Heritability of Grain Yield and Its Components and Selection for Drought Tolerance in Wheat Double Haploid Lines

Drought is one of the most important environmental factors affecting plant growth. The double haploid method is one of the most common breeding methods in wheat. Using old cultivars in cross-breeding programs can be effective for restoring genes lost during evolution. In this study, in order to evaluate the genetic diversity and to select the drought-tolerant introgression wheat lines, 151 double haploid (DH) lines (derived from cross of old and modern cultivars) were evaluated under two moisture conditions (non-stress and drought-stress) in field. Considerable genetic variation was observed among DH lines for most of the traits indicating that selection for these traits can be effective to develop lines with higher performance or for specific purposes. The effect of drought stress was significant for most of the traits. For example, drought stress reduced grain yield by 40%. Comparison of old and new parent genotypes showed that the new parent was earlier in maturity, dwarf and had higher grain yield, yield components and harvest index. Transgressive segregation was observed for most of the traits indicating the possibility of selection for superior lines. In both moisture condition, plant height had the highest narrow sense heritability (46%) and leaf relative water content had the lowest one (12%). Grain yield had negative correlation with day to flowering indicating that selection for earliness can improve drought tolerance. According to the results of tolerance indices and biplot of principle component analysis, superior lines were identified. For example superior lines for grain yield, early flowering and higher harvest index were recognized for future studies.