Wood quality and quantitative genetics of Pinus radiata D. Don: fibre traits and wood density

This paper reports on a study of wood microstructure traits (density, trach eid cross-section dimensions, coarseness and specific surface area) in a ra diata pine progeny test using SilviScan-1, an automated image analyser and x-ray microdensitometer. Wood was sampled from a 23 year old, 4 by 4 dialle l progeny test involving parent 80055, the progeny of which is renowned for producing bright thermomechanical pulp at low refining energy. Tracheid ta ngential diameter was phenotypically the least variable trait. Tracheid wal l thickness and coarseness were calculated from the measured tracheid diame ters and wood density. Density was highly heritable but to a lesser extent than tracheid diameter. Narrow sense heritability of derived traits had lar ge standard errors. Maternal, reciprocal and other non-additive effects wer e negligible for all wood microstructure traits. As expected, the progeny o f 80055 possessed the largest tracheid diameter and tracheid coarseness. Th e progeny also had the lowest density because of the exceptionally large tr acheid diameter, which would contribute to low strength in the solid timber .