Abstract
【Objectives】 It is very serious that abuse of chemical fertilizers causes environment destruction for chasing productivity in tea garden, so it is very important that reasonable application of nitrogen, phosphorus and potassium fertilizers. In this paper, effects of different application of nitrogen,phosphorus and potassium fertilizer on photo-biological characteristics, such as Pn, Tr, Gs, Ci, WUE and contents of N, P and K in new shoots and amino acid components of tea plants in spring, were studied to provide theoretical guidance for balanced fertilization and accurate fertilization in tea gardens. 【Methods】 We got by single factor design in the experiment and used totally 14 fertilizer treatments with nitrogen, phosphorus and potassium fertilizers, including single application of nitrogen, phosphorus and potassium fertilizers with three treatments (N1, N2, N3, P1, P2, P3, K1, K2 and K3), combined application of nitrogen-phosphorus, nitrogen-potassium and phosphorus-potassium fertilizers (NP, NK and PK), combined application of nitrogen, phosphorus and potassium fertilizers (NPK), and no fertilizer (CK). When the tea new shoots grow to 1 bud and 3 leaves, samples are collected. We used Li-6400 photosynthesis system to determine the photo-biological characteristics, and automatic amino acid analyzer to determine the contents of amino acid and its components. Using the Kjeldahl method, vanadium-molybdenum-yellow colorimetry and atomic absorption spectrophotometry to determine the contents of N, P and K in the new shoots. We analysed effects of different fertilizer treatments on the photo-biological characteristics and the contents of amino acid components, and we set up regression and path analyses of N, P, K, Tr, Gs and Ci on Pn in spring. 【Results】 Compared with CK, Pn of the tea plants under the NPK treatment is increased by 9.70%. The Tr values under the P2, P3 and NPK treatments are significantly increased by 10.60%, 14.92% and 14.25%, respectively, and Gs under the NPK treatment is significantly increased by 23.15%. Gs exhibits the same variation trend with Tr, and they have significant correlation. Ci is increased with the increase of nitrogen fertilizer, phosphorus fertilizer or potassium fertilizer amounts, while WUE is decreased. The contents of N and P in new shoots under the NPK treatment are higher, and the content of P in new shoots is lower than the contents of N and K in the same treatment. The path analysis shows that the contents of P, Ci and Gs have greater direct effects to Pn, and the direct coefficients are 0.3688,-0.8139 and 0.4677, respectively. Pn=12.955+26.624P -0.087Ci+38.233Gs. The contents of amino acid, Thea, Asp, Thr, Ser, and Cys are significantly increased by 27.88%, 26.60%, 35.78%, 35.06%, 24.41% and 24.41%, respectively. 【Conclusions】The Pn of the tea plants is improved by the contents of P and Gs, but Ci has some subduction to Pn. The combined application of nitrogen, phosphorus and potassium fertilizers significantly improves Gs of the tea plants, ensures a higher P content in new shoots, and further improves Pn. The combined application of nitrogen, phosphorus and potassium fertilizers also improves the quality of the spring tea by significantly increasing the contents of amino acid and components, which indicates that the contents of amino acid and components are improved by nitrogen, phosphorus and potassium nutrition. These results provide a theoretical guidance for fertilization of nitrogen, phosphorus and potassium. Therefore, the combined application of nitrogen, phosphorus and potassium fertilizers can improve the yield and quality of the spring tea in tea gardens.
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