Effect of ABA on the Germination of Rice Seed and Growth of Its Seedling

The effect of ABA on the germination of rice seed, growth of rice seedling and drought resistance of rice seedling were studied. The results showed that ABA at lower concentration (less than 0. 5 mg/L -1.0 mg/L) has no effect on the seed germination, but could effectively inhibit the elongation of bud and roots. ABA at high concentration ( 5. 0 mg/L) effectively inhibited the seed germination and elongation of bud and root. ABA could inhibit the increment rate of plant height significantly, and the plant height was decreased. ABA could effectively enhance the relative water content in the leaves of rice seedling during the drought stress period, as well as enhance the tolerance of rice seedling to the drought stress, the activities of superoxid dismutase (SOD) and catalase (CAT) were found to be kept at higher levels in ABA-treated seedling leaves than that of the control (water) , the content of malondialdehyde ( MDA) was decreased in ABA-treated seedling leaves than that of the control (water) , while the ascorbic acid content was increased in ABA ?treated seedling leaves than that of control(water) .