Genetic variation and relationships to growth traits for microfibril angle, wood density and modulus of elasticity in a Picea abies clonal trial in southern Sweden

Genetic variation in wood density, microfibril angle (MFA), wood stiffness (MOE), height, diameter and volume was investigated in a 26-year-old Norway spruce [(Picea abies (L.) Karst.] clonal trial in southern Sweden. Wood quality measurements were performed on 10 mm increment cores using SilviScan. For MFA, mean values of annual rings showed the highest value (30 degrees) at ring 2 counting from the pith, followed by a steep decrease and a gradual stabilization around ring 12 at approximately 14 degrees. MOE showed a monotonic increase from 5 GPa to 14 GPa when moving from pith to bark. High broad-sense heritability values were found for wood density (0.48), MFA (0.41) and MOE (0.50). All growth traits displayed heritability values of similar magnitudes as reported in earlier studies. The generally high age-age correlations between different sections of the wood cores suggested that early selection for wood quality traits would be successful. Owing to unfavorable genetic correlations between volume and MOE, the correlated response indicated that selection for volume only at age 10 would result in a 0.27% decrease in weighted MOE at age 26 for every 1% increase in volume.