Written Paper

Effect of nitrogen fertilizers on composition of catechins in shoots of tea cultivars  [2009]

Matsunaga, A., National Inst. of Vegetable and Tea Science, Shimada, Shizuoka (Japan) Saba, T. Nesumi, A.

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A field experiment was conducted using 14 cultivars to evaluate the effects of different application rates of nitrogen fertilizers on catechins composition in tea shoots. Tea plants were planted in 2000 at Kanaya Tea Research Station of National Institute of Vegetable and Tea Science. They were treated with ammonium nitrate fertilizers applied at annual rates of 200, 400 and 600kg /ha. Tea shoots were plucked in 2005, 2007 and 2008. The concentrations of epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) in shoots of the first and second harvest seasons were determined by HPLC. In the concentration of each catechin in shoots of the first harvest season, there were significant differences at the 1% level between nitrogen fertilization treatments, cultivars and harvest years. Reduction of nitrogen application resulted in increase in the concentrations of EC, EGC, ECG and EGCG in the shoots of the first harvest season. Apparent increases of concentrations of EC, EGC, ECG, and EGCG were observed with 200kg/ha nitrate fertilization. The concentrations of catechins of the second harvest season were higher than those of the first harvest season. The interaction between cultivars and nitrogen application levels was very small and not significant at the 1% level in the concentrations of catechins in each harvest season.