The Athabasca Oil Sands deposit in Northern Alberta is the site of large-scale mining operations (Syncrude Canada Ltd. and Suncor Energy Inc.) that produce relatively saline tailings water, sand and fine tailings. Reclamation goals for the site of current mining operations include the establishment of a productive forest, however the salt tolerance of many native forest plants, including jack pine, is largely unknown. The objective of thesis research program was to determine the effects of water associated with composite tailings (CT water) and its main salts, NaCl and Na2SO4 on the growth and physiology of jack pine (Pinus banksiana Lamb.), and to investigate the mechanisms of salt injury and tolerance.

Jack pine seedlings were grown in sand or solution culture, and exposed to solutions of NaCl, Na2SO4 or CT water in a series of experiments. Treatment of one-year-old seedlings with NaCl had a more detrimental effect than did isomolar Na2SO4 with respect to most of the parameters measured, suggesting that ion toxicity is the dominant effect. While Na2SO4-treated plants showed reduced tissue K +and Ca2+, of which deficiencies are often associated with salt stress, plants treated with NaCl had significantly increased levels of several nutritional elements. Shoot Na was greater in NaCl-treated plants than in plants treated with Na2SO4 at equivalent Na levels, and was correlated with tissue injury only in the former. Tissue electrolyte leakage was more closely related to treatment Cl level, than to Na level, suggesting that Cl is associated with increased membrane permeability. Transpiration rates were similar in all salt treatments, and the greater translocation of Na in NaCl-treated plants was the result of greater root permeability to Na.

Seedlings treated with CT water exhibited similar growth inhibition and injury to plants treated with salts, and injury was related to both shoot Na and Cl levels. The uptake of mineral nutrients may be influenced by the high pH of the treatment solution. Because jack pine appears to be sensitive to substrate Cl, planting of this species is recommended only on sites where Cl is low.