Low temperature and short light length were the main environmental factors causing fall dormancy of Medicago sativa. The experiment was conducted in the laboratory with three Medicago sativa varieties of different fall dormant classes and under different temperature and light length treatments to study the changes in physiological traits. The results showed that the effects of interaction between temperature and light length reduction on physiological traits of alfalfa varieties were significantly ( P <0.05) greater than that of single treatments;when temperature or light length decreased,the POD,SOD activities increased and the contents of MDA and free proline indicated an increasing trend, and these physiological traits of Algongui fall-dormant type changed obviously under decreasing light length. Reduction of temperature and light length was the adverse environmental factors for Medicago and enzymatic activities and the contents of permeability regulating substance were in connection with fall dormancy.%低温和短日照是引起苜蓿秋眠的主要环境因子.本试验研究了降温与缩短光长对不同秋眠型紫花苜蓿品种生理特征变化的影响机制,并探讨其与秋眠性之间的关系.结果表明,缩短光长和降温互作处理对于苜蓿各项生理指标的影响显著(P＜0.05)大于单一处理;缩短光长或降温使各个品种SOD、POD活性升高,丙二醛、游离脯氨酸含量呈上升趋势,且秋眠型品种阿尔冈金生理指标的变化受短日照影响更为明显.短日照和低温都是苜蓿生长的一种逆境,晦活性以及渗透性调节物质含量的变化与苜蓿秋眠性存在某种关联.
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