Assessment of Phenotypic Diversity and Trait Relationships in Barley Genotypes Using Genotype × Trait Biplot Analysis

Barley is an important cereal crop with extensive genetic variation, which is essential for sustainable crop improvement and food security. This investigation evaluated the genetic diversity among twenty barley genotypes through morphological traits using a genotype × trait biplot approach. A field trial was conducted in the Moghan district and fertile tillers (FT), tillers per plant (TP), seeds per plant (SP), single-plant yield (YSP), seed yield performance (SYP), thousand-seed weight (TSW), plant height (PH), straw yield (SY), spike length (SL), and biological yield (BY) were measured. The biplot explained 66% of the variation (43% and 23% by the first and second components, respectively), effectively capturing genotype-trait interaction. Vector analysis revealed positive associations among yield-related traits, with SP correlated YSP, SYP associated with TSW, and SY, PH, SL, and BY forming a correlated group. Tiller-related traits were independent of biomass-related traits, indicating that selection for higher tillers may improve specific yield components without affecting plant size or straw yield. The polygon-view biplot identified vertex genotypes exhibiting trait-specific superiority; G10 excelled in SP, YSP, SYP, and TSW; G12 was superior in FT and TP; and G13 performed best for SY, PH, SL, and BY. Genotypes such as G5, G7, and G16 were located in less favorable sectors, indicating suboptimal performance. The ideal trait view highlighted SYP as the most informativeness trait, followed by YSP, TSW, and SP, suggesting that these traits are most valuable for for multi-trait selection. The biplot approach visualized phenotypic diversity and trait relationships and identified promising barley genotypes for selection.