Abstract: In order to investigate the effects of ⁶⁰Co-γ radiation on the physiological and biochemical indexes of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ seedlings under NaCl stress,different doses of ⁶⁰Co-γ radiation (600 Gy,900 Gy,1 200 Gy and 1 500 Gy) were applied to the ‘Longmu 806’ seeds. Contents of SP,Pro,SS,and the activities of POD,PPO and MDA,RC of leaves and roots of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ seedlings were determined under NaCl stress. The results showed that the contents of SP,Pro and SS,POD and PPO activity in leaves and roots of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ increased first and then decreased with radiation dose increasing,the highest value appeared at 600 Gy radiation group;the contents of MDA and RC increased gradually with radiation dose increasing,with the highest value in 1 500 Gy radiation group. The results of correlation analysis showed that Pro in leaves was positively correlated with SP and POD,POD in roots was positively correlated with SP,and MDA was positively correlated with RC in leaves and roots.The subordinate function of each index of NaCl stress in leaves and roots of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ seedlings was analyzed synthetically. The NaCl resistance of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ seedlings treated with different radiation was in the order of 600 Gy > 0 Gy > 900 Gy > 1 200 Gy > 1 500 Gy. 600 Gy radiation dose can effectively improve the resistance of Medicago sativa×Meliloides ruthenica ‘Longmu 806’ to NaCl,which is the appropriate dose for mutation breeding.

Key words: Medicago sativa×Meliloides ruthenica ‘Longmu 806’, ⁶⁰Co-γ radiation, NaCl stress, Physiological and biochemical indicators, Correlation analysis, Membership function analysis

摘要： 为了探究⁶⁰Co-γ辐射对NaCl胁迫的‘龙牧806’苜蓿（Medicago sativa×Meliloides ruthenica ‘Longmu 806’）幼苗生理生化指标的影响，本试验对苜蓿种子进行不同剂量（600 Gy，900 Gy，1 200 Gy和1 500 Gy）的⁶⁰Co-γ辐射处理，测定NaCl胁迫下苜蓿幼苗的叶片和根的可溶性蛋白（Soluble protein，SP）、脯氨酸（Proline，Pro）、可溶性糖（Soluble sugar，SS）、过氧化物酶（Peroxidase，POD）、多酚氧化酶（Polyphenol oxidase，PPO）、丙二醛（Malondialdehyde，MDA）和相对电导率（Relative conductivity，RC）。结果表明：苜蓿叶片和根的SP，Pro和SS含量及POD和PPO活性均随辐射剂量的增加呈先升后降的趋势，在600 Gy辐射组达到最高值；MDA含量和RC随辐射剂量的增加呈逐渐升高的趋势，在1 500 Gy辐射组均达到最高值。相关性分析结果表明：叶中Pro与SP，POD均呈极显著正相关，根中POD与SP呈极显著正相关，而叶和根中MDA与RC均呈显著正相关。苜蓿幼苗的叶片和根对NaCl胁迫各指标的隶属函数进行综合分析得出，不同辐射处理苜蓿种子的幼苗对NaCl抗性由强到弱依次为：600 Gy > 0 Gy > 900 Gy > 1 200 Gy > 1 500 Gy，600 Gy辐射剂量能有效提高‘龙牧806’苜蓿对NaCl的抗性，是诱变育种的合适剂量。

关键词: ‘龙牧806’苜蓿, ⁶⁰Co-γ辐射, NaCl胁迫, 生理生化指标, 相关性分析, 隶属函数分析