Influência de diferentes fontes de nitrogênio no processo de infecção de plantas de feijoeiro por Fusarium oxysporum f. sp. phaseoli

Abstract

With the aims to study the efflux of H+ or OH- due nitrogen sources on the process of infection of Fusarium oxysporum f. sp. phaseoli in the rhizosphere of two beans cultivars Diamante Negro (susceptible) and Ouro Negro (more resistant), a series of experiments were done in greenhouse and growth chamber. Were applied to three different sources of nitrogen (N-N2 N-NO3- and N-NH4+) in three nitrogen concentrations (0, 30 and 120 kg ha-1), in plants grown in clay and sand soil. In addition, an experiment was conducted with different concentrations of inoculum of Fusarium (0, 10 ³ and 106 conidia mL-1) in greenhouse in order to know the concentration that would affect the infection and when applied the fungi. Overall, the results suggested that nitrate decreased the infection process of Fusarium and ammonium increase. The association between nitrate with the cultivar more tolerant Ouro Negro, decreased the perceptual infection of fungi. The source of nitrogen influence of pH of rhizosphere occurred interaction with the type of soil. In all the experiments, found lower numbers of nodules. The concentration of inoculum or the times of inoculation not produce effect in the perceptual of infection.