Salinity Stress as an Elicitor for Phytochemicals and Minerals Accumulation in Selected Leafy Vegetables of Brassicaceae

The potential role of NaCl (50–200 mM) as an eustressor for the accumulation of health promoting phytochemicals and maintaining the homeostasis of macro- and micro-elements in three, hydroponically grown Brassica leafy vegetables (Chinese cabbage, white cabbage, and kale) was investigated. Considering K+/Na+ ratio and proline contents as reliable stress markers, we confirmed more prominent stress status in Chinese cabbage followed by white cabbage and kale. Low to moderate salinity treatments (50 and 100 mM NaCl) caused an increase in most of the phenolic compounds in the analyzed Brassica leafy vegetables. Total glucosinolates were elicited by NaCl in a dose dependent manner. Salt treatment caused an increase in total chlorophylls but did not significantly affect carotenoid content. Furthermore, low to moderate treatments did not significantly disturb homeostasis of macro- and micro-elements, particularly in white cabbage and kale where the K level did not decrease significantly and Ca was even increased in white cabbage. We may conclude that salinity may elicit phytochemical accumulation in selecting vegetables grown on saline soils without undesirable disturbance in macro- and micro-elements homeostasis depending on salt concentration and species/varieties. This information may be of great importance in the selection of crops grown on saline soils.