Understanding the increased maize productivity of intercropping systems from interactive scenarios of plant roots and arbuscular mycorrhizal fungi

Abstract

Abundant evidences have demonstrated that below-ground feedback mediated by crop diversification is essential for enhancing crop productivity. However, there is a knowledge gap about the mechanism underlying intercropping-driven productivity gain from the perspective of interactive scenarios of root traits and arbuscular mycorrhizal fungi (AMF). Herein, a ten-year field experiment was employed to reveal the differences of rhizosphere AMF community and root functional traits between maize monocropping and intercropping systems (maize-peanut, maize-soybean, maize-gingelly, and maize-sweet potato), as well as their relationships with maize productivity. AMF community traits were identified by high-throughput sequencing combined with bioinformatics and ecological analysis. Plant biomass, carbon (C) and nutrient content and accumulation were considered as productivity indicators, and root activity and morphology were considered as root functional traits. Compared with monocropping system, intercropping systems showed higher maize biomass, C accumulation and nutrient uptake (P < 0.05), and the intercropping advantage varied at different growth stages. Monocropping and intercropping systems showed a significant difference in maize root activity and morphology. AMF colonization significantly increased in all systems as maize developed, with the maize-peanut and maize-soybean consistently keeping higher colonization than other systems. The AMF communities of all systems except maize-gingelly were with greater force governed by deterministic assembly processes (MST < 50 %), in which monocropping system presented the lowest stochasticity ratio. AMF community composition in maize-soybean system was most deterministically driven and most diffusion-limited in neutral model. Compared with monocropping system, AMF community network showed a higher robustness in intercropping systems. And the ASVs of AMF community enriched by intercropping systems mainly belonged to genus Paraglomus, Glomus, and Claroideoglomus. The colonization, Shannon index, community composition, and core taxa (Glomus) of rhizosphere AMF influenced plant biomass and C and nutrient accumulation directly or indirectly by regulating root activity and morphology. Root activity also affected these maize productivity indicators directly or indirectly by regulating AMF community composition and core taxa (Claroideoglomus and Paraglomus). This work highlights the benefits of rhizosphere AMF in productivity gain of intercropping systems, and meanwhile, underscores the importance of AMF and root interactions in crop production.