Analysis of Hybrid Vigour and Combining Ability for Major Agronomic Traits of Highland Hulless Barley

Highland hulless barley is a core grain crop on the Qinghai–Tibet Plateau. Limited research on hybrid vigour and combining ability has constrained hybrid breeding progress. This study employed eight Himalayan barley varieties as parents and utilized the NCII design to generate 16 hybrid combinations. Hybrid vigour, combining ability, and genetic parameters were analyzed for 11 core ear and grain agronomic traits. Results indicated significant hybrid vigour across all traits: combination 1789 × 84 showed the highest total ear weight (midparent advantage: 116.74%, super-parent advantage 104.60%) and grain weight per ear (mid-parent advantage 126.78%, super-parent advantage 120.13%) in combination 1789 × 84, while thousand-grain weight showed the strongest hybrid vigour in combination 74 × 84 (mid-parent advantage 41.64%). Complementarity ability analysis revealed that parent 69 exhibited extremely significant positive general combining ability (GCA) effects across multiple core traits, making it the optimal parent for comprehensive traits; combination 1791 × 69 demonstrated the highest specific combining ability (SCA) effects. Genetic parameters indicated that traits such as the number of filled grains and total ear weight were primarily influenced by additive effects, as indicated by the higher GCA variance components compared with SCA variance components for these traits. Furthermore, thousand-grain weight was identified as a key integrative trait linking spike and grain characteristics, and its improvement can simultaneously enhance multiple yield-related traits. The superior parents (69, 1789, 1791) and strong-advantage combinations identified in this study provide a scientific basis for parent selection, combination screening, and breeding strategy formulation in high-yielding hybrid breeding of barley.