Bioorganic fertilizers improve the adaptability and remediation efficiency of Puccinellia distans in multiple heavy metals-contaminated saline soil by regulating the soil microbial community

Soil salinization and heavy metals (HMs) pollution have become global environmental problems. Bioorganic fertilizers have a potential role in improving the phytoremediation efficiency of HMs-contaminated saline soils, but its microbial mechanism has not been explored. This study investigated the role of bioorganic fertilizers in improving phytoremediation of natural HMs-contaminated saline soils, and revealed its mechanism from the perspective of microbial interactions and functions. For this purpose, greenhouse pot trials of three treatments were performed, including control (CK), manure bioorganic fertilizer (MOF), lignite bioorganic fertilizer (LOF) treatments. The results showed that compared with CK, MOF and LOF significantly increased the shoot (453% and 1105%), root biomass (249% and 364%) and the accumulation of HMs (Pb, Cd, As, Zn and Cu), Na and Ca (41% to 2065%) of Puccinellia distans, with the highest in LOF. Soil physical and chemical properties (including soil organic carbon, water-stable aggregates and available nutrients) were significantly improved with MOF and LOF application. LOF enriched more beneficial biomarkers. Network analysis confirmed that MOF and LOF increased the number of bacterial functional groups and enhanced the correlation between fungi; Bacteria play a greater role in phytoremediation; The correlation of microorganisms with plant growth, HMs and salt accumulation was increased; LOF possesses more the correlations between microorganisms and plant, which improved the phytoremediation efficiency better. Most of the keystone taxa identified in MOF and LOF had roles in promoting plant growth and stress resistance. In summary, this study suggested that MOF and LOF further improve the phytoremediation efficiency by enhancing the interaction between microorganisms, soil and plants, among of LOF plays a greater role.