Effect of Ethylene on Abscission, Chemical Constituents and Quality of Plucked Tea Shoots during the Storage

Abstract

Effects of exogenous ethylene on plucked tea shoots were investigated.
1) Plucked tea shoots, which consisted of a bud and three leaves, were stored in 0, 1, 10, and 100 ppm ethylene at 20°C or 5°C for 2 days. Sixty two percent abscission of the leaves was observed in the case of 1 ppm ethylene, moreover abscission reached about 100 percent at ethylene more than 10 ppm. Zero percent abscission was, however, observed when the shoots were stored at 5°C in 100 ppm ethylene.
2) The contents of chlorophyll a and chloro-phyll b maintained similar level among the shoots stored in 0, 1, 10 and 100 ppm ethylene at 20°C for 3 days.
3) The content of ascorbic acid remarkably decreased independently on presence or absence of ethylene during the storage at 20°C for 2 days. However the content of ascorbic acid did not decreased, when the leaves were stored at 5°C in 100 ppm ethylene.
4) The contents of tannin (catechins), caffeine, and amino acids.such as lysine, histidine, arginine, aspartic acid, threonine, serine, glutamic acid, alanine, valine, isoleucine, leucine, phenylalanine increased independently on presence or absence of ethylene during the storage at 20°C for 3 days. On the contrary, theanine (L-glutamic acid r-ethylamide) decreased.
5) With respect to the quality of green tea, there was no significant difference among the shoots stored in less than 100 ppm ethylene, however, it was found that ethylene had a tendency to increase bitterness in tea infusion at 500, and 1, 000 ppm.