中文摘要：

以小麦济南17和山农8355为材料,在低温胁迫条件下,测定了不同茎蘖功能叶和叶鞘超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性及丙二醛（MDA）和可溶性蛋白含量,并利用主成分分析、聚类分析对其抗冻性进行综合评价.结果表明：低温胁迫条件下,小麦拔节期不同茎蘖功能叶和叶鞘中SOD、POD和CAT活性均不同程度地上升,MDA和可溶性蛋白含量则不同程度地上升或下降.利用主成分分析和聚类分析,将济南17不同茎蘖分为3类：主茎和一级分蘖Ⅰ、Ⅱ属强抗冻蘖组,一级分蘖Ⅲ、Ⅳ和二级分蘖Ⅰp属中度抗冻蘖组,二级分蘖Ⅱp属弱抗冻蘖组;将山农8355不同茎蘖分为3类：主茎和一级分蘖Ⅰ、Ⅱ、Ⅲ属强抗冻蘖组,一级分蘖Ⅳ和二级分蘖Ⅰp属中度抗冻蘖组,二级分蘖Ⅱp属弱抗冻蘖组.表明冬小麦拔节期不同茎蘖存在抗冻性差异,且低位蘖较高位蘖抗冻.

英文摘要：

Taking two winter wheat cultivars Ji’nan 17 and Shannong 8355 as test materials, this paper measured the superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） activities and the malondialdehyde （MDA） and soluble protein contents in the functional leaves and sheaths of the tillers at different positions at stem elongation stage under low temperature stress, and then, the freezing resistance of the tillers was comprehensively evaluated by the methods of principal component analysis and cluster analysis. The results showed that under low temperature stress, the SOD, POD, and CAT activities in the functional leaves and sheaths of each tiller at stem elongation stage increased, but the MDA and soluble protein contents increased or decreased to some extent. By using principal component analysis and cluster analysis, the tillers of each cultivar were grouped into three kinds of freezing resistance type. For Ji’nan 17, the main stem, tiller Ⅰ, and tiller Ⅱ belonged to high freezing resistance type, the tiller Ⅲ, tiller Ⅳ, and tiller Ⅰp belonged to medium freezing resistance type, and the tiller Ⅱ p belonged to low freezing resistance type. For Shannong 8355, the main stem, tiller Ⅰ, tiller Ⅱ, and tiller Ⅲ belonged to high freezing resistance type, the tiller Ⅳ and tiller Ⅰp belonged to medium freezing resistance type, and the tiller Ⅱp belonged to low freezing resistance type. It was concluded that the freezing resistance of the winter wheat tillers at different positions at stem elongation stage differed, with the lower position tillers being more resistant than the higher position tillers.