A New Shading Method for Improving Free Amino Acid Content and Yield of ‘Yabukita’ Kabuse-cha

Abstract

In this study, we paid attention to free amino acid content, which is one of the indices of tea quality, and aimed to develop a shading method to produce tea leaves having high free amino acid content without decreasing the yield. As a result, we found that a two-stage shading method, comprised of 85% shading for 9 days and then 98% shading for 5 days, is effective for this purpose in the ‘Yabukita’ tea cultivar.
This method makes it possible to raise the free amino acid level provided from a unit area of a tea plantation. This two-stage shading method also increased the free amino acid content of the ‘Mieuejima’ and ‘Okumidori’ tea cultivars. However, the change in individual components differed according to the tea variety and the leaf stage when shading started, so the choice of shading method will likely depend on its purpose.