Crop genotypic richness enhances biomass production and phosphorus acquisition in maize‐mycorrhiza symbiosis

Societal Impact Statement Our study tests how soil and plant biodiversity can enhance sustainability of crop production in Kenya. We tested whether mixtures of maize varieties performed better than monocultures and tested their response to arbuscular mycorrhizal fungi. Mycorrhizal responsiveness differed significantly by maize variety, and genetic mixtures outperformed monocultures. These findings demonstrate the benefits of using naturally‐occurring soil microorganisms in combination with genetic mixtures of crops to enhance food security. Summary Plant genetic diversity is a key component of biodiversity but one that is often overlooked when considering the adoption of sustainable strategies to enhance crop production, such as inoculation with arbuscular mycorrhizal (AM) fungi. Here, we tested the hypothesis that the biomass of the most responsive maize genotypes to AM fungal inoculation when grown in genetic monoculture would be enhanced when grown in mixtures comprising a mix of genotypes (polyculture). In a first experiment, maize varieties were inoculated with Rhizophagus irregularis or Funneliformis mosseae or left uninoculated. We measured key growth parameters, AM fungal colonisation and phosphorus uptake and calculated mycorrhizal responsiveness. A second experiment evaluated the effect of crop genetic diversity on productivity by growing the four most responsive varieties as either monocultures or polyculture, with and without AM fungal inoculation. Mycorrhizal responsiveness differed significantly by maize variety, with some varieties demonstrating greater benefits from AM fungi. Polycultures outperformed monocultures in terms of AM fungal colonisation, biomass and phosphorus capture, which were driven by a combination of complementarity and facilitation effects resulting from biodiversity. Our findings demonstrate the critical role played by AM fungi in shaping crop genotype performance and the potential benefits of moving away from cropping systems that rely on genetic monocultures. The use of AM fungal inoculum in combination with targeted locally adapted crop genotype mixtures maximises plant nutrient efficiency and productivity and provides a sustainable approach to maize production in sub‐Saharan agroecological systems.