Abstract: In order to study the physiological response of alfalfa seedlings under freeze-thaw and freeze-thaw+soda saline alkali stress，'Longmu 807’ alfalfa seedlings were used as experimental materials to explore the physiological and biochemistry response of alfalfa to artificial simulated freeze-thaw cycles [10℃(T-F10)→5℃(T-F5)→0℃(T-F0)→—3℃→0℃(F-T0)→5℃(F-T5)→10℃(F-T10)] and freeze-thaw cycles + soda saline-alkali(150 mmol·L^-1)stress. The effects of freeze-thaw cycle and soda saline alkali on physiological and biochemical characteristics of alfalfa leaves were discussed. The results showed that:the contents of soluble sugar,proline,soluble protein and the activities of peroxidase and superoxide dismutase in alfalfa leaves increased first and then decreased during the whole cycle of thawing (T-F) and freezing-thawing (F-T) and freezing-thawing cycle + soda saline alkali stress,and reached the maximum at —3℃. The activities of catalase,ascorbate peroxidase and relative electrical conductivity increased gradually. The membership function method was used to analyze the 9 physiological and biochemical indexes,we found that the membership values were —3℃ > F-T0 > F-T10 > F-T5 > T-F0 ＞ T-F5 > T-F10 > CK under freeze-thaw cycles stress,and were —3℃ + saline alkali > F-T0 + saline alkali > F-T10 + saline alkali > F-T5 + saline alkali > T-F0 + saline alkal > CK + saline alkali > T-F5 + saline alkali > T-F10 + saline alkali > CK under freeze-thaw + soda saline-alkali stress.The comprehensive correlation degree of freeze-thaw and freeze-thaw + soda saline-alkali stress with each index from high to low was proline > superoxide dismutase > catalase > soluble sugar > ascorbate peroxidase > soluble protein > malondialdehyde > peroxidase > relative conductivity.

Key words: Alfalfa, Freezing-thawing and soda saline-alkali stress, Physiological response, Membership function analysis, Grey relational degree

摘要： 为了研究苜蓿（Medicago Sativa L.）幼苗在冻融和冻融+苏打盐碱胁迫下生理反应，以‘龙牧807’苜蓿幼苗为试材，对其进行冻融循环[10℃（T-F10）→5℃（T-F5）→0℃（T-F0）→—3℃→0℃（F-T0）→5℃（F-T5）→10℃（F-T10）]和冻融循环+苏打盐碱（150 mmol·L^-1）胁迫，以常温未胁迫处理的幼苗为对照（CK），探讨冻融循环和苏打盐碱对苜蓿叶片生理生化的影响。结果表明：在冻融循环、冻融循环+苏打盐碱胁迫，苜蓿叶片可溶性糖、脯氨酸、可溶性蛋白含量和过氧化物酶、超氧化物歧化酶活性呈先升后降趋势，且在-3℃低温胁迫时达最大值；过氧化氢酶活性、抗坏血酸过氧化物酶活性和相对电导率呈逐渐上升趋势。采用隶属函数法对9项生理生化指标分析表明，冻融循环胁迫下隶属值由高到低依次为：—3℃>F-T0>F-T10> F-T5> T-F0＞T-F5>T-F10> CK，冻融循环+盐碱胁迫下隶属值由高到低依次为：—3℃+盐碱>F-T0+盐碱>F-T10+盐碱>F-T5+盐碱>T-F0+盐碱> CK+盐碱＞T-F5+盐碱＞T-F10+盐碱＞CK；冻融循环和冻融循环+盐碱胁迫与各指标综合关联度由高到低为脯氨酸＞超氧化物歧化酶＞过氧化氢酶＞可溶性糖＞抗坏血酸过氧化物酶＞可溶性蛋白＞丙二醛＞过氧化物酶＞相对电导率。

关键词: 苜蓿, 冻融+苏打盐碱胁迫, 生理响应, 隶属函数, 灰色关联度