Studies On Relationship Of Seed Dormancy And Germination Of Two Important Psammophvtes Inhabiting Old Channel Of Lower Yellow River With Their Sandy Environments

Plants play an important role in the restoration and reconstruction of desertificating areas, and the study on physiological and ecological adaptation of their seeds may have great application prospects. However, most studies are on ecological restoration of sandy lands in the inland arid and semi‐arid regions, and few studies are related to sandy areas in the riverbed of semi‐arid regions. Using the two different life‐history plants inhabiting the semi‐fixed sand dunes in old channel of lower Yellow River, Lespedeza potaninii Vass.and Corispermum chinganicum Iljin we studied what type of are the seed dormancy of these two species and how their seeds adapted to sandy environments. The main conclusions are as follow:1．The seed dormancy of L. potaninii was physical dormancy. The water imbibition of scarified seeds was significantly higher than that of intact seeds. And at all temperatures, the percentages of germination of scarified seeds were up to100%, but percentages of intact seeds were lower than10%.2. Sulfuric acid has an significant impact on dormancy breaking of L. potaninii seeds. All treatments with sulfuric arid can significantly improve the germination percentage of their seeds (p<0.05). At the treating time from5min‐25min, the percentage of seed germination at20minutes was highest.3. The percentages of seed germination of L. potaninii can be remarkably improved by dry heat and wet heat, especially dry heat. As the increase in treating time, seed germination first increased and then decreased. Under dry hot conditions, the germination percentage was highest to95%after treated at80℃for30min. While under wet hot conditions, it was highest after treated at65for30min, up to86%.4. The germination percentage of seeds of L. potaninii on the sand surface was highest after one month of burial in different depth of sand layers in its habitat. As the increases in burial time and depth, the dormancy breaking of their seeds decreases, and thus these seeds will forme potential soil seed bank.5The scanning electron microscope observation showed that there were no cracks on the seed coat of freshly mature seeds of L. potaninii, but obvious cracks appeared in special area of seed coat and then other areas after these seeds were treated by dry heat, wet heat and buried in sand. This may explain why freshly mature seeds did not germinate but they germinated after treated.6. The inherent dormancy of seeds of C. chinganicum was shallow physiological dormancy. And seed germination of this species was inhibited by light.7. The germination percentage of freshly mature seeds of C. chinganicum at variable temperature was higher than that at constant temperature whenever under dark or light conditions. The germination percentage of their seeds was highest at5/15℃under dark conditions.8. When seeds of C. chinganicum were buried in their natural habitat, the germination percentage was highest at5cm.