Mohamed Baker Alabd Alwahed*¹, Faisal Bakor¹ and Thamer Alhenish²

1 Department of Field Crops, Faculty of Agriculture, Homs University, Homs, Syria.
2 Crops Research Administration, General Commission for Scientific Agricultural Research (GCSAR), Damascus, Syria.
(*Corresponding author Mohamed Baker, Email: Baker963949351833@gmail.com).

Received: 31/01 / 2025         Accepted: 12/03 /2026

Abstract: 

Three single crosses of bread wheat (Triticum aestivum L.) were studied at the Qarahta Research Station during the 2020-2021 and 2021-2022 seasons with the aim of estimating genetic parameters and understanding the nature of gene action controlling yield traits and their components. The experiment was designed according to a Randomized Complete Block Design (RCBD) with three replications, and the data were statistically analyzed to estimate the phenotypic coefficient of variation (PCV) and the genotypic coefficient of variation (GCV), broad-sense heritability (HBS) and narrow-sense heritability (HNS), and expected genetic advance (GA%). The results showed a close proximity between the values of (PCV) and (GCV) for spikes per plant (SPP), where the values of (PCV) ranged between (10.37 and 12.31%) and the values of (GCV) ranged between (8.89 and 11.12%). Similar proximity was observed for grains per spike (GPS) with a range of (PCV) (9.47 – 9.68%) and (GCV) (8.58 – 8.91%), and for thousand kernel weight (TKW) with a range of (PCV) (6.86 – 7.49%) and (GCV) (6.18 – 6.76%) in all crosses. This proximity indicates the limited environmental influence and the stability of these traits. The results of the genetic analysis revealed that broad-sense heritability was high to very high for all traits in all crosses (ranging between 0.73 and 0.85), whereas narrow-sense heritability varied, as the first cross was characterized by moderate values of (HNS) for grain yield (0.56) and high values for harvest index (0.91), while these values decreased markedly in the second cross in favor of non-additive gene action. The values of expected genetic advance showed clear variation, as the first cross recorded the highest genetic advance for grain yield reaching (24.31%) and for harvest index (50.78%), indicating the predominance of additive gene action. The results confirm that direct selection for improving grain yield and harvest index is effective and feasible in the first cross starting from early generations, whereas in the second and third crosses it is recommended to delay selection to advanced generations to ensure the dissipation of dominance effects, due to the predominance of non-additive gene action controlling yield inheritance in them.

Keywords: Bread Wheat, Genetic Parameters, Heritability, Genetic Advance, Gene Action.

 Full paper in Arabic: PDF