The experiments were made to know the influ-ence of successive cropping to the growth of taro, edible burdock, carrot and Japanese radish.
(1) Taro causes a severe damage by its successive cropping. The growth and the yield remark-ably decrease after 2 years of its successive crop-ping. The deficiency of the exchangeable cal-cium and the increase of the exchangeable acidity are some of the causes of the damage by the successive cropping, but other causes are not yet known.
(2) Edible burdock is also severe in the damage by its successive cropping. In this case, the main cause seems to be the damage by nematodes in the soil.
(3) Carrot ordinarily causes no damage by its successive cropping, but rather improves its quality. Nevertheless, the increase of nematodes in the soil prevents its successive cropping.
(4) Japanese radish causes no damage by its successive cropping at all. The length and the growth of the root are rather developed by its successive cropping for about 10 years.

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1. Cucumber seedlings are set under long day (15hrs.) and high night temperature (30°C) treat-ment of two or four days duration at each stage of their development, for the purpose of detecting the influence of those environmental factors reflected upon the sex pattern of the flowers. In some plots, treatments are thrice or five times repeated-ly applied. A plot is set under the long day and high night temperature through the whole seedling stage.
Control plot is set under short day (8hrs.) and medium night temperature (20°C) through the whole seedling stage.
2. Long day and high night temperature favor the staminate flower development and restrict the pistillate flower formation.
As the first pistillate flower of the control plant flowered at the eighth node, the adverse influence of the long day and high night temperature treat-ment reveals its effect apparently only at the higher nodes. At the lower nodes, even on the control plants, there bloomed only the staminate flowers.
3. Treated at the fourth period, just when the primordia of the seventh to the tenth nodes are going to differentiate sexually, those primordia were all transformed into the staminate flowers. Even the treatment applied at the first period influenced on the sex differentiation of the primor dia of the seventh to the eighth nodes. The treatment at the second period influenced upon the sex of the primordia of the seventh to the ninth nodes. The treatment at the third period influenced upon the primbrdia of the seventh to the tenth nodes.
4. The effect of the treatment of four days duration always manifested itself stronger than that of two days duration applied at the same stage.
5. It seems that these environmental conditions influence the sex differentiation by inducing the physiological change around the primordia just going to differentiate sexually, being invigorated as much as the duration of the treatment elongated, or the repetition times of the treatment multiplied, and fainting as time elapses.

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The data here reported include results of studies on (1) the histological display of the heading pro-cess of chinese cabbage, (2) the effect exerted by the artificial supplement of the growth substance on the behavior of the leaves, (3) relationships between the native auxin and carbohydrates and nitrogenous constituents with regard to heading.
1. The leaves of chinese cabbage plants incurve as they are brought into the dark place. The in-curving portion consists of vigorously growing tis-sues and it is observed that the cells of the dorsal side of the incurved portions are much more elon-gated than the cells of ventral side of the leaves. It seems that the incurving process of the leaves is of hyponastic nature responding to shading.
2. As the hyponastic development seemed to be brought about by the hormonal displacement, the artificial supplement of auxin to the plant body by means of the naphthaleneacetic acid applied in various ways, was conducted for the purpose of detecting the response of the leaves as influenced by the applied growth substances, compared with the incurving development arising in natural sequence.
a) The leaf blade responds to the supplement of the growth substance more sensitively than the leaf petiole, and wider expands the leaf area, the more active is the response.
b) The tips of the leaf blade responds most sensitively to the supplement of the growth substance, being followed by the middle and the basal part in the order decreasing sensitiveness.
c) The trend of the incurving response to the supplement of the varied concentrations of naph-thaleneacetic acid shows that there is the optimal -concentration for incurving.
d) The hyponastic development of the leaves rich in carbohydrate content is much invigorated, and weakened, however, when the leaves are
rich in nitrogen content.
3. It was proved that native auxin in the leaves of chinese cabbage was indoleacetic acid by means of paperchromatographic color tast and avena straight growth test.
a) The native auxin content is high in the leaf blade and less in the petiole.
b) The native auxin content of leaves varies with the phyllotactical order. The inner leaves are more rich in the auxin content than the outer leaves. The higher concentration of auxin is found in the leaves which compose the outermost part of the head. The etiolated leaves folded in the head, however, show less auxin content than the green leaves.
4. The results of the chemical analysis of the leaves show that both the nitrogenous constituents and carbohydrates increase phyllotactically inwards and the carbohydrate content is so much that the ratio of carbohydrate to nitrogen increase inwards.
5. It may be concluded that the head formation of chinese cabbage is brought about by the incurv-ing development of hyponastic nature under the shaded condition. The outer rosette-typed, green and broad leaves shade the later developing inner leaves, which incurve and compose the head. It was proved by the authors in the previous ex-periment that the defoliation of the outer leaves inhibited the incurving development of the inner leaves and sometimes the latter did even expand outwards.
Accordingly, auxin activity in the leaves is the most essential internal factor responsible for the heading process togather with the nitrogenous constituents and carbohydrates. The higher the auxin and the carbohydrate content, the auxin activity is enforced more vigorously. It is observ-ed that the heading movement arises in the leaves, most abundant in the auxin content and favored with higher carbohydrate ratio to nitrogen.

