The Cold-resistance Evaluation Of Twenty-two Alfalfa Varieties At Home And Abroad

In this study, twenty-two alfalfa varieties at home and abroad were used as the experiment material. The over-wintering rate and content of soluble sugar, total nitrogen and MDA were determinated and the content of free amino acid were analysed, so as to investigate the dynamic changing of every index, and compare the difference of every index in diversity alfalfa varieties sowing in same year and the difference of the same alfalfa variety growing in different small environment (flat and slop land) in Linxi county of Innermongolia, from 2005 to 2007. Finally, the cold resistance of different alfalfa varieties were synthetically evaluated. The results indicated:1. There were significantly positive correlation between soluble sugar, free amino acid, arginine in alfalfa root and cold resistance. The content of these indexes increased from late autumn and early winter, and kept higher level during the entire winter, then decreased in regreen time in the next spring. There were significantly negative correlation between the content of MDA in alfalfa root and cold resistance, the content of MDA increased in autumn and decreased with the falling of temperature in late autumn.2. The content of total nitrogen and free proline increased in late autumn and early winter, and decreased in the next spring, but there was little correlation with the cold resistance of alfalfa.3. With the increasing of the growth year, the accumulation ability of soluble sugar, total nitrogen, free amino acid, free proline and arginine decreased in alfalfa root, so the cold-resistant capability of alfalfa declined, moreover, the content of MDA decreasesd under low temperature stress.4. The accumulation abilities of soluble sugar, free amino acid, free proline and arginine in alfalfa root and cold resistance were better which growing in flat land than in slope land. But accumulation ability of nitrogen and membrane anti-oxidant ability were better in alfalfa root growing in slope land under lower temperature.5. Membership function is a better way to analyze the cold-resistant of alfalfa varieties than cluster analysis. The cold resistance of twenty-two alfalfa varieties is analyzed by membership function. The results are: Medicago falcate, Caoyuan No.2, Zhongmu No.1 and Longmu 803 are high cold-resistance breeds, Zhungeer Alfalfa, Zhaodong Alfalfa, Aohan Alfalfa and Algonquin are cold-resistance breeds, Rambler, Gold Empress, Rangelander, Victoria, Tumu No.2, Baralf, Gannong No3, Euver Alfalfa, WL323, Makiwakaba Alfalfa, Derby, Liangmu No.2 and Affinity are middle cold-resistance breeds, Vertus Alfalfa is non cold-resistance breed. The cold resistance of most of home alfalfa varieties is better than abroad alfalfa varieties.