Question: 108. Which one of the following phytohormones promotes nutrient mobilization which helps in the delay of leaf senescence in plants?
(1) Ethylene
(2) Abscisic acid
(3) Gibberellin
(4) Cytokinin
Answer: Option (4)
Explanation:
Cytokinins are phytohormones that promote cell division and delay ageing in plant tissues.
They are known to promote nutrient mobilization towards young leaves and developing organs.
This redistribution of nutrients helps in delaying leaf senescence.
Ethylene promotes senescence and fruit ripening.
Abscisic acid is a growth inhibitor and promotes dormancy and senescence.
Gibberellins mainly promote stem elongation and seed germination.
Hence, cytokinin is the phytohormone that delays leaf senescence by promoting nutrient mobilization.