Analysis of variance (ANOVA) was performed for all eleven characters, as shown in Table 1. The Line ´ Tester interaction indicated that differences among treatments, parents, lines, parents vs. crosses, crosses and line vs. testers were highly significant for all characters in F1s. A similar finding was reported by
El-Gammaal et al. (2018), except for thousand grain weight, where no significance was observed for the parent vs. crosses. Variance due to testers was highly significant for all characters except for harvest index in F1s. Variance due to line vs. tester was highly significant for all characters except for 1000-grain weight in F1s. Line effects were not significant for any trait, while tester effects were highly significant for plant height, flag leaf area and 1000-grain weight. Analysis of variance for most parents and crosses revealed significant genotypic effects for all characters under study. This confirms the presence of sufficient genetic variability among lines, testers and hybrids, supporting further general combining ability analysis. Similar findings were reported by
Fellahi et al., (2013) and
Roy et al., (2021).
Component of variance
The estimates of Component of variance presented in Table 2. SCA variance was higher than GCA variance for all eleven traits, indicating the presence of non-additive gene action controlling these traits. A similar finding was reported by
Akram et al., (2011); Srivastava et al., (2012) and
Istipliler et al., (2015). Dominance genetic variance (σ2D) was greater than additive genetic variance (σ2A) and the average degree of dominance was greater than one (>1) for nine traits, including days to 50% flowering, spike-bearing tillers per plant, spike length, number of spikelets per spike, number of grains per spike, biological yield per plant, harvest index, 1000-grain weight and grain yield per plant, suggesting over-dominance for these traits. In contrast, for plant height and flag leaf area, additive genetic variance (σ2A) was higher than dominance genetic variance (σ2D), with average degrees of dominance less than one (<1), indicating partial dominance. A similar result for plant height was reported by
Ullah et al. (2009). The predictability ratio was less than one for all characters in F1s, indicating the presence of non-additive gene action for most traits, with some additive gene action for others. Similar results were found by
Joshi et al., (2004); Seelam et al., (2006); Dhadhal et al., (2008) and
Riaz et al., (2021).
Heritability in the narrow sense was high for five traits, days to 50% flowering, plant height, spike length, flag leaf area and 1000-grain weight suggesting that selection would be highly effective for these traits. A similar result was reported by
Saeed et al., (2017).
Combining ability
General combining ability
The general combining ability of all thirteen genotypes (ten lines and three testers) is presented in Table 3. The significant and positive gca effects for seed yield per plant were exhibited by three lines and one tester which in order of merit were PBW677, 10
th HPYT438 and 10
th HPYT422, among lines and HD3226 among the testers
. On the basis of gca effects and mean performance, parent PBW677 (12.38) was found good combiner for grain yield per plant along with days to 50% flowering, spike bearing tillers plant
-1, spike length, flag leaf area, biological yield plant
-1 and harvest index. Parent 10
th HPYT438 (6.93) for grain yield per plant with days to 50% flowering, plant height, number of spikelet spike
-1, number of grains spike
-1, biological yield plant
-1 and 1000 grain weight. Parent 10th HPYT422 for grain yield per plant with spike bearing tillers plant
-1, spike length and biological yield plant
-1, while, among testers, HD3226 (4.72) was found good general combiner for grain yield per plant in addition to flag leaf area, number of spikelet spike
-1, number of grains spike
-1, harvest index and 1000 grain weight.
The presence of significant general combining ability (GCA) values suggests the importance of additive or additive x additive gene effects, as previously reported by
Griffing (1956). These parents demonstrate strong potential for the development of improved wheat lines through hybridization programs. Similar finding has been reported by
Sharma et al., (2019).
Specific combining ability
Table 4 presents the specific combining ability (SCA) of thirty crosses. Fourteen crosses showed significant positive SCA effects for grain yield and other yield components. The top ten promising crosses were: PBW677 x PBW725, 10
th HPYT422 x HD3226, PBW677 x DBW222, 10
th HPYT402 x DBW222, 10
th HPYT423 x HD3226, HD2967 x DBW222, 8
th HPYT489 x HD3226, 10
th HPYT438 x DBW222, 9
th HPYT425 x PBW725 and 10
th HPYT403 x HD3226. Notably, PBW677 x PBW725 (29.49) showed the best SCA effects for grain yield, plant height, spike-bearing tillers, biological yield and harvest index in F1s. Other promising crosses include 10
th HPYT422 x HD3226 (18.60) for most traits except days to 50% flowering and flag leaf area, PBW677 x DBW222 (16.01) for plant height and 10
th HPYT402 x DBW222 (15.75) for all traits except plant height, spike length and flag leaf area in F1s.
According to
Kenga et al. (2004), cross combinations with high means, favorable SCA estimates and at least one parent with high GCA can enhance favorable alleles for improving target traits. In this study, the fourteen F1s crosses mentioned above showed the similar results and hence can be considered for breeding programs aimed at yield enhancement. Similar results were reported by
Kumar et al., (2005); Jogendra and Raje (2007);
Kumar et al., (2008); Jaiswal et al., (2010); Hakeem et al., (2020) and
Riaz et al., (2021).