re-inoculation moments of Rhizobium tropici in common beans in no-tillage implementation

In Brazil, the common beans (Phaseolus vulgaris L.), is a culture of economic and social relevance that, can be viable to produce at different technological levels, is part of the Brazilian basic daily nutrition, and the plants nutritional status is one of the factors more limiting to yield. For plant nutrition, in common beans it is possible to use biological nitrogen fixation (FBN), a cheaper and more sustainable alternative, allowing a reduction in the use of mineral fertilizer. However, due to the lower bacterial / plant specificity, FBN does not meet all the nutritional demand of the crop, being necessary the complementation with other N sources. The work aimed to evaluate, in winter beans, the possibility of supplying N for a longer period, through the formation of new nodules, through the reinoculation of Rhizobium tropici in two development stages (V4 or R5) in an area of implementation of no-tillage system. The experiment was carried out, in the autumn-winter period of 2018 and 2019, in Selvíria (MS), in a soil classified as a typical clayey dystrophic RED LATOSOL. The treatments were arranged in a randomized block design, in split plot (5x3) with four replications, the plots were constituted by the forms of management involving nitrogen fertilization, inoculation and co-inoculation (Inoculation with Rhizobium tropici in the seeds, Inoculation with Azospirillum brasilense in the seeds, Co-inoculation with R. tropici + A. brasilense in the seeds, absence of inoculation in the seeds + topdressing fertilization with 90 kg ha-1 of N "urea", absence of topdressing fertilization + absence of inoculation in the seeds) and the subplots by the three moments of reinoculation with R. tropici (Without reinoculation, Reinoculation in V4, Reinoculation in R5). Topdressing mineral fertilization of 90 kg ha-1 of N and inoculation with A. brasilense in the seeds increased dry mass of aerial part and dry mass of root. The treatments with mineral fertilization in topdressing of 90 kg ha-1 of N and co-inoculation increased in mass of 100 grains in 2018. The absence of reinoculation (control), showed a higher N content in the grains. Inoculation and co-inoculation provided significant yields similar to topdressing fertilization of 90 kg ha-1. The topdressing fertilization of 90 kg ha-1 of N reduced the number and dry mass of nodules while the inoculation with R. tropici or A. brasilense and co-inoculation ensured a greater number of nodules and dry mass of nodules in R5 and R7. (AU)