Distinct Vermicompost Fractions Improve Salt Stress Tolerance in Arabidopsis via Antioxidant Defense and Metabolic Reprogramming

Modern agriculture seeks eco-friendly alternatives to support plant growth under abiotic stress. This study explored the effects of three distinct vermicompost (VC) fractions on Arabidopsis plants under salt stress using integrated metabolomics and phenotyping. Salt stress caused significant oxidative damage, evident from elevated MDA and EL levels, and impaired photosynthetic efficiency, as shown by reduced Fv/Fm and qP. It also triggered the accumulation of stress-related metabolites like GABA and proline. Application of VC, particularly DOM1 and DOM2 (aqueous extracts of vermicompost), significantly alleviated these adverse effects, improving photosynthetic performance and reducing oxidative stress markers. DOM1 decreased MDA by 71% as compared to the control under stress conditions. VC treatments also enhanced antioxidant defense, as indicated by a higher GSH/GSSG ratio. Specifically, the DOM1 application increased the GSH/GSSG ratio by 101% under optimal conditions and 103% under stress conditions compared to the control. Metabolomic analyses revealed a shift from stress-induced secondary metabolites to primary metabolites (e.g., D-ribulose-1,5-bisphosphate, trehalose 6-phosphate) linked to improved growth and resilience following VC application. These findings highlight the potential of specific VC fractions to enhance salt stress tolerance through metabolic modulation and antioxidant enhancement.