The correct option is
A is true but R is false
Explanation
The question addresses the physiological phenomenon of Apical Dominance in plants. This process is regulated by the interaction of specific plant growth regulators (hormones), primarily Auxins and Cytokinins, which control the growth pattern of the shoot system.
Statement-wise Analysis
- Assertion (A): Correct
Decapitation involves the removal of the shoot tip (apical bud). The shoot tip is the primary site of Auxin synthesis. When the tip is removed, the concentration of Auxin decreases, lifting the inhibition on the lateral (axillary) buds. Consequently, these buds break dormancy and grow into lateral branches. This principle is widely applied in tea plucking and hedge making to promote bushiness.
- Reason (R): Incorrect
The apical bud produces Auxins (not Cytokinins), which are responsible for inhibiting the growth of lateral buds. Cytokinins are primarily synthesized in the root tips and transported upwards to the shoots. Unlike Auxins, Cytokinins actually promote the growth of lateral buds and help overcome apical dominance.
Key Takeaway: Apical dominance is caused by Auxins produced in the shoot apex, which inhibit lateral bud growth. Cytokinins, produced in roots, antagonize this effect and promote lateral shoot growth.