Rhizophagus irregularis inoculum versus natural mycorrhizal inoculum for vine growth stimulant under controlled conditions

Abstract

[eng] Arbuscular mycorrhizal fungi (AMF) form mutualistic associations with the roots of most terrestrial plants and offer a sustainable alternative to conventional fertilizers, helping reduce chemical inputs in agriculture. This study investigated the effects of inoculation with Rhizophagus irregularis, both alone and in combination with native rhizospheric microbial communities, on the growth and microbial functioning of Vitis vinifera. Plants were assigned to six treatments: a sterile control; inoculation with R. irregularis; inoculation with a native AMF community (Natural); simultaneous co-inoculation with R. irregularis and native AMF (Mix); and two sequential inoculations—one with R. irregularis followed by native AMF (R+Nat), and the reverse (Nat+R). Biomass production, physiological parameters, mycorrhizal colonization, and microbial functional diversity (via Biolog® EcoPlate™) were assessed. All AMF-inoculated plants exhibit increased aerial biomass, enhanced photosynthetic capabilities, and higher levels of mycorrhizal colonization. Among them, R+Nat yielded the greatest plant biomass, while Nat+R and Natural treatments exhibited the highest colonization rates. Functional microbial diversity was higher in all inoculated treatments, yet no clear patterns were detected in substrate utilization profiles among AMF groups. Overall, our results support the positive role of AMF symbiosis in grapevine growth and physiology. However, no consistent differences in plant or microbial responses were found between single and co-inoculation strategies, nor between native and commercial AMF. These findings highlight the complexity of microbial interactions in the rhizosphere and suggest that, while AMF inoculation is beneficial, the outcomes may vary depending on the specific inoculum combinations and environmental context