| dc.description.abstract | Genetic variation In traits potentially affecting the waterrelations
of balsam poplar (PopuIus balsamifera L.) clones from
four provenances along a transect from northern Wisconsin to
Pickle Lake in northwestern Ontario was examined both in the
field and In the greenhouse. Traits measured were transpiration
rates, stomatal conductance, internode length, average single-leaf
abaxial area and oven-dry weight, specific leaf weight, and
stomatal density and length. Additional traits measured In the
greenhouse provenance trial were shoot length, number of leaves
per plant, total abaxial leaf area per plant, total oven-dry root,
shoot and leaf weight, and oven-dry root/shoot weight ratio. Most
of the observed variation in traits was attributable to clones
within provenances and to ramets within clones. As much as
eighty-five percent of the observed variation was attributable to
variation among and within clones within provenances. The
provenance effect had a significant Influence on leaf size and
morphology traits, with an apparent north-south clinical trend.
Leaves from northern sources were smaller In area, lighter In
weight, and were thicker than leaves from southern sources. As
expected stomatal conductance was positively correlated with
measured transpiration rates. The only other trait significantly
correlated with transpiration rates was stomatal length, and this
only occurred in the greenhouse provenance trial. Larger stomata
were associated with higher rates of transpiration. | |
