Evaluation of the capacity of three halophytes to desalinize their rhizosphere as grown on saline soils under nonleaching conditions Mokded Rabhi 1 *, Chokri Hafsi 1 , Abdelbasset Lakhdar 1 , Saı ¨d Hajji 1 , Zouhaier Barhoumi 1 , Mohamed He ´di Hamrouni 2 , Chedly Abdelly 1 and Abderrazak Smaoui 1 1 Laboratory of Plant Adaptation to Abiotic Stresses (LAPSA), Centre of Biotechnology, Ecopark of Borj Cedria, PB 901, 2050 Hammam-lif, Tunisia and 2 Ministry of Agriculture-Direction of Soils, 17 Hedi Karray Street, 2080 Ariana, Tunisia Abstract 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 intro- duced 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. Key words: aridity, halophytes, nonleaching conditions, rhi- zosphere, sodium accumulation, soil desalination capacity Re ´sume ´ Dans la sebkha de Soliman (N-E de la Tunisie), des e ´chan- tillons de sol ont e ´te ´ pre ´leve ´s dans les 20 cm supe ´rieurs pendant la pe ´riode la plus se `che de l’anne ´e (juillet-aou ˆt) a ` l’inte ´rieur et a ` l’exte ´rieur des touffes de deux halophytes pe ´rennes, Arthrocnemum indicum (Willd) Moq. et Suaeda fructicosa Forsk., appartenant tous deux a ` la famille des Chenopodiaceae. L’analyse des e ´chantillons s’est base ´e sur la conductivite ´e ´lectrique de la pa ˆte sature ´e (ECe) et le con- tenu en sodium (Na + ) soluble. Par ailleurs, les touffes d’halophytes ont e ´te ´ re ´parties en trois cate ´gories selon leur taille, puis des touffes repre ´sentatives de chaque cate ´gorie ont e ´te ´ re ´colte ´es pour la de ´termination de la biomasse et la charge en Na + de leurs parties ae ´riennes. Nos re ´sultats ont montre ´ que l’accumulation de ces ions au niveau des or- ganes ae ´riens contribue conside ´rablement au dessalement de la rhizosphe `re. La capacite ´ des deux halophytes locales A. indicum et S. fructicosa de dessaler des sols salins a e ´te ´ compare ´e a ` celle d’un halophyte introduite, Sesuvium portu- lacastrum L. (Aizoaceae). De jeunes plantules ont e ´te ´ cultive ´es sous serre dans des pots contenant chacun huit kilos de sol salin. Les pots ont e ´te ´ irrigue ´s a ` l’eau de ville pendant 170 jours sans lessivage. Nos re ´sultats ont confirme ´ la contribu- tion de l’accumulation de Na + par les organes photosyn- the ´tiques au dessalement du sol. Ils ont montre ´, e ´galement, que, parmi les trois espe `ces e ´tudie ´es, S. portulacastrum semble e ˆtre la plus prometteuse pour un tel programme dans les re ´gions arides et semi-arides ou ` les pre ´cipitations sont assez faibles pour lessiver les sels de la rhizosphe `re. Introduction Salt-affected soils are widespread in all continents and at least 75 countries worldwide have serious salinization problems (Goudie, 1990). Several methods were estab- lished to reclaim such soils and were grouped into *Correspondence: E-mail: mokdedrabhi@yahoo.fr Ó 2009 The Authors. Journal compilation Ó 2009 Blackwell Publishing Ltd, Afr. J. Ecol., 47, 463–468 463