Effects of NaCl and Na2SO4 on red-osier dogwood (Cornus stolonifera Michx)seedlings

Sodium chloride and sodium sulfate are commonly present in extraction taili ngs waters produced as a result of surface mining and affect plants on recl aimed areas. Red-osier dogwood (Cornus stolonifera Michx) seedlings were de monstrated to be relatively resistant to these high salinity oil sands tail ings waters. The objectives of this study were to compare the effects of Na 2SO4 and NaCl, on growth, tissue ion content, water relations and gas excha nge in red-osier dogwood (Cornus stolonifera Michx) seedlings. In the prese nt study, red-osier dogwood seedlings were grown in aerated half-strength m odified Hoagland's mineral solution containing 0, 25, 50 or 100 mM of NaCl or Na2SO4. After four weeks of treatment, plant dry weights decreased and t he amount of Na+ in plant tissues increased with increasing salt concentrat ion. Na+ tissue content was higher in plants treated with NaCl than Na2SO4 and it was greater in roots than shoots. However, Cl- concentration in the NaCl treated plants was higher in shoots than in roots. The decrease in sto matal 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+ from roots to shoots when external concentrations are 50 mM or less.