Genetical analysis for wheat genotypes using a half-diallel model under different sowing conditions

Abstract Using a half-diallel model, six genotypes of bread wheat were crossed during 2021/2022 season, then in the next season of 2022/2023, parents and their F1 crosses were examined under optimum and late sowing dates to determine the genetic effects. The variance of sowing dates was significant or highly significant for all characteristics except for grain yield plant−1. The sowing dates × genotypes interactions were significant or highly significant for most traits. The variances of general (GCA) and specific (SCA) combining abilities were P < 0.05 for most traits. GCA/SCA ratio was more than unity for spikelets spike−1, kernels spike−1, spike length, and grain yield plant−1 under normal and late sowing dates, and kernels weight spike−1 under normal sowing date. The highest positive heterosis percentages over their mid-parent were obtained by crosses P1 × P6 (9.34%) and P5 ×  P6 (20.45%) under normal sowing date. On the other hand, positive heterosis values over their mid-parent were obtained by crosses P1  ×  P5 (7.73%), P4  ×  P6 (12.38%), and P5 ×  P6 (20.78%) under a late sowing date. While positive and the highest percentages of heterosis over their better parent were obtained by crosse P1  × P6 (9.34%), P2 ×  P4 (7.09%), and P5 ×  P6 (7.8%) under normal and late sowing dates for grain yield. These findings suggest that the continued use of these hybrids in successive studies is advisable until pure lines are achieved in the fifth segregating generation. This process may serve as a model for breeding programs aimed at developing new pure lines with early maturity, high productivity, and superior quality traits, as well as enhanced tolerance to variable climatic conditions, particularly under late planting scenarios.