Genetic parameters for diameter, basic density, fibre properties and cellulose content for Eucalyptus nitens

Genetic parameters were estimated for stem diameter, basic density, fibre length, fibre coarseness and cellulose content from 12-year-old Eucalyptus nitens progeny trials in Tasmania. Heritability for diameter averaged 0.19 at 6 years, 0.38 at 12 years, and 0.45 for the diameter increment between 6 and 12 years. Heritability for basic density, fibre length and cellulose content averaged 0.70, 0.58 and 0.79 respectively and differed significantly between sites. Heritabilities for fibre coarseness were highly variable and correlations between sites low. There were favourable genetic correlations between diameter/cellulose (0.79), diameter/fibre length (0.37) and cellulose/fibre length (0.54). There were adverse genetic correlations between basic density/diameter (-0.57) and basic density/cellulose (-0.45). Genetic correlations between fibre length/density were variable (0 to 0.75). There was no significant genotype by environment interaction for diameter and fibre length. For basic density and cellulose content, interactions were significant but small.