Morfologia das fibras do lenho de clones de Eucalyptus urophylla X Eucalyptus grandis em diferentes topografias e altitudes

Abstract

The quality of the wood depends on its anatomical characteristics, among other factors. Understanding the effects of environmental changes in the anatomy of wood contributes to the appropriate choice of its final use. This work aims to study the influences of topography and altitude on the size and morphology of the fibers in the stem of Eucalyptus urophylla x Eucalyptus grandis. The experimental design was completely randomized, with five replications and three factors: Clone (2 levels), Growth conditions (4 levels) and Radial position (3 levels). The growth conditions were: low/sloping, low/flat, high/sloping and high/flat. Wood samples were obtained in three equidistant radial positions and taken at the height of 1.30 meters above the ground (DBH). The variables studied in the fibers were: length, width, cell wall thickness, rigidity coefficient, flexibility coefficient and Runkel ratio. The effect of the growth condition depends on clone and/or radial position. The sloping topography of the low region and the flat topography of the high region resulted in smaller fiber length and higher fiber cell wall thickness. The wood produced in the sloping topography had lower fiber width, regardless of altitude. In general, smaller values of rigidity coefficient were observed in flat topography. The flexibility coefficients of clone 2, for intermediate and external radial positions, were affected by growth conditions. The flat topography of the high region and the sloping topography of the low region showed the highest Runkel ratios. These results suggest an adaptive response of the xylem of Eucalyptus to the growth conditions limited by water, wind, gravity and lightness.