Effects of some commercial herbicides on <i>rhizobia</i> and their symbiosis with peanuts

Abstract

Summary Four herbicides commonly used in Israel for controlling weeds in peanuts were evaluated under field and screenhouse conditions. Terbutryn (Terbutrex 50, w.p.), ethalfluralin (Sonalan 333, e.c.), dinitramine (Cobex 240, e.c.) and alachlor (Alapaz 480, e.c.), used at recommended levels, had no adverse effect on nodulation rate, nitrogenase activity, total nitrogen of peanut tops or pod yield, compared with control (inoculated but herbicide non‐treated) plants. Studies were conducted to determine the relative toxicity in vitro of the herbicides on each of four Rhizobium strains used for commercial peat inoculant production. The results showed that at up to 94 μg g −1 the herbicides has no inhibitory effect on the growth of rhizobia. The sensitivity of Rhizobium strains to different rates of the chemicals decreased in the order: dinitramine&gt;alachlor&gt;ethalfluralin&gt;terbutryn. It was found that various strains differ in their sensitivity to the herbicides tested.