Genetic parameters for growth and wood chemical properties in Eucalyptus urophylla × E. tereticornis hybrids

KEY MESSAGE : Growth and wood chemical properties are important pulpwood traits. Their narrow-sense heritability ranged from 0.03 to 0.49 in Eucalyptus urophylla × E. tereticornis hybrids, indicating low to moderate levels of genetic control. Genetic correlations were mostly favorable for simultaneous improvement on growth and wood traits. Additive and non-additive genetic effects should be considered in making a hybrid breeding strategy. CONTEXT: Eucalypt hybrids are widely planted for pulpwood production purposes. Genetic variations and correlations for growth and wood chemical traits remain to be explored in Eucalyptus interspecific hybrids. AIMS: Our objectives were to clarify the heritability of growth and wood chemical traits and determine the genetic correlations between traits and between trials in E. urophylla × E. tereticornis hybrids. METHODS: Two trials of 59 E. urophylla × E. tereticornis hybrids derived from an incomplete factorial mating design were investigated at age 10 for growth (height and diameter) and wood chemical properties (basic density, cellulose content, hemi-cellulose content, lignin content, and syringyl-to-guaiacyl ratio). Mixed linear models were used to estimate genetic parameters. RESULTS: Narrow-sense heritability estimates were 0.13−0.22 in growth and 0.03−0.49 in wood traits, indicating low to moderate levels of additive genetic control. Genetic correlations were mostly positively significant for growth with basic density and cellulose content but negatively significant with hemi-cellulose and lignin contents, being favourablefavorable for pulpwood breeding purpose. Type-B correlations between sites were significant for all the traits except diameter and lignin content. CONCLUSION: Hybrid superiority warrants the breeding efforts. An appropriate breeding strategy should be able to capture both additive and non-additive genetic effects.