[in Japanese]

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In order to derive an essential information for producing tea haploid plant from pollen grain by anther culture, the effects of the concentrations of sucrose and the growth substances in media to pollen grains in anther were investigated.
Investigations were made on the relation between sucrose concentrations and the division of pollen grains in anther. As a result, pollen grains with three nuclei (2V+1G) which connected with abnormal pollen division were found in plots of 5%, 10% and 15% of sucrose concentrations. But, as shown Figure 2, ratio of the dead anther increased in plot of 15% sucrose concentration. From these results, it seemed that 5% and 10% of sucrose concentrations in media were effective.
The effects of concentrations of sucrose and 2.4-D in media to pollen grains in anther are shown in Figure 5 . Ten percent of sucrose concentration was better than that of 5% and frequency of anthers with divided pollen grains was increased by supplementing 2.4-D.
From the relations between kinetin in media and pollen grains in anthers (Fig.6), in lack of kinetin in media, divided pollen grains were found till 7 days after culture, but the suitable concentration of kinetin in media was considered 10ppm for the division of pollen grains.
In plot of medium with 10% of sucrose and lppm of kinetin, pollen grain divided into about 30 cells after 21 days of culture (Plate 1-B).
Chlomosome number of callus formed was 2n=30. From observation of anther of cross sections after 21 days of culture, callus was derived from not pollen grain but the connective tissue of anther.

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In order to obain basic informations for the study of regenerative abilty of tea plant, varietal differences in the rooting-characteristics of nursery plant from cutting were observed 21 months of ter planting.
In both varieties Yabukita and Yutakamidori, a number of slender roots grew out from the upper part of the underground region of the cutting stems. In the most of these plants, thickening growth was observed the root developed region of the cutting stems. But in variety Fujimidori, the roots were grew out from the lower part only, so the thickening of the stems not observed.
The slender roots were removed from twoyear-old nursery plants of variety Yabukita, and these plants were replanted immediately. The thickening growth of cutting stems was compared between treated and non-treated plants. 7 months after replanting, the thickening growth did not observed in treated plants, while the thickening was observed in non-treated plants.
It is know that the variety Yabukita is more sensitive to the root rot disorder than Fujimidori, and suffered tea plants sometime have abnormal thickening growth in roots derived from cutting stems. Therefore, the results obtained from these observations arouse one's interest in research on the mechanism of root rot disorder.

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Effects of irrigation in the tea field was investigated for 4 years from 1974 to 1977 by using intercept apparatus of the rain.
Amount of 15 mm, 20mm, 25 mm and 30 mm were irrigated when pF at a depth of 15 mm in the plot of 30mm attained 2.8 (1975) or 2.5 (1976 -'77).
The yield of green leaf was the following order;30mm>25mm>20mm>15mm plot.
Irrigation had little effect on the lst crop of green leaf, but had an effect on the 2nd and 3rd crop of green leaf.
For the number of buds there was no difference among treatments at lst crop, but at the 2nd and 3rd crop of green leaf, the more amount of watering was, the more number of buds was.
The weight of bud was the same as the case of the number of buds.
Evapo-transpiration of tea plant was about 2mm per a day in March and April, 2-3mm in May-July, 5-6mm in Auggust and 2-3 mm in September-October. respectively.
Evapo-transpiration decreased according as value of pF increased.
Evapo-transpiration of tea plant was related to climatic factors and showed the high co relation to solar radiation, sunshine duration, air temperature and evaporation,
Soil moisture in March-July was extractedmainly from upper layer and in August-October mainly from lower layer.
From the results of soil moisture extraction, amount of irrigation and yield of green leaf, it was considered suitable that the volume of TRAM was irrigated at pF 2.3 in the tea field.

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The influence of manuring method on the cold resistance of young tea plants during the occurrence period of the bark splitting injury was investigatad.
The young tea plants fertilized with one third of the current doses of nitrogenous fertili-zer and with no nitrogenous fertilizer in autumn, Sept. to early Oct., obtained the cold hardiness more early than the normally fertilized one did.
However, normal usage of autumn fertilizer in due time after summer fertilization was omitted and the normal doses of nitrogen if their application was made very early, such as in early Aug. or suspended untill such late as, Nov. accelerated a cessation of autumn growth and the hardening of the young tea plants.
The growth of the young tea plants well-fed with basal manure plus summer dressing was not affected by the time of autumn manuring.
The potassium effect on cold resistance of the tea plants was not detected, although there has been many reports on it.
These results suggest that the later manuring in autumn is better choice for prevention or reduction of bark splitting injury in dangerous region.

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[in Japanese]

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Recently, yellow tea thrips, Scirtothrips dorsalis HOOD, has been the serious pest of tea at the east region in Shizuoka prefecture. The most of the insecticides used in tea field at present are semi-persistent, so the insecticides need applying every few days to maintain a toxic dose on the leaves for effective control of this thrips. Cartap applied at about 5 day intervals controls it satisfactorily, and it is more effective to spray with Methomyl at the bud opening and then Cartapt at the opening of Ist leaf of tea. This application can control simultaneously smaller tea tortrix, tea green leafhopper and other pests.

