Germination and antioxidant responses to salt stress of Tunisian endemic Limonium species at early vegetative stage

Halophytic plants growing in extreme environments have developed morphological, anatomical, biochemical and physiologi- cal adaptations. In this research, the effect of salinity (up to 500 mM NaCl) on the germination parameters and the antioxidant responses of two halophytic Limonium species was evaluated. Seed germination parameters (rate, speed), ROS production and the contents of phenolic compounds and antioxidant enzymes of Limonium delicatulum and Limonium vulgare were investigated, with respect to their tolerance to salt treatments and their ability to recover from salt stress conditions. L. vulgare seeds were less affected by salt treatments than L. delicatulum, and consequently recovered more rapidly full germination. Moreover, L. vulgare seedlings had more antioxidant phenolics and enzyme activities than L. delicatulum. The highest ability of L. vulgare to recover from salt treatment might be the result of its adaptation to a highly stressful environment constituted by inland salty soil, whereas L. delicatulum grows closer to the sea, thus receiving diluted salt spray. This distinction makes L. vulgare a good candidate for biosaline agriculture as edible crop plant.