Question

Assertion (A): Decapitation of shoot tip in plants induces the growth of their lateral buds

Reason (R): Accumulation of auxins in lateral buds causes inhibition of their growth

• A. Both A & R are true and R explains A
• B. Both A & R are true and R does not explain A
• C. A is true and B is false
• D. Both A & B are false

Answer 1

The correct option is A Both A & R are true and R explains A

The growing apical buds of plants produce the phytohormone auxin that inhibits growth of lateral or axillary buds, increasing the vertical length of the plant. This phenomenon is called apical dominance. To promote lateral growth, it is a common practice to remove the apical buds by decapitation. When the apical bud is removed, the source of IAA is removed. Since the auxin concentration is much lower, the lateral buds can now grow. In fact, their growth will be stimulated by a relatively small drop in auxin concentration. Thus, decapitating (or pruning) a shoot will cause it to branch.