Canadian Forest Service Publications

Water stress preconditioning of black spruce seedlings from lowland and upland sites. 1994. Zine El Abidine, A.; Bernier, P.Y.; Stewart, J.D.; Plamondon, A.P. Canadian Journal of Botany 72: 1511-1518.

Year: 1994

Issued by: Laurentian Forestry Centre

Catalog ID: 16642

Language: English

Availability: PDF (request by e-mail)

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One-year-old seedlings from two pairs of upland-lowland populations were subjected to three cycles of drought preconditioning. During a subsequent fourth cycle, preconditioned seedlings and seedlings that had been maintained under well-watered conditions were subjected to a final soil drought. During the drought periods, small but significant differences in gas exchanges and water relations were observed between upland and lowland seedlings but the differences were not consistent either within each lowland-upland pair or over the four cycles. During the final drought period, preconditioned seedlings maintained significantly higher net photosynthesis rate, stomata1 conductance, and transpiration rate than unconditioned seedlings. In contrast, no significant differences were found in midday water potential, total sugar content, or water relations parameters between preconditioned and unconditioned seedlings. The results suggest an absence of ecotypic variation with respect to drought tolerance in black spruce. They also suggest that preconditioning in black spruce seedlings occurs mostly through the acclimation of stomata1 and photosynthetic mechanisms to drought, without active osmotic adjustment.