Modeling germination responses of three stem-succulent halophytes of Mediterranean salt marshes to salinity and temperature

Abstract

Quantification of germination niches under salt stress, temperature, and their interaction using population-based threshold models is important to predict seedling emergence patterns. Seeds of Sarcocornia fruticosa, Sarcocornia alpini, and Salicornia emerici were treated with various temperatures at different NaCl concentrations. Results indicated that the median base NaCl concentration was roughly steady (0.68, 0.73, and 0.70M, respectively) at sub-optimal temperature, then decreased linearly at supra-optimal temperature until the ceiling temperature (Tc). The estimated base, optimum and ceiling temperatures, in water, were − 0.5, 15 and 29°C for Sarcocornia fruticosa, − 2.5, 11 and 24°C for Sarcocornia alpini, and 9.5, 25 and 40°C for Salicornia emerici, respectively. At all species, the base temperature has not changed with the salinity while both optimum and ceiling temperatures decreased. Also, Salicornia emerici showed rapid and synchronized germination when salinity decreases during the rainy season coinciding with favorable temperatures compared with other species.