EN
The laboratory experiments tested the influence of selected pesticides on the symbiotic efficiency and nitrogenase activity of Rhizobium teguminosarum bv. trifolii KGL, Sinorhizobium melilotii Bp and Bradyrhizobium sp. Ornithopus B bacteria entering into symbiosis with clover, lucerne and serradella, respectively. The results obtained indicate that the pesticides used in the experiments (Funaben T seed dressing and Pivot 100SL herbicide) caused reduced nitrogenase activity in active strains tested. In addition, a toxic effect of the applied pesticides on the nodulation and root growth of the tested plants was observed.