Co-inoculation of cyanobacteria, rhizobia, and azospirilla associated with fertilizer N increases the common bean grain yield

A large number of beneficial microorganisms have been used as inoculants in agriculture to increase grain yield. The objective of the study was to evaluate the response of common bean (Phaseolus vulgaris) to inoculation and co-inoculation with rhizobia, azospirilla and cyanobacteria combined with doses of N-fertilizer. A field experiment was carried out in two growing seasons to assess twelve treatments using single and combined inoculation of rhizobia (Rhizobium tropici + R. freirei), Azospirillum brasilense, Anabaena cylindrica, and Calothrix brevissima, and application of 30 and 60 kg N kg ha-1 as topdressing in a factorial design. A control without N-mineral and inoculation was included. Co-inoculation of common bean (cv. IPR Curi & oacute;) using A. cylindrica, C. brevissima with rhizobia, and A. brasilense, with the application of 30 kg N ha-1 in topdressing increases grain yields. Regardless of the growing season and the N dose, the dual inoculation of rhizobia and C. brevissima stood out in the increase of grain yield concerning the control without inoculation, showing that it is an efficient agronomic practice for common bean under tropical conditions.