Effects of nitrogen fertilizer on the constituents of new shoots in tea [Camellia sinensis] cultivars 'Yabukita', 'Sayamakaori', 'Kanayamidori' and 'Meiryoku'
2003
Anan, T. (National Inst. of Vegetable and Tea Science, Ano, Mie (Japan))
Summary The effects of nitrogen fertilizer on the contents of several chemical constituents related to the quality of green tea in the new shoots of tea plants were investigated in a field experiment. Ammonium sulfate was used as a nitrogen source, and rates of nitrogen application were 0-120kgN/10a/year (Exp. 1) and 25-100kgN/10a/year (Exp. 2). Samples were obtained at optimum plucking time from the tea cultivars 'Yabukita', 'Sayamakaori', 'Kanayamidori' and 'Meiryoku', and shoots (four or five leaves and a bud) were selected for analysis. Concentrations of total nitrogen, free amino acids, catechins, caffeine, ascorbic acid and neutral detergent fiber in the new shoots were determined. The results showed that the total nitrogen content and the sum of contents of the main six free amino acids in the new shoots of tea plants grown in a plot in which the rate of nitrogen application was 100-120 kgN/lOa/year were higher than those in new shoots grown in a plot in which the rate of nitrogen application was 25-30 kgN/lOa/year, while there was no significant difference at the 5% level between those in new shoots grown in plots with nitrogen application rates of 50-60 and 100-120kgN/10a/year. The concentrations of catechins, caffeine, ascorbic acid and neutral detergent fiber in new shoots grown in a plot in which the rate of nitrogen application was 50-60kgN/10a/year were not significantly different at the 5% level from those in new shoots grown in a plot in which the rate of nitrogen application was 100-120 kgN/10a/year, too.
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