A field investigation was carried out to determine the influence of herbicides on peanuts (Arachis hypogaea cv. Tatu) Bradyrhizobium sp. symbiosis. The herbicides studied were trifluralin, metolachlor and linuron, applied, respectively, in pre-planted-incorporated, pre-emergence and post-emergence. The results evaluated 30, 50 and 80 days after germination, showed no difference between inoculated and non inoculated treatment. Linuron was the only herbicide that caused damage to nodulation, affecting the number and dry weight nodules and also inhibiting the nitrogen fixation (determined by nitrogenase activity). Metolachlor and trifluralin showed no damage effects on nodulation and in the nitrogenase activity.
peanuts; nitrogenase activity; nodulation; herbicides