Effects of different shading treatments on microclimate of tea garden and the quality of flake tea

【Objective】In order to study the effects of shading conditions on microclimate of tea garden and quality of flake tea, to find out suitable covering methods and provide theoretical basis for improving the quality quality of flake tea.【Method】Longjing 43 was used as the test variety, and black shading net was used as the covering material. There were 18 groups of shading treatments with three shading degrees(55%, 75%, 95%), two covering heights(direct covering 0.6 m and shed covering 1.8 m) and three covering times(15, 20 and 25 d), and no covering as the control. The effects of different mulching treatments on microclimate, fresh leaf yield, chlorophyll content, internal substance contents and sensory quality of flake tea were analyzed in spring and autumn.【Result】Shading could effectively reduce the light intensity, photosynthetically active radiation, the daily maximum temperature, the daily range of air temperature, and increased the air humidity. The stable effect of shed covering on microclimate of tea garden was better than that of direct covering. After shading, the total chlorophyll content in the fresh leaves of tea plants increased. The chlorophyll content of the treatments 75% shading degree+direct covering for 15 d and 95% shading degree+shed covering for 15 d were respectively the highest in autumn and spring, 33.86% and 57.27% higher than the control. The content of amino acids increased with shading. The amino acid content in the treatments of direct covering with 95% shading degree for 25 and 20 d were respectively the highest in autumn and spring, higher than the control by 127.55% and 144.06%. After covering, the content of tea polyphenols decreased, the coverage days were negatively correlated with the content of tea polyphenols. The treatments of 95% shading degree+shed covering for 25 d and 75% shading degree+direct covering for 25 d were respectively the lowest in autumn and spring, which were 54.04% and 55.19% lower than the control. The content of caffeine increased with shading. The content of caffeine in the treatment 95% shading degree+direct covering for 20 d was the highest both in autumn and spring, 58.91% and 62.98% higher than the control. Covering in autumn reduced the water extract content. High shading and longterm shading treatments were not conducive to dry matter accumulation, and the yields of the treatment which directly covered with 95% shading degree were the lowest in two seasons. After covering, the sensory quality was higher than that of the uncovered tea. The appearance color of the flake tea was green, the soup color was yellow green and bright, the fragrance was fresh, the taste was fresh.【Conclusion】Shading is beneficial to stabilize the microclimate of tea garden. The quality of flake tea can be improved by prolonging shading time and increasing shading degree. Excessive shading will lead to the decrease of yield. The best quality of flake tea is obtained after 25 d of shed covering with 95% shading degree net, which can be popularized in production.