Effect of salt stress on growth, electrolyte leakage, Na+ and K+ content in selected plant species

This study monitors the effect of salt stress induced by a NaCl solution (0 - deionized water, 50, 100, 200, 300 mmol/L) in lettuce (Lactuca sativa L. cv. Orion), New Zealand spinach (Tetragonia tetragonoides (Pall) Kuntze) and common purslane (Portulaca oleracea L. cv. Green Purslane) over the course of 50 days. The diverse reactions of these monitored species to salt stress are well apparent from the results. Lettuce proved as the most sensitive to salt stress, showing a significant reduction of dry weight, where even lower concentrations of salt affected membrane stability through increased electrolyte leakage value and an imbalance in the content of Na+ and K+, observed in the form of lower ratios of K+/Na+. In case of T. tetragonoides, lower salt concentrations positively affected growth and this species appears to particularly accumulate sodium. In case of P. oleracea no significant reduction of dry weight took place with the increasing concentration of NaCl and a naturally high content of potassium contributed to maintaining a favourable ratio of K+/Na+ even at higher salt concentrations, which is one of the prerequisites of salt-stress tolerance.