Abstract: Aluminum toxicity is one of the main limiting factors for alfalfa (Medicago sativa) planting in acid soil areas in the South. It is very important for alfalfa to be widely used in southern China to select alfalfa materials which can grow well in acid-aluminized soil. In this study,27 Yunnan alfalfa resources were selected as experimental materials to study the changes of plant height,proline,root activity and organic acid content under 100 mg·kg^-1 aluminum concentration. The results showed that aluminum inhibited the growth of alfalfa,and different materials have different sensitivities. Aluminum inhibited plant height and root activity of alfalfa.The content of free proline and organic acid in alfalfa leaves under aluminum treatment was significantly increased (P<0.05),The relative proline content of all tested materials was greater than 100%,but the relative organic acid content of different materials is quite different. Clustering analysis and membership function method were used to comprehensively evaluate the tolerance of the tested materials. The results showed that NO.15,NO.12,NO.14 and NO.13 were superior and could be used to breed alfalfa varieties suitable for acid-aluminized soil.

Key words: Alfalfa, Aluminum stress, Organic acids, Comprehensive assessment

摘要： 铝毒是紫花苜蓿（Medicago sativa）在南方酸性土壤地区种植的主要限制性因素之一。筛选能够在酸性富铝化土壤中生长优良的苜蓿材料，对于紫花苜蓿在南方大面积推广具有重要意义。本研究选用27份云南紫花苜蓿为材料，研究100 mg·kg^-1浓度铝胁迫处理下供试材料株高、脯氨酸、根系活力以及有机酸含量的变化。结果表明，铝对苜蓿生长具有明显的抑制作用，且不同材料反应敏感性不同。铝对供试苜蓿株高和根系活力有明显抑制作用；铝处理下苜蓿叶片中游离脯氨酸、有机酸含量显著积累（P<0.05），所有供试材料的相对脯氨酸含量均大于100%，但不同材料相对有机酸含量表现差异较大。采用聚类分析及隶属函数法综合评价供试苜蓿材料的耐受性，以15，12，14，13号材料表现较优，可用于选育适应酸性富铝化土壤的苜蓿品种。

关键词: 苜蓿, 耐铝性, 有机酸, 综合评价