Physiological Adaptation to Water Salinity in Six Wild Halophytes Suitable for Mediterranean Agriculture

Owing to the high interspecific biodiversity, halophytes have been regarded as a tool for understanding salt tolerance mechanisms in plants in view of their adaptation to climate change. The present study addressed the physiological response to salinity of six halophyte species common in the Mediterranean area: <i>Artemisia absinthium, Artemisia vulgaris, Atriplex halimus, Chenopodium album, Salsola komarovii</i>, and <i>Sanguisorba minor</i>. A 161-day pot experiment was conducted, watering the plants with solutions at increasing NaCl concentration (control, 100, 200, 300 and 600 mM). Fresh weight (FW), leaf stomatal conductance (GS), relative water content (RWC) and water potential (WP) were measured. A principal component analysis (PCA) was used to describe the relationships involving the variables that accounted for data variance. <i>A. halimus</i> was shown to be the species most resilient to salinity, being able to maintain FW up to 300 mM, and RWC and WP up to 600 mM; it was followed by <i>C. album</i>. Compared to them, <i>A. vulgaris</i> and <i>S. komarovii</i> showed intermediate performances, achieving the highest FW (<i>A. vulgaris</i>) and GS (<i>S. komarovii)</i> under salinity. Lastly, <i>S. minor</i> and <i>A. absinthium</i> exhibited the most severe effects with a steep drop in GS and RWC. Lower WP values appeared to be associated with best halophyte performances under the highest salinity levels, i.e., 300 and 600 mM NaCl.