1. During a period of 1958-1960, a series of experiments was carried out with various kinds of chemicals such as plant growth regulators, vitamins, amino acids, organic acids and inorganic substances, in order to examine their stimulating effect on the pollen germination of pears, apples and persimmons on the artificial media. A similar experiment was also conducted on the stigmas of pears and apples grown in the field.
2. Of these substances tested, tartaric acid, oxalic acid and glutamic acid (sodium salt) were the most effective in promoting the pollen germination. Particularly, in the artificial pollination, a high percentage of fruit set was obtained in either case, when the pollens of pears suspended in the sodium of glutamic acid solution were sprayed on the stigmas, or when the flowers of apples were treated with the sodium of glutamic acid solution soon after the blooming prior to the pollination.
3. From the standpoint of practical application, it was very convenient for us that glutamic acid could be used in a wider range of concentrations giving no injury to plants, as compared with the other effective chemicals examined in these experiments.

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Morphological studies on the fruit development of the Early Satsuma orange (Citrus unshiu MARC. var. praecox TANAKA), the Hassaku orange (C. Hassaku Y. TANAKA) and certain other species were made respectively. By comparing these results together with those obtained previously with the Satsuma orange, the general characteristics and specific or varietal differences in the citrus fruit growth were investigated. Noteworthy features of this investigation were as follows:
1. In the growing citrus fruit, the peel and the pulp seem to show different growth cycles. At first, the peel increased in thickness rapidly, next came a vigorous growth of the pulp, which was again followed by a decrease in the peel thickness. Thereafter the peel and the pulp grew in harmony with one another.
The peel continued to grow for a longer period of time than did the pulp. As the fruit became mature, the decline and the cessation of growth occurred earlier in the pulp than in the peel. It seems that the peel maintains its growth activity even after the fruit maturation, although the extent of this post-maturation activity varies among different forms. This characteristic of citrus was most clearly indicated by the conspicuous growth of the peel in the mature fruit of Shuto, a variety of C. aurantium LINN. during spring and summer.
2. In young citrus fruit the peel increased its thickness rapidly when the cell multiplication in the albedo tissue became very vigorous. In the Hassaku orange, which has a thick peel, the albedo tissue cells multiplied more vigorously, continued to do so for a longer period, and as a result became greater in number than in the Satsuma orange.
3. The development of citrus fruit was divided into three stages as follows: Stage I, the cell division period; Stage II, the cell enlargement period; and Stage III, the maturation period. The duration of each stage could be determined by external changes associated with the pulp growth. The period from the emergence of juice sacs to the beginning of their remarkable elongation was referred to as Stage I. In the Satsuma orange, it was observed previously that when the juice sacs began to enlarge abruptly most of their epidermal cells also initiated to elongate. This period was therefore referred to as the cell enlargement period, Stage II. Stage III was defined by a conspicuous decline of the growth in width of the pulp segments.
The species and varieties of citrus fruits used in the present study differed in the durations of these three stages, whereby they could be arranged in the following order (from the longest to the shortest of each stage): Stage I-Hassaku orange, Early Satsuma orange, Satsuma orange; Stage II-Satsuma orange, Hassaku orange, Early Satsuma orange; Stage III- Hassaku orange, Satsuma orange, Early Satsuma orange. The fruit with longer duration of Stage I grew rapidly in Stage II and attained larger size. The duration of Stage II was not directly related either to the final fruit size or to the time of fruit maturity, while the latter was proportional to the duration of Stage III.
4. Despite their larger size, the fruits of Hassaku and Iyokan (C. Iyo TANAKA) contained much fewer juice sacs than did those of the Early Satsuma orange and Satsuma oranges. Consequently, their juice sacs were relatively large, especially so in Hassaku. On the other hand, in every kind of citrus under observation there was a tendency within the same form that the larger the fruit the more juice sacs were found in it. However, the degree of this association was not uniform among different kinds. Thus there were greater regressions of the number of juice sacs on the pulp weight in the Early Satsuma orange or the Satsuma orange than in Hassaku or Iyokan.

