Determining the genetic heritability of wood properties of Sitka spruce critical to timber strength

Summary Description:

The aim of the Sitka spruce breeding programme has been to increase productivity whilst improving timber quality for use in the construction industry. While increasing productivity has largely been achieved, higher rates of growth achieved have raised concerns that wood properties associated
with timber strength may be compromised due to a greater proportion of weaker juvenile
wood being present.

This project studied the problem of final timber strength by determining genetic heritabilities and
correlations of certain wood properties of Sitka spruce critical to timber strength within
the outer zone of the juvenile core. The ultimate aim is to determine whether progenies
with both favourable growth rate and timber strength properties can be identified from
within the breeding population.

Project Outcomes:

In this study timber stiffness was found to be mainly determined by microfibril angle and wood density. With increasing growth rate, wood density generally decreases however there is little correlation between growth rate and microfibril angle. The moderate heritability of microfibril angle should enable gains in wood stiffness to be achieved without compromising growth rate.