Heritability and correlation studies of morpho-physiological traits for drought tolerance in spring wheat

Six wheat genotypes were crossed in 6 x 6 half diallel fashion. The parents and 15 F1 hybrids were evaluated in a randomized complete block design (RCBD) with four replications and two irrigation treatments. The analysis of variance revealed significant effect of water stress on yield and physiological traits which allowed determining the heritability and correlations for such traits. For yield traits, the parents TD-1, Sarsabz, Moomal and SKD-1 gave relatively minimum reductions on individual mean basis in stress conditions, whereas hybrids TD-1 x TJ-83, Kiran x Sarsabz and Kiran x Moomal recorded minimum declines in most of yield traits showing their feasibility for wheat hybrids in water shortage conditions. Similar to physiological traits, parents TD-1, Sarsabz and SKD-1 maintained their higher relative water content, greater leaf area and less stomatal conductance, while hybrids TD-1 x T.J-83, Kiran x Sarsabz and Sarsabz x Moomal expressed maximum RWC%, more leaf area and minimum stomatal conductance under drought conditions. The heritability estimates in broad were high whereas in narrow sense were low, moderate and high for yield and physiological traits, yet these estimates were greater in stressed than in non-stressed conditions. It indicated that the characters studied were predominantly controlled by additive type of genes and the stressed responsive genes were activated due to drought conditions. Thus, selection for such traits would be more effective for drought tolerance. Generally, the correlation coefficients were also greater in stressed than in non-stressed environments. In stressed conditions, the correlations between yield and physiological traits revealed that grains per spike, seed index, grain yield per plant, grain yield kg per ha and harvest index were positively correlated with relative water content, leaf area, spike fertility, root length and root biomass, nevertheless, all the yield traits were negatively correlated with only stomatal conductance.