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Foliar application of essential nutrients is a rapid and promising strategy to enhance the concentration and bioavailability of essential nutrients in tea plants (Camellia sinensis). A field experiment was carried out to explore the effects of iron (Fe), zinc (Zn), copper (Cu) and the hyperaccumulator manganese (Mn) foliar application on the biochemical components of free amino acid (FAA), caffeine (CAF), and tea polyphenols (TP) in the black tea made from the tea plant cultivar 'HuangDan'. The foliar application of Fe, Zn, Cu, and Mn showed significant effects on FAA and TP contents of black tea (P < 0.05), but had no significant effect on the CAF content. Iron and zinc spraying significantly increased thearubigin and theabrownin content, whereas copper spraying significantly decreased thearubigin content while increasing theabrownin content. Additionally, the gene expression patterns of the POD family members CsSPX1, CsAPX1, CsGPX1, CsGPX3, CsPOD13, and CsPOD18 were identified to investigate the roles of these phenolic constituents influenced by the foliar appli-cation. The expression patterns of CsGPX3 and CsAPX1 were found to be involved in the production of TFs. POD-catalyzed TFs formation might serve as a molecular marker to identify varieties of tea plants suitable for brewing high-quality black tea beverages by regulating catechin oxidation throughout the tea processing process.