Canadian Forest Service Publications
Early testing of Douglas-fir: wood density and ring width. 2006. Krakowski, J.; Park, Y.S.; El-Kassaby, Y.A. Forest Genetics 12: 99-105.
Available from: Atlantic Forestry Centre
Catalog ID: 26141
CFS Availability: Order paper copy (free)
Early genetic control over juvenile ring width, ring density, and earlywood-latewood density ratio in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) was assessed using seven disconnected diallel crosses with six clones in each set. Annual and composite traits were measured for 104 families over three years. Variance due to general combining ability for density traits was significant. Heritability estimates were consistent with earlier reports on the same species (annual: 4-22%; combined: 9-34%). Variance due to specific combining ability and heritability increased with age. Year by family interaction was always significant, except for composite wood density ratio. Random error variance accounted for 64-82% of total phenotypic variance for individual years, and 50-78% cumulatively. The relatively stable general combining ablity variance over years indicates that wood properties will respond incrementally to selection in a breeding program and that genetic trends in early traits will strengthen over time. Although inversely correlated, coarse-filter selection for wood density and diameter growth is feasible on three-year-old progeny based on ranks of the top and bottom few crosses; however, selections should be made on older trees since genetic parameters vary before stabilizing by age twelve to fifteen in this species.
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