Seed Germination and Seedling Growth in Suaeda salsa (Linn.) Pall. (Amaranthaceae) Demonstrate Varying Salinity Tolerance among Different Provenances

SIMPLE SUMMARY: Soil salinization is a widespread problem, causing soil degradation and limiting agricultural productivity worldwide. However, the protection and restoration of halophyte species communities can effectively help improve and reconstruct saline–alkali land. We collected seeds of Suaeda salsa (Linn.) Pall., a highly salt-tolerant and widely distributed halophytic species, from seven different saline–alkali habitats, numbered S1–S7, of Songnen Plain, China, and tested their germination and seedling growth responses to saline–alkali stress. Results showed a strong saline–alkali tolerance in S. salsa seeds, but the germination characteristics and saline–alkali tolerance varied across provenances, highlighting the geographical variations in germination responses. The saline–alkali tolerance of S1 and S7 locations was significantly higher than that of others. Suaeda salsa has important applications in the restoration of saline–alkali soil. However, the seeds from appropriate provenances must be screened to ensure the best saline-alkaline tolerant variety. The germplasm materials from the selected varieties can also be used as high-quality sources to study the mechanism of saline–alkali tolerance in halophytes. These seeds can also serve as excellent germplasm resources for the restoration of saline–alkali soil. ABSTRACT: Salinity is a pressing and widespread abiotic stress, adversely affecting agriculture productivity and plant growth worldwide. Seed germination is the most critical stage to seedling growth and establishing plant species in harsh environments, including saline stress. However, seed germination characteristics and stress tolerance may vary among geographical locations, such as various provenances. Suaeda salsa (Linn.) Pall. (S. salsa) is a halophytic plant that exhibits high salt tolerance and is often considered a pioneer species for the restoration of grasslands. Understanding the germination characteristics and stress tolerance of the species could be helpful in the vegetation restoration of saline–alkali land. In this study, we collected S. salsa seeds from seven different saline–alkali habitats (S1–S7) in the Songnen Plain region to assess the germination and seedling growth responses to NaCl, Na(2)CO(3,) and NaHCO(3), and to observe the recovery of seed germination after relieving the salt stress. We observed significant differences in germination and seedling growth under three salt stresses and among seven provenances. Resistance to Na(2)CO(3) and NaHCO(3) stress was considerably higher during seedling growth than seed germination, while the opposite responses were observed for NaCl resistance. Seeds from S1 and S7 showed the highest tolerance to all three salt stress treatments, while S6 exhibited the lowest tolerance. Seeds from S2 exhibited low germination under control conditions, while low NaCl concentration and pretreatment improved germination. Ungerminated seeds under high salt concentrations germinated after relieving the salt stress. Germination of ungerminated seeds after the abatement of salt stress is an important adaptation strategy for black S. salsa seeds. While seeds from most provenances regerminated under NaCl, under Na(2)CO(3) and NaHCO(3), only seeds from S4 and S7 regerminated. These findings highlight the importance of soil salinity in the maternal environment for successful seed germination and seedling growth under various salinity-alkali stresses. Therefore, seed sources and provenance should be considered for vegetation restoration.