Assessing the impact of Djdi on the growth, nutrient uptake, and secondary metabolite production in Eruca vesicaria (L.) Cav.

Abstract Background This pioneering research aims to assess Djdi Ocher (Khuzam Shale), a naturally occurring Pharaonic fertilizer from Southern Egypt, as a unique sustainable soil amendment. The study focuses on blending Djdi with sandy clay soil (CS) in various ratios to evaluate its effects on the growth and development of Eruca vesicaria. Results In a pot experiment, E. vesicaria seeds were germinated in three different Djdi-to-soil ratios: (1:1; Djdi: CS1), (1:2; Djdi: CS2), and (1:3; Djdi: CS3). After 15 days, seedlings were harvested for comprehensive analysis. XRD analysis characterized Djdi as a sandy loam enriched with minor and major oxides, particularly iron oxides. Soil analysis revealed that Djdi: CS2 and Djdi: CS3 treatments recorded the highest sum of anions (CO 3 -2 , HCO 3 - , Cl - , and SO 4 -2 ) and cations (N + , P + 5 , Ca + 2 , Na + , K + , Fe + 2 , and Mg + 2 ). In plants, the Djdi: CS3 treatment significantly enhanced the accumulation of N + , P + 5 , K + , Ca + 2 , and Fe + 2 . Furthermore, Djdi: CS3 achieved the highest germination rates, mineral absorption, and growth parameters, alongside an increase in secondary metabolites (phenolics and flavonoids). Notably, stress biomarkers (MDA and H 2 O 2 ) were significantly elevated in all Djdi-treated samples. RT-PCR analysis confirmed the up-regulation of key secondary metabolite genes, including chalcone synthase (CHS), phenylalanine ammonia-lyase (PAL), flavonol synthase (FLS), and chalcone isomerase (CHI), particularly in the Djdi: CS3 group. Conclusion The study concludes that the Djdi: CS3 (1:3) ratio serves as a novel, eco-friendly fertilizer that improves soil fertility, promotes plant growth, and boosts bioactive constituents. These findings align with Sustainable Development Goals (SDGs) by enhancing soil productivity for subsequent crop cycles.