Abstract: Under the treatment of low temperature (2°C or 5°C ) in dark for 1-2 days, the activity of both superoxide dismutase (SOD) and peroxidase (POX) in the rice seedlings of these varieties of different cold-endurance in Yunnan Plateau were decreased with varying degress. The activity of both SOD and POX in these varieties with strong cold-endurance at light (28 °C, 2500 Ix) after chilling treatment are much higher than control. But the activity in these varieties with weak cold-endurance still are lower than control. The contents of ascorbic acid (ASA) and glutathione (GSH) were decreased gradually but the content of malondialdehyde (MDA) was increased with lenghthening time exposed to chilling temperature, strengthening chill-stress and recovery at light. Decrease of contents of ASA and GSH in these varieties with strong cold-endurance is smaller and increase of content of MDA is smaller, too.

Key words: Rice seedlings. Chilling stress

摘要： 经低温（2℃或5℃）暗处理(1-5d)的耐寒性不同的云南高原水稻幼苗，超氧物歧化酶(SOD)过氧化物酶（POX）的活性均有不同程度的下降。胁迫后光下（28℃，2500 1X）恢复，耐寒性较强的品种SOD，POX活性均比对照值明显提高，耐寒性弱的品种仍低于对照值。随着低温时间的延长，低温胁迫程度的加深和光下恢复，抗坏血酸（ASA）和谷胱甘肽（GSH）含量逐渐减少，两二醛（MDA）含量则逐渐增加。耐寒性强的品种ASA和GSH含量减少较小，MDA含量增加也较小。

关键词: 水稻幼苗, 低温胁迫, 超氧物歧化酶, 抗坏血酸, 丙二醛