Estimation of Components of Heterosis for Harvest Index in Durum Wheat Under Normal and Late Plantings

Parental, F₁, F₂, BC₁, BC₂, BC₁s, BC₂s, BC₁₁, BC₁₂, BC₂₁ and BC₂₂ generations of three crosses involving six diverse cuitivars of durum wheat (Trlticum durum Desf.) were used to analyze the gene effects, heterosis and inbreeding depression for harvest index and grain yield under normal and late plantings. Significant heterosis was recorded for crosses Cocorit 71 x A-9-30-1 and HI 8062 x JNK-4W-128 under both the sowing dates for harvest index and grain yield. Of the epistatic interactions, dominance x dominance x dominance (z) and additive x dominance x dominance (y) trigenic interactions contributed more frequently towards maximum significant heterosis for harvest index under the two diverse environments. Whereas additive x additive x dominance (x) and dominance x dominance x dominance (z) trigenic interactions contributed more for grain yield. The crosses Cocorit 71 x A-9-30-1 and HI 8062 x JNK-4W-128 showed stability of heterobeltiosis for harvest index as well as grain yield, hence, these crosses could be exploited in breeding programme for tangible advancement of durums. Biparental mating and/or diallel selective mating system seems to be the best breeding method to improve the trait for amelioration of grain yield in durum wheat.