Shading Effects And Influences On Photosynthesis And Quality Component Of Tea In Tea Plantation

As a major tea producing area in China, subtropical red soil hilly tea plantation with abundant sunshine and long duration of high temperature is not suitable for tea's growth and development, it is extremely negative to the production of high quality organic tea as well. Taking agronomic measures to improve natural environment in tea plantation and create the ecological conditions which meet the requirements for tea growth and development is of significant research values and practical meaning for improving high-quality, safe and high-efficient production of tea.The experiment carried out in Taoyuan experimental station of agricultural ecology of Chinese Academy of Sciences, located in Taoyuan County of Hunan Province. The study aimed to determine the effects of shading on photosynthesis and quality component of tea in tea plantation in summer and autumn seasons which with high temperatures. The paper investigated the ecological conditions, tea growth, photosynthesis and quality component under different shading treatments 75%,56%, 30%,0% in tea plantation. Main research results are as follows:1. shading with shade cloth improved the tea growth environment effectively, the daily average temperature in tea plantation under 75%,56% and 30% shade treatments were 1.7℃,1.1℃and 0.7℃higher than unshaded control, and daily average soil surface temperature were 8.2℃,5.7℃,3.5℃lower than control, at the same time, the daily average temperature about 5cm soil profile were 5.4℃,3.4℃, and 2.3℃lower and daily average relative humidity were 2.7%,1.6% and 0.9% higher than control. Soil water content under 75% shading was nearly two percentage points higher than unshaded control.2. the water content of one-bud-three-leaves under 75% shading was 21.8% higher and the average leaf area of the third mature leaf was 8.96 cm2 bigger than unshaded control in summer.3. Diurnal variation of net photosynthetic rate of tea plantation was single-peak curve under 75% and 56% shading and two-peak curve under 30% and control in summer, the total net photosynthetic rates under different shading were 56%> 75% >30%> 0%. Diurnal variation of net photosynthetic rate of tea plantation was single-peak curve under 75% shading and two-peak curve under56%,30% and control in autumn, the total net photosynthetic rates under different shading were 56% > 75%>30%> 0%. Photosynthetic active radiation made the biggest difference among a number of ecological factors influencing diurnal net photosynthetic rate of the tea.4. After shading, tea polyphenol decreased, tea polyphenol content respectively reduced by 14.0%; chlorophyll,acid aminol and caffein increased, chlorophyll,amino acid's and caffeine content respectively increased by 25.0%,16.9% and 19.4%. Thus, tea tenderness enhanced, the taste of fresh and brisk increased,the taste of bitterness reduced and the colour of tea got greener. In a word, tea quality enhanced.