Effects Of Water And Salt Stress On Seed Germination Of Four Desert Plant Species

Desert plants have formed special germination strategies for survival in the most stressful environment during the plant life cycle. The germianion strategies usually vary among the species. The comparision of the variation is part of the plant diversity study. Haloxylon ammodendron, Reaumuria soongorica, Ceratoides latens and Suaeda glauca play a significant role in the northwest arid desert region of china. The seeds of four species were collected from Alashan arid desert, Inner Mongolia, and a serious laboratory test were, therefore, conducted to study effects of water and salt stress on seed germination of the four desert plants, so are the rate of germination recovery after soaked with different concentration NaCl solutions and osmotic PEG..The main results are as follows:1. The germination declined as osmotic potential decreased from 0 to -3.0 MPa. The lowest thresholds of osmotic potential for seed germination were -3.0 MPa in H. ammodendron and -2.1 MPa in R. soongorica and C. latens and-1.5 MPa in S. glauca. The germination and seedling of H. ammodendron have the highest resistance to drought stresses, Slight drought stress can promote germination, germination index, the plumule growth of R. soongorica and S. glauca, so are germination and radical growth of C. latens. S. glauca grew well between 0 MPa and - 0.9 MPa. The plumule growth of C. latens was inhibited by drought stress all the time.2. The germination declined as concentration of NaCl increased from 0 to1.8 mol/L, The highest thresholds concentration of NaCl for seed germination were 1.8 mol/L in H. ammodendron and 0.6mol/L in R. soongorica and 0.9mol/L in C. latens and 0.5 mol/L in S. glauca. The germination and seedling of H. ammodendron can endure the highest salinity. Sight salt stress can promote germination, germination index, and the radical growth of S. glauca. so is the germination of C. latens. It also stimulated the plumule growth of H. ammodendron, R. soongorica and S. glauca. The germination of R. soongorica was inhibited by NaCl stress all the time, its germination index was always the lowest and its plumule length was always the shortest than the other species'.3. Under optimum condition the germination recovery sequence of four desert species was: Haloxylon ammodendron>Reaumuria soongorica>Ceratoides latens>Suaeda glauca after the relieved stress caused by different concentrations of PEG. solution. For example, seed germination decreased to 10,22,45 and 76 percent respectively after five days stress compared with control. hort time soak with PEG. soulution can promote germination of R. soongorica, stimulate the radical and plumule growth of H. ammodendron, so is the radical growth of R. soongorica and C. latens. Differently, the radical and plumule growth of S. glauca and the plumule growth of R. soongorica and C. lateens were inhibited by different PEG. solution.4. Under optimum condition the germination recovery sequence of four desert species was: Reaumuria soongorica>Haloxylon ammodendron>Ceratoides latens>Suaeda glauca after the relieved stress caused by different concentrations of NaCl solution. For example, the days of germination inhibited entirely were: 50,25,20 and 10 respectively. Short time soak with NaCl solution can promote germination of R. soongorica, stimulate the radical growth of H. ammodendron, R. soongorica and C. lateens, so is the plumule growth of H. ammodendron and R. soongorica.