Co-inoculation with rhizobacteria in association with humic acid and nitrogen on common bean development

Studies on co-inoculation of strains with high symbiotic potential, as well as the use of humic substances are of great importance for obtaining increases in nodulation, biological nitrogen fixation and yield of the bean crop. Thus, this study aimed to evaluate the effects of the co-inoculation of Rhizobium tropici and Azospirillum brasilense in association with humic acids and nitrogen (N) on the behavior of different bean genotypes, cultivated in a protected environment. The experiment was carried out at the Federal Institute of Education, Science and Technology of Rondônia, Campus of Colorado do Oeste-RO, Brazil, from February to April 2015. The experimental design was completely randomized, with four replicates. Common bean seeds of the cultivars ‘Pérola’ and ‘BRS Esplendor’ were previously co-inoculated with Azospirillum brasilense and Rizhobium tropici. Shoot dry matter production in the cultivar ‘Pérola’ increased by 76.12% when co-inoculated with rhizobacteria. N use efficiency in the bean cultivar ‘Pérola’ is higher when co-inoculated with Azospirillum brasilense and Rizhobium tropici, confirming that co-inoculation alone is sufficient to provide the N necessary for plant development.