Abstract: Seed dormancy in the populations of Eremosparton songoricum, Ammodendron bifolium and Glycyrrhiza uralensis from the Gurbantunggut Desert and Tucker Guillermo Chonghuer Desert, Xinjiang was investigated through laboratory experiments with a view to understand the dormancy release mechanisms and population adaptation strategies. The treatments were the manual scarification, cold stratification (5 ℃), dry-hot and wet-hot treatments at simulated high temperature field conditions. The results showed that the three species had hard seed coat, there was no significant effect of cold stratification on dormancy release of these seeds. However, manual scarification broke effectively the seed physical dormancy. Dry-hot and wet-hot treatments and the treatment duration affected significantly the dormancy breaking of the three species, but treatment interactions were not important for E.songoricum and A.bifolium. There was a positive correlation between the dormancy release percentage and the temperature for E.songoricum and A.bifolium seeds, but a negative one for G.uralensis seeds. The dormancy release percentages of E.songoricum and A.bifolium seeds were the highest at 80 ℃ and 65 ℃, reaching (70.48±2.92)% and (78.13±3.67)% respectively. While the dormancy release percentage of G.uralensis seeds was decreased with the increase of temperature, and the highest germination percentage reached (85.23±3.82)% at 40 ℃. The wet-hot treatment was the most effective for dormancy release of the three species. Results suggested that the extremely high temperature in summer is effective to release seeds from dormancy, however rare precipitation is the main inhibitor of seed germination, and may cause the low seedling rate and survival rate of the three endangered species.

Key words: desert plant, seeds, temperatures, dry/wet conditions, physical dormancy