Assessment On Drought Tolerance, Salt Tolerance And Acid-aluminum Tolerance Of 66 White Clovers In The Germination Stage

At present,a series of policies were issued by the government to promote the development of “crop planting change to forage planting“ and “Grass and animal husbandry”,making the forage industry in China get new opportunities.The breeding and cultivation of good grass is the priority to expand cultivated area of forage grass,increase benefits of forage planting and promote the development of grass industry.White clover as leguminous forage of high yield and good quality,could be compared with alfalfa which have the reputation of "king of the forage grass",and it has a long history of planting in China,and became a main forage in the south of China.But white clover have the characteristic that poor resistance to drought,salt and acid-aluminum in growth habit,which is the important fact to influence its use.Therefore,cultivating the hardy varieties of white clover is the key to promote the planting.66 white clover materials which contains 57 germplasm resources from Russia and 9 cultivars bred at home and abroad,have been studied to assess stress tolerance in germination stage in this paper,in order to screen out good white clover materials in resistance,and provide the scientific basis and theoretical guidance for the resistance breeding or planting promotion of white clover.The main research conclusions are as follows:1.Through the comparison about drought stress group and control group’s index data,the conclusion was obtained that drought stress,salt stress and acid-aluminum stress all have a negative effect on white clover,which can inhibit its seed germination and cause the variation of seedling growth appearance.2.Through the correlation analysis and factor principal component analysis,the germination tolerance assessment indexes of white clover under the different stress types have been picked out.Among them,the drought tolerance assessment indexes include Relative vigor index,Relative root volume and Relative ratio of root length to bud length.The salt tolerance assessment indexes include Relative vigor index and Relative germination rate.The acid-aluminum tolerance assessment indexes include Relative vigor index,relative germination potential and relative root average diameter.3.The weighted Subordinate function was used to synthetically assess 66 white clover materials’ drought tolerance,salt tolerance and acid-aluminum tolerance in germination stage.Through the hierarchical cluster analysis,five white clover germplasm materials with good drought tolerance were screened out,they are Haifa,ZXY06P-2475,ZXY06P-2528,Huia,ZXY06P-1879;ten white clover germplasm materials with good salt tolerance were screened out,they are ZXY06P-2576,ZXY06P-1798,ZXY06P-2561,ZXY06P-2598,Huia,ZXY06P-2659,ZXY06P-2614,ZXY06P-1806,ZXY06P-1806,ZXY06P-2233 and ZXY06P-1768;six white clover materials with nice acid-aluminum tolerance are Haifa,ZXY06P-1927,ZXY06P-1768,ZXY06P-1879,ZXY06P-2029,ZXY06P-2659.4.Through the method of Runk Sum Ration,six white clover germplasm materials with both the strong resistance to drought and salt stress were screened out,they are Huia,ZXY06P-1768,ZXY06P-2614,ZXY06P-1806,ZXY06P-2475 and Haifa;six white clover germplasm materials with both the strong resistance to drought and acid-aluminum stress are Haifa,ZXY06P-1879,ZXY06P-1768,ZXY06P-2614,ZXY06P-2528 and ZXY06P-2029.