Background: Soil salinity poses a significant limiting factor in relation to Global agricultural output. Soil salinity is affecting over 1.1 billion hectares worldwide and the area of land being affected is growing by an estimated 2000 hectares every day. Halophytes such as Salicornia europaea are now significant model species for understanding salt tolerance/adaptation and ionic balance/regulation in saline ecosystems.
Objectives: The intent of this paper is to investigate: (i) the role of S. europaea with respect to regulating soil ionic dynamics; (ii) the physiological and biochemical mechanisms of salt tolerance associated with S. europaea; and (iii) the potential for using S. europaea in phytoremediation and sustainable land management.
Methods: Research was done to evaluate plant/soil relationships using laboratory-controlled tests (e.g., controlled environments) along with experiments done outside (e.g., field tests) that evaluated different types of plants. Biochemical and ionic methods such as Ion Chromatography, Flame Photometry, ICP Spectroscopy, Electrical Conductivity (EC) of soils, & Soil Enzyme Assays were utilized in the development of this information.
Results: Growing S. europaea produced large decreases in sodium (Na+) in the soil (42 - 58%). Additionally, the K+/Na+ ratios and rates of Na+ absorption were improved. There was an increase in microbial biomass carbon and enzyme activity (phosphatase, dehydrogenase, urease) in the rhizosphere (30 - 65% greater than the controls). Na+ accumulation in succulent tissues was found to be selective while K+ levels were maintained via HKT-mediated exclusion and vacuolar compartmentalization of Na+ in the plant. Profiling of osmolytes in the rice shoot 7showed that proline and glycine betaine increased with high salinity (≥ 200 mM NaCl), contributing to osmotic balance, as well as protecting enzymes.
Conclusions: Through ionic regulation and the stimulation of biogeochemical processes, Salicornia europaea has a great ability to phytoremediate saline soils. Additionally, it also demonstrates the ability to improve soil quality, promote carbon sequestration, and facilitate ecological restoration for biosaline agriculture and climate adaptation. More detailed and long-term studies should be conducted in various agroecosystems to determine how best to utilize Salicornia europaea.