Salt-alkali tolerance during germination and establishment of Leymus chinensis in the Songnen Grassland of China

The effects of the seed maturation time on salt-alkali tolerance during the germination stage and seedling establishment at different burial depths were determined for the seeds of Leymus chinensis, a species that is considered to be the most promising grass species for grassland rehabilitation in northeastern China. Seeds were collected at different maturation times (24 d, 29 d, 34 d and 39 d after peak anthesis) and germinated under salt stress (NaCl: 50, 100, 200 and 400 mM), alkali stress (Na2CO3: 25, 50, 100 and 200 mM), and also at different burial depths (1-cm, 2 cm and 3 cm). The results showed that the highest germination and recovery percentages in Leymus chinensis were observed for seeds that matured at 39 d after peak anthesis under both salt and alkali stresses, but the lowest percentage was recorded in seeds that matured at 24 d. In addition, the deeper the seeds in the soil, the lower and slower the germination and seedling emergence. A 1-cm depth is optimum for planting the seeds of this species. Moreover, the seeds that matured at 39 d after peak anthesis also showed the strongest vigor at all burial depths. The above results suggest that although these seeds have the ability to germinate at different maturation times, the seeds that matured at 39 d after peak anthesis have the strongest capacity to establish seedlings and resist salt-alkali stress. Our results will help to develop a better understanding of the relations between seed development and quality, and they will also provide an important theoretical basis on how to use the best seeds for restoring deteriorated grassland.