Microorganisms domesticated with different green manures regulate maize growth via plant-soil feedback

Abstract:

[Background] In agricultural ecosystems, the mechanisms of interactions between soil microorganisms and plants remain unclear. [Objective] To strengthen the understanding of plant-microorganism interactions and screen out the key microorganisms or microbial groups that cause different feedback effects. [Methods] The soil in the 0-20 cm layer of the fields domesticated with leguminous green manure Vicia sativa (V) or cruciferous green manure Brassica napus (N) and the remnant prairie (R) were collected as inoculants in the greenhouse for plant-soil feedback (PSF) test. Maize was planted in the substrate containing 10% inoculant and 90% sterilized soil with the same physical and chemical properties. The sterilized soil inoculum was set as the control (CK). For each inoculation treatment, two phosphorus levels, 50 mg/kg (high phosphorus, HP) and 5 mg/kg (low phosphorus, LP), were designed. After maize was harvested, we measured the yield and phosphorus content in the shoots and sequenced the soil samples to analyze feedback effects of microorganisms on crop growth under different nutrient supply conditions. [Results] High phosphorus and soil feedback both promoted the growth of maize. In the case of LP, the aboveground biomass of maize in the V, N, and R treatments all increased compared with that in the CK. Moreover, the increase in the N treatment (38%) was significantly higher than that in the V treatment (28%) and R treatment (16%). The V, N, and R treatments showed no significant difference in maize aboveground biomass compared with CK under the HP condition. The phosphorus content in the shoots of maize treated with the three soil inoculants was significantly higher than that of CK in the case of LP, while it showed no significant difference between treatments in the case of HP. There are differences in the composition of main species at each treatment phylum level, N treatment enriched more Proteobacteria and Bacteroidetes. KEGG pathway enrichment analysis showed that the abundance of functional genes phoB, phoA, phoR, phnA and glpR involved in phosphorus activation significantly increased in N treatment. [Conclusion] The soil microorganisms domesticated with cruciferous green manure could improve the phosphorus absorption ability and promote the growth of maize cruciferous green manure enriched more microorganisms and functional genes associated with phosphorus dissolution.