Abstract: In order to elucidate the effect of waterlogging stress on the root phenotype of alfalfa with different fall dormancy,the variations of total root length,root surface area,root volume,root average diameter,number of root tips,and the correlation of fall dormancy level with root phenotypic traits 30 alfalfal varieties with the fall dormancy scale of 2 to 10.2 were investigated. The results showed that the root growth were inhibited by waterlogging stress for all the varieties with different fall dormancy. There were a decreasing trend for total root length,root surface area,root volume and number of root tips,and an increasing trend for the root average diameter. Under waterlogging stress,fall dormancy level was negatively correlatedwith total root length and root surface area. Total root length was significantly positively correlated with root surface area,root volume and number of root tips,whereas average root diameter was significantly negatively correlated with total root length,root surface area and root volume. Cluster analysis revealed that the fall dormancy level of waterlogging tolerant varieties were intermediate and had a relatively high level of root number,root surface area and root volume,whereas the varieties with higher level of fall dormancy were mostly waterlogging sensitive and had a relatively lower root parameters. Those results indicated that the increased lateral roots and absorption area could contribute to the waterlogging tolerance of alfalfa.

Key words: Waterlogging stress, Fall dormancy, Alfalfa, Root phenotype

摘要： 为明确渍水胁迫对不同秋眠级紫花苜蓿（Medicago sativa）根系形态的影响，本研究以30个秋眠级为2~10.2的紫花苜蓿品种为材料，分析了渍水胁迫下苜蓿总根长、根系表面积和体积、根平均直径和根尖数的变化以及秋眠级与根系形态及耐渍性的相关性。结果表明：渍水胁迫下不同秋眠级苜蓿根系生长均受到抑制，总根长、根系体积和表面积以及根尖数呈下降趋势，而根平均直径呈上升趋势；苜蓿品种的秋眠级与总根长和根系表面积呈显著负相关；总根长与根系表面积、根系体积和根尖数呈极显著正相关，而根系平均直径与总根长、根系表面积和体积均呈极显著负相关。聚类分析表明耐渍性较强品种其秋眠级中等和较低，根的数量、表面积和体积均相对较高，而秋眠级较大的品种耐渍性较弱，其根系形态各参数较低，表明在渍水胁迫下，侧根生长旺盛，根数较多，有利于提高紫花苜蓿的耐渍性。

关键词: 渍水胁迫, 秋眠级, 紫花苜蓿, 根系形态