Implications of arsenic exposure for the soybean-Bradyrhizobium symbiosis

Little is known about the effects of As exposure on the legume-rhizobium symbiosis, and thus, on the potential for N-fixation. As contaminated ecosystems. A solution culture experiment was conducted to test the effects of As on the,Glycine max (soybean) - Bradyrhizobium japonicum symbiosis. Increasing As in the solution increased the time to production of the first nodule (P<0.01) and decreased the number of nodules per plant (P=O. 007), probably due to a decrease m root hairs reducing infection sites for B. japonicum However, biomass was greater in inoculated, compared to uninoculated, plants even at high. As concentrations, where nodulation was minimal (P<0. 05) and tissue N (P=O. 082) and As (P>O. 100) concentrations were not significantly affected by inoculation status. It is suggested that future research investigate the potential of free-living B. japonicum to mitigate the negative effects of excess. As on the biomass production of plants.