Which one of the following plant hormones can retard the ageing of plant organs by controlling protein synthesis?

Cytokinins are plant hormones that play a critical role in retarding the ageing (senescence) of plant organs [1]. They function as growth promoters by stimulating cell division and delaying the degradation of proteins and chlorophyll [1]. This phenomenon, often referred to as the Richmond-Lang effect, involves the mobilization of nutrients and the maintenance of protein synthesis, which prevents the wilting and yellowing of leaves [1]. While auxins and gibberellins also contribute to delaying senescence [t1][t4], cytokinins are specifically recognized for their potent anti-ageing properties by controlling metabolic processes and protein turnover [t7]. In contrast, abscisic acid (ABA) and ethylene act as growth inhibitors that promote senescence and leaf abscission [t2][t8]. Therefore, cytokinin is the primary hormone responsible for retarding organ ageing through the regulation of protein synthesis.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > Activity 6.2 > p. 108