Changes in autumn canopy structure of tea bushes between early-plucked (here after EP,yield was 421 kg/10a on Aug. 1st in 2005), late-plucked (LP, 827 kg/10a on Aug. 8th) and not-plucked(NP) of the third crop was investigated by a stratiform clip method. All canopies of three bushes were cut with every 2 cm layer by a self-rail-tracking tea plucker on Oct. 19th in 2005. The result of vertical distribution of canopy biomass showed that the third crop plucking caused a decrease in leaf weight and bud number at the upper layers of the autumn canopy, but caused an increase in their lower layers. Although leaf weight of EP was same as that of LP, Leaf area index of EP was smaller however leaf specific weight was larger than LP. An analysis of relationship between autumn skiffing positions and bud number of the canopy surface was performed in order to estimate influences of the third crop plucking on new shoot number of the next first crop. The result was follows; the bud number of EP and LP was larger than that of NP at a lower autumn skiffing position (4 cm upper above the second plucking position), while bud number of NP was larger than EP and LP at a higher autumn skiffing position (6 cm upper).

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The mulberry scale Pseudaulacaspis pentagona (Targioni) is one of the most important pests on tea trees in Japan; in particular, severe outbreaks have occurred in Shizuoka Prefecture in recent years. Natural enemies of the scale are considered to be one of important factors for controlling the scale population, and it is necessary to clarify the actual condition of the natural enemies of the scale in tea fields. We investigated the species and species composition of natural enemies of the scale in tea fields in Shizuoka Prefecture of Japan in 2002 and 2003 by identifying the parasitoids that emerged and dissecting the adult female scales. We identified 4 species of primary parasites, namely, Arrhenophagus albitibiae Girault, Pteroptrix orientalis (Silvestri), Thomsonisca indica? Hayat (this species was identified as T. amathus in Japan) and Epitetracnemus comis Noyes & Ren, and 2 species of hyperparasites, namely, Marietta carnesi (Howard) and Zaomma near lambinus (Walker). We also identified the following 3 species of coleopteran predators: Pseudoscymnus hareja Weise, Chilocorus kuwanae Silvestri, and Cybocephalus nipponicus Endrody-Younga. Further, 1 species of Cecidomyiidae (predatory gall midge), namely, Dentifibula sp. was confirmed. The primary dominant parasitoid and predatory beetle species were A. albitibiae and P. hareja, respectively. The species composition of the parasitoids that emerged changed with location and generation of the scale, and A. albitibiae was the major species in the overwintering generation of the scale. However, from the first to the second generation, the frequency of species other than A. albitibiae increased, i.e., species diversity increased. The percentage parasitism of all of the parasitoids increased with the alternation of scale generations, and there were tea fields in which the predatory Cecidomyiidae Dentifibula sp. became the primary dominant species at the second generation of the scale. Therefore, it was suggested that interspecific competition and intraguild predation occurred among the natural enemies.

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The ability of the Valencia slug Lehmannia valentiana (Férussac) to prey upon egg masses of the Oriental tea tortrix Homona magnanima Diakonoff (OTT) and the Smaller tea tortrix Adoxophyes honmai Yasuda (STT) was investigated in a rearing cage and in tea fields. In the cage, Valencia slugs prey upon an average of 6.1 to 9.3 egg masses of OTT out of placed 20 egg masses per night. In the case of STT the slugs preyed upon an average of 14.3 egg masses out of 20 egg masses per night. The total number of eggs preyed upon by a Valencia slug was equivalent to the number of eggs oviposited by one OTT female or two STT females. In tea fields, Valencia slugs preyed upon the egg masses of OTT that were both experimentally attached to tea leaves and oviposited on the leaves. The number of egg masses preyed upon by slugs differed among the tea fields, and it tended to be related to the number of slugs captured in traps. Copper sprayed on the egg masses of tea tortrix had no influence on predation by Valencia slugs, however, spraying of organophosphorus and carbamate insecticides did have an influence on slugs predation.

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We developed a simple and low-cost storage method for keeping crude tea in a daikai-bag.
(1) Oxygen in the daikai-bag could be replaced with nitrogen by allowing a continuous flow of nitrogen gas into the airtight container that fed the daikai-bag.
(2) When the nitrogen gas mass flow per hour into the container was the same as the volume of a container and the pressure in the container was 0.01 MPa or more, the oxygen concentration in the daikai-bag became 1% or less within 10 hours. Moreover, since there was pressure, mixing with the open air was suppressed.
(3) The oxygen concentration in the daikai-bag kept 1% or less for six months by maintaining pressure in the container.
(4) The quality of crude tea after six months storage by the new storing method was changed very little compared with tea stored using the conventional storing method which put tea in the aluminum bag and was filled up with nitrogen gas.

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This research aims to identify key odorants in roasted green tea. The aroma extract dilution analysis revealed 25 odor-active peaks with the flavor dilution factors of ≥ 16. We identified 2-ethyl-3,5-dimethylpyrazine as the most important odorant in roasted green tea with the highest flavor dilution factor of 4096. In addition, tetramethylpyrazine, 2,3-diethyl-5- methylpyrazine were also detected as potent odorants with the high flavor dilution factors. These three alkylpyrazines would be key contributors to aroma of roasted green tea.

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