Genetic diversity among barley genotypes and path analysis of several agronomic and physiological characters at normal and salinity stress conditions

The current research was performed to evaluate 150 barley cultivars based on several agronomic and physiological traits. The experiment was conducted as an alpha lattice design with five incomplete blocks in two replications at normal and salinity stress (EC= 12 dsm-1) conditions at Agriculture and Natural Resources Research and Education Center, Yazd, Iran, for two years. The combined analysis of variance showed a significant difference among genotypes in all traits except harvest index and relative water content, indicating the existence of genetic diversity among the evaluated barley genotypes. Phenotypic correlation coefficients based on the average of two cropping years showed that biological yield, days to physiological maturity, and leaf chlorophyll index under normal conditions and biological yield, harvest index, number of fertile tillers, and plant height under salinity stress had a significant positive correlation with grain yield. According to the path analysis, the days to physiological maturity and number of fertile tillers had the highest positive direct effect on grain yield in normal and salinity stress conditions, respectively, followed by leaf chlorophyll index in the normal conditions and plant height under salinity stress. Cluster analysis by Ward’s method grouped the studied genotypes into three clusters in both environments based on an average of two years. The discriminant function analysis was used to determine the number of clusters and check the accuracy of the grouping in the cluster analysis. Percentage deviation from the grand mean of clusters under salinity stress showed that genotypes of the first cluster had the highest grain yield and have the shortest maturity period. In the second cluster, physiologically efficient genotypes, and in the third cluster, late maturing and low-yielding genotypes were included. Therefore, according to the results of this study, it can be concluded that under salinity stress, the genotypes of the first cluster with the highest grain yield and earliest maturity dates can be used in future breeding programs to improve the salinity tolerance.