Inoculation with Native Bradyrhizobia Strains Improved Growth of Cowpea Plants Cultivated on a Saline Soil

Selection of osmotolerant rhizobia gained importance because of increasing soil salinity in many regions. A field experiment in the Cauto Valley was conducted to determine the effect of seed inoculation with two native strains of Bradyrhizobium sp. on biological nitrogen (N)-fixation of cowpea (Vigna unguiculata) on a salt affected soil. Inoculation with both strains resulted in higher numbers of nodules, specific N-fixation, and yields of cowpeas than the control without inoculation. The strain VIBA-1 (Bradyrhizobium liaoningense) was partly superior to VIBA-2 (Bradyrhizobium yuanmingense). This study indicates that the strains inoculated are competitive against other natural strains and able to nodulate cowpea.