Elevation-dependent productivity trade-offs in wild Elymus sibiricus populations across the Qinghai–Tibet Plateau zone

Forage yield was primarily influenced by population morphology, which was determined by plant height and leaf width, while seed yield was driven by the reproductive architecture, supported by leaf length and effective tillering. Accession 2019-001 achieved the highest comprehensive evaluation score and demonstrated optimal performance, indicating that its elevation of 3147 m may represent a suitable altitudinal range for wild <i>E. sibiricus</i>. These findings provide a theoretical foundation and data support for the breeding of <i>E. sibiricus</i> in alpine regions.