Abstract: A comparative study on the photosynthesis and senescence in two line and three line hybrid rice indicated that leaf senescence was associated with the decrease in superoxide dismutase activity and chlorophyll, soluble protein content, and the marked increase in malondialdehyde content. Significant differences were observed within the same kind of hybrid rice but not between the two kinds of hybrids, so did for the canopy photosynthetic rate of these hybrids. After heading stage, the canopy photosynthetic rate correlated positively with the dry matter production during ripening stage.

Key words: hybrid rice, leaf, photosynthetic rate, superoxide dismutase, malondialdehyde

摘要： 对籼型两系与三系杂交水稻群体光合作用和衰老特性进行了比较，研究结果表明齐穗后剑叶叶绿素和可溶性蛋白质含量、超氧化物歧化酶活性、群体光合速率、脂质过氧化产物丙二醛含量、群体干物质生产量在组合间差异达极显著水平，两系和三系中各有指标值高低的组合；群体光合作用和衰老特性的差别主要在组合间，而不在两系和三系两种类型之间，两系杂交稻未有明显的优势。籼型两系杂交水稻的配组中应选配齐穗后叶片衰老慢、群体光合速率高的组合，提高抽穗至成熟期的物质生产量。

关键词: 杂交稻, 叶片, 光合速率, 超氧化物歧化酶, 丙二醛