The effect of tree (and cambium) age on genomic prediction for solid wood properties in Norway spruce

Genomic selection (GS) or genomic prediction is considered as a promising approach to accelerate tree breeding and increase genetic gain by shortening breeding cycle. We investigated the predictive ability (PA) of GS based on 484 progeny trees from 62 half-sib families in Norway spruce ( Picea abies (L.) Karst.) for wood density, modulus of elasticity (MOE) and microfibril angle (MFA) measured with SilviScan, as well as for measurements on standing trees by Pilodyn and Hitman instruments. GS predictive abilities (PA) were comparable with those based on pedigree-based selection. The highest PAs were reached with at least 80-90% of the dataset used as training set. Use of different statistical methods had no significant impact on the estimated PAs. We also compared the abilities to predict density, MFA and MOE of 19 year old trees with use of models trained on data from coring at different ages and to different depths into the stem. The comparison indicated that close to the maximal PAs can be reached at age 10-12 by drilling only half way (ringwise) towards the pith, thereby reducing the impact on the tree.