Effect of Manganese on Growth and Nodulation of Mimosa caesalpiniaefolia (Benth.)

Soil pollution by heavy metals is mainly caused by poor management of tailings generated by mining during exploration and processing of metals. Given the concern about the soil environment, this study aimed to evaluate the tolerance and effectiveness of isolates of rhizobium strains native to soils of Mn2+-mining areas in association with Mimosa caesalpiniaefolia (Benth.) cultivated under increasing concentrations of Mn2+. Isolates of rhizobium strains, obtained from Mn-mining area, were authenticated and morphologically characterized. Effect of Mn2+ on the growth and nodulation of M. caesalpiniaefolia was subsequently evaluated. We obtained 14 isolates which were similar, differing only in the form of colonies. Mn2+ did not inhibit the symbiotic process between isolates and plant species. The isolates from mining area showed higher efficiency than native strains. All isolates are Mn2+-tolerant, and those from mining area can increase the tolerance of M. caesalpiniaefolia to excess Mn2+ in the soil.