Synthesis of Silver Phosphate (Ag3PO4) and Its Supplementation to Enhance Phytochemical Accumulation and Antioxidant Activity of Cryptocoryne albida Under Hydroponic Cultivation

This study investigated the supplementation of silver phosphate (Ag3PO4) to enhance the growth and antioxidant activity of Cryptocoryne albida in a hydroponic system. Ag3PO4 was synthesized via a simple precipitation method using AgNO3 and (NH4)2HPO4 as precursors, with alcohol employed as the reaction medium to control particle growth and agglomeration. FTIR analysis confirmed the presence of characteristic phosphate (PO43−) functional groups, while XRD revealed diffraction peaks consistent with Ag3PO4 as the dominant crystalline phase. The SEM image exhibits relatively uniform spherical particles of 300–500 nm. Moreover, the XRF results for the synthesized Ag3PO4 indicated 86.80% of Ag2O and 12.60% of P2O5 as the major components. The application experiment was conducted in a DFT hydroponic system containing different concentrations of Ag3PO4-derived supplementation (0.00, 0.01, 0.10, and 1.00 ppm). The highest concentration (1.00 ppm) of Ag3PO4 in the KMITL2 nutrient solution significantly reduced plant growth (p < 0.05). In contrast, Ag3PO4-derived supplementation with 0.01 ppm resulted in significantly higher phytochemical accumulation, including total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities evaluated by DPPH and ABTS assays (p < 0.05). These results suggest that low-concentration Ag3PO4-derived supplementation may promote phytochemical accumulation and antioxidant activity in C. albida. Overall, this study highlights the potential of Ag3PO4-derived supplementation for modulating phytochemical accumulation and antioxidant activity in hydroponically cultivated C. albida.