The Effects of Shading on Total Content and Components of Catechins in Tea Plant leaves

In this study, Huang Dan was selected as experimental materials, using the technique of artificial cover shading of tea garden which could adjust the light, then steamed green tea and oolong tea samples were prepared for comparative analysis of the contents of total catechins, ester and non-esterified catechins.The results showed cover shading had affects on the total content of catechins both in steamed green tea and oolong tea samples.With the increase of shading degree, the total contents of catechins in both tea samples showed declining trend overall, the mass fraction change (compared with CK, similarly hereinafter) ranged respectively:steamed green tea samples, from 3.08%to 10.61%, and oolong tea samples, from 2.65%to 10.61%;in both samples the mass fraction of ester catechins ranged respectively from-1.63%to 5.28%and from-19.96%to 10.35%;the mass fraction of non-esterified catechins ranged respectively from 9.90%to 24.18% and from 2.90%to 19.82%.Although both ester and non-erterified catechins declined as the increasing of shading degree, but the ester catechin percentage of total catechin was increased, ranged from 4.32%to 10.05%;on the contrary, the esterified catechin was declined from 5.10% to 15.17%.While, the ratio of ester and non-esterified catechins also showed bigger with the increasing of shading degrees.In conclusion, the study showed that the effects of shading treatment on total content and components of catechins could reach or be close to the levels of the difference among different tea plant varieties.