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Abstract: This study examined the feasibility of using water relations to screen black spruce (Picea mariana (Mill.) BSP) planting stock for salt tolerance, prior to planting in saline oil sands tailings. To do so, water relations parameters were derived from pressure-volume curves for individual seedlings prior to salt stress treatments. Pressure-volume curves were constructed for branches removed from the seedlings and the seedlings were subsequently treated with 60 mM NaCl, 120 mM NaCl, or 90 mM Na^sub 2^SO^sub 2^ in solution culture. After 2 weeks of treatment, seedlings treated with NaCl solutions had greater needle electrolyte leakage and visible needle injury compared with equimolar and isoosmotic solutions of Na^sub 2^S0^sub 4^, suggesting that chloride played a role in needle injury. At turgor loss point, a more negative osmotic potential was significantly correlated with lower electrolyte leakage in seedlings treated with Na^sub 2^SO^sub 4^ but not in those treated with NaCI. The results suggest that, in contrast with NaCl, Na^sub 2^SO^sub 4^ injury to black spruce seedlings may be largely due to osmotic stress and that drought tolerance parameters may be more helpful in predicting salt tolerance in plants treated with Na^sub 2^SO^sub 4^ than in those treated with NaCl.
Key words: osmotic stress, salt stress, drought tolerance, water relations, ion toxicity, black spruce.
Resume : Les auteurs ont examine la faisabilite d'utiliser les relations hydriques pour selectionner des plants de l'epinette noire (Picea mariana (Mill.) BSP) tolerants au sel, avant leur plantation dans les residus de sables bitumineux salins. A cette fin, on obtient les parametres des relations hydriques h partir des courbes pression-volume chez les plants individuels, avant les traitements par stress salin. On construit les courbes pression-volume pour des branches prelevees sur les plants, et on traite subsequemment les plants avec des solutions de culture contenant du NaCl 60 mM, du NaCl 120 mM ou du Na^sub 2^SO^sub 4^ 90 mM. Apres 2 semaines de traitement, les plants traites avec les solutions de NaCl perdent plus d'electrolytes au niveau des aiguilles et montrent des dommages aux aiguilles comparativement aux solution equimolaires ou aux solutions isosmotiques de Na^sub 2^SO^sub 2^, ce qui suggere que le chlore joue un role dans le dommage subi par les aiguilles. Au point de perte de turgescence,...