THE ROLE OF THE ASCORBIC-ACID SYSTEM IN DELAYING THE SENESCENCE OF OAT (AVENA-SATIVA L) LEAF SEGMENTS

The changes in the ascorbic acid system during the onset of senescence in oat leaf segments were studied. The ascorbic acid level was found to decrease while chlorophyll was being lost. The incubation oi the se gments in the presence of L-galactono-1,4-lactone resulted in both an increased level of ascorbic acid and a lower rate of chlorophyll loss. The ascorbate peroxidase activity was also higher, appearing to be re lated to the ascorbic acid content. The treatment with L-galactono-1,4 -lactone also decreased lipid peroxidation, measured as malondialdehyd e level, which suggested a direct role for ascorbic acid in delaying s enescence in oat leaf segments.