中文摘要：

以不同时期在黄淮冬麦区推广并具有一定代表性的5个小麦品种碧蚂1号、丰产3号、小偃6号、小偃54和小偃81为材料,研究了品种更替过程中小麦旗叶的光合特性以及抗氧化酶活性的变化.结果表明,各小麦品种旗叶净光合速率均于开花后10 d左右达到最大值后下降,并在开花灌浆期有显著差异,且近期品种始终高于早期品种.随着灌浆进程推进,各小麦品种旗叶叶绿素含量、可溶性蛋白质含量、抗氧化酶活性呈现出与净光合速率基本一致的变化趋势（其中过氧化氢酶活性为下降趋势）,而丙二醛含量持续升高,但近期小麦品种始终低于早期品种且差异达到极显著水平（P〈0.01）.研究发现,近期育成小麦品种的旗叶在生育后期具有相对较高的光合速率,可能与其叶绿素和可溶性蛋白含量下降速率较缓、抗氧化酶活性较高、膜脂过氧化程度较轻有关.

英文摘要：

Five wheat cultivars released in different period and popularized in winter wheat fields of Yellow River and Huaihe River district were compared in photosynthetic characteristics and the activities of antioxidative enzymes. The wheat cultivars were ‘Bima 1’,‘Fengchan 3’ ,‘ Xiaoyan 6 ’,‘ Xiaoyan 54’ and‘ Xiaoyan 81’ ,which were released in 50 s,60-70 s,80 s,90 s of the 20^th century and at present,respectively. The results showed that the photosynthetic rate （Pn） of flag leaves reached their maximal values about ten days post anthesis,and then declined gradually. There was a significant difference in Pn among different wheat varieties during grain filling stage. The later released cultivars had higher Pn than that of the ealier released cultivars. The changes of the contents of chlorophyll and soluble protein,activities of antioxidative enzymes in the flag leaves were same as Pn during the grain-filling stage （while the activity of CAT decreased）. Meanwhile the MDA content increased. This tendency was more obvious at later growth stage, at which both the Pn and the chlorophyll content decreased more slowly in the newly cultivars than the old ones. This study indicated that improved photosynthetic capacity and the higher activities of antioxidative enzymes after anthesis are important physiological bases for the high yield of the modern wheat cultivars.