Crescimento e qualidade de mudas de Acacia mangium Willd. em resposta à adubação nitrogenada

Abstract

Forestry species are essential for the economy, as well as for the recovery of degraded areas, source of animal feed, among other functions. However, studies on the silvicultural aspects are scarce, especially on the nutritional requirements during the seedlings production phase in Brazilian soils, especially for those that aim to identify and improve cultivation techniques for seedling production. Therefore, the objective of this work was to evaluate the effects of increasing nitrogen doses on Acacia mangium Willd. and to determine the best dose of this nutrient for seedling production. The experiment occurred at the Nucleus of Education and Research in Urban Agriculture (NEPAU), belonging to the Plant Science Department of the Agricultural Sciences Center of the Federal University of Ceara (UFC), being conducted under direct sunlight in a randomized block design, formed by six nitrogen doses (0, 40, 80, 120, 160, 200 mg dm-3), with five replicates, each experimental unit was formed by six plants. The seedlings were evaluated, obtaining their height (H), collar diameter (DC), number of leaves (NF), aerial part dry weight (MSPA) and root (MSR), calculating the relationships H/DC, MSPA/MSR, H/MSPA and Dickson quality index (IQD). The data were submitted to analysis of variance, means tests and regression analysis. All the evaluated characteristics were significantly affected by the doses of N, with the exception of H/D ratio. Considering the results obtained, the majority of the evaluated characteristics presented better results with the dose of 158 mg dm-3 of N, thus recommending this dose for the production of acacia seedlings.