Phytoremediation Capacity of Saltwort (Salsola imbricata Forssk.) Determined by Tissue Organization and Physio-biochemical traits under Arid Saline Environments

Abstract

Soil salinization is a growing environmental concern of arid regions, but the salt-accumulator species like Salsola imbricata offer a promising solution for phytoremediation of affected soils. In this context, ten naturally occurring populations of S. imbricata from salt-prone arid environments of Cholistan Desert were evaluated for phytoremediation traits, including (i) hypersaline populations (ECe 31.6 to 21.3 dS m⁻¹), (ii) moderately saline populations (ECe 16.0 to 12.2 dS m⁻¹), and (iii) non-saline populations (ECe 2.5 to 1.7 dS m⁻¹). The populations of S. imbricata collected from the highest salinity sites, Rahim Yar Khan (RYK) and Sadiqabad (SA), exhibited restricted growth habits but demonstrated increased accumulation of K⁺, Ca²⁺, Na⁺, and Cl⁻. These populations showed larger root cross-sectional areas with more prominent xylem vessels and cortical region. Sclerification was notably intense in the roots and stems of population. In the leaves, specific adaptations included a reduced lamina area and enhanced succulence due to the development of storage parenchyma. Notable traits associated with the phytoremediation potential of S. imbricata populations included deeper root systems, taller plant, intensive sclerification around storage and conducting tissues, succulent leaves, salt-excreting trichomes, wider xylem vessels, and the accumulation of noxious ions. Furthermore, the RYK and SA populations displayed higher bioconcentration factors, translocation factors, and dilution factors for Na⁺ and Cl⁻, which are considered key traits for effective phytoremediation. The S. imbricata populations in highly saline environments demonstrate superior salt tolerance and efficient toxic salt management, making them ideal for rehabilitating saline, uncultivated lands through green reclamation.