From Seedling Architecture to Grain: Linking Root and Shoot Traits with Yield Potential for Climate-Resilient Wheat Breeding.

Improving wheat for climate change requires understanding how seedling root systems affect adult plant performance. We evaluated 116 spring bread wheat (Triticum aestivum L.) genotypes across 25 traits under non-limiting moisture conditions. Analysis of variance revealed significant genotypic variation (p < 0.01) for all traits. High broad-sense heritability (H2 up to 99.81%) and close alignment between genotypic (GCV) and phenotypic (PCV) coefficients of variation indicated substantial genotypic differentiation among the evaluated accessions under these experimental conditions. A 21-predictor path analysis (R2 = 0.80) identified the number of spikes per plant (NSP; direct effect = 0.51) and heading date (HD; -0.32) as the primary positive and negative determinants of grain yield per plant (GYP), respectively. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) resolved four distinct clusters, revealing a functional trade-off between early vegetative vigor and mature yield: elite cultivars and accessions (Cluster 1) combined compact shoots, a high root-to-shoot ratio (RSR = 1.55), and superior yield (GYP = 11.76 g), whereas excessive seedling biomass was associated with yield penalties. Deep seminal-root angle (DRA) established a steep spatial distribution. The multi-trait genotype-ideotype distance index (MGIDI) identified 17 elite genotypes (e.g., G024, G020, G106, Sids14, and Gemiza11), offering an expected +32.3% genetic gain in GYP. These constitutive baseline architectural criteria provide reliable early-stage tools for breeding climate-adapted wheat.