Crescimento e qualidade de mudas de Acacia mangium Willd. em reposta à adubação fosfatada

Abstract

The production of seedlings is a key step for the success of forest stands and proper nutrition of seedlings plays a fundamental role in this process. Acacia mangium Willd is a forest species that stands out for its multiple uses, besides having a high growth rate, but there is no information on the response of this plant to phosphorus in climatic conditions similar to those in the state of Ceará. This work aimed to evaluate the quality of Acacia mangium seedlings submitted to increasing doses of phosphorus and to determine the best dose of this nutrient for this species. The experiment was carried out in the Nucleus of Education and Research in Urban Agriculture (NEPAU) of the Agricultural Sciences Center of the Federal University of Ceará and conducted in a completely randomized design with six treatments (0, 60, 100, 140, 180 and 220 mg dm-3 of P) and 5 replicates, with 6 plants per experimental unit. The seeds underwent a dormancy breaking process in boiling water and the seedlings were initially produced in a greenhouse, where they stayed for 21 days and then were taken to beds exposed to the sun. At the end of the experiment, 95 days after sowing, the data were collected and the data of the morphological characteristics, height (H), collar diameter (DC), number of leaves (NF), root dry weight (MSR), aerial part dry weight (MSPA), total dry weight (MST), MSR/MSPA ratio, H/DC ratio, H/MSPA ratio and Dickson quality index (IQD). The data were submitted to analysis of variance and means to regression analysis. Acacia mangium seedlings showed a significant response for all characteristics, except for the MSR/MSPA ratio. Based on the dry matter production, the dose of 67 mg dm-3 of P is recommended as the best for the production of Acacia mangium seedlings.