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With45varieties from different units as experimental materials, we studied the effects of lowtemperature on physiological and biochemical indices in wheat leaves in overwintering, jointing andbooting stage during2010-2011. The wheat were grown in field and pot, and then they were moved into thelaboratory, treated by low temperature. The relative electrical conductivity, soluble suger content, solubleprotein content, free proline content, MDA content, SOD and POD activity in wheat leaves were measured.The main results were as follows:1. A certain degree of low temperature induced the increase of the osmotic adjustment materialscontents such as soluble sugar, soluble protein, free proline and the activity of protective enzymes such asSOD and POD in wheat leaves, and then protected the wheat from the harm of low temperature, theadaptability of wheat to low temperature was improved. However, when the temperature reduced lower, thecontent of osmotic adjustment substances was decreased and the free radical scavenging capacity ofprotective enzymes decreased, and then the relative conductivity and the content of MDA in leavesincreased rapidly, the damage that the wheat suffered exacerbated.2. In overwintering stage and jointing stage, low temperature affected the relative conductivity, thecontent of souble sugar, souble protein and MDA and the activity of SOD and POD in wheat leaves. Whilein booting sage, low temperature affected the relative conductivity, the content of souble sugar, and MDAand the activity of SOD and POD in wheat leaves.3. According to those physiological and biochemical characteristics that had high relationship withability of cold resistance, using the method of subordinate function, we calculated the average subordinatefunction values of varieties in different stage, and then made cluster analysis. Among the45varieties inoverwintering stage, Zhoumai16had the strongest cold resistance,33varieties (ShiH083-366, BQ12, et al.)had relative stronger cold resistance,10varieties (Liangxin99, Liangxin619, et al.) had common ability ofcold resistance, and the weakest cold resistance variety was Zhoumai21. Among the24varities in jointingstage, B07-4056had the strongest cold resistance,4varieties (Shannong055843, Zhongyuan6, et al.) hadrelative stronger cold resistance,17varieties (ShiH083-366, Liangxing99, et al.) had common ability of cold resistance, and the weakest cold resistance varieties were Yaomai16and Shunmai1718. Among the24varities in booting stage, Shimai19and Shi4185had relative stronger cold resistance,12varieties(ShiH083-366, B05-6507, et al.) had common ability of cold resistance, and10varieties (Yaomai16, A-9,et al.) had weaken cold resistance.
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