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1. This experiment was conducted with figs, peaches, Japanese pears, apples, Japanese persimmons, grapes, citrus trees and loquats to observe the inter-relation of the growth retarding activity of the root-excretion among various kinds of fruit trees. Young plants of each kind grown in Wagner's pots under sand culture were applied every day with such a large quantity of nutrient solution that a part of it would leak out from a hole at the bottom-side of the pot. The leaked solution which contained the root-excretion was caught in a vessel singly in each kind, and it was applied every day to the other young fruit trees of various kinds grown in clay pots.
2. As the result, when the leaked solution of each kind was applied to the fruit trees of the same kind, their growth was retarded particularly in peaches, figs and grapes, followed by in Japanese pears, apples, loquats and citrus trees in the order, except for in case of Japanese persimmons. Furthermore, each leaked solution of peaches and figs retarded also the growth of fruit trees of other kinds when given to the latters.
3. On the other hand, in peaches, figs and grapes, their growth was readily checked when serviced every day with the leaked solution of other kinds. Thus, with only a few exceptions, it became clear that the root-excretions of any two kinds of fruit trees would retard each other their growth in the similar order, the intra-class correlation coefficient of the retarding activity being+0.6014.

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In the results of successive trial growing of the newly introduced European grapes, the following varieties were observed to grow well even outdoors in Tokyo district of Japan and to have special quality; 1) For table use: Incrocio Pirovano No. 28, Incrocio Pirovano No. 150 (Angelo Pirovano), Incrocio Pirovano No. 192 (Tereza Pirovano). 2) For table and wine use: Seyve-Villard 20-365 (Dattier de St-Vallier), Seyve-Villard 18-285, Seyve-Villard 12-375, Seibel 10076, Moscato bianco, Moscato nero. 3) For brewing of wine: Riesling Italico, Verdiso.

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1. The fruit development of Japanese pears (Nijisseiki) as affected by the concentrations of nitrogen, phosphoric acid and potassium was studied from the standpoint of cell division and cell enlargement. The experiment was conducted under sand culture for a four-year period with the same trees which bore fruits first in the fourth year. The culture solution of the standard plot contained the three elements of each 80 ppm. In the other plots, only one of them was varied so as to be 0, 20, 40, 80, 120 or 160 ppm.
2. Division of flesh cells continued nearly one month from full bloom until mid-May. It was most active at 80 ppm N, at 80 ppm P₂O₅ and at 40 and 80 ppm K₂O respectively among the different plots of each element. The lower the concentration of each element than these values, the more inferior was the cell division, particularly no fruit set at 0 ppm N. No marked difference of cell size was found among the different plots except for at 0 ppm K₂O where the cell size was the smallest. Thus, the fruit size at the harvest time was most superior in the standard plot.
3. When observed with all of fruits which were included through the different plots, a high significant correlation existed between fruit size and cell number per fruit with the coefficient of r=+0.858, and also between fruit size and cell size having the coefficient of r=+0.748. Furthermore, leaf analysis on July 2 showed that there was a high significant correlation of r=+0.603 between K content and cell size, or an adverse high significant correlation of r=-0.524 between N content and cell size.

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In the first experiments reported here, the authors attempted to solve the question whether or not the concentration of soluble salts in culture solution is an accurate index of the occurrence of marginal rot in Chinese cabbage.
Plants grown in the solution A containing anions such as chloride and nitrate at high level suffer from leaf marginal rot in the position between 10th and 20th leaves and from the blackening of hydathodal tissue in the position between 20th and 30th leave counted from the bottom up. Therefore, the occurrence of marginal rot may be connected with a disturbance of water-relation due to the cell degeneration. When the heading begins, physiological activity such as mineral absorption becomes higher, but the fullness in tissue decreases. This apparently indicates that there is an unbalanced metabolism in the head of Chinese cabbage during the heading stage.
The rate of growth increased in proportion to the concentration of the culture solution. It is therefore difficult to relate the occurrence of marginal rot to high osmotic pressure of culture solution. On the other hand, the solutions of single salt in 0.2 molar concentration led to decrease in the rate of absorption of water, the physiological drought, but did not produce the marginal rot.
The second experiment was designed to clear up the effect of calcium supplied to the soil on the CaO content in leaves and on the occurrence of the physiological disorder. The symptom of marginal rot occurred when CaCl2 and Ca(NO3)2 of high rate were applied to the soil. Although the calcium content was high in lower leaves and low in the upper leaves, there was no direct relationship between the occurrence of the marginal rot and the total calcium content.
It seems possible that the marginal or heart rot in Chinese cabbage is a symptom of the relative calcium deficiency and not due to the physiological state produced by the failure of calcium absorption. The conclusion, therefore, is that the calciumm content in younger leaves lies between those of the calcium-deficient and normal leaves, and other factors such as osmotic pressure and/or specific ions enhance the occurrence of the marginal rot in the leaves of Chinese cabbage.

