Unlocking tea's potential: The synergistic role of selenium and phosphorus in enhancing tea quality

Selenium (Se) deficiency is harmful for human health, and producing Se-enriched tea is an effective way to supplement Se. This study systematically analyzed the effects of Se-phosphorus (P) interaction on the absorption and transport of Se and the physiological and biochemical indicators of tea plants. The Se was applied in the form of sodium selenite at three concentrations (0, 50, 100 μmol L^-1), and P was applied as sodium dihydrogen phosphate at three concentrations (0.5, 1.5, and 10.5 mmol L^-1). At the same Se concentrations (50.00 μmol L^-1, 500.00 μmol L^-1), P application could increase the Se content in roots (p < 0.05), while the Se transport coefficient decreased with increasing P concentrations. Gene expression analysis suggested that CsPht1;2a and CsPht1;3a were pivotal in selenite uptake in tea plants. At elevated P concentrations (10.50 mmol L^-1), the application of 50.00 μmol L^-1 Se significantly increased the levels of chlorophyll b and total chlorophyll in the leaves (p < 0.05), whereas a concentration of 500.00 μmol L^-1 Se led to a marked increase in carotenoid content (p < 0.05). Under conditions of moderate P concentration (1.50 mmol L^-1), Se concentrations of 50.00 μmol L^-1 and 500.00 μmol L^-1 were found to exert a significant positive effect on GSH content, as well as the enzymatic activities of SOD, POD, and APX (p < 0.05). At consistent P concentrations (0.50 mmol L^-1, 10.50 mmol L^-1), the application of Se at 500.00 μmol L^-1 significantly elevated the content of tea polyphenols in the leaves (p < 0.05). These findings indicated that appropriate P concentrations could promote the absorption and transport of Se in tea plants, thus improving tea quality.