Effect of some pesticides on the efficiency of the inoculated Rhizobium associated with broad bean plants.

The effect of some pesticides on the efficiency of the inoculated rhizobium in broad bean plants (Vicia faba) was studied in greenhouse experiments. Different pesticides were used in this work, including insecticides, herbicides, nematocides, and a molecide in different concentrations. The study revealed the following conclusions. Application of insecticides in different concentrations generally affected the formation of efficient nodules on the root system of broad bean plants. The inhibitory effect was also reflected to some extent on the dry weight of the plants and total nitrogen fixed by rhizobia in association with the mentioned plants. Birlane (insecticide) was found to be the most inhibitory insecticide on the inoculated rhizobium. Some of the insecticides, such as Temik and Dursban, at lower concentration were found to be a stimulant to symbiotic N-fixation, giving higher amounts of nitrogen fixed in the macrosymbiont.