Impact of Eco-Enzyme Fertilizer on Phytochemical Content and Antioxidant Activity of Turmeric Rhizomes at Early Growth Stage

Background: Turmeric (Curcuma longa L.) is widely recognized for its bioactive compounds, including phenolics, flavonoids, and curcumin, which exhibit significant antioxidant, anti-inflammatory, and antimicrobial properties. These phytochemicals are secondary metabolites that contribute to turmeric's therapeutic potential. However, the influence of plant age and organic fertilization, such as eco-enzyme, on turmeric’s phytochemical content is not fully understood. This study evaluates the phytochemical profile of turmeric rhizomes harvested four months after planting and assesses the impact of eco-enzyme fertilization on secondary metabolite production. Methods: Turmeric rhizomes were collected from plants treated with different concentrations of eco-enzyme fertilizer (0.5%, 1%, and 1.5%) and a control group (no fertilizer). Qualitative and quantitative analyses were performed to determine the presence and concentration of phenolic compounds, flavonoids, and curcumin. Antioxidant activity was assessed using the DPPH assay. Data were statistically analyzed to compare phytochemical content across treatments. Results: Qualitative analysis revealed the presence of phenolics, flavonoids, and curcumin in all treatments. Quantitative results showed that plants treated with 0.5% eco-enzyme had significantly higher flavonoid content (0.12%) and phenolic content (4.911 mg GAE/g extract) compared to other treatments. Curcumin levels were low across all samples, likely due to the young age of the rhizomes. Antioxidant activity, measured via the DPPH assay, was weak, with IC50 values exceeding 200 ppm, consistent with previous findings on immature turmeric rhizomes. The observed differences in phytochemical content may be attributed to eco-enzyme’s enzymatic activity, which enhances secondary metabolism by breaking down complex nutrients into simpler forms. Conclusion: The application of eco-enzyme fertilizer, particularly at a concentration of 0.5%, enhances the phytochemical content of young turmeric rhizomes, notably flavonoids and phenolic compounds. However, the relatively low levels of curcumin and weak antioxidant activity suggest that rhizomes harvested at four months may not have fully developed their secondary metabolites. Further research is needed to investigate phytochemical profiles at later growth stages and optimize eco-enzyme application to maximize bioactive compound production. These findings highlight eco-enzyme’s potential as an organic fertilizer for improving the quality of medicinal plants.