Quality response of clonal black tea to nitrogen fertiliser, plucking interval and plucking standard

Variations in the black tea quality of high-yielding clone S15/10 in response to rates of NPKS 25:5:5:5 fertiliser of 200 and 400 kg N ha−1 year−1, plucking intervals of 7, 14 and 21 days and a selective plucking standard of up to two leaves and a bud or an unselective plucking standard were studied. Generally, quality declined with longer plucking intervals and unselective plucking. Although there was a general decline in quality with increasing nitrogen rate, only the black tea total colour declined significantly on increasing the nitrogen rate from 200 to 400 kg N ha−1 year−1. For each nitrogen rate and each plucking interval, unselective plucking reduced the black tea quality. No significant interactions between any two of the three (nitrogen rate, plucking interval and plucking standard) or all three factors were noted, indicating that the patterns of response were similar. The results demonstrate that black tea quality changes due to the factors studied occur in the same pattern with variations in treatments. Poor black tea quality due to any of the factors studied cannot therefore be corrected by varying the other factors. © 2000 Society of Chemical Industry