Shift in Metabolite Profiling and Mineral Composition of Edible Halophytes Cultivated Hydroponically Under Increasing...

A significant concern today is the dependence on low-quality water sources, such as saline water, in hydroponic systems, especially due to the scarcity of freshwater. Halophytes and salt-tolerant species have emerged as viable candidates for cultivation in saline hydroponics. However, their agronomic performance and physiological responses within hydroponic systems require further investigation.

This research aims to explore the potential of edible halophytes grown in saline nutrient solutions within hydroponic systems within salt-tolerant ranges, focusing on their metabolic profiles and mineral accumulation.

Plantago coronopus (L.), Portulaca oleracea (L.), and Salsola komarovii (Iljin) were grown in walk-in controlled environment chambers in deep water culture hydroponic systems, at 0, 50, 100, 150, and 200 mM·L^-1 NaCl salinity; 16h, 250 µmol m^-2 s^-1, and wide LED spectrum lighting was maintained.

A significant decrease in organic acids, and fresh and dry weight under high saltinity was observed in Plantago coronopus and Portulaca oleracea, but not in Salsola komarovii. An increase in hexoses, particularly glucose, violaxanthin and β-carotene, P⁺ and Zn²⁺, along with a decrease in lutein, K⁺ and Ca²⁺ levels across salinity levels from 0 to 200 mM NaCl was observed in all treated halophytes. Increased salinity did not significantly affect total protein accumulation.

These findings reveal that different shifts in osmolytes, mineral elements, and biomass accumulation in tested halophytes indicate species-dependent osmotic adjustment to increased salinity and may be attributed to the morphological differences among halophytic grasses, dicot halophytes, and those with succulent leaves or stems. The PCA score scatterplot results excluded the response of Plantago coronopus from other tested halophytes; also, it demonstrated that Portulaca oleracea was more sensitive to the hydroponic solution salinity compared to Salsola komarovii and Plantago coronopus.