NEET BIOLOGY

Detailed explanation-1: -This suggests that cytokinin may delay leaf senescence not only as a result of exogenous treatment, but as part of an endogenous developmental program.

Detailed explanation-2: -Primarily, aging and the dropping of leaves are controlled by the plant growth hormone named abscisic acid (ABA). It also helps to control the dormancy of the seeds and to sustain the plant in adverse conditions.

Detailed explanation-3: -Cytokinin production slows down the process of senescence. However, accumulation of sugars during senescence, due to the breakdown of accumulated starch or the preferential export of N2 from the leaf, can block the effect of cytokinin, especially in low light.

Detailed explanation-4: -Ethylene (plant hormone responsible for ripening and senescence), Abscisic acid-ABA (stress hormone), and Auxin (growth hormone) all play a symphony and cause ‘Abscission-falling/separation of leaf tissue’ from the plant.