Na₂SeO₃ seed priming improves seed germination, seedling growth and rhizosphere microbial community structure of Sugar Beet (Beta vulgaris L.) under salt stress

• The adverse effects of salt stress on the germination of sugar beet seeds, the growth of seedlings, as well as the physiological and biochemical aspects. • Seed priming with Na₂SeO₃ can enhance the germination rate and vigor level of sugar beet seeds under salt stress. • Seed priming with Na₂SeO₃ can activate the defense mechanism of sugar beet to alleviate the damage caused by salt stress. • Rhizosphere soil microorganisms play an important role in increasing plant growth parameters under salt stress. Globally, the problem of soil salinization is becoming increasingly severe, posing a serious threat to agricultural production and food security. Sugar beet, as an important sugar - producing crop, is extremely sensitive to salt stress during the seed germination and seedling growth stages. Existing studies have shown that the priming treatment with Na₂SeO₃ has certain potential in coping with salt stress. This study aimed to explore the effects of the Na₂SeO₃ priming treatment on the germination of sugar beet seeds, the growth of seedlings, and the structure of rhizosphere soil microorganisms under salt stress conditions during germination and pot - planting. The research results indicated that salt stress significantly inhibited the germination of sugar beet seeds and the growth of seedlings, reduced the content of photosynthetic pigments, disrupted the ion balance, and increased the degree of membrane lipid peroxidation. However, the priming treatment with Na₂SeO₃ could effectively alleviate these negative effects. Appropriate concentrations (20 μM and 30 μM) of Na₂SeO₃ could accelerate seed germination, improve the seed vitality level, promote seedling growth, increase the content of photosynthetic pigments, improve the ion balance, increase the contents of soluble sugars and soluble proteins, reduce the content of malondialdehyde (MDA), and enhance the activities of antioxidant enzymes. In addition, the study also found that the Na₂SeO₃ priming treatment had a positive regulatory effect on the structure of the rhizosphere soil microbial community. Within a certain concentration range, Na₂SeO₃ could increase the number of microbial species in the rhizosphere soil and significantly enhance the richness and evenness of the community. Under different treatments, the composition of the rhizosphere microbial community showed obvious differences, and there were significant correlations between some dominant genera and plant physiological indicators. In conclusion, the priming treatment with an appropriate concentration of Na₂SeO₃ could significantly enhance the tolerance of sugar beet seeds and seedlings to salt stress, optimize the structure of the rhizosphere microbial community, providing a scientific basis for salt - tolerance research of sugar beets and the screening and development of seed coating agents.