Improvement of Salt Tolerance and Growth in Common Bean (Phaseolus vulgaris L.) by Co-Inoculation with Native Rhizobial Strains

Beneficial association of rhizobial strains with leguminous plants may result in the enhancement of nodulation in the root and overall plant performance. In this study, the efficacy of inoculation was tested with pre-isolated Rhizobium phaseoli R9 and Mesorhizobium ciceri R6 as a single and in combined treatments on common bean (Phaseolus vulgaris L.) in a field experiment at soil salinity level of 5.6 dS m(-1) over two growing seasons. The bacterial inoculations increased the plant height, root and shoot biomass, grain yield, number of nodules per plant, nodule dry weight, and root length of common bean, with a significant difference. Compared to single inoculation, co-inoculation of the rhizobial strains was more effective in all plant parameters and increased the seed yield by 35.1 and 37.9%, respectively, over the two consecutive seasons compared to the uninoculated control. Chemical analysis showed a significantly (P<0.05) higher protein and oil content in the seeds of the co-inoculated plants than those of the control. The result of the experiment showed a strong correlation (r(2)=0.87) between the increased nodule dry weight and seed yield of common bean. It might be concluded that co-inoculation with rhizobial strains could be the most effective biofertilization strategy for achieving greater nodulation and yield of common bean under saline conditions of Uzbekistan.