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In the sabkha of Soliman (N‐E Tunisia), soil samples of the upper 20 cm were taken during the driest period of the year (July–August) from inside and outside tufts of two perennial halophytes: Arthrocnemum indicum (Willd.) Moq. and Suaeda fruticosa Forssk., both from family Chenopodiaceae. Samples were analysed for electrical conductivity of the saturation paste extract (ECe) and soluble sodium (Na+) content. Then, tufts were divided into three size categories and their shoot biomass production and Na+ content were determined. Our results showed a considerable contribution of shoot Na+ accumulation to rhizosphere desalination. The capacity of the two native halophytes A. indicum. and S. fruticosa to desalinize saline soils was compared with that of an introduced halophyte, Sesuvium portulacastrum L. (Aizoaceae). Seedlings were grown under greenhouse conditions in pots containing 8 kg of saline soil each. Pots were irrigated with tap water during 170 days without leaching. Our results confirmed the contribution of shoot Na+ accumulation to soil desalination. They showed also that among the three studied species, Sesuvium portulacastrum L. seems to be the most convenient to be used for this purpose in arid and semi‐arid regions where precipitation is too low to leach salts from rhizosphere.

The interactive effects of salinity and potassium (K+) availability on biomass production, water status, and ionic composition were investigated in Hordeum maritimum, an annual grass growing natively on saline soils. Plants were grown for 7 weeks on Hewitt nutrient solution supplied with NaCl (0, 100, 150, 200, and 300 mM) combined with low (0.232 mM) or high (5.8 mM) K+ levels. Independent of potassium availability, dry matter of both roots and shoots decreased consistently with increasing NaCl levels in the culture medium, in association with a significant reduction of the shoot water content. This salt‐induced growth reduction did not result from a restriction of K+ nutrition, since H. maritimum expressed similar growth under both low and high K+ supply. NaCl decreased shoot K+ concentrations. This effect was more pronounced in plants grown at high K+ supply than in plants grown at low K+ supply. This result suggests that the absorption systems were strongly selective for K+, and that this selectivity was enhanced by salt.