Ecophysiological Studies of Legumes in Botswana: Types of Bacterial Strains from Root Nodules of Cowpea (Vigna unguiculata L. Walp.) and an Assessment of the Symbiotic Status of Grain Legumes Using 15N Natural Abundance

Six genera (Rhizobium, Bradyrhizobium, Sinorhizobium, Mesorhizobium, Azorhizobium and Allorhizobium) within the Rhizobiaceae have the ability to infect roots and form N2-fixing nodules on members of the Leguminosae and in the non-legume Parasponia (Ulmaceae). The major aim of this study was to determine whether the different agroecological zones of Botswana have an effect on the natural distribution of rhizobia and the local Leguminosae.