Soil-Plant Interactions Contribute to the Mineral Composition, Nutritional Quality, and Bioactive Potential of Wild Salicornia europaea L. Populations in Solonchaks of the Bulgarian Black Sea Coast.

Halophytes are valuable models for understanding plant adaptation to saline environments and for developing sustainable crops under increasing soil salinization and freshwater scarcity. Salicornia europaea L. is a highly salt-tolerant edible euhalophyte with considerable nutritional and functional potential. However, the influence of natural variability in Solonchak soils on the nutritional composition, mineral profile, and phytochemical characteristics of wild populations remains insufficiently understood. This study investigated the nutritional composition, mineral profile, antioxidant potential, oxalate content, and soil-plant relationships of six wild S. europaea populations growing on coastal Solonchak soils along the Bulgarian Black Sea coast. The studied soils were characterized by high electrical conductivity (up to 42.10 mS/cm) and strongly alkaline conditions (pH > 9.0). The aboveground biomass was characterized by high ash (48.49 ± 2.46%) and protein (12.91 ± 1.67%) contents, low fiber (6.02 ± 1.11%) and fat (1.03 ± 0.11%) contents, and total oxalates (11.26 ± 3.2 g/100 g), all on a dry weight basis. Na was the predominant mineral (13,866 ± 937 mg/100 g DW), followed by K, Mg, Ca, P, and Fe. The studied populations exhibited high levels of TPC, TFC, and antioxidant activity, reaching 28.6 mg GAE/g, 252.8 mg CE/g and 20.0 µmol TE/g dry weight, respectively. Correlation analysis revealed significant relationships between soil properties and plant mineral composition, oxalate content, and antioxidant traits, indicating that these characteristics are associated with multiple soil factors rather than salinity alone. These findings highlight the potential of wild S. europaea as a valuable source of minerals, protein, and bioactive compounds for functional foods and sustainable agriculture on saline soils.