.
C. It induces differentiation of new shoots from the rootstock.
D. It frees axillary buds from apical dominance.

Answer 1

Hint: Pruning is the process of removing shoot tips or terminal buds of a plant to promote dense bushier growth. This phenomenon is widely used in silvicultural and horticultural practices such as, tea plucking and hedge making. Apical buds on shoots are known to inhibit the growth of lateral buds by releasing hormone auxin. Pruning removes the apical buds and promotes growth of lateral buds.

Complete answer:
> Option A - Pruning is done to remove the apical shoot tips to promote the growth of lateral buds, which makes the hedges dense.

> Option B - Wound hormones are released in plants in response to a traumatic event and heals the damaged tissues by cell division near the wounded site.

> Option C - In case of pruning, only shoot tips are removed. Rootstocks are raised by cutting or seed and are used for the purpose of grafting or budding.

> Option D - Apical dominance is the phenomenon by which presence of apical buds does not allow the nearby lateral buds to grow. Apical buds produce high concentration of hormone auxin which inhibits the growth of lateral buds. When the apical buds are removed by pruning, the lateral buds sprout. This produces dense bushy growth.

Hence, the correct answer is option (D).

Note: Apical dominance is strong in trees with conical shapes and little branching toward the top (e.g., many pines, spruces, firs) and weak in trees that branch more often (e.g., elms, ashes, willows). The hormone cytokinin is also known to promote growth of lateral buds. When appropriate concentration of cytokinin is applied to lateral buds, they grow despite the presence of apical buds. Thus, cytokinin acts antagonistically to auxin which promotes apical dominance.