The Indian Journal of Genetics and Plant Breeding

Gene effects were analysed using mean harvest index of 12 populations, viz., both parents, F₁, F₂, first backcross generations, BC₁ and BC₂, second backcross generations, BC₁₁, BC₁₂, BC₂₁ and BC₂₂ along with BC_1s and BC_2s derived by selfing BC₁ and BC₂ populations of three crosses involving six diverse cultivars of Triticum durum to determine the nature of gene actions governing harvestindex through generation mean analysis under normal and late sown environments. The ten-parameter model was adequate in almost all cases to account for the variability in generation means. Epistatic effects, particularly trigenic type were predominant over additive and dominance effects under both normal and late sown environments. Duplicate epistasis was observed frequently under late sown environment only. Hybridization systems, such as biparental mating and/or diallel selective mating which exploit both additive and nonadditive gene effects, simultaneously could be useful in the improvement of harvest index in durum wheat.