Salt tolerance in Sesuvium portulacastrum

Abstract

Sesuvium portulacastrum, a dicotyledonous halophyte of Aizoaceae family, is a perennial psammophile and potentially useful for the environment protection, e.g. sand dune fixation, desert greenification, landscaping and ornamental uses. This study, which is included in screening programs for cash crop halophytes, was aimed at determining the limits of salt tolerance of this species and identifying physiological and biochemical criteria implied in its capacity to tolerate salinity. Results showed that this species is able to maintain high growth potentialities up to 400 mM NaCl in the medium. Above this concentration, a significant growth reduction was observed, and associated with Na⁺ and Cl⁻ accumulation and tissues impoverishment of K⁺ and Ca²⁺. For the purpose of identifying the factors limiting plant growth in the presence of salt excess, an experiment with a split-rooting system was carried out. It showed that NaCl induced decrease of growth resulted from indirect salt effects (e.g. restriction of K⁺ and Ca²⁺ uptake) rather than that from direct salt effects (high Na⁺ and Cl⁻ accumulation in tissues).