Effects of nitrogen fertilization on yield and quality of tea

The field trials were conducted to study the effects of different nitrogen(N) nutrition levels on dry matter yield and quality of tea. There were four levels of N application, N 90,180,360 and 720 kg/ha. The results indicate that there are obvious effects of different N levels on tea yield and quality, a rational N level could remarkably increase tea yield and improve nutrition quality. Tea yield would not increase when the nitrogen application rate is above N 360 kg/ha. The apparent recovery efficiency and agronomic of nitrogen fertilizer are constantly decreased with increasing of rate of nitrogen fertilizer. At the same basal fertility soils, tea yields are all increased first and dropped later along the increase of N application rates, and there is a parabola relationship between the yields and N application rates.The highest tea yield is obtained by the treatment of N 360 kg/ha. The results of quality analysis show that a suitable N nutrition level could improve the contents of free amino acids, caffeine and water extracts in tea, and chlorophyll contents in leaves, while the contents of tea polyphenols are decreased. The tea yields are increased by 19.59％-25.19％ with an average of 22.39％ under the four treatments. The tea quality components are also increased, especially free amino acids in tea shoots.