© 1987 Heron Publishing—Victoria, Canada
Variation in water relations of black spruce stock types planted in Ontario
T. J. Blake (1, 2) and R. F. Sutton (3)
1. ABL Forest Science Inc., 44 Eglinton Avenue West, Suite 208, Toronto, Ontario M4R 1A1, Canada / 2. Faculty of Forestry, University of Toronto, Toronto, Ontario M5S 1A1, Canada / 3. Great Lakes Forestry Centre, Sault Ste. Marie, Ontario P6A 5M7, Canada / Received February 19, 1987
Summary
Upland, intermediate and lowland sites in northeastern Ontario were planted between May 28 and June 8 with three types of
black spruce (Picea mariana (Mill.) BSP) nursery stock: (1) spring-lifted, 1.5 + 1.5 bareroot plants (BR); (2) 24-week-old, winter-sown, container stock
(CWS); and (3) spring-sown, overwintered, container stock (CO). At the beginning of the growing season, the BR stock had the
lowest xylem pressure potentials (Ψx), stomatal conductances (gwv), and net photosynthetic (Pn) rates. By the end of the growing season, the BR stock still had lower gwvs than the container stock types, but had higher shoot Ψx values. In August, the turgor loss points for the BR, CO and CWS stock types were –2.8, –1.93 and –1.6 MPa, respectively,
while the minimum observed shoot Ψx values were –1.4, –1.7 and –1.9 MPa, respectively. The BR stock produced the greatest dry weight of new shoots and unsuberized
roots. No new shoots were produced by the CWS stock, but they produced a greater dry weight of unsuberized roots than the
CO stock. As a percent of the dry weight of suberized roots, the greatest production of unsuberized roots was by the CWS stock,
the least by the BR trees.
