Relationship Between Ion Content in Seed and Spongy Coat of the Medicinal Halophyte Crithmum maritimum L. and Germination Capacity

Abstract

Halophytes thrive in a wide range of habitats and climates, which may largely determine the seed mineral content, and hence influence both their germination capacity and their subsequent establishment. In order to assess this hypothesis, we performed a comparative study on three Tunisian proveniences of the perennial oilseed halophyte Crithmum maritimum L. The ion (Cl-, K+, and Na+) contents in seeds and fruits were determined and their likely relationship to germination capacity was addressed. Whether seeds were sown in distilled water or under moderate salt solution (100 mM NaCl) germination of the three proveniences was negatively correlated with the seed K+, Na+ and Cl- content. The spongy coats (fruits) were found to accumulate much more Na+ and Cl- than seeds (up to aprox. 8- and 11- fold, respectively for Na+ and Cl-), indicating that efficient mechanisms may take place in order to protect seeds from the harmful accumulation of salt. In addition, the higher selectivity for K+ vs. Na+ within seeds as compared to fruits seemed to be a determining factor in germination capacity of this species.