Identification of salt tolerance of soybean landraces at germination stage in Guangdong

【Objective】The purpose of the study was to identify the salt tolerance of soybean landraces at germination stage in Guangdong,to discover the potential excellent traits in soybean landraces in Guangdong,to screen out germplasms with strong salt tolerance,and to provide high-quality parent materials for the improvement and cultivation of salt tolerant varieties.【Method】A total of 102 Guangdong soybean landrace germplasm resources were selected as the experimental materials,and the germination potential,germination rate,salt injury index,hypocotyl length,radicle length, fresh weight and dry weight were measured after treatment with 150 mmol/L NaCl for salt stress,and distilled water was used as the control. The preliminary classification of salt tolerance was carried out by the salt injury index.The relative values of the remaining indexes were calculated and correlation analysis was performed. The principal component analysis method and membership function method were used to calculate the comprehensive evaluation D value,and the salt tolerance was ranked. Germplasms with strong salt tolerance were screened by cluster analysis method.【Result】According to the preliminary classification result of salt injury index,it was found that highly tolerant germplasm resources accounted for the largest proportion of the 102 germplasm resources,followed by tolerant germplasm resources,moderately tolerant and sensitive germplasm resources accounted for the same proportion,there was no sensitive germplasm resource. Compared with the control,the indexes of soybean germination stage were all reduced under salt stress,and their degree of inhibition was in the order of radicle length>hypocotyl length>fresh weight>dry weight>germination potential>germination rate,and radicle length at germination stage was more inhibited,while germination rate was less inhibited. The results of correlation analysis showed that there was a certain degree of correlation between most of the indexes. Through principal component analysis,two principal components were obtained with a cumulative contribution rate of 88.17%,in which the largest absolute value of the eigenvector in the first principal component(PC1) was relative germination potential, and the largest absolute value of the eigenvector in the second principal component(PC2) was relative germination rate and salt injury index. The two obtained principal components were used as two comprehensive indexes,and the salt tolerance was ranked according to D value. The numbers of top five germplasm resources were 374,310,358,357 and 309 respectively. The salt tolerant germplasm resources were selected by cluster analysis and the numbers were 310,358,374 and 331 respectively.【Conclusion】Four soybean landrace germplasm resources with strong salt tolerance are screened out,which can be used as parental materials for salt tolerant germplasm creation or salt resistant germplasms for development and utilization of salinized land. Relative germination potential and relative germination rate indexes can be used to evaluate salt tolerance of soybean and to screen salt tolerant germplasms.