Abstract: In order to understand the salt tolerance of different alfalfa germplasm and select the evaluation indexes of salt tolerance in seedling stage,this study selected 59 alfalfa germplasm materials at seedling stage from pot-culture,which was stress treated with 200 mmol·L^-1 NaCl salt solution. 12 growth and chlorophyll fluorescence indexes related to alfalfa salt tolerance were measured;tThe salt tolerance of alfalfa seedling materials was evaluated and the related indexes were screened by comprehensive evaluation,correlation analysis,grey correlation and cluster analysis. The results showed that the above ground biomass,underground biomass,root-shoot ratio,leaf area,leaf length,stem width,leaf width,plant height and SPAD varied largely among different germplasm materials and were sensitive to salt stress. The salt tolerance of 59 alfalfa materials at seedling stage was evaluated by weighted membership function (D),and based on the cluster analysis of D value,59 materials could be divided into 5 categories. In the first category,18 germplasm materials with a D value of 0.305 were weakly salt-tolerant. In the second group,there were 8 germplasm materials with a D value of 0.229. In the third group,16 germplasm materials with a D value of 0.384 were moderately salt-tolerant. In the fourth group,there were 13 germplasm materials with a D value of 0.465. In the fifth category,there were 4 germplasm materials with a D value of 0.647. Through comprehensive screening,materials with strong salt resistance such as ‘Mei-11’,‘Zhongmu-1’,‘Aikaixia’ and ‘Zhongmu-3’ were selected,and materials with very weak salt resistance such as ‘SLT’,‘Kangsai’,‘WL903’,‘WL440HQ’,‘Complex 6’,‘Natawwakaba’,‘Luomo’ and ‘Gannong’ 3 were selected. Through correlation analysis and grey correlation,leaf area,chlorophyll fluorescence,SPAD and root-shoot ratio were selected as identification indexes for salt tolerance of alfalfa at seedling stage. This study can provide a theoretical basis for the breeding and utilization of salt-tolerant alfalfa new varieties.

Key words: Alfalfa, Seedling stage, Salt resistance, Screening, Principal component analysis, Subordinate function

摘要： 为了解不同苜蓿种质材料耐盐程度和筛选苜蓿苗期耐盐性评价指标，本研究采用盆栽法对59份苜蓿种质材料苗期进行200 mmol·L^-1 NaCl盐溶液胁迫处理，测定了与苜蓿耐盐性相关的12个生长指标和叶绿素荧光指标，并利用综合评价、相关性分析、灰色关联和聚类分析等方法对其苗期耐盐性进行评价及耐盐指标筛选。结果表明：地上生物量、地下生物量、根冠比、叶面积、叶长、茎粗、叶宽、株高和SPAD（Soil and plant analyzer develotrnent，SPAD，代表相对叶绿素含量）在不同种质材料间变异大，对盐胁迫反应敏感。用加权隶属函数法得到的耐盐性综合度量值（D值）对59份苜蓿材料苗期的耐盐性进行综合评价，基于D值进行聚类分析，可将59份材料划分为5类：第I类有16份种质材料，D值为0.384，属中等耐盐材料；第II类有13份种质材料，D值为0.465，属强耐盐材料；第III类有4份种质材料，D值为0.647，属极强耐盐材料；第IV类有8份种质材料，D值为0.229，属极弱耐盐材料；第V类有18份种质材料，D值为0.305，属弱耐盐材料。综合筛选出耐盐性极强的材料有‘美11’、‘中苜1号’、‘爱开夏’和‘中苜3号’，耐盐性极弱的材料有‘北方SLT’、‘康赛’、‘WL903’、‘WL440HQ’、‘杂6’、‘Natawwakaba’、‘罗默’和‘甘农3号’。通过相关性分析和灰色关联，筛选出叶面积、叶绿素荧光、SPAD和根冠比可作为苜蓿苗期耐盐性鉴定指标。本研究可为耐盐苜蓿新品种选育及利用提供理论依据。

关键词: 苜蓿, 苗期, 耐盐性, 筛选, 主成分分析, 隶属函数