Evaluation of Ionic Osmotica in Succulent and Non-succulent Xero-halophytes Inhabiting Hot Oases

This research was carried out at Kharga and Dakhla, in the western Egyptian desert. The species investigated include basically those of different ecological affiliations as well as different life forms, in order to have comparative indications in the ionic means of adjustment. During winter and summer, the water soluble ions in both soil and plants were analyzed. Also, the total osmotic water potential and the share of ionic radicals of plants were calculated. The data revealed that, halophytic species maintain osmotic adjustment due to accumulation of ions depending on seasonal and species variation and ionic osmotic potential which were 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 and Cressa and affected by the interaction (S x L) in case of Z.coccenium. The ionic osmotic potential of Na+/K+ and Cl- / SO4-2 ratios for salt tolerance in studied species were discussed.