Geo-Environment Science

The shading treatment of tea plants for a few weeks before the harvest enriches tea leaves with free amino acids such as theanine and brings the flavor-rich quality of green tea. Especially, the first crop of tea which produced under the shading treatment is called Gyokuro and famous for its especially high quality. The production of Gyokuro is limited with only the first crop of tea, and the supply of Gyokuro is not enough for the increasing demand. Therefore, it is desired to produce the second and third crops of tea in the hot summer season, which has the flavor-rich quality similar to Gyokuro. However, there are difficulties in producing the flavor-rich green tea in the midsummer under the shading treatment, because of the excessively high temperature condition. The evaporative cooling treatment by sprinkling water over tea plants intermittently in the daytime dropped temperatures of leaves and the ambient air by 3°C, and further the radiative cooling treatment by opening the shade screen net during the nighttime dropped the temperatures by 2°C. Thus, these passive cooling treatments were demonstrated effectively to drop temperatures of leaves and the ambient air in the summer production of green tea.