Recovery of germination from different osmotic conditions by four halophytes from southeastern Spain

Seeds of four halophytes from southeastern Spain (the perennials Halocnemum strobilaceum, Arthrocnemum macrostachyum and Sarcocornia fruticosa, and the annual Salicornia ramosissima) were exposed to iso-osmotic stress with NaCl, MgCl2, MgSO4 and Na2SO4. The osmotic potential that enforced dormancy in the majority of seeds was determined. The percentage of ungerminated seeds that recovered when they were transferred to distilled water did not differ significantly from the percentage germination of seeds in distilled water controls, irrespective of the salt used to impose the stress. Therefore, the factor responsible For the dormancy of seeds seems ro be the decrease in osmotic potential. Such osmotic pretreatments promoted an increase in the rate of recovery germination which, in Arthrocnemum macrostachyum and Sarcocornia fruticosa, doubled their rates of germination compared to distilled water controls. The osmotic potentials of the soils where the four species occur naturally were more negative than those allowing seeds to germinate after osmotic stress. (C) 2000 Annals of Botany Company.