Effects of shading on quality and chemical components of Oolong tea in summer

Three Oolong tea cultivates,including Huangdan,Tieguangying and Benshan,were shaded in summer to probe its effect on tea quality.The results showed that shading in Oolong tea garden during summer could markedly improve the tea quality,decrease the ratio of polyphenol and amino acid,optimize the components of the catechin and fragrance.Under the shading degree of 30%,45% and 60%,the scored of tea quality was much higher than that of control which without shading in summer,and the differences between the treatments were indistinctive.Compared with the control,shading tea garden in summer and hot weather days,the contents of tea polyphenol decreased 2.59%-12.40% and 8.62%-11.05%,the contents of catechin decreased 2.14%-13.63% and 3.09%-10.61%,and that of EGCG decreased 11.17%-29.47%,respectively.The indexes of catechin quality increased 54.13-84.87 and 167-682.The contents of amino acid increased 13.52%-60%,among which the total contents of theanine,threonine and asparagic acid increased 7.57%-19.12%.The fragrance kinds increased by 25-40,and the total contents of the essential oil increased 21.20%-38.85%.The components of fragrance were optimized.