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1. The present study has been conducted to investigate the effect of the length of short-day period before bulbing and the length of long-day period before harvest on bulb formation and sprouting of planted bulbs, and to elucidate the relation between the process of bulb formation and regularity of bulb structure in onion.
2. Under favorable conditions for bulbing in onion (long-day and warm temperature) growth of leaf blade was inhibited. Then about 25-30 days after the beginning of long-day period the stop of production of new leaves and ceasing of growth of the youngest leaf were observed.
3. Basing on the results of investigation in these experiments an intimate relation was recognized among the storage leaf formation, ceasing of leaf growth and falling over of top in onion plants. Whenever conditions became favorable for bulb formation, storage leaves were found in the bulb after 20-30 days, about 10 days before ceasing of leaf growth, followed by falling of the top 20-30 days later.
4. A short-day treatment was given to onion plants prior to their bulbing period and their bulb formation was observed.
The short-day treatment for about 30 days before bulbing period caused an acceleration of growth in onion plants and produced large bulbs. But, in plants under short-days until the initiation of the first tiller bud in the bulb, doubling occurred in many cases.
5. The number of storage-, sprout- and foliage- leaves in a bulb was little influenced by the length of long-day period prior to harvest time. But when the long-day period was below 30 days, the number of storage leaves decreased.
Accordingly, it seemed that a bulb is not formed from definite leaves like tulip, but the regularity of bulb structure in onion is caused by the metamorphosis of leaves in response to the environmental conditions.
6. In planted bulbs the date of sprouting was influenced by the time of their bulbing; the earlier the date of falling, the earlier the sprouting.
Accordingly, it is considered that as the top fell over the bulb enters into dormancy and after a certain period the dormancy of the bulb is broken.

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The present paper describes in detail the effects of external factors on the bulbing in onion plants.
1. As the photoperiod became longer, the plant height rapidly arrived at the maximum, being followed by the remarkable thickening of the bulb.
The final size of bulbs at harvest time significantly correlated with the size of seedlings at the beginning of bulb formation.
2. The effect of the long photoperiod during the course of development was nullified by the interruption with the short photoperiod, and the bulbing phase was reversed to the vegetative growth phase. The number of days necessary for the reversal of bulbing phase to vegetative growth phase increased gradually with the thickening of bulbs, but it is possible to reverse the phase even after the top prostration of the plants.
3. The higher the temperature under long photoperiod, the earlier the bulb development. It was not considered, however, that the high temperature compensates partly day length as the low temperature acts as a part of short days for short day plants.
4. The growth of leaves was promoted by the high temperature, but if the temperature was higher than 25°C, the duration of leaf growth was shortened and the final length of a leaf was rather short.
It is considered that the minimum temperature available for leaf growth is 10°C, and the favorable temperature is ranged from 17 to 25°C. This tendency was more remarkable under the long photoperiod than under the short photoperiod.
The Aichi-Shiro seedlings elongated more remarkably than the Kaizuka-Wase and Imai-Wase seedlings and arrived at its maximum height very early.
Consequently the height of the plants was in the following order;
Aichi-Shiro <Kaizuka-Wase<Imai-Wase
5. It is very noticeable that the bulbing was found under the long photoperiod even at 10°C, the minimum temperature for leaf growth.
6. Under the long photoperiod the initiation of bulb formation was not affected by the light intensity, but the thickening of bulbs was inhibited by the low light intensity.
7. The bulb formation was not affected by nitrogen top dressing under the long photoperiod, but a heavy nitrogen application considerably inhibited the thikening. Under the critical day length, the nitrogen application retarded the initiation of bulb formation, though producing the large bulbs at later harvest time.
8. When the long photoperiod was given to the different sized plants, their height began to increase and arrived at their maximum at the same time. This result showed that the initiation of bulb formation was not affected by the size of plant at the beginning of long day treatment, but the thickening was considerably affected by the size of the seedlings.

