Successful prediction of crop yield increases after inoculation with arbuscular mycorrhizal fungi

Summary in the original language of the document

Mineral fertilizers and pesticides pose significant challenges due to their detrimental effects on the environment and human health. Alternative solutions are needed and include inoculation with arbuscular mycorrhizal fungi (AMF). In pot experiments, AMF can increase plant nutrient uptake and growth; however, successful inoculation with AMF depends on the soil properties and the soil microbiome. To solve the context dependency, we conducted on-farm experiments in 54 fields in Northern Switzerland and quantified the effects on maize growth. We calculated the mycorrhizal growth response (MGR) and found MGR to be greater than 10% in one quarter of the fields. We developed a predictive model combining selected soil parameters and soil fungal OTUs. Interestingly, the fungal OTUs had a greater impact than the soil parameters in predicting MGR. Finally, we analyzed the root fungal communities and observed that the introduced mycorrhizal strain replaced mostly native arbuscular mycorrhizal fungi in low MGR fields, while in high MGR fields, the relative abundances of several plant pathogenic fungi were significantly reduced. These findings suggested that the introduced mycorrhizal fungi outcompeted pathogenic fungi in the roots, leading to improved maize growth. Overall, the research highlights the importance of considering soil fungal communities and specific pathogenic fungi when predicting the success of mycorrhizal inoculation and subsequent crop growth. By assessing soil parameters and fungal composition prior to inoculation, it becomes possible to anticipate the effectiveness of mycorrhizal treatments and enhance sustainable agricultural practices.