Hybrid performance in finger millet (Eleusine coracana) for grain yield and component traits under well-watered and drought-stress conditions

Abstract

Introduction Finger millet (Eleusine coracana) is a high-potential, climate-resilient and nutrient-rich small cereal with growing potential for food, feed, and other value-added products across various market segments. Knowledge on the combining ability and heterosis of breeding populations under contrasting water regimes is essential for genetic improvement of the crop for economics traits. The aim of this study was to determine the combining ability, heterosis, and the nature of gene action of selected Ethiopian finger millet parents for economic traits in hybrid combinations to guide the selection of best families and new breeding populations. Methods A 7 × 10 line × tester mating design was used, and the resultant 70 F1 hybrids and 17 parents were evaluated under non-stressed (NST) and drought-stress (ST) conditions across greenhouse and field environments. Genotypes were profiled for major agronomic traits: plant height (PTH), days to 50% flowering (DTF), days to maturity (DTM), number of productive tillers per plant (NT), primary finger length (FL), ear length (EL), number of fingers per ear (NF), grain yield (GY), harvest index (HI), and thousand seed weight (TSW). Results Line (GCAL), tester (GCAT), and line × tester (SCA) mean squares were significant (p < 0.001) for all assessed traits, indicating contributions of both additive and non-additive gene actions in the inheritance of agronomic and physiological traits. Grain yield declined by 57% in parental genotypes and 62% in F1 hybrids under drought stress; however, several superior crosses exhibited relatively lower yield penalties (-51%), indicating enhanced drought resilience. Additive genetic effect predominantly conditioned the inheritance of DTF, EL, DTM under ST conditions, whereas non-additive effects were more important for NT and DTM under NST conditions. Broad-sense heritability (H2) for GY was higher under ST (0.51) than NST (0.13) conditions, necessitating multiple testing environments for drought tolerance evaluation and selection. Lines such as G3, G2, and G4 and testers such as G14, G8, G13, G17, and G10 exhibited higher general combining ability effects for GY in a desirable trend, in that order. Furthermore, crosses G85, G31, G79, G38, G48, G54, G64, and G65 exhibited higher specific combining ability effects and heterosis for GY under ST conditions. Discussion The results demonstrated substantial genetic variability for grain yield and related traits with additive and non-additive gene actions. This guides effective selection based on additive and non-additive gene effects in finger millet improvement. The selected parents and the top crosses are recommended for breeding and selecting new-generation, drought-adapted finger millet genotypes.