Abstract: Cold and drought stresses are both urgent problems in alfalfa growing. 8 alfalfa cultivars were selected and grew in the lab pots to study the combined effects of cold and drought stresses on the morphology and physiology of alfalfa by measuring physiological and morphological indexes,including plant height,chlorophyll,peroxidase POD),and catalase (CAT). The results showed that under combined stress treatment,the morphological indexes of alfalfa,such as plant height,leaf length and leaf width,decreased,and the physiological indexes,such as chlorophyll content,nitrogen content,enzyme activities of peroxidase (POD) and catalase (CAT),also decreased. The pearson correlation coefficient showed significant correlation between the comprehensive evaluation of membership function and three indexes including plant height,chlorophyll content,and nitrogen content. According to the comprehensive evaluation of membership function for the combined stress resistance of eight alfalfa cultivars,the best performing varieties were ‘Dongmu No.2’ and ‘Gibraltar’.

Key words: Alfalfa, Cold and drought, Stress resistance, Physiological characteristic

摘要： 紫花苜蓿种植中普遍遭受低温和干旱胁迫，是亟需重视的问题。本研究选择8个代表性的紫花苜蓿品种作为试验材料，采用盆栽方式模拟低温和土壤干旱环境，通过测定株高、叶绿素、过氧化物酶(Peroxidase,POD)、过氧化氢酶(Catalase,CAT)等形态生理指标，来研究低温干旱复合胁迫对紫花苜蓿的影响。结果显示，与对照组相比，低温干旱处理后各品种紫花苜蓿的形态指标如株高、叶长、叶宽等以及叶绿素含量、氮含量、POD、CAT等生理指标均呈下降趋势。隶属函数综合评价与株高、叶绿素含量和氮含量均呈显著相关关系，表明这三个指标是评价苜蓿抗低温干旱复合胁迫的重要参数。基于隶属函数值综合指数对紫花苜蓿品种在低温干旱环境下的抗逆性进行评价，表现较好的品种为‘东苜2号’及‘北极熊’。

关键词: 紫花苜蓿, 低温胁迫, 干旱胁迫, 抗逆性, 生理特征