The combined Cp2-EPS and rhizobium inoculation enhance the growth of alfalfa under salt stress

Abstract The interaction of plant and soil microbial communities can promote plant growth and increase stress tolerance. Exopolysaccharide (EPS) is a secondary metabolite produced by certain bacteria and important signal molecules between plants and microorganisms, which has the potential to alleviate salt stress in plant. The study explored the effects of combined Erwinia persicina Cp2-EPS and rhizobium strain (Gz5) inoculation on seed germination and seedling growth of alfalfa under salt stress. The results showed that under 100 mmol·L-1 NaCl stress, each treatment had a very significant positive effect on seed germination and seedling growth compared with the control. The germination index aboveground and underground fresh and dry weight, aboveground and underground length, root index, chlorophyll content, SOD and CAT activities and SS content of combined Cp2-EPS and Gz5 inoculation both achieved maximum value, MDA and H2O2 content reached a minimum value. And relative conductivity and preserved amino acid content were significantly improved compared with the control. Therefore, combined inoculation had positive effects on seed germination and seedling growth of alfalfa under salt stress, and had a more remarkable effects than single inoculation (R/EPS). Our findings provided valuable insights for enhancing the salt tolerance of alfalfa and saline-alkali land improvement.