Tolerance of competitive spring barley cultivars to weed harrowing

Two experiments were conducted in 14 spring barley cultivars to investigate if crop tolerance to post-emergence weed harrowing is related to morphological traits that reflect competitiveness. The experiments were carried out in organically grown fields where low weed densities and biomass production were assumed to be without significant influence on crop growth. The experiments showed that different cultivars responded differently to post-emergence weed harrowing in terms of yield reduction. Taller and higher yielding cultivars with high leaf area index (LAI) tended to be less tolerant to post-emergence weed harrowing than shorter and lower yielding cultivars with low LAI. This conclusion, however, is only valid for 13 of 14 cultivars because one very tall cultivar was tolerant to harrowing. Although the tallest and highest yielding cultivars were damaged the most, they remained the highest yielding cultivars after weed harrowing. This study is the first attempt to relate competitiveness of cereal cultivars to tolerance to harrowing, and it is thought provoking that competitiveness and tolerance is found to be counterproductive.