Inoculation and co-inoculation of the winter bean and chemical treatment of the seeds

Given the large differences in the results of inoculation and co-inoculation in the bean crop, an experiment in cultivating winter beans was carried out in 2019 under greenhouse conditions with the aim of evaluating the performance of the beans and a possible increase in plant growth and grain production, using seeds inoculated or co-inoculated with Rhizobium tropici and Azospirillum brasilense, with and without fungicide and/or insecticide, in sandy and clayey soils. A total of 112 pots were used, and 14 treatments were applied in a completely randomised experimental design, with four replications. The Scott-Knott test was used to analyse the results, and showed that whether using untreated seeds or carrying out complete chemical treatment with fungicide and insecticide plus co-inoculation with R. tropici and A. brasilense, winter bean production was reduced in clayey soil, while the joint use of fungicide and insecticide, fungicide and R. tropici, or fungicide, insecticide and R. tropici, favoured shoot development. Inoculating with A. brasilense, without R. tropici and with insecticide, or insecticide and fungicide, favoured greater root growth in clayey soil. In sandy soil, grain production was higher using seeds treated solely with insecticide, solely with R. tropici, or with a combination of both. Production was lower in the joint treatment with fungicide, insecticide and the co-inoculation of bacteria, or when using insecticide together with A. brasilense.