Stoichiometric characteristics of plants and carbon, nitrogen and phosphorus in soils of precious tea species Camellia tetracocca Zhang in Guizhou Province

【Objective】In order to provide scientific basis for the rational cultivation and sustainable development and utilization of precious tea species Camellia tetracocca Zhang in Pu'an County, Guizhou Province, the differences and internal correlations of ecological stoichiometric characteristics between the tea plant and the soil were studied.【Method】The tea population of C. tetracocca with 5, 15, 25 and 40 planting years were taken as the research objects. The contents of carbon(C), nitrogen(N) and phosphorus(P) in tea plant and soil were determined. The relationship between the ecological stoichiometric characteristics of tea planting years and soil was analyzed, and the circumstances of element limitation was studied under different tea planting years.【Result】With the increase of planting years, the C content in the 0-20 cm soil and leaves increased first and then decreased, and 25-year cultivation of the tea tree reached the highest level. The C content of soil at 25 years was 27.33% and 23.33% significantly higher than that of 5 and 15 years(P<0.05, the same below), the C content of old leaves was 13.75%, 13.07% and 10.78% significantly higher than that of 5, 15 and 40 years, and the C content of new leaves was 21.12%, 8.79% and 25.63% significantly higher than that of 5, 15 and 40 years, respectively. The N content decreased first and then increased, and the P content gradually increased. With the increase of planting years, the C:N of soil, new leaves and old leaves increased first and then decreased(25-year cultivation of the tea tree reached the highest level). With the increase of planting years, the C:P and N:P decreased gradually. The N:P of soil at 15, 25 and 40 years were 27.95%、29.01% and 33.25% lower than that of 5 years, respectively. The nutrient absorption efficiency and growth rate of C. tetracocca were decreased greatly in planting 40 years. The P regression level of tea garden soil was higher, but the N regression level was lower. With the increase of planting years, the growth of old leaves were restricted by N element, and the growth of new leaves gradually changed from P-limitation to N-limitation. There were significant correlations between P, C:P, N:P of leaves and C, P content of surface soil. The N and P contents of old leaves were extremely positively correlated with those of new leaves(P<0.01, the same below). The C:P and N:P of leaves were significantly or extremely negatively correlated with P content of leaves.【Conclusion】Appropriate planting ages(≤ 25 years) is conducive to the accumulation of organic matter and the improvement of the soil ecological environment. If the planting ages is too long(≥ 40 years), the soil quality would be reduced, and the nutrient cycling process would be limited. Measures such as increasing N fertilizer and supplementing organic matter should be taken to improve the soil environment of the tea orchards, so as to facilitate its sustainable development and utilization.