Yield stability of contrasting orchardgrass (Dactylis glomerata L.) genotypes over the years and water regimes

Stability of combining ability and the nature and extent of genetic and genotype × environment interaction is poorly understood in orchardgrass especially under climate change conditions. This study was conducted to evaluate the adaptability and yield stability of orchardgrass families in order to facilitate comparison among HS families and environments and identify suitable families for future breeding studies. In the present study, first-generation half-sib families of orchardgrass derived from the polycross of 25 parental genotypes were evaluated in the field during five years under two irrigation regimes of normal and water deficit. Considerable genotypic variation was observed among half-sib families for all of the evaluated traits, demonstrating high potential for improving these traits through half-sib mating. The effects of water deficit on dry forage yield increased from the first to fifth year and consequently declined the persistence of half-sib families. Results showed that both genetic and non-genetic gene actions played a role in the control of dry forage yield. The environment effect was a predominant source of variation which explained 58.6% of total variation, whereas G and GE captured 4.2% and 21.5%, respectively. The partitioning of GGE through GGE biplot analysis showed that the first two PC accounted for 65% and 11% of the GGE sum of squares respectively, explaining a total of 76% variation. The stability of general combining ability, plant productivity, and drought tolerance clearly identified G4, G5, G6, and G14 as the superior and stable parental genotypes able to transmit both stability and forage productivity to their progenies.