Abstract: The evaluation of heat tolerance at grain filling stage was studied on 65 early season rice varieties from differentgene sources ,and the physiological reaction around high temperature stress at grain filling stage was compared between the varieties with much difference in heat tolerance. The results indicated that the stress index of unfilled grain rate, filled grainweight, head rice rate, chalkiness and protein content could be regarded as the five indexes of heat tolerance for field directevaluation at grain filling stage in rice. There was much difference in heat tolerance among the different varieties according tothe comprehensive evaluation of heat tolerance by subordinate function value. Thus several varieties with high heat tolerancewere screened. The photosynthetic ability of rice can be affected seriously by high temperature stress,but the decrease extentof flag leaf photosynthetic rate of varieties with high heat tolerance is significantly lower. The recovery level is also higher after removing stress. The changing trend of chlorophyll content, RuBPc activity and endogenous polyamine content is thesame,which is the important physiological characteristics of heat tolerance in rice.

Key words: heat tolerance, photosynthesis, filling period, polyamine, indexes, rice

摘要： 对65个不同来源的早籼稻品种进行了灌浆期耐热性的鉴定研究，并比较了耐热性相差很大的品种灌浆期高温胁迫前后的生理反应。结果表明：秕粒率、实粒重、整精米率、垩白度、蛋白质含量的胁迫指数可作为水稻品种灌浆期耐热性田间直接鉴定的 5个指标，可采用隶属函数值法对各品种的耐热性进行综合评价；不同品种的耐热性存在相当大的差异，筛选出了几个耐热性很强的品种；高温胁迫严重影响水稻的光合能力，但耐热性强的品种剑叶的光合速率高温胁迫后下降幅度明显较小，胁迫解除后恢复的程度也更高，叶绿素含量、RuBPc 活性及内源多胺含量的变化趋势与光合速率相一致，是水稻耐高温逼熟的重要生理特征。

关键词: 耐热性, 光合作用, 灌浆期, 多胺, 指标, 水稻