Genetic Parameters of Somatic Clones of Coastal Douglas-fir for Growth, Stem and Wood Traits at 6½ or 7½-Years in Washington and Oregon, USA

Five genetic tests involving 70 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March-April 1999 in Weyerhaeuser plantations across western Washington and Oregon states, USA. Four of the tests are in the Longview and Twin Harbors regions of Washington, and one test is in Springfield, Oregon. Each test is designed as single-tree plots with 12 randomized complete-blocks. The 70 coastal Douglas-fir clones were propagated by somatic embryogenesis (SE) from two full-sib families created by crossings among three parents. Results are reported for height, diameter at breast-height (DBH) and stem volume measured at 71/2-years; and stem sinuosity, stress wave velocity (SWV) and pilodyn at 61/2-years. Withinfamily clonal heritabilities (or repeatabilities) were estimated as the ratio of the variance between-clones within- families to the overall phenotypic variance. Variance between families was not included in the numerator of the heritability equation because the 70 SE clones are from only two full-sib families. Height had a within-family clonal heritability of 0.31 ± 0.04, DBH 0.27 ± 0.04, volume 0.24 ± 0.04, stem sinuosity 0.13 ± 0.02, SWV 0.45 ± 0.04 and pilodyn 0.31 ± 0.04. The three growth traits were all closely genetically associated with clonal correlations among them of 0.86 to 0.98. Clonal performance for growth proved quite stable across tests with an overall betweentest clonal correlation of 0.80 ± 0.04 for stem volume, meaning that clone x test interactions only accounted for a minor part of the total variance. The between-test correlation was 0.79 ± 0.06 for sinuosity, 0.96 ± 0.01 SWV and 0.86 ± 0.03 for pilodyn.