Abstract: Four rice cultivars (Oryza sativa L. ) and two wild rice species (O. officinalis, O. spontanea) were grown under two big tents in the field and exposed to natural sunlight. The CO₂ concentrations in these tents were kept at 350 μL/L(ambient) and 600 μL/L(elevated), respectively, which was monitored by an infrared CO₂ analyzer and controlled by a computer. Under natural conditions, the activities of antioxidative enzymes (SOD, CAT, POD) in leaves of six rices differed with their origin. In comparison to ambient CO₂ control plants in the tents, the content of malondialdehyde (MDA) and PODactivity in rice leaves growing in the tent with elevated CO₂ concentration decreased to different extents, but the activities ofSOD and CAT showed intraspecific variations. When leaf segments were submitted to methyl viologen photooxidation under a light intensity of 20 umol/m2·s, the activities of antioxidative enzymes showed significant changes. CAT activity was enhanced by 1. 7 6. 5 folds (at ambient CO₂) and 1. 0-3. 8 folds (at elevated CO₂) of untreated control. On the contrary, SOD and POD activities were all reduced in leaves of three tested rices growing either at 350 μL/L or at 600 μL/L CO₂. Photooxidation resulted in an increase of MDA content, but the MDA increment was inhibited by elevated CO₂ concentration. The results indicated that activities of the three antioxidative enzymes in rice leaves were regulated by CO₂ concentration and photooxidative condition. Elevated CO₂ concentration showed a protective effect against the peroxidative damage of lipids inducedby methyl viologen photooxidation.

Key words: carbon dioxide enrichment, catalase, enzyme activities, lipid peroxidation, peroxidase, photooxidation, superoxide dismutase

摘要： 以4个栽培稻品种和2种野生稻为材料，比较了长期生长在高浓度CO₂(600 μL/L)和普通空气CO₂浓度(350 μL/L)下抽穗期水稻叶片抗氧化酶活性的变化以及对甲基紫精光氧化的响应。在自然条件下其抗氧化酶(SOD、CAT和POD)活性因品种和种性的不同而存在一定的差异。与生长在普通空气CO₂浓度的水稻相比，高浓度CO₂下叶片的膜脂过氧化产物MDA含量和POD活性都有不同程度下降，SOD和CAT活性则因品种的不同而呈不同的变化趋势。光氧化条件下，生长在普通空气CO₂浓度下的水稻叶片CAT活性增加了1.7～6.5倍，高浓度CO₂下则增加了1.0～3.8倍，而SOD和POD活性在光氧化条件下都降低。光氧化导致了水稻叶片的MDA含量的增加，高浓度CO₂下生长的水稻叶片MDA含量增加的幅度小于在普通空气CO₂浓度下生长的水稻，显示高浓度CO₂对光氧化损伤具防护效应。

关键词: 高浓度二氧化碳, 过氧化氢酶, 酶活性, 膜脂过氧化, 过氧化物酶, 光氧化, 超氧歧化酶