Salinity and temperature effects on germination for three salt-resistant euhalophytes, Halostachys caspica, Kalidium foliatum and Halocnemum strobilaceum

The effects of three salinities (0, 100 and 500 mM NaCl) and four constant temperatures (10, 20, 30 and 35 degrees C) on seed germination of Halostachys caspica (M. B.) C. A. Mey., Kalidium foliatum (Pall.) Mop. and Halocnemum strobilaceum (Pall.) Bieb. were investigated. After seeds were treated with different concentrations of NaCl at constant temperatures of 10-35 degrees C for 16 days, ungerminated seeds were transferred to distilled water for 10 days to investigate the total germination; after this time, the ungerminated seeds from the 10 and 20 degrees C treatments were then moved to 35 degrees C for another 5 days to determine the final germination. The three plant species in the present experiment are salt-resistant euhalophytes growing in high saline soils in the Zhungur Basin in Xinjiang, a northwest province of China. Compared with germination under control conditions, germination percentages of all three species were not affected by 100 mM NaCl at 10-35 degrees C, while severely inhibited by 500 mM NaCl; germination percentages were very low at 10 degrees C up to 100 mM NaCl for all species; the optimum temperature for germination of H. caspica and K. foliatum was 20-30 degrees C, while 35 degrees C for H. strobilaceum, up to 100 mM NaCl; seeds did not suffer ion toxicity for all species, as evidenced by the high total germination after ungerminated seeds pretreated with 500 mM NaCl were transferred to distilled water at constant temperatures of 10-35 degrees C for 10 days, and the high final germination after the ungerminated seeds from the 10 and 20 degrees C treatments were subsequently moved to 35 degrees C for another 5 days; Halostachys caspica had greater sensitivity to increasing temperatures from 10 and 20 degrees C to 35 degrees C compared with the other two species.