Genotype of Wheat and Barley Affects Light Penetration and Wild Oat Growth

Cereal breeders have selected for traits that confer resistance to diseases and insects, with the goal of stabilizing yield potential and reducing inputs. The possibility exists that, by selecting for growth habits that impede weed development, cultivars can be developed with increased tolerance to weed infestations. Our objective was to determine whether wheat ( Triticum aestivum L.) and barley ( Hordeum vulgare L.) lines differ in their ability to prevent penetration of light into interrow spaces and suppress wild oat ( Avena fatua L.) growth. Based on our results, significant genotypic variation exists within winter and spring wheat and spring barley for the amount of sunlight allowed to penetrate to interrow spaces. A negative correlation existed between height and light penetration in four of seven nurseries studied. Six barley lines and six spring wheat lines, of similar heights but allowing different amounts of light penetration, were tested for suppression of wild oat growth. Barley was a much better competitor with wild oat than wheat was, allowing approximately one‐half the wild oat biomass and seed production. Barley lines allowed approximately 43% less light penetration than wheat. Significant variation for wild oat growth variables also existed among lines within the crops. High positive correlations of light penetration with wild oat growth existed within barley, suggesting that lines may be selected to contribute to integrated wild oat management.