Under drought condition, the drought-tolerant riee cultivar "Xiangzhongxian No.2" showed lower relative plasmalemma permeability and less reduction in chlorophyllcontent as compared with drought-sensitive cultivar "Xiangzaoxian No. 12" , whichindicated that the drought-tolerant cultivar was less demaged by drought stress. Ascorbate-peroxidase (AsA-POD) activity decreased in both cultivars, but less decreased in drought-tolerant one. The glutathione reductase (GR) activity increased at the beginning of drought in drought-tolerant cultivar，but that did not change obviously in drought-sensitive one．The results also showed that GR activity could be induced by paraquat(0.01 mmol／L)and H202(0.1 mmol／L)in drought-tolerant cultivar，but they had no effects on drought_sensitive one，which indicated that the increase of GR activity in drought-tolerant cultivar under drought stress might result from the induction by oxidative stress．In addition，the contents of ascorbate (AsA) and reduced glutathione (GSH) showed a tendency of being increased at first，then decreased in both cultivars，but with greater increase in the drought-tolerant cultivar．The results suggested that drought_tolerant cultivar had better protection system in chloroplasts against drought stress than the drought-sensitive cultivar.
