Can arbuscular mycorrhizal fungi improve competitive ability of dill+common bean intercrops against weeds?

•Weed diversity indices was improved by intercropping of dill and common bean.•The crop biomass and seed yield increased, but weed density decreased as a result of intercropping.•Funneliformis mosseae colonization improved nutrient uptake, plant bimass and seed yield of the crops at different cropping systems.•Arbuscular mycorrhizal colonization also enhanced competitive ability of intercropped plants against the weeds. Competition for soil resources plays a key role in the crop yield of intercropping systems. There is a lack of knowledge on the main factors involved in competitive interactions between crops and weeds for nutrients uptake. Hence, the purpose of this work was to compare the effects of arbuscular mycorrhial fungi (Funneliformis mosseae) colonization in interspecific competitive relations and its effect on nutrients uptake and weed control in dill and common bean intercropping. Two field experiments were carried out with factorial arrangements based on randomized complete block design with three replications during 2013–2014. The factors were cropping systems including a) common bean (Phaseolus vulgaris L.) sole cropping (40 plantsm−2), b) dill (Anethum graveolens L.) sole cropping at different densities (25, 50 and 75 plantsm−2) and c) the additive intercropping of dill+common bean (25+40, 50+40 and 75+40 plantsm−2). All these treatments were applied with (+AM) or without (-AM) arbuscular mycorrhiza colonization. In both cropping systems, inoculation with F. mosseae increased the P, K, Fe and Zn concentrations of dill plants by 40, 524, 57 and 1.0μgkg−1DW, respectively. Intercropping increased Mn concentration in common bean (4.0μgkg−1DW) and dill (3.0μgkg−1DW), and also seed yields of both crops (198gm−2 and161gm−2, respectively). AM colonization improved seed yields of dill and common bean by 169 and 177gm−2 in 2013 and 2014, respectively. Moreover, AM application enhanced competitive ability of dill+common bean intercrops against weeds at different intercropping systems. Intercropping significantly changed weed density compared to sole cropping, as weed density was decreased in the dill+common bean intercropping. Diversity (H), Evenness (E) and richness of weed species of weeds for intercrops were higher than those for sole crops.