Response of Soybean [Glycine max (L.) Merrill] to Local Nitrogen Fixing Bacteria Inoculation in Divo Area, Center-south of Côte d’Ivoire

Experiment was conducted on farm in Divo to evaluate the elite native rhizobia strains on soybean nodulation, growth and yield. The experiment was layout in a randomized complete block design with three replications. The treatments include seven native strains, one exotic strain (Bradyrhizobium japonicum IRAT FA3), one synthetic fertilizer NPK 12-22-22 formulation and one negative control. Agronomic parameters (plant height, plant dry biomass, nodules number plant-1, pods number plant-1, pods weight plant-1, 100-seeds weight and seeds yield ha-1) were measured. Results showed that all tested local rhizobia enhanced nodules number, plant growth and soybean yield as compared to negative control. Among these native rhizobia, RSC324 and RSC502 induced more nodules than the introduced strain B. japonicum IRAT FA3. These same bacteria induced more pods per plant than the introduced bacterial strain IRAT FA3 and synthetic fertilizer (12-22-22). They induced the the highest pods number plant-1 (144 and 133 pods plant-1 respectively) and seeds yield (2.5 t.ha-1). In addition to these bacteria, the local strain RSC508 increased soybean pods yield compared with synthetic fertilizer. Therefore, this study suggests that local rhizobia RSC324 and RSC502 proved to be the most effective and competitive strains for soybean cultivar Canarana and could be use for inoculum sources in Divo area.