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The purpose of this study was to find the most promising F₁ hybrids by crossing several self-incompatible strains of induced pseudogamy in Matsushima No. 2 and Chiba No. 1 chinese cabbage.
The authors obtained 48 F₁ hybrids by crossing 23 self-incompatible strains. The seeds of these F₁ hybrids were sown on the two different dates. The hybrid vigor and the various characteristics which appeared in these F₁ hybrids, were observed.
(1) In crossing these self-incompatible strains, hybrid vigor was affected by different cross-combi-nations and different sowing dates, and especially the total weight, head weight etc. were increas-ed by hybridization.
(2) The rate of increase in F₁ hybrid yield was greater than that of their parents, in both early and late sowing, and the variation in their yield was greater than those of other characteristics. It is thus possible to find a fairly productive F₁ hybrid.
(3) Generally, the degree of hybrid vigor which appeared in early maturity and leaf number was less in comparison with those of other charac-teristics. However, a few of these cross-combi-nation showed marked vigor in early maturity and leaf number characteristics. Therefore, it was possible to select the hybrids that matured earlier, and had more leaves per head than Matsushima No. 2.
(4) There was correlation between a superior parent yield, an average yield of parents and F₁ hybrid yield, respectively, but no correlation be-tween an inferior parent yield and F₁ hybrid yield. The F₁ hybrid resulting from crossing productive parents showed increased vigor, when their parents were homozygous.
(5) In general, F₁ hybrids resulting from the crossing of these self-incompatible strains did not have more excellent characteristics than those of standared variety, Matsushima No. 2. However, some of these F₁ hybrids seemed markedly promising. Finally, we selected 6 F₁ hybrids that had showed adaptability to early sowing and late sowing, which were superior in early maturity, yield, uniformity and disease-resistance (soft rot) to Matsushima No. 2.

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1. To investigate the effects of aeration on the growth and uptake of nutrients of vegetable crops, extensive studies were carried out in the nutrient solutions, in which the amount of dissolved oxygen was regulated in three grades as follows:
(1) Solution aerated continuously by bubbling air
(2) Solution not aerated, ordinary solution culture
(3) Solution not aerated and the oxygen from the air prevented from dissolving into the solution by vinyl film coverings
2. In autumn and winter crops, the effect of aeration was observed to be most remarkable in radishes, cabbages and peas, and next to them in Welsh onions, but in such crops as broad beans, strawberries and onions, aeration was not so effective.
On and after April the growth of onions and broad beans was accelerated by aeration, while in the early season greater growth of them was observed in the solution in which aeration was prevented.
3. In summer crops, tomatoes and cucumbers showed a greater increase of growth by the aeration, while on egg-plants, peppers and sweet potatoes aeration had little effect and “Fujimame” and asparagus beans grew well in non-aerated solution.
The growth of cucumbers was accelerated by aeration, but on the other hand, it continued to grow pretty well even in the solution with lower oxygen pressure.
4. The absorption of NH₄-N, P, and K was disturbed by the decrease of oxygen in the solution, however, that of NO₃-N was not so much affected. In some crops the absorption of NO₃-N was increased rather at low oxygen pressure. One reason for the distinct increase of growth in the early stage of broad beans under lower oxygen condition, may be due to this phenomenon.
5. In Welsh onions, cabbages, and radishes the absorption of NO₃-N was not so remarkable at lower oxygen pressure.

