Dissecting the Genetics of Forage Yield and Related Traits in Soft Red Winter Wheat

The use of wheat as forage remains underutilized, particularly in the southeastern U.S., despite its potential to fill seasonal forage gaps when warm-season forages are dormant. Genetic improvement of forage yield traits in wheat has been limited. A genome-wide association study on 182 soft red winter wheat lines was conducted to identify quantitative trait loci for five forage yield traits. The panel was evaluated across four environmental-year combinations in Georgia (2023-2025). ANOVA revealed significant phenotypic variation, with heritability ranging from low to moderate in combined locations and from low to high within individual locations. Correlation analysis revealed significant positive associations between growth stages (GS), forage height (FHt), fresh forage weight (FWt), and dry forage weight (DWt). Using 47,339 SNP markers, we identified 192 marker-trait associations. Twenty-two major-effect QTLs explained 10% of the phenotypic variance, of which six were multi-trait. Chromosomes 7A, 1B, and 6B harbor key regions for FHt, FWt, and DWt. Accumulating favorable alleles showed significant increases in FHt (7 cm), FWt (1611.2 kg/ha), DWt (58.6 kg/ha), and germination counts (G) (4.5%), while reducing GS (0.81 units). QTLs (QFht.uga-7A, QFht.uga-4A) were possibly allelic with known loci, and the remaining 20 QTLs appeared novel. Candidate genes were identified for 10 of 22 QTLs related to plant growth and development. This study provides promising candidates for forage yield improvement in wheat under forage-production systems, supporting marker-assisted selection. Upon further validation, these results can be used in breeding for desirable plant architecture to improve wheat potential for forage yield.