LIPID-PEROXIDATION AND PEROXIDE-SCAVENGING ENZYMES OF NATURALLY AGED SOYBEAN SEED

Aging is known to reduce seed viability in many crop species. The phenomenon is due in part to the aging-induced lipid peroxidation, which has the potential to damage membranes of the seed tissues. This study was undertaken to evaluate the effect of natural aging on germination and several physiological characteristics related to peroxidation in the seeds of two edible soybean cultivars produced in different seasons. Natural aging was achieved by sealing the seeds in aluminum foil bags coated with polyethylene and storing the seeds at 5 or 25 degrees C for for 3, 6, 9, and 12 months. The results indicate that at both 5 and 25 degrees C, aging inhibited seed germination and enhanced lipid peroxidation, but with more rapid seed deterioration and a greater extent of lipid peroxidation at the latter temperature. Aging also inhibited the activity of peroxidase, catalase, ascorbate peroxidase, superoxide dismutase and lipoxygenase. The seeds harvested from the spring crop were more susceptible to aging than the seeds harvested from the autumn crop. The changes in germination and physiological activities, expressed as a function of growing season and aging condition, were similar in the two cultivars.