Abstract: Changes of activated oxygen and H₂O₂, malondialdehyde (MDA) content, autoxidation rate, lipoxygenase(LOX) and activity of enzymes involving cell defense in leaf of super high yielding rice (Pei’ai 64S/9311 and Xieyou 9308) after heading stage were studied. Results suggested that the possible process of leaf senescence in Pei’ai 64S/9311 and Xieyou 9308 followed activity of enzymes involving cell protective enzymes (SOD,CAT,POD,ASP) decrease and LOX activity increase, which further led to lipid peroxidation, with consequence degradation of chlorophyll and protein. The leaf senescence rate of Pei’ai 64S/9311 was faster than that of Xieyou 9308.

Key words: rice, leaf, senescence, activated oxygen, protective enzymes, lipid peroxidation

摘要： 对超高产水稻培矮64S/9311和协优9308从抽穗到籽粒成熟过程中剑叶中H2O2 、膜脂过氧化产物丙二醛（MDA）、组织自动氧化速率、脂氧合酶（LOX）及保护酶超氧物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶（POD）和抗坏血酸过氧化物酶（ASP）的动态变化过程进行了测定。结果表明，协优9308的剑叶衰老较慢。2个材料的剑叶叶片衰老可能原因是叶片内SOD、CAT、ASP活性过早下降，LOX活性增加，进而导致膜脂过氧化，使活性氧代谢失调，引起叶绿素和蛋白质降解，培矮64S/9311的各项生理指标比协优9308早衰老，而且乳熟期是培矮64S/9311早衰的关键时期。

关键词: 水稻, 叶片, 衰老, 活性氧, 保护酶, 脂质过氧化