Nodulation in peanut (Arachis hypogaea L.) roots in the presence of nativeand inoculated rhizobia strains

There is considerable interest in improving nitrogen fixation in legumes to increase soil fertility, particularly in the developing countries. The eff ect of inoculation of peanut (Arachis hypogaea L.) seed with Bradyrhizobium sp. USDA 3187 was examined under field conditions. In order to determine n odule occupancy, bacterial cells from surface-sterilized nodules of inocula ted plants were isolated and characterized by their intrinsic antibiotic re sistance and by agglutination test. Results obtained revealed that peanut r oots were nodulated by native strain rather than the introduced one, indica ting that strain USDA 3187 was not as competitive as naturalized peanut rhi zobia. Data also showed that there were no significant differences in nodul e dry weight, plant dry biomass, nitrogenase activity and seed yield betwee n uninoculated and inoculated treatments. (C) 1999 Elsevier Science B.V. Al l rights reserved.