Performance of Testcrosses, Heterosis, and Combining Ability in Quality Protein Maize Inbred Lines under Moisture Stress and Non-Stress Environments in Ethiopia

Abstract

The performance of newly developed, nutritionally enhanced, and stress-tolerant elite Quality Protein Maize (QPM) hybrids was evaluated under both moisture stress and non-stress conditions to assess their heterosis and combining ability. One hundred six hybrids were developed by crossing twenty-eight elite QPM inbred lines and four QPM testers following a line × tester mating design. The 106 F1 hybrids and four checks (standard and commercial hybrids) were evaluated in a 5×22 alpha-lattice design across four stress and non-stress environments in Ethiopia. Significant (P ≤ 0.05) genetic variation was observed for most agronomic traits and grain yield. Across drought stress and non-stress conditions, inheritance of traits was governed by additive gene action, whereas under optimal moisture-growing conditions, additive and non-additive effects dominated inheritance of most traits. For grain yield, inbred line L16 showed the highest general combining ability (GCA). F1 QPM hybrids, L16 × T1, L16 × T3, L25 × T4, L10 × T4, and T12 × T1 resulted in grain yield higher than the commercial QPM and non-QPM hybrid checks, ranging from 20–42%, signifying high average parent (154–282%) and better-parent (120–249%) heterosis. Thus, this study identified important QPM lines for developing high-yielding and stress-tolerant QPM varieties where malnutrition and recurrent drought conditions prevail.