Study On Low Temperature Physiological Response And Adaptability In Central Region Of Inner Mongolia Of Trifolium Repens

White clover(Trifolium repens L.)is a high-quality legume forage with important ecological value.As far as the north is concerned,the natural overwintering survival rate of white clover is not high,which has become the key restricting factor for its scale popularization and application.Therefore,it is of great significance to study the cold resistance and regional adaptability of white clover for screening excellent germplasm,breeding white clover varieties with the best cold resistance and feeding traits in production practice.In this study,XPX,LSL and HF were used as experimental materials to study the response of white clover to low temperature by low temperature stress in the laboratory.The phenological period,agronomic traits,production performance,feeding quality and overwintering rate of the tested materials were compared and expounded in four regions of central Inner Mongolia,and then the adaptability of the new white clover lines was evaluated,aiming to lay a foundation for the approval of new white clover lines and the breeding of new white clover varieties with strong cold resistance.The main results are as follows:(1)Under low temperature stress,the germination rate,germination potential,germination index,vigor index,root length,shoot length and seedling fresh weight of XPX were higher than those of the control variety.It showed that the cold resistance of XPX at germination stage was stronger than that of control varieties.(2)Under low temperature stress,REC and MDA content of XPX were significantly lower than those of the control variety,and the contents of SS,SP,PRO and the activities of SOD,POD and CAT were significantly higher than those of the control variety.It shows that the cold resistance of XPX at seedling stage is stronger than that of the control variety.(3)XPX and the control variety can normally complete the process of flowering and fruiting in the four regions of central Inner Mongolia in the same year of sowing,and there was no significant difference in phenological period among the tested materials.Environmental factors have a significant effect on the phenology of white clover,and temperature is the main environmental factor affecting the phenology of white clover.In the four regions,the comprehensive performance of root length,inflorescence number per plant and floret number per inflorescence of XPX was better than that of the control varieties,and the comprehensive performance of stem,leaf and seed was worse than that of the control varieties.(4)In the four regions,the average fresh grass yield of XPX was 10529.06 kg/hm~2,and the hay yield was 1816.66 kg/hm~2,which was not significantly different from the control variety.The seed yield was 578.02 kg/hm~2,lower than that of the control variety.There was no significant difference in DM content between XPX and the control varieties.The contents of CP and Ash in the XPX were higher than those in the control variety,the content of EE,NDF and ADF was lower than that of control varieties,indicating that the feeding quality of XPX was better than that of the control variety.(5)In four regions,the average overwintering rate of XPX was as high as 91.00%,and in each region,the overwintering rate of XPX was significantly higher than that of LSL(37.44%)and HF(10.38%),indicating that the cold resistance of XPX was stronger than that of control varieties.