Effects of fertilizing with N, p, se, and zn on regulating the element and functional component contents and antioxidant activity of tea leaves planted in red soil.

New fertilizing strategies (with exogenetic N, P, Se, and Zn) were explored to regulate the element (Se, Zn, Mn, and Al) and functional component (polyphenol, catechins, free amino acid, polysaccharide, and caffeine) contents of new (a bud and two leaves, grown for about 10 days) and old tea leaves (grown for >3 months) cultivated in a hilly red soil region. Using four different fertilizing strategies (A, Se + Zn; B, Se + Zn + N; C, Se + Zn + P; D, Se + Zn + N + P), the Al and Mn contents of tea leaves in both new and old leaves were significantly decreased. Meanwhile, the contents of Se and Zn were increased, and the contents of some functional components as well as the antioxidant activities in tea leaves were improved. In particular, fertilizing strategy C showed the highest Se (0.444 μg/kg), total polyphenol (28.294%), and catechins (131.852 mg/g) contents and antioxidant activities (DPPH, 95.06%; FRAP, 3.81 mmol FeSO4/g; reducing power, 1.26) as well as the lowest Al (222.005 mg/kg) content among these four strategies, whereas fertilizing strategy B showed the highest Zn (34.235 mg/kg), total free amino acid (5.60%), tea polysaccharide (5.79%), and caffeine (56.684 mg/g) contents as well as the lowest Mn content (747.658 mg/kg). It has been proven that exogenetic elements (N, P, Se, and Zn) as fertilizers could be an effective way to produce tea leaves with higher Se, Zn, and functional component contents and antioxidant activity as well as lower Al and Mn contents in a red soil region.