Abstract:

In order to select germplasms of alfalfa suitable for growing in saline soil,a solution culture was conducted to investigate the growth rates (GR), number of green leaves (NGL), seedling height (SH), chlorophyll content (Chl), relative conductivity (REC),survival rate (SR) and dry weight (DW)of the forty-eight alfalfa accessions exposed to the different NaCl treatments(0.0%,0.3%,0.5%,0.7%,0.9%) for fifteen days, and the salt tolerant coefficient (STC) about these indexes were assessed overall and classified by principal components analysis, cluster analysis and stepwise regression analysis. The results showed that the seven indexes at seedlings of different alfalfa accessions under NaCl stress could be classified into five independent comprehensive components which might represent 90.14% of the raw data information by means of principal components analysis. The salt-tolerance comprehensive evaluation value (D value) of different accessions was obtained by means of subordination function method, the D value of M-1409 was the highest (0.751) and it was the most resistant to salt stress, while that of M-820 was the lowest(0.326) and it had the least tolerance to salt stress. The forty-eight accessions were divided into four salt-tolerant types by cluster analysis, eleven of the forty-eight materials were higher salt-resistant type, eighteen were medium salt-resistant type, ten were weaker salt-resistant type, and nine were salt-sensitive type. A mathematical evaluation model for alfalfa salt tolerance was established by stepwise regression analysis. Furthermore, based on this model (D=-0.522+0.779GR+0.382SH+0.084REC+0.297SR), four indexes closely related to the salt tolerance were screened out, including growth rates, seedling height, relative conductivity and survival rate. The aim of the study was to provide an important theoretical basis for evaluating germplasm resources and breeding new varieties of alfalfa.

Key words: Alfalfa, NaCl stress, Salt tolerance, Comprehensive evaluation

摘要：

为筛选出适合在盐渍土壤中生长的紫花苜蓿（Medicago sativa L.）种质，采用水培法，对48份紫花苜蓿种质材料在不同NaCl浓度（0.0%，0.3%，0.5%，0.7%，0.9%）处理15 d的生长速度（GR）、绿叶数（NGL）、苗高（SH）、叶绿素含量（Chl）、叶片相对电导率（REC）、存活率（SR）、植株干重（DW）等7项指标进行测定，以各单项指标的耐盐系数作为衡量耐盐性的依据，运用主成分分析、聚类分析和逐步回归等方法进行综合评价及分类。结果表明：通过主成分分析，本试验将NaCl处理下紫花苜蓿苗期的7个单项指标转换成5个彼此独立的综合指标，代表了试验材料90.14%的信息；通过隶属函数法分析，得到不同种质材料苗期耐盐性综合评价值（D值），材料M-1409的D值最高（0.751），耐盐性最强，材料M-820的D值最低（0.326），耐盐性最差；并通过聚类分析，将48份材料划分为4个耐盐群体，其中强耐盐材料11份，中等耐盐材料18份，弱耐盐材料10份，敏盐材料9份；进一步利用逐步回归法建立了紫花苜蓿种质材料苗期耐盐性预测回归模型：D=-0.522+0.779GR+0.382SH+0.084REC+0.297SR，筛选出显著影响紫花苜蓿苗期耐盐性的4个单项指标（GR，SH，REC，SR）；本研究可为紫花苜蓿耐盐种质资源评价及新品种选育提供科学理论依据。

关键词: 紫花苜蓿, NaCl胁迫, 耐盐性, 综合评价