Antioxidant enzyme activity in germination of Dalbergia spruceana seeds under different temperatures

Antioxidant enzyme activity can be used to measure heat stress and predict the tolerance of a species to heat stress. This study investigated the effects of temperature on germination and antioxidant enzyme activity in Dalbergia spruceana Benth. seeds. Seeds were incubated at constant temperatures of 20, 25, 30, 35, and 40 degrees C for ten days; and germination percentage, germination speed index, antioxidant enzyme activity, and electrical conductivity were evaluated. Temperature affected the seed germination process but not antioxidant enzyme activity. Germination percentage and germination speed index were higher at 25 and 35 degrees C and lower at 20 and 40 degrees C. Superoxide dismutase activity was not affected by temperature. Catalase and peroxidase activities were too low to be used as indicators of temperature stress. The pattern of increasing electrolyte leakage manifested a trend toward loss of cell membrane semipermeability at higher temperatures.