Seed germination responses to salinity and temperature in Limonium supinum (Plumbaginaceae), an endemic halophyte from Iberian Peninsula

Abstract

Limonium supinum, a perennial herb with interest for the restoration and gardening of arid zones, is widely distributed in saline areas from southeastern Iberian Peninsula. Laboratory experiments were carried out to assess the effects of temperature and salinity on seed germination and on germination recovery from the effects of saline conditions after transfer to distilled water. Seed germination responses were determined over a four temperature regimes (20/10, 25/15, 30/20 and 35/25 °C; 12 h light/12 h dark photoperiod) and six salinities (0, 100, 150, 200, 400 and 600 mM NaCl). The higher germination percentages were obtained in non-saline conditions, under all temperature regimes. An alternating temperature of 20 °C light and 10 °C dark yielded the maximum germination for any saline concentration. Increase in salinity delayed the beginning and end of germination and reduced the final percentage of germination, which becomes completely inhibited at 600 mM NaCl. The adverse effect of salinity is reinforced by high temperatures (30/20 and 35/25 °C). The germination rate was also negatively affected by the increase in salinity and temperature. The final recovery percentages in high salt treatments were near 100%, indicating that exposure to high concentration of NaCl did not inhibit germination permanently.