Stiffness and wood variation of 3-year old Pinus radiata clones

The objective of this study was to explore wood variation, especially modulus of elasticity (MOE), density, and microfibril angle (MFA), in a three-year old Pinus radiata tree clone trial. Moreover, the study examined the potential for genetic selection of radiata pine clones with high MOE using current acoustic technology. The clone selection criteria were based on growth traits, basic density, and sound velocity indices to mirror the range in wood density and MOE amongst c. 1000 clones. The selected 22 clones, represented by two trees each, were measured for MOE, spiral grain. wood density. compression wood percentage, and MFA. Good agreement was found between static MOE and dynamic MOE. Both static and dynamic MOE measurements were found to be primarily dependent on MFA (clonal range 28-39 degrees). Although wood density (clonal range 300-400 kg/m(3)) did not have a significant influence on MOE alone, it was significant in combination with MFA. Compression wood tended to reduce MOE and inflate wood density. The opportunities for genetic selection of radiata clones with high stiffness seem promising as the 22 selected clones exhibited a two-fold range of static MOE (2.2-4.7 GPa) and the clonal heritabilities (H-i(2)) for MOE, density and NIFA Were high.