Impacto da adubação nitrogenada na infestação de pragas e na produção do milho

Abstract

The corn, Zea mays (Linnaeus, 1753) (Poaceae), has been one of the most produced cerals in the world. However, among the physiological and nutritional aspects, the nitrogen (N) is one of the elements that most often limits grain yield. However, the excess of this nutrient can cause the reduction of the production, as well as to favor the incidence of pests. Thus, the objective of this work was to evaluate the development, production and incidence of pests in corn plants as a function of the application of increasing doses of nitrogen. The treatments consisted of one control (without nitrogen fertilization) and the application of nitrogen fertilization in four levels of urea (10; 20; 30 and 40g/pit). The observed variables were: Chlorophyll A content, Chlorophyll B content, Total Chlorophyll content, Diameter of Colmo, Height of Flag Leaf, Spike Height, Plant Weight; Weight of Spike With Straw; Number of Spikes and occurrence of pests. The experimental design was in randomized blocks, with 5 blocks. The trend of linear growth was verified only in the variables Chlorophyll B (F4, 20 = 3.9446; p = 0.0205), Total Chlorophyll content (F4, 20 = 3.6995; p = 0.02570), Plant Weight (F4, 20 = 3.0936; p = 0.045884), Occurrence of Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) (F4, 20 =14.08; p = 0.0013) and Helicoverpa sp. (Lepidoptera: Noctuidae) (F4, 20 = 3.71; p = 0.0254). The values of Weight of Spike With Straw were a parable (F4, 20 = 3.7975; p = 0.023480), with an estimated maximum dose at the dose of 2.63 n. The increasing doses of N did not affect the other variables. Therefore, the N affects the maize production and contributes to pest infestation in the growing area.