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We investigated the genetic control of wood properties as a function of cambial age to enable improvement of juvenile wood attributes in white spruce ( Picea glauca (Moench) Voss). Increment cores were taken from 375 trees randomly selected from 25 open-pollinated families in a provenance–progeny trial repeated on three sites. High-resolution pith-to-bark profiles were obtained for microfibril angle (MFA), modulus of elasticity (MOE), wood density, tracheid diameter and cell wall thickness, fibre coarseness, and specific fibre surface with the SilviScan technology. Heritability estimates indicated that genetic control of cell anatomy traits and wood density increased with cambial age, whereas the genetic control of MFA and MOE remained relatively low across growth rings. Wood density, radial cell diameter, cell wall thickness, and specific fibre surface were highly heritable, indicating that significant genetic gains could be expected in tree improvement programs, although cambial age at selection may strongly influence the magnitude of realized gains. In contrast, growth-related properties, such as ring width, core length, and tree height, gave weak or nonsignificant heritability estimates. Adverse correlations between mechanical strength and properties related to paper quality suggest that breeding strategies must incorporate both types of traits to improve white spruce wood quality for different end uses.

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