Arbuscular mycorrhizal fungi and rhizobium facilitate nitrogen uptake and transfer in soybean/tobacco intercropping system

Introduction The tripartite symbiosis of legume-AMF-rhizobia is widely considered to facilitate nitrogen (N) uptakeby legumes, but its effect on non-legume plants in intercropping systems remains unclear. Methods A pot experiment with three root separations (PS, MS, NS) was conducted using ¹⁵N isotope tracing in a soybean/tobacco intercropping system with double inoculation of Claroideoglomus etunicatum (CE) and Bradyrhizobium japonicum 5016 (BJ). Results Double inoculation (CE+BJ) significantly increased bioaccumulation, N uptake, and N transfer from soybean to tobacco compared to single or no inoculation. Mycorrhizal colonization in soybean increased by up to 45.55% in the NS system. All measured parameters in tobacco were significantly higher in NS than in PS or MS systems. Discussion The legume-AMF-rhizobium triple interaction positively affects N uptake and translocation in tobacco, showing potential for sustainable tobacco production, though the underlying mechanisms require further study.