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

This study deeply explored the multiple impacts of sodium selenite priming on the germination, growth, physiology, and rhizosphere microbial community of sugar beet seeds under salt stress. The results showed that salt stress had a significant inhibitory effect on the germination and growth of sugar beet seeds and seedlings. Using sodium selenite as a seed priming agent to soak sugar beet seeds, the experiment found that low-concentration sodium selenite soaking could significantly improve the germination and growth of sugar beet seeds and seedlings under salt stress, but when the sodium selenite concentration was too high (such as 40 μM), it had an inhibitory effect on the germination and growth of sugar beet seeds and seedlings. In addition, sodium selenite seed soaking could increase the contents of chlorophyll and carotenoids, maintain ion balance, increase the content of soluble sugar and soluble protein, maintain cell elasticity and cell membrane stability, and improve the plant's resistance to salt stress. Salt stress led to a significant increase in the content of malondialdehyde (MDA) in sugar beet seedling leaves, and after sodium selenite soaking, the MDA content could be significantly reduced, reducing the accumulation of reactive oxygen species (ROS) and lipid peroxidation of cell membranes. At the same time, it could increase the activities of antioxidant enzymes (SOD, POD, CAT, and APX), promote the clearance of intracellular ROS, and protect plants from oxidative damage. Low-concentration sodium selenite soaking could increase the richness and diversity of the rhizosphere bacterial community of sugar beets under salt stress. Different concentrations of sodium selenite soaking would lead to different enriched bacteria in the microbial community. Microorganisms might interact with plants, participate in plant growth and development, maintain species diversity and community structure stability, and thus improve the salt tolerance of sugar beets. Sodium selenite soaking made the differential species in each group different, and they might be important species for maintaining the health of saline-alkali soil, but their specific functions still needed further research. As a priming agent, sodium selenite still needed further in-depth research on the specific molecular mechanism of improving plant salt tolerance. In the future, multi-year field trials could be carried out to verify its effect in actual production, and the use concentration of sodium selenite could be further optimized to better play its role in improving the salt tolerance and yield of sugar beets, providing new ideas and methods for improving the cultivation and production of sugar beets.