Genetic variation in veneer quality and its correlation to growth in white spruce

This study investigated the genetic variation in veneer quality of white spruce (Picea glauca (Moench) Voss) and its correlation with tree growth and wood density. A total of 270 sample trees from 35 families were harvested from 36-year-old provenance-progeny trials at two sites through a thinning operation. A 36-cm long bolt was collected from each sample tree at an 8-foot (or 2.45 m) height for this veneer quality study. The results indicate that conversion of fast-grown white spruce into veneer and plywood may present some problems. Low wood density, numerous knots, and possibly a high proportion of juvenile wood appear to be major factors contributing to low veneer stress grading, resulting in a production of low-quality veneer. This study also showed that the environmental factors at the two sites played an important role in determining veneer quality and tree radial growth. The narrow-sense heritability for veneer density, veneer modulus of elasticity, and veneer roughness were 0.62, 0.13, and 0.14, respectively. The results revealed considerable phenotypic variation and relatively high additive genetic variation in the veneer modulus of elasticity. The phenotypic and genetic correlations between ring width and veneer density or veneer modulus of elasticity were negative. A positive phenotypic and genetic correlation was found between veneer density and veneer modulus of elasticity. This suggests that selection for tree volume growth in white spruce would lead to a decrease in wood density and veneer stiffness.