低温胁迫对不同秋眠类型苜蓿抗寒性影响的研究

了解秋眠性对苜蓿抗寒能力的影响，用11个美国苜蓿秋眠标准对照品种，每品种随机分为1个对照组和3个处理组，研究低温胁迫对苜蓿幼苗存活和生理生化指标的影响。结果表明：在-8℃处理6h，苜蓿幼苗的存活率仅为2.75%，表明-8℃为本试验的致死温度。而非秋眠型和极非秋眠型苜蓿的存活率要低于秋眠和半秋眠类型苜蓿,秋眠习性与耐寒性存在显著相关。各品种相对电导率和丙二醛（MDA）含量随着胁迫程度加重均呈显著增加。脯氨酸含量的变化总体上呈增加趋势，而不同处理对其变化的影响有差异。超氧化物歧化酶活性随着温度的降低呈增加趋势。

The Effect of Low Temperature on Cold Resistance of Alfalfa with Different Fall Dormancy Type

In order to understand the influence of fall dormancy on alfalfa（Medicago sativa）cold tolerance,11 American alfalfa varieties from standard fall dormancy control were tested,and each variety were randomly divided into a control group and three treatment groups to study the low temperature effect on alfalfa seedling survival and physiological biochemical indexes.The test results showed：when 6h was treated at-8℃,the survival rate of alfalfa seedlings was only 2.75%,indicating that the-8℃ was its lethal temperature.The survival rate of alfalfa seedlings from non fall dormancy and extremely non fall dormancy type was less than that of fall dormancy and semi-fall dormancy types,which also indicates that fall dormancy were significantly associated with cold tolerance.Besides,with increasing temperature stress levels,the relative conductivity and MDA content of each alfalfa variety increased significantly;proline content showed an increasing trend in general,its changes varied in different treatments;the activity of superoxide dismutase inclined to increase with decreasing temperatures.