Genetic variation for agronomic characters and drought tolerance among the recombinant inbred lines of wheat from the Norstar × Zagross cross

Abstract

Interest in developing drought tolerant varieties is growing due to global warming. Identification of genetic variability for drought tolerance is a prerequisite to achieve this objective. In this study a sample of 28 recombinant inbred lines (RILs) of wheat developed from the cross of Norstar and Zagross varieties, together with their parents, were evaluated for two years (2010-2012) under normal and water stress conditions using split plot design with three replications. Main plots included two irrigation treatments of 70 and 140 mm evaporation from Class A pan and sub-plots consisted of 30 genotypes. The effect of genotypes and interaction of genotypes with years and water regimes were significant for all characters. Significant genotypic effect implies the existence of genetic variation among the lines under study. Heritability estimates were high for 1000 grain weight (0.87), flag leaf area (0.84), and days to heading (0.82). Biomass, grain yield, and straw yield showed the lowest heritability values (0.42, 0.50, and 0.51, respectively). Moderate genetic advance for most of the traits suggested the feasibility of selection among the RILs under investigation. Some RILs were higher yielding than either parent at both environments. Transgressive segregation was also observed for geometric mean productivity (GMP) and stress tolerance index (STI), indicating the possibility of selecting lines that are more drought tolerant than Norstar and Zagross varieties. Cluster analysis based on yield in the normal and water stress conditions, STI, and GMP identified six promising lines that can be evaluated further for drought tolerance in more environments.