Estudo do teor de fósforo em madeiras de clones de eucalyptus em diferentes sistemas de condução

Abstract

Eucalyptus wood stands out mainly for the large number of species and adaptations to the most diverse planting sites. The phosphorus content in wood can negatively influence the quality of metallic alloys by making them harder and, therefore, more fragile and is also considered a strong pollutant when it is eliminated by the dense and black smoke in the ovens of large industries. The objective of this work was to determine the phosphorus content found in the wood of four genetic materials, namely: E. grandis x E. urophylla, Eucalyptusurophylla, E. urophylla x E. grandis (implantation) and E. urophylla x E. grandis (reform), at different ages (5.0; 5.1 and 6.1). 3 trees were obtained per genetic material and 5 disks from each tree, totaling 15 samples and 12 Eucalyptus trees. The P2O5 content was evaluated by genetic material and by its longitudinal variation along the bole, considering the commercial height of each tree. The analyzes were estimated by the determination of phosphorus by the vanadate yellow method. The results were submitted to analysis of variance (ANOVA) and Tukey's test. It was possible to verify that the presence of phosphorus is highly found in the youngest part of the trees, located in the fraction 100% of its commercial height and the lowest phosphorus content was pointed at position 0% (base) of commercial height which is characterized by the most aged fraction of the tree. It was also possible to evaluate that the species E. urophylla x E. grandis (reform) has a higher value in phosphorus content, probably because its planting comes from conduction.