中文摘要：

以野生型水稻中花11及其耐热型突变体（hst）为材料,于抽穗扬花期高温处理7d（40℃,每天处理6h）,探讨开花期水稻颖花生理特性与耐热性之间的关系。研究表明,花期高温导致剑叶叶绿素含量、颖花可溶性蛋白和可溶性糖含量均显著下降,突变体hst的降幅明显小于野生型中花11;同时,高温下颖花中丙二醛（MDA）、过氧化氢（H_2O_2）及游离脯氨酸含量均显著增加,而突变体hst的增幅明显低于野生型中花11。在抗氧化酶活性方面,超氧化物歧化酶（SOD）、过氧化物酶（POD）及过氧化氢酶（CAT）活性对水稻开花期高温胁迫的响应有所不同,其变化与耐热性之间的相关性有待进一步验证。高温胁迫下水稻剑叶中保持较稳定的光合作用,颖花中保持较多的渗透调节物质及较低的MDA和H_2O_2含量,是突变体耐高温的生理基础。

英文摘要：

To ascertain the effect of high temperature stress on the physiological characteristics of rice spikelet at flowing stage,wild type Zhonghua 11（ZH11）and its heat-resistant mutant（hst）were exposed to heat stress（40℃,6hper day）for 7days in growth chambers.The results showed that under heat stress the chlorophyll content in flag leaf,soluble protein and soluble sugar contents in spikelet of rice decreased obviously with lower decline in the mutant hstcompared to the wild type ZH11.While malonyldialdehyde（MDA）,hydrogen peroxide（H2O2）and free proline contents in spikelets increased significantly with greater increase in wild type ZH11 than in the mutant hst.Superoxide dismutase（SOD）,catalase（CAT）and peroxidase（POD）activities showed different responses to high temperature stress,and the correlation between the enzyme activities and the thermal sensitivity would be further investigated.Under high temperature stress,higher photosynthesis efficiency,better osmotic adjustment ability as well as lower MDA and H2O2 content of spikelets in the mutant could be the physiological basis of high temperature tolerance.