Phytodesalination : A Solution for Salt-affected Soils in Arid and Semi-arid Regions
摘要
The present work is a survey of several phytodesalination investigations carried out in our laboratory showing the ability of some obligate halophytes to desalinize their rhizosphere through field and greenhouse experiments. This evaluation was based on (i) the decrease in soil salinity, sodicity, and sodium concentration, (ii) phytodesalination (PHD) capacity of the halophyte, and (iii) the ability of a glycophyte to grow on the desalinized soil. In field experiments, we found that tufts of perennial halophytes such as Tecticornia indica (Willd.) subsp. indica and Suaeda fruticosa (Forssk.) offer to numerous annual glycophytes a microhabitat favorable for their development. This was probably due to two major factors: sodium accumulation within the halophyte shoots and the facilitation of its leaching in the soil. We estimated PHD capacity in a Tunisian sabkha at about 0.65 t Na. ha in summer and 0.75 t Na. ha in winter. In greenhouse experiments, tested halophytes (T. indica, S. fruticosa, and Sesuvium portulacastrum) showed noticeable PHD capacity under non-leaching conditions (about 1 t Na ha in the case of S. portulacastrum). On soil taken from inside halophyte tufts, glycophyitic Medicago species exhibited higher biomass production than on soil taken from outside tufts. In addition, the cultivation of Hordeum vulgare L. (test culture) on saline soil previously desalinized by S. portulacastrum showed that the decrease in soil salinity and sodicity was beneficial to coleoptile emergence as well as to biomass production, tissue hydration, sodium accumulation, and potassium acquisition.