Diversity in the response of two potential halophytes (Batis maritima and Crithmum maritimum) to salt stress

Abstract

In this study, we compared the response to NaCl of Batis maritima and Crithmum maritimum, two potential halophytes with a different range of salinity tolerance. At high NaCl concentrations (800 mM for B. maritima and 300 mM for C. maritimum), the growth of both plants was significantly reduced. A split root experiment aimed at determining whether high NaCl conditions limit growth of plants through toxic effects of excessive salt accumulation in shoots or through impairment of some essential nutrient acquisition. The split root experiment was performed with three treatments. In the first treatment (B/S), half of the roots were immersed in a basal medium (B) and the other half in the same medium supplemented with NaCl (S). In the two other treatments, the two halves of the root system were immersed either in salt-free medium (B/B) or in the basal medium containing salt (S/S). Under split-root conditions, B. maritima and C. maritimum accumulated Na in their shoots, and displayed improved growth as compared to control plants. In C. maritimum, the B/S treatment partially restored K provision to the shoots but not that of Ca, suggesting that the inhibition of K⁺ uptake by salt could only limit its growth under high salinity. In B. maritima (B/S plants), the concentration of K⁺ and Ca²⁺ were diluted by growth. The inhibition of K⁺ and Ca²⁺ uptake by salt did not seem to limit growth of B. maritima growth under high salinity. The growth of B. maritima and C. maritimum could be also limited by the restriction imposed by NaCl on N uptake.