Germination screening of nine annual Amaranthaceae halophytes identifies candidates for saline-alkali tolerant crop...

Screening of halophytes is the key to biological improvement of saline-alkali soils. This study sought to determine the influence of low, moderate, and high combined saline-alkaline stress on the germination period of different halophytes and evaluate the salt-alkali tolerance of halophytes.

The paper-based culture method be used to determine the germination and growth indices of 9 halophytes under low, moderate, and high combined saline-alkaline stress.

The study emphasizes (1) the germination strategies of the 9 annuals halophytes showed significant differentiation, falling into 2 categories: "rapid-type" and "slow-type". Seeds of Suaeda corniculata, Halogeton arachnoideus (LZ), and Chenopodium quinoa belonged to "rapid-type", completing germination within merely 1~3 days. (2) The combined saline-alkali stress exerted a typical "low-promotion and high-inhibition" effect. Under moderate stress (MS, salt content 0.55%, pH 8.90, EC 6.38 mS cm^-1), the fresh weight of Salicornia europaea, Atriplex centralasiatica and Chenopodium glaucum was significantly higher than that of low stress (LS, salt content 0.27%, pH 8.03, EC 3.62 mS cm^-1) and high stress (HS, salt content 0.73%, pH 9.63, EC 9.54 mS cm^-1) treatments. Specifically, compared with the LS treatment, the fresh weights were increased by 18.73%, 9.87%, and 13.42% for the three species, respectively; compared with the HS treatment, the corresponding increases were 71.76%, 88.95%, and 127.46%, respectively. High stress preferentially inhibited radicle length, thereby affecting biomass. Taking Atriplex centralasiatica and Chenopodium quinoa as examples, the inhibition rate of radicle length (94.19%, 95.57%) was significantly higher than that of inhibition rate of germ length (40.54%, 32.48%). (3) Correlation analysis revealed a positive correlation between seed germination vigor and root development along with biomass accumulation. Seed germination performance in saline-alkali environments is determined by the plant's genetic background, the external stress intensity, and their complex interaction.

Suaeda salsa demonstrated the strongest overall tolerance, while Suaeda corniculata, Salicornia europaea, and Halogeton arachnoideus are recommended for rehabilitating high, moderate, and low saline-alkali soils, respectively. This study elucidates halophyte germination strategies under combined saline-alkali stress, providing a theoretical basis toward effective species selection for saline-alkali land bioremediation.