中文摘要：

对两个耐热性不同的水稻材料进行高温处理（8：00-17：00,37℃;17：00-8：00,30℃）,研究了高温胁迫对水稻剑叶净光合速率和叶绿素荧光参数的影响。结果表明,高温胁迫下两个材料的剑叶光合速率迅速降低,热敏感的4628比耐热的996下降幅度更大。高温下996PSⅡ反应中心和天线系统受到的伤害轻,反应中心过剩激发能积累少,可藉较高的qP和qN进行过剩光能的耗散,保护光合机构免受高温伤害;而4628 qP下降快,Ex增加较多,但qN却随高温延长而下降,说明它的反应中心和天线系统都受到了严重的伤害,导致光合速率下降。

英文摘要：

The net photosynthetic rate and chlorophyll fluorescence parameters of flag leaves were measured under high temperature by using the high-temperature tolerant line 996 and high-temperature sensitive line 4628.Rice plants were subjected to high temperature（8：00-17：00,37℃;17：00-8：00,30℃）treatment for seven days after heading.The net photosynthetic rates of flag leaves of the two rice lines decreased dramatically under the high temperature stress,with a greater decrease in the high-temperature sensitive line 4628 than in the high-temperature tolerant line 996;less accumulation of excess excitation energy in the reaction centers did less harm to the centers and the antenna systems in 996 under high temperature stress.Accordingly,higher qP and qN in 996 helped to dissipate the excess excitation energy and protect the reaction centers from heat injury.However,in 4628,qP declined rapidly,while Ex increased as the high temperature stress persisted.This indicates that the reaction centers and antenna systems in 4628 were damaged severely under high temperature stress,which led to the lower photosynthetic rate.