Revisiting Legume Response to Inoculation with Arbuscular Mycorrhizal Fungi and/or Rhizobia: What a Meta-analysis Tells Us?: A Review

Plant co-inoculation with different beneficial microbes, such as rhizobia (RH) and arbuscular mycorrhizal fungi (AMF), is a promising technology for improving crop yield and quality and contributing to sustainable agriculture. This is why the use of mixed microbial inoculants, rather than single inoculants, has increased, with remarkable success in some parts of the world. However, we do not have an overview of the effects of dual inoculation of AMF + RH on plant growth. Sometimes, experimental results show synergistic, additive, negative or no effect on plant growth even reduced growth. In this context, the present study aimed to quantify through a meta-analysis the effects of RH+AMF co-inoculation on nutrient uptake and growth of legume yield (crop, weeds and tree) and to discuss the key mechanisms that underpin enhanced plant growth promotion. A literature search was conducted across Scopus, Web of Science and Google Scholar, focusing on studies examining RH and AMF co-inoculation’s impact on nutrient uptake and biomass. The mean effect sizes were calculated using Cohen’s d at 95% confidence intervals (CIs). A total of 59 articles was analyzed. Our results show that inoculation and particularly co-inoculation significantly enhanced plant nutrient uptake, root infection and plant biomass yield (N and K uptake, p<0.001; shoot and root biomass, p<0.0001). Similarly, dual inoculation effects were significant at 95% CIs. This analysis provides a clearer understanding of the co-inoculation process, highlighting its benefits for leguminous plants and suggesting potential solutions for sustainable agriculture amidst climate change.