Assessment of phyto-compatibility after soil remediation: Insights from plant growth, physiological, and metabolomic analyses

Soil contamination from heavy metals and organic pollutants represents a significant global concern. In this context, biochar and microbial communities have been identified as promising remediation tools. Indeed, the structural characteristics of biochar facilitate contaminant immobilization, while the presence of microbial communities promotes their biodegradation, thereby enhancing soil recovery. Besides, phytoremediation has been successfully applied to restore contaminated soils. Historically, the success of soil remediation has been predominantly contingent on chemical parameters. However, recent approaches have focused on soil health, fertility, and ecological function after remediation. In this framework, through phytotoxicity tests, this study investigates the phyto-compatibility of a soil contaminated with hydrocarbons and copper after the treatment with 5 distinct remediation strategies: i) natural attenuation (S), ii) treatment with biochar (SB), iii) treatment with microorganism-enriched biochar (SBB), iv) treatment with biochar and phytoremediation (SBP), and v) treatment with microorganism-enriched biochar and phytoremediation (SBBP). Moreover, chlorophyll fluorescence and untargeted metabolomics analyses were performed in plants to get a more comprehensive understanding of responses of plants grown on remediated soil. The results of this study demonstrated significant variations among the plants treated with soil recovered from the different remediation strategies. Compared to other treatments, SBB promoted L. sativum plants growth showing limited induction of stress markers. However, a certain degree of photoinhibition was observed in all treatments, highlighting the importance of characterizing the phyto-compatibility of remediated soils.