Genetics of wood quality attributes in Western Larch

Abstract

Wood quality traits are important to balance the negative decline of wood quality associated with selection for growth attributes in gymnosperm breeding programs. Obtaining wood quality estimates quickly is crucial for successful incorporation in breeding programs. The aims of this paper are to: (1) Estimate genetic and phenotypic correlations between growth and wood quality attributes, (2) Estimate heritability of the studied traits, and (3) Assess the accuracy of in situ non-destructive tools as a representative of actual wood density. Wood density (X-ray densitometry), tree height, diameter, volume, resistance drilling, acoustic velocity, and dynamic modulus of elasticity were estimated, along with their genetic parameters, for 1,200, 20-year-old trees from 25 open-pollinated families. Individual tree level heritabilities for non-destructive evaluation attributes were moderate ( $$ {\widehat{h}}_i^2=0.37-0.42 $$ ), wood density and growth traits were lower ( $$ {\widehat{h}}_i^2=0.23-0.35 $$ ). Favorable genetic and phenotypic correlations between growth traits, wood density, and non-destructive evaluation traits were observed. A perfect genetic correlation was found between resistance drilling and wood density (rG = 1.00 ± 0.07), while acoustic velocity and dynamic modulus of elasticity showed weaker genetic correlations with wood density (rG = 0.25 ± 0.24; 0.46 ± 0.21, respectively). This study confirmed that resistance drilling is a reliable predictor of wood density in western larch, while the weak genetic correlations displayed by acoustic velocity and dynamic modulus of elasticity suggest limited dependability for their use as fast in situ wood density assessment methods in this species.