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.

Performance and Genetic Parameters of Somatic and Zygotic Progenies of Coastal Douglas-fir at 71/2-Years across Washington and Oregon, USA

Five genetic tests involving 37 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March 2000 in Weyerhaeuser plantations across western Washington and Oregon States, USA. Four of the tests are in Longview, Twin Harbors and Vail regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 37 coastal Douglas-fir clones were propagated by somatic embryogenesis from four full-sib families. Zygotic seedlings from two of these full-sib families were planted across all five tests to allow comparison between somatic and zygotic trees of the same pedigree. Results are reported for survival, stem height, diameter at breast-height (DBH), volume and stem sinuosity at 71/2- years. On average the total population of 37 somatic clones had less stem sinuosity, but grew more slowly than zygotic trees across the five tests studied. However, the best 20% of somatic clones for growth produced 25% greater stem volume at 71/2-years than the zygotic fullsib families. Height had a clonal heritability of 0.61 ± 0.09, DBH 0.64 ± 0.06, volume 0.58 ± 0.08 and stem sinuosity 0.26 ± 0.06. The clonal genetic correlation between height and DBH at 71/2-years was 0.98 ± 0.01, while stem sinuosity was adversely genetically correlated with growth. Clonal performance for growth and stem sinuosity was stable across tests with overall between-test correlations of 0.96 to 0.98. This clonal stability resulted in little variance due to clone x test interactions.

Genetic Parameters of Somatic Clones of Coastal Douglas-fir at 5½-Years across 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 Longview and Twin Harbors regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 70 coastal Douglas-fir clones were propagated by somatic embryogenesis from two full-sib families that had the same female parent. Results are reported for survival, height, diameter at breast-height (DBH) and volume growth at 5½-years. These tests provide evidence of acceptable growth and survival of somatic trees of coastal Douglas-fir across a range of site conditions. Height had a clonal heritability of 0.25 ± 0.01, DBH 0.21 ± 0.01 and volume 0.20 ± 0.01. The growth traits were all strongly genetically associated with clonal correlations of 0.92 to 0.99. Clonal performance for growth proved quite stable across tests with an overall between-test correlation of 0.84 ± 0.04. There was little variance due to clone x test interactions.

Resistance of Castanea Clones to Phytophthora Cinnamomi: Testing and Genetic Control

Summary The resistance of chestnut clones to Phytophthora cinnamomi was evaluated by a soil inoculation experiment under controlled environmental conditions, as well as by excised and intact stem tests. One-year-old plants of fifty different clones were inoculated with two isolates of Phytophthora cinnamomi and evaluated fourteen weeks after inoculation. There were significant differences among clones for all root and collar rot variables. There were significant differences for isolates of P. cinnamomi but only for the collar rot variables. A total of 84% of plants grown in infested soil showed symptoms of root rot but only 50% of the plants with root rot, showed also had collar rot. The roots of resistant clones were able to confine the colonization, in roots and from roots to collar. Percentage circumference of collar rot was the best indicator or descriptor of sensitivity, a 50% of clones were resistant or highly resistant clones, with respectively less than 20% and than 10% circumference of collar rot. Percentage of survival of plants is not sufficient to indicate resistance to the pathogen, as mortality may be affected by environmental conditions or by other pathogens. The clonal heritability of collar rot variables ranged between 0.54 and 0.71. The plants grown on inoculated soil showed a reduction in growth. The phenotypic and genotypic correlations between soil infestation characteristics and the length of necrosis in both intact and excised stem tests were positive and highly significant and indicated similar resistance rankings of the clones.