[Effect of heavy metals and reclaimers on formation and functioning of legume-Rhizobium symbiosis].

The influence of a mixture of salts of heavy metals Cd2+, Cu2+, Pb2+, Zn2+ on the efficiency of legume-rhizobial symbiosis and a part of reclaimers in the decrease of toxic effect of pollutants have been studied under conditions of the vegetative and field experiment on small plots. Concentrations of salts of heavy metals were tested in the interval of 1 to 20 MPC (maximum permissible concentrations). Negative effect of the tested substances on the growth, photo-assimilation properties of soybean plants, nodulation intensity, nitrogenase activity and yield (correlation coefficients made, respectively, -0.58; -0.86; -0.88; -0.84 and -0.86 under reliability 95-99.9%) has been established. The increase of concentration of heavy metals was accompanied by the decrease of the indices of symbiosis efficiency. The complete suppression of symbiotic system of soy-beans was registered under the maximum of test doses which was equal to 20 MPC. The reclaimer white zeolite has displayed protective properties with respect to legume-rhizobial symbiosis against a background of soil contamination with high doses of heavy metals. The use of combined reclaimer gypsum-streptomycete may be also considered promising for decreasing negative effect of heavy metals on legume-rhizobial symbiosis.