Identification and evaluation for salt tolerance of tropical rice germplasm resources in whole growth period

【Objective】 The purpose of the study was to identify the appropriate concentration and key indicators for salt tolerance in tropical rice germplasm resources in whole growth period, to screentropical rice germplasm resources with strong salt tolerance,and to provide theoretical support for carrying out research on salt tolerance mechanism and variety breeding of tropical rice.【Method】 Three treatments with salt(NaCl) concentrations of 0(CK), 0.3% and 0.6% were set to carry out salt stress experiments on 23 tropical rice germplasm resources in whole growth period. Nine salt tolerance indicators were selected,and multivariate statistical analysis method were used to carry out the identification and evaluation salt tolerance in whole growth period.【Result】 Under 0.6% NaCl stress,the results of analysis of variance and correlation analysis showed that the survival rate, panicle number per plant,total grains per main spike, 1000-grain weight,and yield per plant of tropical rice germplasm resources were significantly lower than that of CK(P<0.05, the same below),while malondialdehyde and sodium contents were significantly higher than CK. There were significant or extremely significant(P<0.01) correlations between most of the salt tolerance indicators, and the relationship between indicators was relatively close. Therefore,the appropriate NaCl concentration for identifying salt tolerance of tropical rice in whole growth period was determined to be 0.6%. The principal component analysis method was used to rank the comprehensive evaluation values(D) of salt tolerance of the tested tropical rice germplasms. Among the tested materials, six tropical rice germplasm resources(ST007,W25S/ST003,ST017,ST018,ST019 and ST020) had a D value above 0.70,indicating strong salt tolerance. Using cluster analysis based on the D value, the tested tropical rice germplasm resources could be divided into three major groups,and six tropical rice germplasm resources with strong salt tolerance were selected. The clustering results were basically consistent with the D value rank. The salt tolerance of tropical rice germplasm resources in different groups was mainly manifested as differences in survival rate, panicle number per plant, yield per plant, and total grains per main spike. Further stepwise linear regression analysis results indicated that the total grains per main spike,survival rate and panicle number per plant could be used as key indicators for evaluating salt tolerance of tropical rice in whole growth period.【Conclusion】 The appropriate NaCl concentration for identifying salt tolerance of tropical rice in whole growth period is 0.6%. Three key indicators(the total grains per main spike,survival rate and panicle number per plant) are selected to establish regression equations for evaluating salt tolerance of tropical rice in whole growth period. Six tropical rice germplasm resources with strong salt tolerance are obtained,namely ST007, W25S/ST003,ST017,ST018,ST019 and ST020.