Ion uptake in Pinus banksiana treated with sodium chloride and sodium sulphate

Within its wide range across Canada, jack pine is exposed to salinity from both natural and anthropogenic sources. To compare the effects of Cl and SO4 on salt injury, sand and solution-culture grown jack pine (Pinus banksiana Lamb.) seedlings were treated with nutrient solutions containing 60 or 120 mM NaCl, 60 mM Na2SO4, or a mixture of 60 mM NaCl and 30 mM Na2SO4. After 5 weeks of salt treatments, concentrations of Cl, K, Na, and SO4 were determined in roots, stem and needles of the current and previous years growth, and in necrotic needles. To determine the role of water uptake in the absorption and translocation of salts in plants, total transpiration was measured as the loss of water from a sealed system and related to total plant uptake of Cl, Na, and SO4. Sodium uptake and root-to-shoot transport rates were greater in treatments containing Cl. A delay in root-to-shoot transport of both Na and Cl indicates retention of these ions in the roots. Electrolyte leakage of needles was more closely related to treatment Cl concentrations than treatment Na concentrations. The transport of Na ions to the shoot was related to the presence of Cl, but was not related to transpiration rate.