Salinity Tolerance Mechanism of Crithmum maritimum L.: Implications for Sustainable Agriculture in Saline Soils

Abstract

Edible halophytes are attracting attention due to their potential for agriculture in saline and marginal areas. The salt tolerance mechanism was analyzed in Crithmum maritimum L., based on ionic, osmotic, and redox homeostasis strategies under salt stress. The methodology involved growing C. maritimum seeds in pots under controlled greenhouse conditions and exposing them to different NaCl concentrations (0, 100, 200, and 300 mM) for five months. High salinity levels decreased plant length and biomass, but the shoot-to-root length and biomass ratio increased significantly. Photosynthetic pigments (chlorophyll and carotenoids) were quantified using spectrophotometric analysis, while macro- and micro-nutrient contents were determined via the Kjeldahl method, flame photometry, and atomic absorption spectrophotometry. Osmolyte accumulation, including proline and glycine betaine, was analyzed using specific biochemical assays, and antioxidant enzyme activities (SOD, CAT, and POX) were measured to assess redox homeostasis. Photosynthetic pigments in C. maritimum leaves slightly increased at 100 mM NaCl, but significantly declined at 200 and 300 mM NaCl. A high Na content in the shoots indicated no restriction in mineral uptake in the roots. Nitrogen and phosphorus slightly decreased under high salinity. The cation content in the shoots varied: potassium decreased, while calcium and magnesium increased with salinity, although the Mg+2/Na+ and K+/Na+ ratios showed similar declining patterns. The micro-nutrients iron and manganese increased in the shoots, while copper remained unchanged. The content of osmolytes proline and glycine betaine significantly increased under the 200 and 300 mM NaCl treatments. Antioxidant enzyme activities (SOD, CAT, and POX) decreased at 100 and 200 mM NaCl, but were strongly induced at 300 mM NaCl. The total antiradical activity of the leaves increased with higher salinity levels. Our results indicated that the facultative halophyte characteristics of C. maritimum emerged after exposure to 200 mM NaCl. Increased calcium content may be a key factor in salinity tolerance. We concluded that C. maritimum employs strong osmotic adjustment and redox homeostasis mechanisms, making it a promising candidate for cultivation in saline environments.