Mitigating salt stress in Zea mays: Harnessing Serratia nematodiphila-biochar-based seed coating for plant growth promotion and rhizosphere microecology regulation

Salt stress poses a significant challenge in contemporary agricultural practices. In response, using plant growth-promoting bacteria (PGPB) in conjunction with biochar coatings has emerged as an innovative biological strategy to mitigate salt stress in crops. Through a dual screening process based on gradient salt concentration and plant growth-promoting performance, a highly salt-tolerant PGPB, Serratia nematodiphila , was identified in this study. And a seed-coating formulation incorporating S. nematodiphila was developed using biochar as a carrier. With the help of potting experiments, this paper investigated the impact of this S. nematodiphila -biochar-based seed coating on Zea mays under salt stress, while also analyzing functional alterations in the core microbial community. These findings indicate that the S. nematodiphila -biochar-based seed coating selectively enriched beneficial microbial populations, such as Proteobacteria, Gammaproteobacteria, Verrucomicrobiae, and Bacteroidia, fostering a symbiotic association with the Z. mays root system. These beneficial consortia facilitated the accumulation of osmotic solutes, including soluble sugars, soluble proteins, and proline, thereby modulating leaf photosynthetic activity and alleviating salt stress (sodium and potassium homeostasis) in Z. mays . This investigation provides refined technical approaches for alleviating salt stress in Z. mays , contributing to developing sustainable agricultural practices. • Created a seed coating agent with S. nematodiphila and biochar. • Seeds coated with S. nematodiphila and biochar mitigated salt stress in Zea mays. • S. nematodiphila- biochar-based seed coating recruited beneficial bacterial communities. • Specific soil bacterial community can influence salt tolerance in Z. mays.