Genetic relationship between wood properties and growth traits in Larix kaempferi obtained from a diallel mating test

Knowledge of the genetic relationship between growth traits and wood properties is critical for their simultaneous genetic improvement. We measured the height and diameter at breast height (DBH) and wood quality traits, including stress wave velocity (SWV) as the selection criteria for wood stiffness, wood density, and Pilodyn penetration depth as selection criteria for wood density, at a progeny test site at stand age ca. 30, which comprised of full-sib families by a full diallel mating design with eight plus Larix kaempferi tree clones. We estimated the genetic parameters for each trait and phenotypic, genetic and residual correlation between traits. The contribution of specific combining ability and reciprocal effects were small for all traits. Growth traits showed high positive genetic correlation with average wood density of the outermost five rings (0.912 for height, 0.826 for DBH) and with SWV (0.738 for height, 0.762 for DBH), irrespective of small phenotypic correlations between them. Wood density and SWV also showed high genetic correlation. Pilodyn penetration depth showed high selection efficiency for average wood density of the outermost five rings (79.8 %) whereas SWV showed higher selection efficiency for wood density. Thus, simultaneous genetic improvement of growth traits and wood properties of L. kaempferi appears possible.