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Abstract
Sodium chloride and sodium sulfate are commonly present in extraction tailings waters produced as a result of surface mining and affect plants on reclaimed areas. Red-osier dogwood (Cornus stolonifera Michx) seedlings were demonstrated to be relatively resistant to these high salinity oil sands tailings waters. The objectives of this study were to compare the effects of Na^sub 2^SO^sub 4^ and NaCl, on growth, tissue ion content, water relations and gas exchange in red-osier dogwood (Cornus stolonifera Michx) seedlings. In the present study, red-osier dogwood seedlings were grown in aerated half-strength modified Hoagland's mineral solution containing 0, 25, 50 or 100 mM of NaCl or Na^sub 2^SO^sub 4^. After four weeks of treatment, plant dry weights decreased and the amount of Na^sup +^ in plant tissues increased with increasing salt concentration. Na^sup +^ tissue content was higher in plants treated with NaCl than Na^sub 2^SO^sub 4^ and it was greater in roots than shoots. However, Cl^sup -^ concentration in the NaCl treated plants was higher in shoots than in roots. The decrease in stomatal conductance and photosynthetic rates observed in presence of salts is likely to contribute to the growth reduction. Our results suggest that red-osier dogwood is able to control the transport of Na^sup +^ from roots to shoots when external concentrations are 50 mM or less.[PUBLICATION ABSTRACT]