Características das fibras de madeira de Eucalyptus brassiana plantado no Sertão de Pernambuco

Abstract

Eucalyptus wood is one of the main raw materials for several forest products. The anatomy of the wood is an important point in the determination of a product, as it is directly related to the quality of the source wood. In this perspective, the aim of the study was to evaluate the quantitative parameters of anatomical structure in relation to fiber morphology of eucalyptus clonal wood at different spacings. The material used was an eight-year-old clone of Eucalyptus brassiana from an experimental plantation carried out at the Araripe Experimental Station, belonging to the IPA, located in Araripina-PE. To evaluate the anatomical properties of the wood, six trees were collected from each treatment from which discs (samples) about 5 cm thick were removed in the different positions in the longitudinal direction, at 1.30 m height of the soil (DAP), 0%, 25%, 50%, 75% and 100% referring to commercial height. Each disc was sectioned into four wedges, of which a wedge was used to determine the parameters referring to the fiber dimensions. The wedges were reduced to chips, homogenized and from these obtained more compact fillets. The dissociation of wood fragments was carried out according to the methodology, which consists in preparing the macerating solution from the mixture of nitric acid with acetic acid in the proportion 1:3 in a water bath (100 ºC) for three hours. Then, the macerated fiber solutions together with the safranin dye and with glycerin ratio 1:1, with glycerin dissolving in water 1:1 ratio were transferred to a temporary lamina and forty fibers were individually measured per treatment, determining the length, width, lumen diameter and wall thickness. For the measurements of the length, fiber width and lumen diameter, an optical microscope (40X and 4X objective lenses) was used, with an imaging system through a coupled camera. Fibers were visualized on the monitor and the capture of the image and fiber measurement occurred with the help of Honestech TVR 2.5 and Image Pro Plus software, respectively. The thickness of the cell wall of the fibers was determined indirectly from the difference between the wall width and the lumen diameter divided by two. Based on the measured characteristics, the Runkel Index, Enfeltrination Index, Flexibility coefficient and wall fraction were calculated. Based on the properties evaluated on the quality of the wood for the energy sector, the T3 treatment presented the most satisfactory result. For the pulp and paper industry, the treatment T1 presented the most suitable result for its use.