GENETIC-VARIATION OF THE PILODYN-GIRTH RELATIONSHIP IN NORWAY SPRUCE (PICEA-ABIES L [KARST])

Genetic variability in the relationship between pilodyn pin penetratio n (an indirect measure or wood density) and stem girth of individual t rees was assessed at three levels (provenance, family [half-sib] and c lone) in 15-year-old Norway spruce. The relationship between pilodyn a nd girth was found to be linear at all three levels, but estimated par ameters of the linear regression differed among genetic entities at th e three genetic levels: provenance, family and clone. Hence, accuracy of models relating wood density to stem growth is increased when using parameters specific to the genetic entity of interest. Nevertheless, model parameters for specific genetic entities were moderately correla ted with mean values for pilodyn and girth. Therefore, and at least at clone level, selecting for high girth is a way to select for low intr a-clone variability for wood density.