Genetic variation of wood properties in balsam poplar (Populus balsamifera L.)
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Genetic variation in wood properties among and within three provenances of balsam poplar was investigated. Between 1982 and 1984, clonal populations were sampled along the Longitude 9QOW in North Wisconsin (Lat. 45°N to 46°N); Thunder Bay, Ontario (Lat. 48°N to 49°N); and Pickle Lake, Ontario (Lat.50°N to 51°N). Rooted cuttings were planted in a field test near Lakehead University, Thunder Bay. In 1994, 30 clones from each provenance with 4 ramets per clone were measured for growth characteristics, and specimen disks were cut at tree base. Ring width, relative density, percent moisture content, fibre length, and vessel element length were determined in the laboratory. Univariate analyses of variance showed significant differences among the three provenances in growth rate and cell length. The southern provenance had the fastest growth rate and the longest cells. Provenance differences in relative density and moisture content of the wood were not statistically significant. Canonical multivariate analysis, using growth rate, relative density, and fibre length as dependent variables, showed differences between the southern and northern provenances, with the local source in an intermediate position. Estimates of broad sense heritability were different for each of the three provenances. Heritability was more uniform and higher for wood properties than for growth characteristics. Genetic correlations and coefficients of genetic prediction showed relative genetic independence of growth characteristics from relative density and moisture content. Phenotypically positive correlation between growth rate and cell length was genetically based in the northern provenance, while it was influenced more by environment in the local and southern provenance. Results justified selection based on growth characteristics, wood properties or a combination of these two.
- Retrospective theses