The varietal difference of tea plants to the infestation of mulberry-scale (Pseudaulacaspis pentagona TARGIONI) was investigated by using 276 varieties planted in tea fields of Tea Branch, Miyazaki Agricultural Experiment Station and Kagoshima Tea Experiment Station.
There are great varietal differences in infestation to mulberry-scale. The number of resistant varieties were more in Assam hybrid, Camellia sinensis var assamica × C. sinensis var sinensis, than that of C. sinensis var sinensis.
Scince of many progenies of the parent or parents of the resistance varieties were resistant, and heredity of the resistance to mulberry-scale was admitted.

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Yellow tea thrips, Scirtothrips dorsalis HOOD is an important sucking pest of tea plants especially on young tea fields. To demonstrate the damage control of S. dorsalis by mulching the near-ultraviolet radiation reflective film on the young tea fields, damage indices of tea plants by S. dorsalis were compared between the mulched area and untreated areas under the application of insecticides except for synthetic pyrethroids. The rate of severely damaged leaves more than injury level 3 was about 1/5 of that in the untreated area. The mean damage index per plant was also significantly lower in the mulched area. Furthermore, the adult and larval density of S. dorsalis in autumn was apparently lower in the mulched area than in the untreated area. The shoot length in summer was significantly different between the two treatments but clear difference was not observed in the plant height in autumn. These results indicate damages of tea plants by S. dorsalis were effectively suppressed by mulching near-ultraviolet radiation reflective film on young tea fields.

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Subsoil improvement, which is executed at the last stage of opening of new tea fields, is one of the important processes which improve mainly physical properties of a closed surface soil. This time, for subsoil improvement, a mixing tillage method was investigated, in which a rotor-bucket is mounted to a back hoe.
A rotor-bucket has iron blades in a bucket, which are rotated by a hydraulic motor, mixing tillage is performed breaking clods.
(1)The mixing tillage by a rotor-bucket breaks un-weathered soft rocks by a rotating rotor, and changes the soil swelling and soft, which was closed by runs of large-size machines, so it seems to be highly effective in soil improvement of mainly physical properties.
(2)The mixing tillage by a rotor-bucket is able to mix organic materials applied for soil improvement with comparative uniformity.
(3)The mixing tillage by a rotor-bucket is expected to bring good effects for growing of tea plants.

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The elution rates of major tea components (catechins, caffeine and theanine) eluted in the infusion were analyzed by using capillary electrophoresis. Ester-type catechins ( (-)-epigallocatechin galalte and (-) -epicatechin gallate) were not easier to elute in the infusion than free catechins ( (-) -epigallocatechin and (-) -epicatechin ). Caffeine was rapidly eluted in hot water (90°C) and also mostly eluted in cold water (20°C) after 20 min elution.

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