The Effects of Local Weed Species on Arbuscular Mycorrhizal Fungal Communities in an Organic Winter Wheat ( L.) Field in Lebanon

We examined the potential effects of weed species on the arbuscular mycorrhizal fungi (AMF) in an organic winter wheat () field in Lebanon. In this agroecosystem, the field and its surroundings were covered with spontaneous vegetation corresponding to local weeds. The coexistence between wheat and weeds did not modify AM fungal community diversity and colonization in but changed their composition. We evidenced 22 operational taxonomic units (OTUs) specifically shared between wheat associated with weeds (Td) and weeds, regardless of their localization and 12 OTUs with an abundance of variation between wheat without neighboring weeds (Td) and Td. The number of AM propagules and total C and N contents were higher in soil covered with wheat associated with weeds (TdW) vs. wheat without neighboring weeds (Td). In greenhouse experiments, the shoot biomass and root mycorrhizal intensity of used as a trap plant, were higher using TdW vs. Td as the inoculum. Positive correlations were observed between soil AM propagule numbers and shoot biomass, on the one hand and mycorrhizal intensity, on the other hand. Weeds seemed to exert significant effects on root AM fungal composition in and these effects may contribute to enhanced AMF development in the field.