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(-)Epicatechin-gallate ((-) ECg) and (-) epigallocatechin-gallate ((-)EGCg) effectively inhibited the local lesion formation on Nicotiana glutinoaa when these were administered to the plants through their stalks from which roots had been removed. The percentages of inhibition were 90 to 99 with (-)ECg or (-)EGCg at 1000 or 2000ppm. However, when both catechins at 1000 ppm were mixed and administered separately to tobacco plants, Ky-57, through their roots, browning of vascular bandies and red specks on leaves appeared. (-)ECg and (-) EGCg were administered to tobacco plants, Ky-57, for 7 days and the polyphenols present in the plants were analyzed by paper chromatography. Besides the known polyphenols, scopoletin, caffeic acid, chlorogenic acid and rutin, and two unidentified phenols that are present in untreated plants, 3 spots of unidetified phenols were detected from the catechin-treated plants, suggesting that the catechins were actually absorbed by the plants.

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The investigation was made on the changes in the total nitrogen, free amino acids, caffeine and tannin of tea leaves with special reference to the development of new shoots during the begining time of the first crop season to the middle time of the second crop season, using the five-year-old clonal variety "Yabukita" under field condition.
1. The total nitrogen contents of new shoots increased until stage of 2.7 unfold leaves (12 days before optimum plucking time, "-12 days") and then decreased continuously with the growth of new shoots.
The total nitrogen contents of mother leaves, which started to decrease from the stage of 1.6 unfold leaves of new shoots (-21 days), turned to increase as soon as new shoots were plucked, doing so until a stage of two unfold leaves of the second flushes.
2. The principal free amino acids of new shoots consisted of theanine, glutamic acid, arginine, serine and aspartic acid, and theanine constituted about seventy percents of total free amino acid all the time. Total free amino acid and theanine which slightly increased until the stage of -5 days, and other three principal amino acids except glutamic acid which slightly increased until the stage of -12 days, began to decrease rapidly from mentioned dates respectively, lowering to such a low level as two third to a half of their maximum contents at mentioned younger stage even at the optimum plucking time (stage of 4.6 unfold leaves and 60 percents of Banji shoots). Glutamic acid alone, however, appeared to have nothing to do with aging or presence of new shoots, tending to persist in almost the same level throughout the period investigated.
3. The contents of total amino acids and the proportion of theanine in mother leaves were very much low compared with those of new shoots, being about a third of them, although there was no difference in the constituents of the principal amino acids between mother leaves and new shoots. Each amino acid of mother leaves could be grouped into three types according to their behaviors indicating their respective physiological and biochemical roles in tea plant as follows : (1) Theanine type (theanine), which decreases incessantly during growing period of new shoots, but increases rapidly on plucking of new shoots, being main form for storage and translocation of nitrogen.
(2) Glutamic acid type (glutamic acid, aspartic acid and free ammonia), which tends to keep constant level irrespectively of growing stage or presence of new shoots, being key amino acids for transamination.
(3) Minor amino acids type (all the other amino acids than members of type (1) and (2)), which increases sharply when leaving new shoots intact after the optimum plucking time, whereas it decreases gradualy when plucking of new shoots, suggesting the occurrence of nitrogen metabolism changeable to either direction, synthetic or decomposing ones, depending upon new shoot's requirement for nitrogen.
4. The caffeine behaved like total nitrogen whose change with time was far more moderate than those of theanine and total amino acid.
5. Tannin also acted in similar way to nitrogenous compounds in new shoots. With mother leaves, however, it went on increasing slowly until the optimum plucking time. After that, when new shoots were allowed to grow, it increased more rapidly than before, but when they were removed by plucking, it decreased rapidly after momentary abrupt rise for a few days.

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The problem of P placement in tea fields, where "all layer" or "deep layer" application are difficult to be practiced, was examined by technique of root splitting solution culture, in which comparison was made between the "semiroot feeding" method and the normal feeding one instead of "surface layer" application and "all layer" application in field, respectively, in terms of efficiency of P uptake and its translocation to P unfed root systems. In the "semi-root feeding" method, P concentration in solution was doubled to provide equal amount of P per plant for two feeding methods. It was ascertained that there was no difference in efficiency of P uptake between two methods. As for the translocation of P absorbed by P fed root systems to P unfed root systems, when an experiment was conducted with the plants having initially excessive P, it occured to rootlets but not to larger lateral roots. However, when a semicircular ringing was applied to the stem on ground level from which P unfed root systems had arisen, or when the plants having lower P contents compared with the P excessive plants were tested, this translocation did not occured to rootlets as well. From this it seemed that this translocation proceeded via aerial parts of the plants, hence it was dependent upon the P demand there.
It was also found that uptakes of other nutrients by P unfed roots were affected by this translocation of P to them.
After all, these data indicated that the problem of P placement was a question of easiness of P translocation among root systems differently fertilized with P. Therefore futher researches on this aspect of P nutrition by isotopic technique or by long term solution culture are needed.

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In order to examine the changes in aroma constituents during the manufacture of green tea of var. Yabukita, aroma concentrates prepared from fresh, steamed, primary rolled, and final rolled leaves were respectively analyzed with gas chromatographic and combined gas chromatographic-mass spectrometric techniques.
During steaming of 30 sec most constituents increased, especially cis-3-hexen-1-ol, cis-3-hexe-nyl acetate and linalool oxides greatly increased. When the steaming time was prolonged to 120 sec, most constituents decreased, especially the above three components, linalool and dimethyl sulfide markedly decreased. During the process from primary to final rolling almost all constituents decreased with the progress of tea manufacturing.

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Zonate leaf spot of tea was a new disease that Nonaka named recently. The disease occurred only in Kagoshima prefecture before now. However, in May to June, 1976, the disease was confirmed in the tea field at Kakegawa city in Shizuoka prefecture. Under this circumstances it was assumed that the occurrence of the disease was caused by some weeds infected with the fungus, spread to mulch in tea field.

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[in Japanese]

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