Abstract
This research was carried out at Kharga and Dakhla oases, in the western Egyptian desert. The species investigated include basically those of different ecological affiliations and different life forms, to have comparative indications on the ionic means of adjustment. During winter and summer, the water-soluble ions for both of soil and plants were analyzed. The total osmotic water potential and the share of ionic radicals of plants were also calculated. The data revealed that halophytic species were able to maintain osmotic adjustment due to the accumulation of ions, depending on seasonal and species variations, and the possession of ionic osmotic potential that related to chlorides, sodium and potassium. The seasonality or location has the dominant effect on Na+, K+ , Cl- and SO4-2 concentrations in halophytes, Suaeda monoica and Cressa cretica, and also affected by the interaction between both factors (S x L) in the case of Zygophyllum coccenium. The ionic osmotic potential of Na+/K+ and Cl-/SO4-2 ratios for salt tolerance in studying halophytic species were also discussed.