Over the last decades, tillage, chemical fertilizers, and pesticides have reduced the beneficial fungal population size in arable soils. Though soil inoculation can be a practical way to restore arbuscular mycorrhizal fungi (AMF) population size, weeds may also be benefited, as well. This study was aimed to evaluate the effect of three AMF species (Funneliformis mosseae, Rhizoglomus fasciculatum, andRhizoglomus intraradices) on photosynthetic rate, secondary metabolites content, reproductive organs percentage and nutrient uptake inSolanum nigrumL. andDigitaria sanguinalisL. weed species.Our results showed species variation in response to AMF inoculation, so that, while inoculation withR. intraradicesfungal species decreased total biomass inS. nigrumplants significantly, it increased total biomass ofD. sanguinalisplants by 26-49%. In addition, inoculation withF. mosseaespecies increased phenol, anthocyanin, and total terpenoid content inS. nigrumplants much more thanD. sanguinalis. Increased photosynthetic rate, secondary metabolites content, and flowering percentage in AMF-inoculatedS. nigrumplants show the enhanced competitive ability and allelopathic potential of this weed when associated with AMF, which makes it a good competitor against other plant species in the environment.