ObjectivesThis article explored effects of inoculating arbuscular mycorrhizal fungi (AMF) and different root separation methods on plant growth, nitrogen (N) uptake and available nitrogen content in soils.

MethodsTwo mycorrhizal treatments without inoculation (NM) and with inoculation of Funneliformis mosseae (FM) and three root separation methods (no separation, partial separation and full separation) were set up, and N uptakes by intercropping plants and available N contents in red soils were determined.

ResultsResults showed that the roots of maizes and soybeans were all infected by FM fungi, the mycorrhizal colonization rates were the lowest under the partial separation treatment. The root separation methods had obvious influence on the mycorrhizal dependency of maize and soybean, and the mycorrhizal dependency of soybean was increased along with the increase of intercropping interaction strength. Compared to the NM treatment, the FM inoculation increased the shoot and root biomass significantly regardless of the roots separation methods, and the shoot biomass of maize inoculated with FM was 11.7% to 81.4% higher than the NM treatment and the root biomass of the FM treatment was 18.8% to 166.7 higher than the NM treatment. The biomass of soybean was significantly decreased by the FM inoculation under root separation conditions. Under the same root separation way, FM inoculation increased the N uptake of maize plants and N uptake efficiency of roots obviously. Under no-separation condition, the N uptake by soybean shoots was increased by the FM inoculation significantly, but those were decreased under the partial separation and full separation conditions. Under the partial separation way, the N uptake by soybean roots was significantly decreased by the FM inoculation, and those were also decreased under the no-separation and full separation conditions. The N uptake efficiency of soybean roots under FM inoculation was increased under the partial separation condition, but it was decreased obviously under the full separation condition. The N uptake efficiency of soybean roots was the lowest under the NM and no-separation condition in all complex treatments. The available N contents in soils were significantly and negatively correlated with the N uptakes by maize and soybean plants.

ConclusionsThe interactions between AMF inoculation and root separation methods could affect the growth and N uptake of maize and soybean in different degrees, and could also influence the available N contents in soils. Among all compound treatments, the enhanced effect of the combination treatment of the AMF inoculation and partial separation on maize and soybean growth and N utilization was the largest, and it could also decrease the available N contents in soils.