Senescence regulation in leaf discs of Raphanus sativus L. by plant growth regulators in dark

From mature and fresh leaves of Raphanus sativus L. cv. Chetki long, discs were punched out and treated with two different concentrations of kinetin (KN, 0.375 and 3.75 μM) and a morphactin (MOR, CME 74050, 3.64 and 36.4 μM) in order to make a comparative assessment of plant growth regulators (PGR's) with regard to senescence regulation. A gradual breakdown of chlorophylls, carotenoids, proteins and an increment in protease and peroxidase activity were noticed. Total sugars also registered an increasing trend. Applications of both PGR's could delay senescence by minimizing degradation of chloroplast pigments and bringing down protease and peroxidase activity as well as sugar accumulation. Protein breakdown was reduced markedly by only KN.