Partner quality matters - overyielding in a maize/soybean mixture depends on the initiator of common mycorrhizal networks

Abstract

Aims Cereal/legume intercropping has advantages in yield and nutrient uptake. However, how common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi (AMF) play a role in those benefits has not been fully clarified. This study aimed to explore how CMNs initiated by different host plants affected plant performance and nutrient acquisition in a maize/soybean mixture. Methods Microcosms with three compartments were used; these were separated by 30-µm nylon mesh. Two compartments were root compartments (RCs), and the third compartment was a hyphal compartment (HC). One RC was inoculated with the AMF Rhizophagus irregularis and the plant in this compartment was referred to as CMNs donor, and the plant in the other RC compartment as CMNs receiver. Results Maize biomass was twice that of soybean. Nitrogen (N) and phosphorus (P) content of both maize and soybean were higher in the presence of CMNs compared with the treatment without AMF. When maize was the CMNs donor, shoot biomass, N and P content of the mixture were higher than the expected biomass, N and P content based on monocultures, and effect not seen when soybean was the CMNs donor. Overyielding in biomass but not in N and P content, suggesting a disconnect between an AMF-induced increase in N, P acquisition and biomass increases. Conclusion CMNs asymmetrically increased biomass, N and P content of the larger-biomass species in this crop mixture compared with monocultures.