中文摘要：

通过盐胁迫实验对紫花苜蓿突变体根部各项指标进行了研究，进一步深刻了解了紫花苜蓿的耐盐性。利用根系扫描仪和根系分析系统，测定了盐碱混合胁迫下紫花苜蓿突变体根系形态结构变化，包括根总面积、根总长度、平均直径和根尖数。通过测定盐胁迫下气孔导度、净光合速率、蒸腾速率和水分利用效率，分析其与根系响应机制。结果显示，不同盐浓度下苜蓿根系形态均有不同程度的变化，轻度盐胁迫可以促进其生长，当盐分持续升高时才表现出明显的抑制作用。

英文摘要：

Through experimental studies on physiological characteristics of root system of alfalfa under the salt stress, we can really understand the salt tolerance of alfalfa. Delta - t scan software is used to scan the picture and analyze specific root morphological parameters including to- tal root area, root length density, mean diameter and the number of root tips. 6400 photosynthetic apparatus was used to observe the stomatal conductance, net photosynthetic rate, transpiration rate and water use efficiency and measure different germination under salt stress in alfalfa. The results showed that changes of root morphology were different under different salt concentration. Mild salt stress can promote their growth, while the salinity increased it showed obvious inhibition. This experiment laid the foundation for screening salt tolerant alfalfa germplasm resources, and it has a profound significance to expand the utilization of alfalfa in saline alkali land.