Estimation of heterosis for yield and some yield components in bread wheat

The heterosis study for grain yield and its attributes was carried out in bread wheat [Triticum aestivum L. em. Thell] through half diallel mating design in four environments. The pooled analysis revealed significant differences between the environments for all the characters, indicating that environments had significant effect on the expression of different characters. The variance due to parents and F1 were also significant for all the characters studied demonstrating the presence of significant variability among the material used in the study and presence of average heterosis for all the characters. The magnitude of heterobeltiosis and standard heterosis altered for all the crosses and for all the characters studied. For the traits viz., flag leaf area, 1000 grain weight, grain yield per plant and number of grains per spike quite a large number of crosses manifested positive significant heterosis over the checks. In contrast to these, least heterotic effects were observed for days to heading and harvest index. The hybrids HI 1544 x HD 2987, Raj 4037 x HD 2987, PBW 175 x HD 2987, HD 2932 x Raj 4079 and PBW 175 x Lok 1 exhibited the highest, significant and positive heterotic effect and mean performance for grain yield per plant and some of its important component traits. This could be exploited commercially for heterosis breeding in wheat.