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二十世紀梨の柚肌病について,その発生経過を組織解剖学的に観察した。その結果は次の通りである。
1.柚肌発生樹に着いた果実では,既に7月下旬～8月上旬に,果肉内に維管束に近接して空隙を生じ,その空隙内部には細胞の分裂異常増生による乳頭状の突起が観察され,また維管束末端の果肉細胞に木栓化が認められた。
2.収穫時の柚肌果では石細胞の発達が著しく,特に果心と外果皮に近い果肉に多く,また果皮の硬化部直下では,維管束末端の果肉柔細胞に木栓質が甚だしく発達し,その附近には多量の澱粉が遺存した。
3.従つて,柚肌果の果皮に凹凸を生ずるのは,以上のような障害部の発育が遅れて健全部の果肉の肥大が行われるためと思われる。また,柚肌果の果肉硬化の現象は,石細胞の発達と共に果肉柔細胞の全面的木栓化によるものと考えられた。
4.正常樹と雖も, 6月下旬～7月下旬に人為的に土壌の乾燥処理を行うと,果肉内部に柚肌発生樹の果実におけると同様な組織変化を生じ,収穫時に柚肌果を認めた。
5.健全果の果肉内に稀にspotとして認められる木,栓質(Cork spot)は,乾燥した年に多量に発生する傾向にあり,また柚肌果の果皮の凹凸とは直接の関係は少いようであるが,柚肌果には多量に存在した。

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Insect visitors to the flowers of peaches, one of which was the pollen nonviable variety “Yamato-hakuto”, and the other was the pollen viable variety “Hakuho”, were investigated at Nara Experiment Station in 1954 and 1955.
In the blooming season of 1954 when it was gene-rally cloudy and rainy, the insect visitors were classified into 59 species of 21 families. Diptera were most frequently observed to the flowers of peaches, especially to the “Hakuho”, and “Hymenoptera” came next in number to the “Hakuho”.
In the blooming season of 1955 when it was generally fine, the insect visitors were classified into 46 species of 20 families. Hymenoptera were, most frequently observed to the flowers of peaches, especially to the “Hakuho” and Diptera came next in number.
Lepidoptera and Coleoptera were rarely observed to the flowers of peaches in both years.
The time of their visit was not definite in 1954, but in 1955 they visited most frequently during a few hours around noon, and least in early morning and evening. When it rained, their visit was very seldom. It is guessed that their visit has: something to do with temperature, rainy weather, and the conditions of flowers.

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In the previous papers the auther reported that growth substances may be successfully used for delaying flowering of chrysanthemum. The present study deals with the effects of combined applica-tion of electric light and auxin on delaying flowering and on flower characters.
In the light culture of chrysanthemum, the light effect for delaying flowering decreases with an increase in distance from the light source due to the reduction in light intensity.
If the auxin supply complements the deficiency of light intensity, then its application would be an advantageous method to save the cost of electric equipment.
The variety “December King”, which is popularly cultivated by delaying its flowering for winter sale in Japan was used in this study. “Yellow Boyce”, which is a mid-season autumn variety and is not suitable for delaying was added for compari-son with “December King”. The materials were propagated by cuttings on July 11, planted in 6 inch pots on Aug. 4, and pinched on Aug. 14. Three shoots were selected for every plant.
Total materials were divided into three lots each containing 13 pots. In each lot, pots were arranged in a row which extended from under the lamp to 3.2 meters away, and were labelled with no. 1, 2, 3, ……13. These pots were placed in the green-house which was heated with an electric cable after early January.
The intensity of illumination from the 80 W Mazda lamp decreased from 60 lux nearest for the lamp to 2 lux at a distance 3.2 meters away. The first lot was applied with 50ppm of NAA, the second lot with 100ppm of NAA, and third lot was control. The auxin was supplied at every three day intervals. The long day (17 hrs.) and auxin treatments were started on Aug. 25 and ended on Oct. 10.
At the termination of both treatments slight inhibition of growth of plants of “December King” was seen in the lot with 50ppm of NAA and heavy inhibition in the lot with 100ppm of NAA. However, with “Yellow Boyce” heavy inhibition seen in both of the treated lots. In this variety was the treated plants did not differentiate flower buds and showed the rosette habit after the termina-tion of treatments. Budding date, flowering date, . height of plant, number of leaves and flower size, , etc. were recorded.
The experimental results on “December King” are summarized as follows:
(1) The budding dates of control plants were delayed according to the position in relation to the light source. In the control, the budding date in the 10th pot was Oct. 12, while in the first pot which was placed nearest for the lamp, it was Nov. 16.
With 50ppm of NAA the date of budding was delayed 17 days in the 13th pot, and 5 days in the first pot in comparison with the 13 th and the first pot of control respectively. However, they were delayed at the same rate in all plants applied with 100ppm of NAA.
(2) The date of flowering in the treated plants were delayed according to the delay in bud-ding compared with control, however, those of the first pot treated with 50ppm of NAA and control were the same.
(3) In the control and 50ppm of NAA lots, it was observed that the earlier the flowering date the shorter is the stem length. After the termina-tion of auxin spray all inhibited plants recovered their growing power and elongated.
(4) There is no difference in number of florets among the flowers which opened before the last of December, but the flowers opened after late January had slightly fewer florets.
(5) The differences in stem length, flower size, number of florets and number of leaves be-tween the treated lots and control were not' re-markable. From these results, it may be conclud-ed that, the application of auxin for delaying chry-santhemum flowering is practical. However, it is important to select a variaty which grows vigorously.

