Calcium Silicate and Limestone Decreasing the Toxicity of Heavy Metals in Legumes Inoculated with Selected Strains of Cupriavidus Necator.

The concern with environmental contamination by heavy metals in mining areas is growing every day. In this context, phytoremediation of these areas has been a topic of current relevance for research. The objective of this study was to evaluate the effectiveness of strains of Cupriavidus necator in symbiosis with various legumes in soil contaminated with heavy metals after the application of inorganic materials with ameliorating characteristics. The application of lime and calcium silicate, provided significant increases in pH and reduction of up to 99 and 94% in the availability of Zn and Cd in soil solution, respectively, providing better nodulation of the species Mimosa caesalpiniaefolia, Mimosa pudica and Leucaena leucocephala in different contamination levels. Nodulation in the root system by strain UFLA01-659 in L. leucocephala and Mimosa pudica, and by the strain UFLA02-71 in Mimosa caesalpiniaefolia effectively increased the levels of nitrogen in the shoots up to 36, 40 and 39 g kg-1, respectively. The ameliorating effect of calcium silicate provided greater dry matter production of shoots, number of nodules and higher rates of fixed nitrogen. These findings show that a combination between rhizobia-legume-silicate may represent a key factor in the revegetation of areas contaminated by heavy metals.