XVI International Botanical Congess

Sixty days old Vigna radiata Var. aureus plants were treated with soil applied paclobutrazol at the rate of 500 ?g/10 inch pot. After seven days of treatment pots were transferred to the dark for induction of senescence. Upon transfer in dark, chlorophyll and protein content declined in both control and treated plants, but the decline was much faster in controls. The activities of catalase declined markedly in controls while it remained low in the treated plants. Peroxidase, protease, superoxide dismutase (SOD) activities and malondialdehyde (MDA) content remained higher in controls in dark compared to the treated plants. The results suggest that paclobutrazol delays dark-induced senescence and this delay is associated with maintenance of higher activity of catalese and the prevention of senescence linked rise in protease and peroxidase activities and also lipid peroxidation.