MGIDI-based ideotype selection and genetic variation for wheat agronomic traits and bread-making quality (BMQ) under...

Enhancing flour quality is key to bread wheat marketability. It requires evaluating agronomic traits, bread-making quality (BMQ), and baking parameters to develop high-yielding varieties. This study assessed genetic variation and the effects of drought stress on these traits in a core collection of wheat cultivars, landraces, and lines. Field experiments used a split-plot design with three replications over two seasons under well-irrigated (WI) and drought-stress (DS) regimes (irrigation ceased at flowering). Genotype-by-irrigation interactions revealed significant genetic heterogeneity under water-limited conditions. Trait ranges varied with regime: the gluten index (GI) and grain hardness (GH) were broader under WI, while protein content, Zeleny sedimentation value (ZSV), water absorption, and dough development time were broader under DS. Drought increased tensile strength, protein content, and dough stability, indicating inconsistent trait responses. Genotype and genotype-by-environment (GGE) biplot analysis revealed that drought-stressed environments (E2, E4) were most discriminating for grain yield (GY) and GI. Several genotypes (Shiraz for GY; Satin for GI) showed close association with E2 and E4 environments, indicating adaptation to drought. A desirability index combining mean performance and stability identified Shiraz (GY) and Satin (GI) as superior for GY and GI, respectively. However, no single genotype consistently excelled across all traits, confirming trait-specific adaptation. Genetic coefficient of variation was higher for BMQ than agronomic traits in both regimes. Heritability was high for ZSV (> 0.90), GI (> 0.80), and spikelet number per spike (> 0.70) across regimes but inconsistent for other traits. Canonical correlation analysis identified two significant pairs, linking ZSV and GH indirectly with yield components. The multi-Trait Genotype-Ideotype Distance Index (MGIDI)-based selection identified top performers (Danesh, Line 181, Shiraz). It also quantified irrigation-dependent outcomes: drought drove gains in GI (+ 60.0%) and yield traits but increased GH (+ 16.1%). In contrast, WI favored yield with reduced GH (-8.7%). These findings highlight MGIDI's utility in resolving trait trade-offs for environment-specific breeding. The GGE biplot models effectively visualized mega-environment differentiation and genotype stability, providing a complementary framework to MGIDI for selecting wheat varieties with both drought resilience and BMQ. Results reveal inconsistent interrelationships between agronomic and BMQ traits, notably a yield-quality trade-off (GH, GI) under contrasting irrigation regimes.