Genetics of Eucalyptus wood properties

Traditional methods of assessing wood properties are both destructive and expensive, limiting the numbers of samples that can be processed. Over the past decade, non-destructive sampling techniques and new assessment methods have been developed leading to a large increase in the numbers of trees and traits that can be evaluated. This technology has enabled the assessment of progeny trials to determine the patterns of variation, degree of genetic control and economic importance of many wood traits, leading to the inclusion of wood properties in many eucalypt-breeding programs. Issues addressed in this paper include the potential markets and products for plantation eucalypts leading to a definition of which wood properties should be assessed for a range of products. Current recommendations for non-destructive sampling for basic density, fibre length and predicted pulp yield in Eucalyptus globulus and E. nitens are provided. Other non-destructive assessment techniques are illustrated including cellulose content, acoustic testing methods for wood stiffness and SilviScan X-ray densitometry and diffraction analysis for density and microfibril angle. The degree of genetic control for wood properties is compared to tree growth traits and a series of issues and challenges for the future presented.