Physiological response and cold tolerance evaluation of 30 alfalfa germplasm to low temperature stress
[Objective]The aim of the study is to screen and evaluate low temperature tolerant alfalfa germ-plasm.[Method]30 alfalfa germplasm growing for 30 days at home and abroad were treated with low temperature stress by nutrient solution sand culture method.The physiological indexes of alfalfa were measured at-7℃after 2 h,4 h,6 h and 8 h treatment.[Result]With the extension of low temperature stress time,the contents of chlorophyll a,chlorophyll b and total chlorophyll decreased by 6.1%～71.10%,6.61%～63.01%and 6.18%～69.03%com-pared with the control,respectively.The electrical conductivity and malondialdehyde content increased.Compared with the control,the contents of proline,soluble sugar and soluble protein and the activities of peroxidase and catalase first increased and then decreased,and increased to the maximum under low temperature stress for 6 h.The activity of superoxide dismutants increased first,then decreased and then increased again,with the highest increase at 4 h and the lowest increase at 6 h.[Conclusion]The 30 alfalfa can be divided into 4 categories by the comprehensive evalua-tion of membership function,among which the new strains P1,P2,P3 and P4 have good low temperature tolerance,and can be used for the breeding of new alfalfa varieties with low temperature tolerance.
alfalfalow temperature stressphysiological characteristicscomprehensive evaluation
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