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(1) Under the natural conditions in Kagawa, the predifferentiation stage of flower bud in Platycodon grandiflorum, Samidare variety, was observed among the terminal buds of the plants on May 12, 1955.
(2) After one week, on May 19, initial sepal stage, petal stage, and stamen stage were found among the terminal buds, and predifferentiation stage and sepal formation stage were observed among the several upper axillary buds. Average height of plants at this time was 56.7cm. and number of leaves 101.3. From May 11 to May 20 the average maximum temperature was 23.4°C and the average minimum temperature was 13.5°C.
(3) On May 26, flower bud differentiation had progressed to pistil formation stage in the largest bud, and began to bloom on June 2.

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Experiments were carried out to determine the factors affecting the time of flower bud initiation and flowering in Platycodon grandiflorum (var. Samidare), by means of the following procedure:
(A) Temperature test: in which the night temperatures were maintained at about 20°, 15° and 0_??_5°C from January 18 to April 13, 1956.
(B) Day length test: in which artificial lighten-ing during the night and shading with black vinyl film from 5p.m. to 9a.m. were carried out from April 25 to July 2, 1956.
The results are summarized as follows:
(A) Temperature test
(1) Flower bud initiation was first observed among the plants exposed to 20°C, on February 27, 40 days after planting. The plants exposed to 15°C began initiating their flower bud on May 19, 60 days after planting, and the plants exposed to 0_??_5°C began initiating their flower buds on April 24, 95 days after planting.
(2) Flowering of plants at 20°C began on March 27, 68 days from planting. The plants at 15°C began flowering on April 16, 88 days from planting. and the plants at 0_??_5°C began flowering on June 1, 134 days from planting.
(3) The plants grown at 0_??_5°C were the largest and those at 20°C were the smallest in height of plant, number of leaves, and number of flowers. on a plant.
(4) From these results the author concluded that the time of flower bud initiation and flowering in Platycodon grandiflorum A. DC. can be controlled by temperature treatment.
(B) Day length test
No difference was observed among the plants. exposed to long days, short days and those of control, in time of flower bud initiation and flowering, height of plant, number of leaves, and number of flowers on a plant.

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1. From the observation for several years on many varieties of tulips, authors are led to conclude that the types of dropper of tulip bulbs can be classified into the following four groups: mono-dropper type, di-dropper type, poly-dropper type, and branching dropper type (Fig. 1, 2, 3).
2. The formation of dropper was conspicuously different with the varieties. It was seldom to find the dropper in such varieties as Peach Blossom, Boldnage, Capri, etc., while in Kansas, Mozart, Eriford Keizerskroon and Inglescombe Yellow, they were apt to form the dropper. However it was difficult to find the correlation between the formation of dropper and the horticultural families, or earliness of flowering, and the formation of dropper was also not related to the content of soluble matter in bulbs or the number of root.

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