The main objective of this study was to determine variations of density, mechanical and anatomical properties of Eucalyptus wood from the point of view of solid wood utilisation. The relationships between these traits have been studied.
The genetic material used was twenty-six eight-years-old clones of E. grandis x E.urophylla hybrids, planted over four experimental sites installed in Brazil.
The intra-clonal variation of basic density was found to be very low. The variations between clones were statistically significant for all density and mechanical properties and for anatomical characteristics. Except for wall thickness the
between-site variations were statistically significant for all properties.
Clone x interaction studies suggested that the interactions were complex for all characteristics and in most cases it was not possible to predict a wood property produced on one site from its value at another site. Except for resilience, grain
angle and microfibril angle, estimates of broad sense heritability for all properties studied were relatively high.
Wood from inner, intermediate and outer regions of the log was statistically different for all characteristics studied. In the radial direction of the log different patterns of wood variation were observed depending on the characteristic. However, from basal to top bolt the difference was normally relatively small and for some properties not significant.
Relationships between properties revealed that the microfibril angle was negatively correlated with fibre dimensions. The best correlation observed was between microfibril angle and fibre length: however, none of the correlations resulted in a significant coefficient. The prediction of the nominal density using fibre dimensions as predictors showed that 50% of its variation may be significantly determined by wall thickness, 40% by lumen diameter and 19% by fibre diameter. In general the best predictor for the mechanical properties-( compression strength parallel to grain, modulus of rupture - MOR and modulus of elasticity - MOE) was the nominal density. The anatomical traits were more influential for MOR and MOE than for compression strength parallel to the grain. Only MOE was significantly predicted by microfibril angle.
The wide range of variations between clones and between sites means that it should be possible to select clones which will produce solid wood suitable for different end uses.