Comparison of two halophyte species (Salsola soda and Portulaca oleracea) for salt removal potential under different soil salinity conditions

Abstract

Salt-induced land degradation has gradually increased in several major irrigation schemes within arid and semiarid regions. To maximize crop productivity under saline conditions, either salt tolerance crops should be cultivated or areas should be desalinated. One of the most promising and cost-effective ways to maximize crop productivity is to use salt tolerant plants to remove salt from the soil. For this study, four levels of saline soils were cultivated with the halophyte species Salsola soda L. and Portulaca oleracea L. in pots. The soils had the following salinity levels: 1) nonsaline soil (NSS, 0.9 dS m-1), 2) slightly saline soil (SSS, 4.2 dS m-1), 3) moderately saline soil (MSS, 7.2 dS m-1), and 4) highly saline soil (HSS, 14.1 dS m-1). To assess the salt tolerance capacity of the halophytes, physiological and biochemical parameters as well as the accumulation of leaf Na+ and Cl? ions in the halophytes were investigated. Soils were additionally evaluated for electrical conductivity, pH, and soil ion concentrations prior to planting and the following harvest.The fresh and dry weights of both halophytes increased with increasing salinity levels (P ≤ 0.05). The proline contents of S. soda and P. oleracea were 3.1 and 4.6 times higher, respectively, than within the same species grown under control conditions. The malondialdehyde and membrane stability index values for S. soda were insignificant under all salt conditions. Only P. oleracea showed significantly higher membrane damage under HSS conditions. In a similar manner, the chlorophyll content of both halophytes was not impacted for all of the salinity levels. Na+ and Cl- concentrations significantly decreased in soils that were planted with both halophytes (P ≤ 0.05). The impact of S. soda on the removal of Na+ from HSS was significantly higher than that of P. oleracea and removed 151.4 mmol Na+ pot-1 as compared to the removal of 61.2 mmol Na+ pot-1 by P. oleracea.