Differential impacts of Funneliformis mosseae and Rhizophagus intraradice on soil quality and rice yield in paddy fields: mediated by AMF-rice-rhizosphere microbe interactions

While the positive impact of arbuscular mycorrhizal fungi (AMF) on rice growth has been well established, the specific mechanisms through which different species of AMF regulate rice growth and the rhizosphere microecosystem are still not fully understood. This research investigated two AMF species, Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri), to uncover their distinct effects on rice rhizosphere soil characteristics, microbial community structure, and rice yield. Field experiments showed that the Fm treatment resulted in a significantly higher yield increase (26.96%) compared to Ri (21.19%). Although both AMF species significantly increased mycorrhizal colonization rates (Fm: 78.23%, Ri: 70.13% at maturity), they induced distinct improvements in soil properties. Specifically, Fm significantly boosted soil enzyme activity, with urease and cellulase activities 47.29% and 24.62%, respectively, higher than Ri Conversely, Ri promoted the accumulation of soil available phosphorus (69.81% higher than Fm). Additionally, the two AMF strains influenced the rhizosphere microbial community through different regulatory mechanisms. Fm significantly enriched carbon cycle-related bacterial groups such as Chloroflexota and Actinomycetota. Ri, however, not only significantly increased microbial α-diversity but also specifically enriched sulfur cycle functional bacterial groups. Crucially, the two AMF species optimized the "AMF-rice-rhizosphere microorganisms" interaction network through differential structural modifications. In the Fm treatment, fungal community network modularity was significantly enhanced, while the bacterial network under Ri treatment exhibited stronger connectivity. This study elucidates the distinct mechanism by which AMF species synergistically enhance rhizosphere soil microenvironment quality and increase rice yield. These findings provide a theoretical basis for the sustainable management of rice fields and suggest new directions for developing environmentally friendly agricultural technologies.