Use of beneficial microorganisms in bean cultivation: strategies employed to increase productivity.

The common bean is of great importance for human nutrition worldwide as its grain is a cheap source of protein, but it has a high-cost production system due to the use of synthetic inputs such as nitrogen fertilizers and pest and disease control products. An alternative to promote the sustainability of the production system and increase crop productivity is the use of co-inoculation of plant growth-promoting rhizobacteria (PGPR) to reduce and/or replace the use of nitrogen fertilizers and pest and disease control products. Since 2010, Brazil has stood out on the international stage with research focused on the application of rhizobia combined with PGPR in bean crops. Currently, the use of microorganisms that effectively promote plant growth through different mechanisms of action is already a consolidated reality in Brazil, with experimental results proven by years of research. Despite these advances, there are still challenges to overcome to maximize the potential of co-inoculation in bean crops. These include the need to develop more efficient formulations containing elite microbial strains and optimized microbial consortia, as well as the search for inoculation methods that optimize root colonization by the bacteria and maximize their beneficial effects on the plant. In this review, we discuss the history of common-bean production and the types and doses of inoculants marketed, as well as the challenges for the efficiency of co-inoculation and for the development of inoculants of rhizobial consortia with PGPRs for the common-bean cultivation.