Abstract: Morphological characteristics of different alfalfa varieties were explored during the cold hardening period in sandy habitats,and their relationship between morphological characteristics and semi lethal temperature of alfalfa was analyzed to screen the alfalfa cold tolerant varieties that suitable be planted in Horqin sandy land. The results showed that the dormancy of Zhaodong"and "Gongnong No. 1" began early period of cold hardening,and "Zhaodong","Donglu No. 1" and "Grassland No. 3" were more sensitive to low temperature. When it was getting cold,the number of autumn dormant buds,root neck diameter,root weight,root length and root-shoot ratio of alfalfa increased. The half lethal temperature of the Logistic equation showed that the cold resistance of the tested 8 alfalfa varieties was ranked as the "Dongmu No.1" > "Caoyuan No.3" > "Nongjing No.1" > "Gongnong No.1" > "Longmu No.801" > "Zhaodong" > "NongJing No.8" > "Caoyuan No.2". The correlation analysis showed that the median lethal temperature of alfalfa had a significant negative correlation with the root weight of alfalfa (P<0.05),but had no obvious correlation with other growth indicators. The alfalfa varieties have strong cold resistant ability are suitable to be planted in Horqin sandy land,such as "Dongmu No.1" and "Caoyuan No.3".

Key words: Sandy habitat, Alfalfa, Morphological characteristics, Low temperature, Cold resistance, Half lethal temperature

摘要： 为筛选适合科尔沁沙地种植抗寒性强的苜蓿品种，本试验探究了沙地生境下不同苜蓿品种在低温锻炼期的形态特征，并分析其与苜蓿半致死温度的关系。研究表明：低温锻炼期“肇东”和“公农1号”苜蓿休眠较早；“肇东”、“东苜1号”和“草原3号”对低温较敏感；随季节性降温苜蓿秋眠芽数增加，根颈增粗，根重增加，根长增长，根冠比增大。根颈活力法拟合Logistic方程所得半致死温度表明，8个苜蓿品种抗寒性排序为“东苜1号” > “草原3号” > “农菁1号” > “公农1号” > “龙牧801” > “肇东” > “农菁8号” > “草原2号”；相关性分析表明苜蓿半致死温度与苜蓿根重呈显著负相关关系（P<0.05），而与其他生长指标无显著相关关系。“东苜1号”、“草原3号”等抗寒性较强的苜蓿品种适合在科尔沁沙地区域种植。

关键词: 沙地生境, 苜蓿, 形态特性, 低温, 抗寒性, 半致死温度