Effects Of Water, Salt And Tempeture On Seed Germination Of Several Desert Plant Species

Summary:In the present study, the effect of water, salt and temperature on seed germination of several xerophyte desert plant species (Ceratoides arborescens, Haloxylon ammodendron, Heyedysarum scoparium) in arid and saline environments, in order to understand the strategies for adaption of xerophyte desert plant species to arid and saline environments during seed germination stage. The main results are as followed:1. The bracts of Ceratoides arborescens have not inhibit seed germination, and it can be propitious to the seed germination in salinity solution. The germination rate of seed with bracts and without bracts decline significantly as salinity concentration increase, and seeds with bracts are higher than seeds without bracts in germination rate, germination index, germination vigor index. The bracts can absorbe or prevente a part of Na~+ and decrease harm to the embryo.2. The seed germination of two xerophytes Ceratoides arborescens and Haloxylon ammodendron treated with different concentration NaCl solutions and iso-osmotic PEG was inhibited. The inhibitory effects of NaCl and water stress mainly reflected in lowering seed germination rate, delaying initial germination time, and extending germination duration. The effect of NaCl on seed germination was due to both ion toxicity and osmatic stress for Ceratoides arborescens and Haloxylon ammodendron, After be treated seeds in -3.2MPa NaCl solution for 10h, the Na~+ contents increased, the K~+ contents decreased, suggesting that high content of Na~+ may inhibit Ceratoides arborescens and Haloxylon ammodendron seed germination.3. The optimum tempeture for germination of Ceratoides arborescens, Haloxylon ammodendron and Heyedysarum scoparium was 15~25℃,15℃and 15℃, respectively. The germination percentages of Ceratoides arborescens, Haloxylon ammodendron, Heyedysarum scoparium were not effected in low salinity, while severely inhibited in high salinity. The germination of Ceratoides arborescens and Haloxylon ammodendron were very low and Heyedysarum scoparium was very high after ungerminated seeds pretreated with low salinity were transferred to distilled water, the germination of Ceratoides arborescens and Haloxylon ammodendron were very high and Heyedysarum scoparium was very low after ungerminated seeds pretreated with high salinity were transferred to distilled water. High salinity and tempeture induce seeds of Haloxylon ammodendron to remain ungerminated, and seeds germination of the Haloxylon ammodendron can be sured only when tempeture and salinity conditions are favorable; high salinity and tempeture permanent inhabit the germination of the Haloxylon ammodendron.