Effect of Certain Pesticides on Nodulation and Nitrogen Fixation by Rhizobium sp. in Groundnut

Abstract

Treatment of Rhizobium inoculated groundnut sced with wet ceresin (1000 opm) did not appreciably after the dry matter weight, total nitrogen content, nodulation and leghemoglobin content of nodules of the plants Although sail application of brassicol at 11 ppm (field rate) d'd not appreciably alter the efficiency of the groundnut Rhizobium symbiosis, higher concentrations of 50 and 100 ppm proved to be harmful. Foliar appli- cation of Dithane Z-78 and copper oxychlorids at the recommended levels of 0.2 and 03 per cent, respectively, did not affect the symbiotic relationship in plants. Seil application of disysson and DDT at field rates increased significantly the dry weight, total nitrogen content. nodulation and leghemoglobin content. However, at 200 ppm. these insecticides exerted a harmful effect on the symbiosis Foliar applica- tion of endrin (at 0.02 and 0.04 %) and parathion (0.025%) crused a significant increase in the dry weight. total nitrogen, nodulation and leghemoglobin content of nodules of plants. Pro-sowing soil application of Lasso and TOK E.25 at field rates caused n significant reduction in dry waight, total nitrogen, nodulation and leghemoglobin content of nodules. At 200 ppm these two herbicides have completely inhibited the nodule formation.