Effects Of Temperature, Salt Stress, Alkaline Stress And Their Interactions On Seed Germination Of Leymus Chinensis In The Songnen Grassland

The Songnen grassland, located in Northeast China, is famous for the natural grassland, which has important economic value and ecological significance. In recent years, due to the continuous degradation of grassland, especially the increasing serious salinity problem has seriously influenced the development of animal husbandry and environment project. Leymus chinensis, also known as alkali grass, is a typical perennial rhizomatous species of Gramineae, widely distributed in the Northeast China Plain, the Northern China Plain and the Loess Plateau of China. As the dominant species in the Songnen grassland, it plays significant roles on the restoration of degraded grassland.This study researched of three major non-biological factors (temperature, salinity and alkalinity) and their interactions effects on seed germination of Leymus chinensis. The results showed that, 20-30°C was the most suitable temperature for seed germination of Leymus chinensis, higher temperature and lower temperature were both significantly decreased the germination percentage and germination rate, and in this temperature, saline stress and alkaline stress effected on the inhibition of seed germination could be reduced to some extent. The germination percentage of Leymus chinensis declined even more sharply under alkaline stress. (Temperature and salinity, temperature and alkalinity) their interactions significantly affected germination percentage and germination rate, especially at 25-35°C, seeds germinated the worst at high saline and alkaline concentrations. The germination recovery percentages of non-germinated seeds under saline and alkaline stress were the highest at 20-30°C. The germination recovery percentages increased with the augment of saline concentration under saline stress, whereas under alkaline stress, the germination recovery percentages first increased and then decreased, so that high alkaline stress made seeds lose their vitality and die, the germination recovery percentage of seeds at alkaline stress was lower than that at salt stress. The germination recovery percentages at high temperature-salinity and temperature-alkalinity interactions were the lowest.Under the salinity-alkalinity mixed stress, the germination percentage and germination rate of Leymus chinensis decreased gradually with the gradual increasing of the proportion of alkaline salts. When the salt concentration was low (50mM), in each treatment group, the germination percentage was still higher, there were no significant difference among all the groups, while with the increasing of salinity, the interactions of high pH and high salinity severely inhibited seed germination of this species, especially in the F treatment, when the salt concentrations >150mM, seeds lost the capacity of germination. With the increase of salt concentration, the germination recovery percentage of seeds raised in each treatment group, when the salt concentration was 250mM, the germination recovery percentage of seeds was the highest.Our study showed the differences between temperature-salinity and temperature- alkalinity effect on seed germination of Leymus chinensis, and also showed that the laws of Leymus chinensis seed germination under different pH and salinity in the Songnen grassland, the data will provide a theoretical basis for sowing Leymus chinensis reasonably and timely in the Northeast degraded grassland.