【摘要】 <正> 植物叶片的衰老、光氧化与体内自由基的积累和膜脂过氧化有关。由于超氧阴离子的累积,导致叶绿素和蛋白质降解。而在植物体内也存在着清除自由基的酶系统（如SOD,CAT,POD等）,对防止叶片衰老和强光等逆境的胁迫起着重要的保护作用。目前用不同水稻品种来研究叶片超氧自由基和内源清除剂之间的关系报道较少。本文研究了在自然条件和光氧化条件下,叶片衰老和光氧化过程中产生的超氧自由基（O₂^■）和超氧物歧化酶（sOD）活性的关系,为生理育种,防止水稻后期叶片的早衰及光氧化伤害提供依据和鉴定指标。更多还原

【Abstract】 The O₂^- production, scavenging capacity, photooxidation, protein content, and SOD activity were studied in leaves of Yayou 2 （indica-japonica hybrid rice） and Shanyou 63 （indica hybrid rice） at filling stage. It was shown that protein content decreased gradually with days of heading in two varieties in natural condition, and the decrease in Shanyou 63 was more than that in Yayou 2. The rate of O₂^- production and SOD activity increased from heading to 20 days after heading, then decreases but still maintained certain levels until 30 days after heading in two varieties. O₂^- production rate in Shanyou 63 was more than that of Yayou 2, but SOD activity was contrary in two varieties. In addition, the change of O₂^- and SOD under photooxidation condition was consistent with the tendency above under natural condition. It was also shown that there was negative correlation between protein degradation and O₂^- / SOD in the process of senescence in flag leavcs after 20 days of heading. It is suggested that O₂^-/SOD could be used as an index of scavenging ability for O₂^- during senescence in rice.更多还原