Exploring the Inheritance Mechanism of Flowering and Yield traits in Facultative × Spring Wheat Crosses through Line × Tester Analysis Approach

In wheat enhancement programs, the creation of new, high-yielding cultivars depends on understanding the genetic variation within the gene pool and its efficient application in breeding efforts. The Line × Tester mating design is a commonly employed method in plant breeding programs to assess genetic inheritance, evaluate the combining ability of parental lines, and identify superior germplasm for enhancing productivity and associated traits in progeny. To overcome yield limitations, one promising strategy for enhancing wheat productivity involves incorporating the gene pool of facultative winter wheat into spring wheat varieties. To achieve this objective, six diverse facultative winter wheat lines originating from semi-arid regions (FWWL-SA) were crossed with three spring bread wheat cultivars using a line × tester mating design throughout the 2021–2022. During the 2022–2023 growing season, six facultative winter wheat lines, three spring wheat testers, and their 18 resulting F1 hybrids were assessed using a RCB design with three replications. Substantial variations among genotypes were noted in traits such as maturity duration, height of plant, length of spike, grains spike-1 and grain yield per plant. The combining ability analysis demonstrated statistically meaningful variations across the lines, testers, lines × testers, lines vs. testers and parents vs. F1 progeny. According to combining ability, the line FAWWL-2 exhibited superior performance for early maturity, reduced plant height, and enhanced grain. Within the testers, 'Parula' emerged as the top performer for early maturity and shorter plant stature. In terms of grain yield, AARI-2011 demonstrated the highest general combining ability within the testers. The following hybrid combinations were identified as the most promising based on specific combining ability: FAWWL-1 × AARI-2011 for maturity duration, FAWWL-4 × Parula for plant height, FAWWL-6 × Punjab-2011 for spike length, and FAWWL-4 × AARI-2011 for grains spike-1. The FAWWL-4 × AARI-2011, FAWWL-2 × Parula, and FAWWL-6 × AARI-2011 were identified as the most effective specific combiners for grain yield. These crosses exhibited high general combining ability (GCA) influences in both the lines and testers. The GCA to SCA variance ratio demonstrated a dominant influence of non-additive gene action, additionally corroborated by the higher dominance variance relative to the additive variance. Moreover, the ratio of σ2A/σ2D was below unity, while the degree of dominance (σ2D/σ2A)1/2 exceeded one, implied a predominant role of non-additive genetic influences. "Findings from the present study indicate that, due to the prevalence of non-additive genetic influences, it may be more effective to postpone the chosen of diverse wheat genotypes until later segregating generations to develop superior lines for six key agronomic traits. Keywords: Additive gene action, combining ability, non-additive, gene action, gene pool, facultative winter wheat, spring wheat, genetic variability.