Abstract

Eight parental genotypes of bread wheat were selected on the basis of broad range of genetic diversity and heat tolerance. 28 F₁ progenies produced by 8×8 half diallel fashion along with parents were evaluated in normal and heat stress environments during 2019-20. Adequacy tests indicated that data for days to anthesis, flag leaf area, grains/ spike, grain yield/plant and chlorophyll content were fitted for additive - dominance model. Additive component of variation (D) was significant (P<0.01) and prominent over H₁ and H₂ components for days to anthesis, flag leaf area, grains/spike, grain yield/plant and chlorophyll content. Partial dominant genes were mainly controlling factors for days to anthesis while flag leaf area, grains/spike, grain yield/plant and chlorophyll content were sustained over dominance by the value of (H₁/D)0.5. Values of H₂/4H₁, h₂/H₂ and [(4DH₁)0.5 + F] / [(4DH₁)0.5 - F] demonstrated asymmetrical and unequal distribution of dominant genes in parents for most of the characters. Days to anthesis exhibited high narrow sense heritability due to the existence of additive gene action with partial dominance suggesting that these traits might be useful for the development of high temperature stress tolerant varieties using modified pedigree selection method.