Changes in the shape characteristics of tea [Camellia sinensis] shoots and application to the estimation of the plucking time
1992
Tanaka, S. (National Research Inst. of Vegetables, Ornamental Plants and Tea, Ano, Mie (Japan)) | Yoshitomi, H. | Nakano, F. | Hakamata, K. | Saba, T.
In order to identify suitable indicators for the optimum plucking time of tea shoots, we analyzed various shape characteristics of plucked tea shoots by using an image processing technique as well as the qualities of processed green tea using a sensory evaluation method at different plucking times. Both in the first and in the second crop seasons, tea shoots were plucked at regular intervals and the images of one hundred tea-shoots were input into a computer system equipped with image processing devices for the subsequent analysis of shape characteristics. Green tea was made from the plucked shoots using tea machines and sensory evaluation tests of tea were also run. Based on the sensory evaluation tests, it was estimated that the tea made from shoots plucked on 30th April showed the best quality in the first crop. Since the ratio of the length of two sides of a circumscribed rectangle and the value of the size and percentage of the tea-shoot area to the area of the rectangle during tea-shoot growth showed a point of inflection at the time when the best quality was estimated, it was considered that these shape characteristics could become suitable indicators for the optimum plucking time of tea shoots. It was also confirmed that the leaves of the tea shoots from the second crop season spread widely because the angle formed by the petiole with the stem was larger in the leaves from the second crop than that in those from the first crop
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