Durum wheat (Triticum turgidum L. subsp. durum) is essential for pasta and semolina production in the Mediterranean basin, where grain yield and quality are highly sensitive to genotype & times; environment (G & times;E) interactions, particularly under drought-prone environments. This study evaluated 20 durum wheat genotypes (16 elite breeding lines from ICARDA and CIMMYT, plus 4 national checks) across six environments (three cropping seasons and two water-regimes: rainfed vs. supplemental irrigation) to dissect G & times;E effects, trait relationships, and identify stable, high-performing lines for multi-trait improvement. Thirteen agronomic and quality traits were assessed. Variance partitioning revealed that environmental effects, driven largely by inter-annual climate variability, accounted for 73.9% of grain yield variation, whereas key quality traits were predominantly genotype-driven (e.g., semolina color: 53.2%; gluten index: 41.5%). Significant G & times;E interactions were observed for most traits, with strong context dependency for functional quality parameters. Correlation analyses confirmed a negative yield-protein trade-off under irrigation (r = -0.29 to -0.51), which weakened under severe drought (r = -0.02 to -0.41), indicating opportunities to select moderate-yielding, high-protein ideotypes adapted to water-limited environments. Genotype-by-trait (GT) biplots and heatmap clustering analyses identified consistently high-quality, stable breeding lines (e.g., ICARDA-derived G6, G7, G8) and high-yielding, drought-adapted lines (e.g., CIMMYT-derived G17, G18). Environment-specific trait syndromes emerged: irrigated conditions favored co-expression of yield, semolina extraction, and bright color, while rainfed adaptation was associated with higher protein, improved sedimentation values, and larger kernel size. These findings support environmentstratified breeding and multi-trait selection frameworks, integrated via GT biplots and pattern-based clustering, to concurrently advance yield resilience and end-use quality in durum wheat for Mediterranean and other semiarid agroecosystems.