Abstract: In this study,5 alfalfa cultivars with different cold resistance ability were used to determine the cold resistance physiological indices of the root in the field during different periods including late fall,winter,and spring of next year.The results shew that root contents of water soluble sugar,free praline,and soluble protein increased as the temperature dropped and decreased as temperature raised,but the correlation between the accumulation amount and cold resistance ability was not significant;root MDA content decreased slightly as the temperature dropped in late fall and beginning winter,and there was a trend of increasing firstly and then decreasing rapidly as the temperature dropped;root POD activity increased as the temperature dropped in late fall and then decreased rapidly as the temperature decreased in winter,and increased slowly with the temperature raised in spring of next year;there was no positive correlation between root POD activity and the cold resistance ability of cultivars.

Key words: Alfalfa, Overwintering, Osmoregulating substance, MDA, POD

摘要： 为了解紫花苜蓿(Medicago sativa L.)在越冬期对低温的适应性,选取抗寒能力不同的5个紫花苜蓿品种,测定其在2003年秋末、深冬至2004年春季田间越冬期间根系的主要抗寒生理指标,结果表明:各品种可溶性糖、游离脯氨酸和可溶性蛋白质含量均呈随着气温下降而增加、随着气温升高而减少的变化趋势,但积累量与抗寒能力相关性不显著;丙二醛(MDA)含量在秋末冬初随着气温的降低都有轻微下降,但随着寒冷的加剧,呈现急速增加,然后急速下降趋势;过氧化物酶(POD)活性都表现为随着秋末温度的下降而增加,随着寒冷的加剧而迅速下降,再随着翌年温度的回升而缓慢增加,过氧化物酶(POD)活力与品种抗寒力不呈正相关。

关键词: 紫花苜蓿, 越冬, 渗透调节物质, 丙二醛, 过氧化物酶