Co-inoculation of Rhizobium and Arbuscular Mycorrhiza Increases Mimosa caesalpiniaefolia Growth in Soil Degraded by Manganese Mining

摘要

Co-inoculation of microorganisms has been frequently used to promote greater plant growth in degraded soils. However, the use of this biotechno-logical strategy for the revegetation of soils contaminated by heavy metals in mining areas is still poorly understood. In our study, we analyzed the influence of the co-inoculation of rhizobia and arbuscular mycorrhizal fungi (AMF) on the initial growth of Mimosa caesalpiniaefolia and its tolerance to excessive manganese (Mn) in a soil degraded by mining. In an experiment in a greenhouse, the species M. caesalpiniaefolia was cultivated to evaluate the establishment potential considering the contribution of the co-inoculation of rhizobia and AMF together or in isolation. In addition, we use control plants, under ideal levels of nutrients. Co-inoculated plants showed greater tolerance to excessive Mn and had their initial growth stimulated. The highest mycorrhizal colonization rate (64%) was observed in the treatment with AMF alone, while the highest abundance of AMF spores in the soil (419.7) was found when the plants were co-inoculated. In addition to favoring the balance of nutrients in the plant and the use of nitrogen and phosphorus from the soil, co-inoculation also provided higher levels of Mn in the roots and lower levels of Mn in the shoot. Morphological and physiological changes, which helped the plants to withstand the excess of Mn in the soil, were also evidenced when they were co-inoculated. Taken together, our results suggest that co-inoculation in M. caesalpiniaefolia regulates toxicity, maximizes early growth, and increases tolerance to excessive Mn in soils degraded by mining.