Combinações de doses de molibdenio e nitrogênio na adubaĺ̃o da cultura do feijoeiro-comum

Abstract

Two experiments were carried out, one in summer-autumn and the other during spring-summer, in Coimbra, Minas Gerais State, in order to evaluate the effect of different doses of nitrogen and molybdenum on bean plants. The experimental design was randomized blocks, with four repetitions, in a 4 x 2 x 2 factorial arrangement, consisting of four levels of molybdenum (0, 40, 80 and 120 g ha-1), applied by foliar spraying at 25 days after plant emergence, two doses of nitrogen during sowing (0 and 20 kg ha-1) and two doses of nitrogen applied on the surface (0 and 50 kg ha-1). In the presence and in the absence of nitrogen in the planting or on the surface, the increment of the molybdenum dose up to 80 g ha-1 elevates the number of pods per plant and the productivity of grains of bean. In general, increasing doses of molybdenum also elevate the number of grains of bean per pod and the mass of 100 seeds, but these effects are more dependent on the presence of sowing nitrogen or surface. The effects of molybdenum on the level of N in the leaves, molybdenum content in the seed and SPAD readings are less solid; for this reason, they should not be generalized.