Early vigour and allelopathy - two useful traits for enhanced barley and wheat competitiveness against weeds

The objectives of this study were to identify traits in spring barley (Hordeum vulgare) and spring wheat (Triticum aestivum) related to the competitive ability of the crop and to determine their importance. Weed biomass 1-2 weeks prior to ear emergence was used as a measure of genotypic differences in competitiveness against weeds. Crop trait measurements comprised early crop biomass, early shoot height, straw length, heading and maturity. Early crop biomass 1-2 weeks prior to ear emergence was used as an overall trait for the various characters related to early vigour. In addition to these morphological traits, the potential allelopathic activity of the tested cultivars was determined using an agar-based bioassay with Lolium perenne (ryegrass). In both barley and wheat, multiple regression analysis revealed that early crop biomass and potential allelopathic activity were the only parameters that significantly contributed to competitiveness. In barley, early crop biomass explained 24-57% of the observed genotypic variance across 4 years, allelopathic activity explained 7-58% and combined they explained 44-69% of the observed genotypic variance. In wheat, the corresponding figures were lower: 14-21% for early biomass, 0-21% for allelopathic activity and 27-37% when combined. Model predictions suggested that new cultivars with increased early vigour and allelopathic activity offer a potential to further reduce weed interference.