ORIGINAL PAPER Genetic stability of wood density and diameter in Pinus radiata D. Don plantation estate across Australia Washington J. Gapare & Miloš Ivković & Brian S. Baltunis & Colin A. Matheson & Harry X. Wu Received: 12 March 2009 / Revised: 28 July 2009 / Accepted: 1 September 2009 / Published online: 17 September 2009 # Springer-Verlag 2009 Abstract Genetic variation for wood quality traits and diameter growth for radiata pine (Pinus radiata D. Don) at age 20/21 years was estimated from eight trials in Australia. The traits studied were wood density, acoustic time-of- flight (an indirect measure of stiffness) and diameter at breast height (DBH). Wood density and DBH exhibited significant additive genetic variation whereas non-additive effects were not significantly different from zero. Time of flight was also not significantly different from zero for both additive and non-additive effects, respectively. Average single-site heritability estimates (±SE) for wood density and DBH were 0.38±0.10 and 0.16±0.08, respectively. Pooled- site heritability estimates for wood density and DBH were 0.38±0.10 and 0.08±0.10, respectively. For density, there was little evidence of genotype-by-environment interaction (GEI) across the eight trials at the additive level (type B additive genetic correlation; r BADD =0.73±0.08) and type B genetic correlation for full-sib families (r BFS =0.64±0.08). In contrast, the type B additive genetic correlation for DBH was lower, (r BADD =0.51±0.14), suggesting evidence of GEI. However, type B genetic correlation for full-sib families was moderate (0.63±0.11) for DBH, suggesting that there may be some stable full-sib families. On the basis of the results of this study, GEI should be considered in order to optimise deployment of improved germplasm in Australia. Keywords Pinus radiata . Additive genetic variance . Full sibs . Genetic correlation . Genotype-by-environment interaction Introduction Forest tree breeding programmes have had a successful impact on increased productivity of plantation forestry around the globe (McKeand et al. 2006; Wu et al. 2007; Burdon et al. 2008). In Australia, two generations of radiata pine (Pinus radiata D. Don) breeding and selection have resulted in substantial economic benefits for the Australian forest industries (Matheson et al. 1986; Wu et al. 2008). For example, through genetic improvement and silviculture, the rotation length for sawn products was reduced from 40–45 to 25–30 years (Li and Wu 2005). Predicted genetic gains for second generation diameter growth were estimated to be 4% to 17% and would result in overall volume gains of more than 10% (White et al. 1999; Wu and Matheson 2005). As radiata pine breeding advances to third genera- tion selections in Australia, there is an increasing need to include wood quality traits in the breeding programme. A large number of studies have been carried out to study variation and genetic control of various wood quality traits of radiata pine (Li and Wu 2005; Dungey et al. 2006; Gapare et al. 2006, 2007, 2008; Baltunis et al. 2007b; Communicated by J. Davis W. J. Gapare (*) : M. Ivković : B. S. Baltunis : C. A. Matheson : H. X. Wu CSIRO Plant Industry, GPO Box 1600, Canberra ACT 2601, Australia e-mail: Washington.Gapare@csiro.au M. Ivković e-mail: Milos.Ivkovich@csiro.au B. S. Baltunis e-mail: Brian.Baltunis@csiro.au C. A. Matheson e-mail: Colin.Matheson@csiro.au H. X. Wu e-mail: Harry.Wu@csiro.au Tree Genetics & Genomes (2010) 6:113–125 DOI 10.1007/s11295-009-0233-x