Abstract:After chilling injury at 4℃ for 36 hours, the rice (Oryza sativa L. )seedlings were sprayed with 1.0 ppm kinetin(KT) or 100 ppm ascorbic acid((Vc). The SOD activity was increased from 101 to 151 enzyme units·g-1 fr. wt with KT treatment, it reached the level as in normal seedlings. With Vc treatment, the SOD activity was 92% of control. The DMA contents and ther rate of cell membrane electrolyte leakage were decreased in seedlings with either. The incorporation of 3H-L-Leucine in to the SOD protein suggested that the rate of SOD biosynthesis was enhanced with KT treatment, which might be the main cause of increased SOD activity with KT treatment. However, no promotion of SOD biosynthesis was observed in the seedlings treated with Vc. With KT or Vc treatment, there was a negative correlation between the SOD activities and the MDA contents, and a positive correlation between the MDA contents and the rates of membrane leakage.