Competition between a native isolate of Rhizobium leguminosarum bv trifolii and two commercial inoculant strains for nodulation of clover

Field experiments were conducted to determine the influence of six commercial herbicides and of hand-hoeing on symbiotic parameters and grain yield of lentil (Lens culinaris Med.). The herbicides were sprayed at the pre-emergence stage. Number of nodules, nodule dry weight and nitrogenase activity were found to decrease with the use of Oxyfluorfen, Linuron, Metribuzin and Oxadiazon, whereas the effects of Terbutryn and Methabenzthiazuron were similar to that of hand-hoeing. Any harmful effect of herbicides on symbiotic parameters was less when seeds were inoculated with Rhizobium leguminosarum.