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The number of viable cells produced by Rhizobium on solid media gives an indication of the strains survivability when used as an inoculant. This study was conducted to determine the viability of different strains of Bradyrhizobium. and their ability to nodulate pigeonpea (Calanus calan) and cowpea (Vlgna unguiculata) genotypes at two temperature regimes: 20/10°C and 30/20°C (day/night). Bradyrhizobium strains USDA 3278, 3362 and 3458 were cultured in yeast mannitol broth for 7 days from which a 10% dilution was made. From this dilution, 0.1 ml of a further 10 dilution was allowed to grow on yeast mannitol agar plates at the test temperatures. Strains cultured at 30/20°C had a higher number of viable cells than those cultured at 20/10°C for 4 days. While there was no difference between Rhizobium strains 3278 and 3362, strain 3458 had the highest number of cells per ml of 7-day old broth culture. Pigeonpea and cowpea plants inoculated at 20/10°C with the three Rhizobium strains and those inoculated with 3362 at 30/20°C had no nodules at 30 days after planting. At 30/20°C, plgeonpea and cowpea plants Inoculated with strain 3458 produced a higher number of nodules than those inoculated with strain 3278. These results indicate that temperature Influences the Rhizobium strains and their ability to nodulate plgeonpea and cowpea.