Characteristics of NH(4)(+) and NO(3)(−) fluxes in tea (Camellia sinensis) roots measured by scanning ion-selective electrode technique

As a vital beverage crop, tea has been extensively planted in tropical and subtropical regions. Nitrogen (N) levels and forms are closely related to tea quality. Based on different N levels and forms, we studied changes in NO(3)(−) and NH(4)(+) fluxes in tea roots utilizing scanning ion-selective electrode technique. Our results showed that under both single and mixed N forms, influx rates of NO(3)(−) were much lower than those of NH(4)(+), suggesting a preference for NH(4)(+) in tea. With the increase in N concentration, the influx rate of NO(3)(−) increased more than that of NH(4)(+). The NH(4)(+) influx rates in a solution without NO(3)(−) were much higher than those in a solution with NO(3)(−), while the NO(3)(−) influx rates in a solution without NH(4)(+) were much lower than those in a solution with NH(4)(+). We concluded that (1) tea roots showed a preference for NH(4)(+), (2) presence of NO(3)(−) had a negative effect on NH(4)(+) influx, and (3) NH(4)(+) had a positive effect on NO(3)(−) influx. Our findings not only may help advance hydroponic tea experiments but also may be used to develop efficient fertilization protocols for soil-grown tea in the future.