Background The salt composition of soda saline-alkali soil is dominated by Na₂CO₃ and NaHCO₃. This type of soil has both salinization and alkalization characteristics. It not only is of strong alkalinity, but also has poor physical and chemical properties, which severely restricts local agricultural production. Planting vegetation adapting to the growth site conditions of soda saline-alkali land is an important measure for the improvement and utilization of soda saline-alkali land. The purpose of this study is to investigate the alkali-tolerant range and alkali-resistance properties of Suaeda salsa.

Methods Using S. salsa seeds as test materials, NaHCO₃ and Na₂CO₃ were mixed at a molar ratio of 9:1, and a total of 6 treatment concentrations of 0 (CK), 50, 100, 150, 200, and 250 mmol/L were set, respectively. And the experiments was carried out with two culture media of distilled water and soda saline-alkali soil, and the difference of seed germination and seedling growth status of S. salsa were analyzed.

Results 1) In the experiment with distilled water as the culture medium, the germination potential, germination rate and germination index of S. salsa seeds were significantly lower than that of CK when the alkali concentration was > 150 mmol/L, and the length of the embryo, the length of the radicle and the seed vigor index were significantly lower than that in CK when the alkali concentration was > 100 mmol/L. 2) In the experiment with soda saline-alkali soil as the culture medium, when the alkali concentration was > 200 mmol/L, the germination rate and seedling surviual rate of S. salsa seeds significantly reduced by 19.36% and 38.10% compared with CK, respectively; under 50 and 100 mmol/L alkali concentration treatment conditions, the young shoot length significantly increased by 23.82% and 19.96% compared with CK, and the young root length of S. salsa was significantly lower than that of CK when the alkali concentration was > 50 mmol/L. 3) The results of redundancy analysis showed that soil EC value and total alkalinity were the main factors affecting the growth of S. salsa, and the degree of interpretation was 48% and 41.1%, respectively; and there was a significant negative correlation with the growth indexes of S. salsa.

Conclusions The seed germination and seedling growth of S. salsa can tolerate a certain range of alkali stress, and the alkali resistance range of S. salsa in the soda saline-alkali soil is higher than that in distilled water.