Abstract: This paper studied the seasonal variation in contents of non-structural carbohydrate in roots of different alfalfa varieties during late autumn (October 15) and early spring (April 8), so as to provide theoretical basis for extension and application of local alfalfa varieties. Twelve alfalfa varieties at home and abroad were taken as experimental materials, the cold resistant physiological characteristics of different alfalfa varieties were compared and studied, through testing the contents of soluble sugar, reducing sugar, total sugar and starch in the roots of these 12 alfalfa varieties during late autumn and early spring. The results showed that there were significant differences (P<0.05) in contents of soluble sugar, reducing sugar, total sugar and soluble sugar/starch value in roots of different alfalfa varietied in late autumn and early spring. And there were significant differences (P<0.05) in contents of starch during autumn, but no obvious difference (P>0.05）was found in spring. There was a large difference in the descent range of non-structural carbohydrate content in roots of different alfalfa varieties from late autumn to early spring next year. And the decline rate in contents of soluble sugar, starch, reducing sugar and total sugar was 8.71%~41.43%, 51.21%~79.37%, 17.47%~56.16% and 26.10%~48.78%, respectively. These 12 alfalfa varieties were classified into 3 groups by clustering analysis. The group I had lower starch content in root, including M1 and M8 varieties, their starch contents were lower than 3.0%. The group Ⅱ had higher starch content in root, including 5 varieties: M3, M4, M6, M7 and M11 and their starch contents were 3.91%~4.82%. And group Ⅲ had higher soluble sugar content in root including 5 varieties: M2、M5、M9、M10、M12 and their soluble sugar contents were over 8.0% and the starch contents were between 3.0%~4.0%.

Key words: alfalfa, root system, non-structure carbohydrates, seasonal variation, clustering analysis

摘要： 研究不同紫花苜蓿品种晚秋和早春时期根部非结构性碳水化合物含量的季节变化动态，以期为当地紫花苜蓿推广应用提供理论依据。以国内外12个紫花苜蓿品种为试验材料，通过测定其在晚秋和早春时期根部可溶性糖、还原糖、总糖和淀粉含量，对不同紫花苜蓿品种抗寒生理特性进行了比较研究。结果表明，秋季和春季不同苜蓿品种根部可溶性糖、还原糖和总糖含量以及可溶性糖/淀粉值差异显著（P<0.05），淀粉含量在秋季差异显著（P<0.05），春季差异不显著（P>0.05）。从晚秋至翌年早春，不同苜蓿品种根部非结构性碳水化合物含量下降幅度差异较大，可溶性糖含量下降率为8.71%~41.43%，淀粉下降率为51.21%~79.37%，还原糖下降率为17.47%~56.16%，总糖下降率为26.10%~48.78%。聚类分析可将12个苜蓿品种分为三类：第一类为根部低淀粉含量类，包含M1和M8号二个品种，淀粉含量低于3.0%；第二类为根部高淀粉含量类，包含M3、M4、M6、M7和M11号五个品种，淀粉含量在3.91%~4.82%之间；第三类为根部高可溶性糖含量类，包括M2、M5、M9、M10、M12五个品种，可溶性糖含量在8.0%以上，淀粉含量在3.0%~4.0%之间。

关键词: 紫花苜蓿, 根系, 非结构性碳水化合物, 季节性变化, 聚类分析