| dc.description.abstract | 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. | |
