Chemical seed treatment, inoculation, and co-inoculation of winter bean combined with nitrogen doses

Faced with the contrasting results of inoculation and co-inoculation in the bean crop, an experiment was carried out in pots, with the objective of evaluating the performance of the bean plant in treatments inoculated or co-inoculated with Rhizobium tropici and Azospirillum brasilense, via seeds, with or without chemical treatment with fungicide and insecticide, combined with 4 top-dressing nitrogen doses (0, 30, 60, and 120 kg ha-1), in a 'Latossolo Vermelho-Amarelo distrófico arenoso' soil collected from the surface layer from 0 to 0.20 m depth. The results of the Scott Knott test and regression showed that co-inoculation via seeds did not alter vegetative growth, components, and grain yield. However, without chemical treatment, co-inoculation increased plant root volume. Root dry matter production was higher when only A. brasilense was used and when combined with fungicide, or with insecticide and R. tropici. While the combination of fungicide, insecticide and A. brasilense increased the dry matter production of shoots and grains per plant. Even with inoculation or co-inoculation, there was a linear response of the common bean to topdressing fertilization up to 120 kg ha-1 of N in vegetative and root growth, pod production and grain per pod.