Research On Tea Plant To Nitrogen Uptake-utilization And Fertilization Technique In Tea Garden

Tea plant [Camellia Sinensis(L.) O. Kuntze] is harvested for leaves, with high demand for nitrogen, which is the most important nutrition element for tea growth as well as the quality of tea. Fertilization status of typical green tea gardens in Zhejiang province was surveyed in this thesis. The characteristics of nitrogen uptake and utilization in tea from tea gardens with various plucking modes(only premium tea plucked, only normal tea plucked and premium tea / normal tea plucked together) was investigated in the study. Furthermore, considering the important role of spring tea in the whole year, the optimized fertilization time for spring top-dressing was also studied by using 15 N tracer technique. Moreover, to solve the problem of labor shortage in rural regions. Using 15 N tracer technique, the application methods of basal fertilizer and spring top-dressing were studied by simulating the mechanical fertilization, as well as in the effect of the controlled-release nitrogen fertilizers on tea yields, quality, ecomonic benefit. These results could provide the parameters for the application in the tea garden. The main findings were:(1) In the primary tea production area of Zhejiang, the averaged N application rate was 521 kg/hm2, with 30% and 41% of the area could be regarded as the N deficiency and over-application, respectively. For the soil condition in the tea production area, 50.4% and 48.8% were P enrichment and K deficiency, respectively.(2) The relationship between N application rate with tea yield, quality or N uptake amount could be described with a linear plus plateau model. The optimized N rate was 300~450 kg/hm2, which could fulfill nitrogen demands in different plucking modes. However, the N rate was variable with different types of tea gardens.(3) The study of 15 N labeling experiment showed that with 2 different N rates, the 285 kg/hm2 and 569 kg/hm2, 38.48% and 34.36% of the applied N were uptake by the tea plant, 34.37% and 38.75% remained in the soil, the 27.50% and 27.07% lost through different paths.(4) Applying basal fertilizer in the ditch at the depth of 15 cm with cover afterwards in the autumn could increase the N use efficiency and the spring tea production. Surface application of spring top-dressing and followed with mixture could increase the root uptake of N.(5) The root uptake rate of N was associated with the temperature and phenology. Either the premature or delay of the spring fertilization application time could affect the N uptake of the spring tea. The period with 50~60 days before the plucking of the spring tea is the best time for fertilization.(6) The mixed application of the controlled-release and inorganic N fertilizers could enhance the N use efficiency in the young shoots, reduce the labor cost and increase the income of the tea farmers.