New extremely late budding green tea cultivar 'Okuharuka' with cold resistance has been bred at the Green Tea Laboratory of Saitama Prefectural Agriculture and Forestry Research Center. 'Okuharuka' was selected from seedlings crossed between Saitama20 and Saitama7 in 1975. Local adaptability, tolerance to bark split frost injury, and blister blight were tested at 14 prefectural tea experiment stations from 2002 to 2011. As a result, it was registered as 'Okuharuka' in 2013.
The shape of the cultivar is spread type, and the growth is vigorous. The plucking time of the first crop of the cultivar is 6 days later than that of 'Yabukita'. The yield of 1st and 2nd crop is more than that of 'Yabukita'. 'Okuharuka' has resistance to cold drought damage and bark split frost injury. However, it has slightly weak resistance to gray blight and blister blight. The green tea quality of 'Okuharuka' with the aroma like preserved-cherry-leaves and rich good taste is better than that of 'Yabukita'. The level of the aroma like preserved-cherry-leaves is enhanced in less steamed processing. 'Okuharuka' is suitable for northern tea producing area and cool semi-mountainous areas for its cold resistance.

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The effect to tea garden within the facility, caused by daytime hail which occurred during the season of first crop, has been thoroughly examined. The hails observed were 10-20mm in size and kept falling for approximately 10 minutes, damaging new shoots and causing leaves to fall.
Extent of damage made by this hail depended on the shape of new shoots, and while bud weight type tea garden had many leaves fallen. Meanwhile, direct covering tea garden achieved to reduce the damage rate of shoots down to 12.2 % in comparison to 55.6% without covering tea garden. Also, weight of new shoots became lighter as the result of hail and the amount of harvest was decreased by around 12%.

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Wind speed and leaf temperature under wind machine running were measured in frost nights. Hot-wire anemometers and thermometers were placed side by side on bush canopies in terms of distance 5.4 m, 10.8 m, 16.2 m, 21.6 m, 27.0 m points ahead of the wind machine. Wind speed showed a maximum at 10.8 m point closest to the wind machine, but changed smaller as distance. Leaf temperature rise showed a maximum at 5.4 m - 10.8 m points, but changed smaller as distance. Between 10.8 - 27.0 m points, leaf temperature rise seemed to increase as wind speed was large. Leaf temperature rise was greater amount despite wind speed is small at 5.4 m point. From these results, frost-protective effect of the air stirring method is dependent on the leaf temperature rise caused by the wind hits the tea bush canopy, but on another factor in the range close to the wind machine.

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In this review, the gallic acid content of tea leaves is described, and the potential biosynthetic pathways of the acid and the enzymes involved in these pathways are illustrated. Three pathways have been proposed as follows: (a) β-oxydation of 3,4,5-trihydroxycinnamic acid, (b) hydroxylation of protocatechuic acid, and (c) dehydrogenation of 3-dehydroshikimic acid. Of these three pathways, the last one is currently considered to be the most probable pathway of gallic acid synthesis.

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[in Japanese]

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[in Japanese]

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