Nitrogen fertilization and application of brassinosteroid in cowpea in the Amazon

Abstract

Cowpea [Vigna unguiculata (L.) Walp.] is a legume of socioeconomic importance in the northern region of the country, however, its production requires high fertilizer costs, especially nitrogen fertilizers. The use of techniques with the potential to increase crop productivity, such as the application of plant regulators (brassinosteroids-BRs) and the use of nitrogen (N) are necessary. Thus, the objective of this work was to evaluate the vegetative and reproductive phases of cowpea (BR3-Tracuateua) in relation to the application of BRs, mineral nitrogen fertilization and inoculation with the bacterium Azospirillum brasilense. The research was carried out in the experimental area of ​​the Federal Rural University of the Amazon, Campus Capitão Poço. An experimental design was used in randomized blocks, with three replications, in a 3 x 4 factorial scheme: three N supply conditions (Without N, with mineral N and with biological N) and foliar application of four doses of BRs (0, 15, 30 and 45nM). The growth and production variables were not significantly influenced by the application of BRs and the forms of N supply. However, M100 and productivity were increased by the supply of N, both mineral and biological. Therefore, inoculation with Azospirillum brasilense in cowpea cultivation becomes a viable practice, with the objective of supplying N to plants, replacing mineral nitrogen fertilization.