Differentiation of Carbonate, Chloride, and Sulphate Salinity Responses In Tall Fescue.

Managing turfgrass under salinity stress is becoming more and more important with the increasing use of recycled water for irrigation.  Tall fescue is a cool-season turfgrass with moderate to high tolerance to salinity.  Very little research investigated different anions and cations simultaneously to determine the underlying mechanism of salinity stress.  The objective of this study was to compare physiological responses of tall fescue leaves to carbonate, chloride, and sulfate under iso-osmotic, iso-Na⁺ strength conditions.  The study was conducted in April to July, 2010.  Two tall fescue cultivars, Tar Heel II (salt tolerant) and Wolfpack (salt sensitive) were seeded in plastic tubes using washed sand as growth medium with pH of 7.7 and EC of 0.04 dS m^-1.  Four salts, NaCl, Na₂CO₃, Na₂SO₄, and CaCl₂ were used in the study at 0 to 225 mM.  Tall fescue leaf firing was mainly caused by an alkaline condition with pH higher than 9 as in Na₂CO₃, or moderate pH combined with high salinity (high EC) as in CaCl₂.  Plant growth was more affected by sodicity which was high in Na₂CO₃ and Na₂SO₄.  The combination of different salts along with the variation of their physical and chemical properties, such as EC, pH, and osmotic potential, made the differentiation of their influence on tall fescue stress rather difficult.  Multiple properties, growth, morphological, and physiological, should be measured to better understanding the effects of different salts.  Current study showed that evaluating tall fescue for alkali, sodic, and saline soil adaptation was often complicated by interaction of ions and pH.