Changes of leaf growth and chemical components in the first crop of tea of Cheju area between north and south of plucking surface at different plucking date were studied. The results obtained are as follows. The north of plucking surface was earlier than the south about 0.6~1 leaf age, and optimal plucking date was l May in the north of plucking surface, and 8 May in the south of plucking surface. One hundred fresh bud weight was 51.3g in the north of plucking surface, 34.2g in the south of plucking surface on 10 May, and daily mean growth rate was 15% both north and south. The change of total nitrogen content was decreased with growing. Optimal plucking date should be decided before total nitrogen content is decreased below 5%. The content of free amino acid had the time of rapid decrease, tea leaves should have been plucked before this time came. The change of theanine content was the same as change pattern of free amino acid. Changes of caffeine and tannin contents were the same as that of total nitrogen content which was decreased with growth, but they could not become a base of plucking date because they did not show a positive correlation to quality. The content of NDF-ash was increased with growing, but it was a negative correlation to quality. To summarize above mention study, optimal plucking date of the first crop of tea in Cheju island in 2000 was 6 May in the north of plucking surface, 8 May in the south of plucking surface, and 6 May when both were plucked at the same time.
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