The elemental composition of halophytes correlates with key morphological adaptations and taxonomic groups

Abstract

Halophytes are crucial in the light of increasing soil salinization, yet our understanding of their chemical composition and its relationship to key morphological traits such as succulence or salt excretion is limited. This study targets this issue by exploring the relationship between the elemental composition of 108 plant species from saline environments in Iran and their eco-morphological traits and taxonomy. Leaves and/or photosynthetic shoots of individual species and soils were sampled and analyzed for 20 elements in plant samples and 5 major elements plus % gypsum content, pH, and EC in soil samples. Eu-halophytes and leaf- and stem-succulent and salt-recreting plants showed high concentrations of Na, S, and Mg and low concentrations of Ca and K. In contrast, pseudo-halophytes, facultative-halophytes and eury-hygro-halophytes, which often lack succulent shoots, showed low Na, S, and Mg and high Ca and K concentrations in their leaves. Clear patterns were identified among taxonomic families, with Chenopodiaceae and Plumbaginaceae having high Na and Mg and low Ca and K concentrations, Caryophyllaceae having high K, Poaceae having low Na, and Asteraceae, Boraginaceae, and Brassicaceae showing high foliar Ca concentrations. We conclude that the elemental composition of halophytes and pseudo-halophytes is related to salt-tolerance categories, eco-morphological types and respective taxonomic groups.