Genotype and Population Performances and their Interactions for Growth of Coastal Douglas-Fir in Western Washington
Abstract:The Washington Wide Adaptability study (WWA) is a series of genetic tests established in 1985 across Cascade, Longview, and Twin Harbors regions of western Washington, measured for diameter over-bark at 13 years (dbh13). WWA involves parents of coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) originally selected from wild populations in Cascade, Longview, Twin Harbors, and Vail. Female parents from each population were crossed using pollen-mixes from the same (“intra”) or different (“inter”) populations. Analyses of variance: Female parent (nested within population) accounted for around 2% of total variation in dbh13. Population of the female or male parents accounted for less than 1% variation. The most important genotype × environment (GE) component was female parent (within population) × genetic test (within region), accounting for around 2% variation. Other GE effects accounted for little or no variation. The female source × pollen source (genotype × genotype, GG) effect accounted for only 0.1% of variation in dbh13. Practical implications: GG and GE interactions for dbh13 do not appear sufficiently systematic or large enough to be of practical importance in breeding coastal Douglas-fir across these regions of western Washington, at least for growth to 13 years. It appears possible to select coastal Douglas-fir genotypes that produce strong, stable growth across this range of environments. Movement of improved seed across Cascade, Longview, and Twin Harbors can lead to positive outcomes for plantation productivity at 13 years. There appears little practical benefit in having separate breeding lines of coastal Douglas-fir for these regions. Indeed, strategies of developing local purebred genotypes tested and deployed solely in a local region would most likely deliver suboptimal genetic gain.
Document Type: Research Article
Publication date: August 1, 2007
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