Xavier, L.J.C.Boyetchko, S.M.Derksen, D.A.2018-09-012018-09-012002-02-20http://hdl.handle.net/10388/9807Arbuscular mycorrhizal fungi (AMF) are soil fungi that intimately associate with most crops and influence their productivity. This study determined (i) the mycorrhizal dependency of eight barley cultivars and (ii) whether barley competitiveness against wild oat was linked to its mycorrhizal dependency. Of the eight cultivars tested, Virden was the most dependent on AMF whereas CDC Earl was the least dependent; Earl and Virden were therefore evaluated for competitiveness against wild oat at weed density ratios of 1:0.5, 1;1, 1:2 and 1:4 with or without AMF. Regardless of the AMF treatment, the total shoot dry weight of both barley varieties decreased with increasing crop:weed ratio. Earl derived 32% less benefit than Virden at a crop:weed ratio of 1: 0.5, and at a crop:weed ratio of 1:1, the total shoot dry weight of wild oat competing against Virden was significantly lower than that of wild oat competing against Earl. Regardless of the crop:weed ratio, (i) both barley varieties responded positively to the AMF mixture, (ii) the total shoot dry weight of AMF-inoculated Virden was 13% higher than that of AMF-inoculated Earl, and (iii) the shoot dry matter ratio of barley:wild oat was greater for AMF-inoculated Virden than Earl. At crop: weed ratios of up to 1:1, AMF-inoculated Virden plants had significantly more total shoot biomass than uninoculated Virden, whereas this was not the case with Earl. In general, wild oat competing against AMF-inoculated Virden had the least shoot dry matter at all the crop:weed ratios compared to all other treatments. These results suggest that the highly mycorrhizal Virden appeared to be more competitive than Earl and indicates that barley competitiveness may be partially linked to its mycorrhizal dependency.enAttribution-NonCommercial-NoDerivs 2.5 Canadaarbuscular mycorrhizal fungimycorrhizal dependencycrop competitivenessPoster Presentation