Abstract: In order to learn influence of soil drying in winter on the overwintering of Medicago sativa L.,freeze-drying environment was simulated by means of temperature control and topsoil replacement in laboratory,influence of freeze-drying environment on freezing tolerance of crowns of alfalfa ‘WL440HQ’ and ‘Zhaodong’ and the causes were analyzed in combination with freezing test,cell damage,tissue moisture content and osmotic regulating substances. Results showed that freeze-drying environment was adverse to the freezing tolerance of alfalfa crowns. Comprared with ‘Zhaodong’,‘WL440HQ’ crowns had fewer soluble sugar and higher water loss rate under the freeze-drying environment,and cells were irreversibly damaged with a relative permeability of cell fluid exceeding 50%. In addition,there were significant differences in contents of proline and soluble protein between two cultivars,and these may be related to the better performance of ‘Zhaodong’ in cold or freezing environment. In order to improve the alfalfa winter survival,it is suggested that water should be replenished in winter in addition to irrigation in early winter.

Key words: Alfalfa, Freeze-drying, Freezing tolerance, Overwintering, Management during winter

摘要： 为了解冬季土壤干旱对紫花苜蓿(Medicago sativa L.)越冬的影响,本研究在实验室内通过控温和更换表土试验模拟低温干旱环境,结合抗冷冻测试、细胞损伤、根颈组织含水量和渗透调节物质变化等,研究低温干旱环境对‘WL440HQ’和‘肇东’苜蓿根颈耐寒性的影响及原因。研究结果表明:低温干旱环境降低苜蓿根颈的耐寒性;与‘肇东’苜蓿相比,低温干旱环境下‘WL440HQ’苜蓿根颈具有较低的耐寒性,根颈组织含有较少的可溶性糖和较高的失水速率,细胞受到不可逆损伤,细胞液相对渗透率超过50%;在低温干旱环境下,根颈内的脯氨酸和可溶性蛋白含量在2个苜蓿品种间差异显著,2种物质可能与‘肇东’苜蓿在低温环境下耐寒性更强有关。综上,为提高苜蓿的越冬能力,建议除在初冬季节灌冻水外,冬季还应适时补水。

关键词: 紫花苜蓿, 低温干旱, 耐寒性, 越冬, 越冬管理