Abstract:

The aim of our study was to investigate the effect of water stress on growth, water status and leaf morphology of 3 alfalfa varieties, and to compare the ability of drought avoidance among them. Pot experiments were conducted in the greenhouse. Three alfalfa varieties were treated by water stress of 4 levels, and root dry matter, stem dry matter, leaf dry matter, leaf water potential, relative water content, leaf length, leaf width, leaf area and stress index were measured. The results showed that the responses of root dry matter, stem dry matter and leaf dry matter depended on the varieties and the degree of water stress. Root/shoot ratio (R/S) tended to increase as water stress increased. Leaf water potential, relative water content, stress index of root water content, leaf water content, leaf length, leaf width, leaf area and stress index of specific leaf area tended to decrease as water stress increased. ‘Aohan’, which presented the highest shoot biomass and the least stress index of specific leaf area among the 3 varieties, is the most resistant to drought, followed by ‘Zhongmu No.1’, and ‘Sanditi’ represented the worst drought resistance.

Key words: Alfalfa, Water stress, Leaf morphology, Dry matter, Root/shoot ratio, Stress index of specific leaf area

摘要：

试验旨在研究紫花苜蓿（Medicago sativa L.）生物量、水分生理状态以及叶片形态对水分胁迫的响应并确定参试紫花苜蓿品种的御旱能力。通过温室盆栽试验，对3个品种的紫花苜蓿进行了4个梯度的水分胁迫处理，测量了根干重、茎干重、叶干重、叶水势、相对叶片含水量、叶长、叶宽、叶面积以及相关指标的胁迫指数。结果显示：紫花苜蓿根、茎、叶的干重对水分胁迫的响应依品种和胁迫程度的不同而不同；随着水分胁迫程度的增加，根冠比呈增大趋势；叶水势、叶片相对含水量、根系含水量胁迫指数以及叶片含水量胁迫指数均呈下降趋势；叶片变短变窄，叶面积变小，比叶面积胁迫指数呈下降趋势。3个紫花苜蓿品种中‘敖汉’的根冠比最大且比叶面积胁迫指数最小，其御旱能力最强，‘中苜1号’次之，‘三得利’最弱。

关键词: 紫花苜蓿, 水分胁迫, 叶片形态, 生物量, 根冠比, 比叶面积胁迫指数