Genetic analysis of wood quality traits in Norway spruce open-pollinated progenies and their parent plus-trees at clonal archives, and the evaluation of phenotypic selection of plus-trees
Canadian Journal of Forest Research 2019, e-First Article
Zhou L, Chen Z, Lundqvist SO, Olsson L, Grahn T, Karlsson B, Wu H, García-Gil MR

Abstract
A two-generation pedigree involving 519 Norway spruce plus-trees (at clonal archives) and their open-pollinated (OP) progenies were jointly studied with the aim to evaluate the potential of plus-tree selection based on phenotype data scored on plus-trees. Two wood properties (wood density and modulus of elasticity, MOE) and one fiber property (microfibril angle, MFA) were measured with a SilviScan instrument on samples from one ramet per plus-tree and 12 OP progenies per plus-tree (total 6288 trees). Three ramets per plus-tree and their OP progenies were also assessed for Pilodyn penetration depth and Hitman acoustic velocity which were used to estimate MOE. The narrow-sense heritabilities (h2) estimates based on parent-offspring regression were marginally higher than those based on half-sib correlation, when three ramets per plus-tree were included. For Silviscan data, estimates of the correlation between plus-tree Breeding Values (BVs) and plus-tree phenotypes, and repeatability estimates, were highest for wood density, followed by MOE and MFA. Considering that the repeatability estimates from the clonal archive trees were higher than any h2 estimate, selection of the best clones from clonal archives would be an effective alternative.

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