Although humans have studied biological nitrogen (N) fixation for nearly two centuries, our understanding of how legumes–microbiome interactions impact agroecosystem function is still evolving. To understand the effects of organic fertilizers and dual inoculation with Rhizobium and arbuscular mycorrhizal fungi (AMF) on root activity, N fixation and nutrient uptake of chickpea (Cicer arietinum), a two-year greenhouse study was conducted in 2020–2021 at the research station of Ferdowsi University of Mashhad, Iran. The experiment design was a randomized complete blocks in the factorial arrangement with three replications. The first factor consisted of two seedbeds including S1 (field soil) and S2 (soil + humic acid + 40 ton ha−1 cattle manure). The second factor included inoculation with Rhizobium alone, mycorrhiza alone, both Rhizobium and mycorrhiza and non-inoculated treatment. The results showed that the application of organic fertilizers increased the number of nodules, nodule weight, AMF colonization, leaf N content, leaf P content, root volume, root biomass and N uptake of chickpea, significantly. Also, the effect of seed inoculation was significant on all studied parameters where the highest root biomass (2 g), root volume (3.6 cm3) and leaf phosphorus (0.54%) were obtained in co-inoculated treatments. There was no significant difference between the effect of single inoculation of Rhizobium and dual inoculation of mycorrhiza and Rhizobium on nodule number, nodule weight, leaf N and N uptake of chickpea. Generally, rhizobia and AMF can benefit nutrient uptake and root activity of chickpea, potentially leading to higher crop production.

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