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When Japanese radish was self-pollinated under high air humidity, its fertilizing power was enhanced to a certain degree (See Table 1, especially the results of 1963). In this case the percentage of pollen germination on the stigma was high, and some pollen-tubes penetrated into the stigma. However, no breakdown of self-incompatibility barrier was observed (Table 2).
The osmotic pressure of the stigmatic papillae measured by a plasmolytic method was isotonic to the 0.30 molal solution of sucrose two days before flowering, 0.45M on the day of flowering, and 0.35 M on the third day. The osmotic pressure of mature pollen grains was isotonic to the approximately 0.40M solution of sucrose (Table 3).
It seems probable that the poor germination of selfed pollen on the stigma is due to water deficiency because the stigmatic surface is covered with cuticule. Consequently, no inhibitory substance seems to be present on the stigma.
These results are in general accordance with those of OELKE (1957) in radish although differ somewhat in details.

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In the previous papers, it was reported that the effect of high temperature on fruit setting and yield differed by the growth stages of seedlings, and it was also suggested that this result was due to the difference in susceptibility of flower buds and flowers of different stages of development on the seedlings to high temperature.
Experiments reported here were conducted to determine the effect of high temperature on the flower buds and flowers of different stages of development, the stages of buds being accurately defined by measuring their length. As high correlation was found between the length of flower buds and the duration of time to their anthesis, the stages of flower buds were expressed in terms of days to anthesis.
Seedlings of two groups (in one group, the first flower of first cluster just opened; and in another group, all the flowers in first cluster opened) were exposed to 40°C for three hours daily, twice.
Percentage of setting of flower buds treated 11 days before anthesis was 100%, 9-5 days before 10-20%, 3 days before 70%, and one day before 100%. Percentage of setting of flowers 1-3 days after anthesis was 20%, and 8 days after anthesis 100%. Thus it was revealed that flower buds of 9-5 days before anthesis and flowers of 1-3 days after anthesis were highly susceptible to high temperature.
Hand pollination with normal pollen increased the setting percentage of flowers which had been treated 7-5 days before anthesis to 60%, but failed to increase the set of flower buds treated at other stages. This result shows that the high temperature treatment affected both pistill and stamen in the flower buds of 9 days before anthesis, while it affected mainly stamen in the buds of 7-5 days before anthesis.
p-chlorophenoxyacetic acid (CPA) spray improved setting of flowers treated with high temperature after anthesis, but did not increase the setting of flowers treated at their bud stages.
Considerable number of small fruits appeared from the flowers treated with high temperature after anthesis. CPA spray on these flowers after high temperature treatment did not alter this tendency.
Percentage of puffy fruits, though degree of puffiness was very slight, was increased by the high temperature treatment. CPA spray increased green gelatinous fruits, and the high temperature had a synergistic effect on the incidence of these fruits.
Highly positive correlation was found between the number of seeds per fruit and fruit weight. Fruit weight per seed was 0.36g in the control, 0.34g in the plot treated with CPA, and 0.49g in the plot treated with high temperature.

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Pot experiments were conducted to study the effects of heavy application of fertilizers on top growth, tuber-formation and -thickening of sweet potatoes. Four kinds of soil differing in their clay content were used. Amounts of nitrogen and potassium were applied each at three levels, the ratio of nitrogen to potassium being 1:1. One cutting was planted in each pot.
Heavy application of fertilizers maintained the top growth vigorous throughout the growing period in every type of soil. The difference in top growth among the fertilizer levels was significant in the soils having higher clay contents.
Though heavy application of fertilizers was unfavorable to tuber formation owing to the vigorous vine growth during the period of tuber formation, it increased tuber yield, especially that of large tubers, as it kept vine growth vigorous during tuber-thickening stage.
The higher was the clay content of of soil, the higher was the fertilizer level favoring the highest dry matter content of tubers, with the exception of clay loam, containing the largest amount of clay among the soils used, in which it was rather low.

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1. Hyacinth (var. Queen of the Blues) bulbs of 13cm in circumference were planted in the field of Toyama prefecture, and their morphological development and changes of chemical composition during the growing season were studied.
2. The separation of a new growing point from the old one took place at the early stage of flower differentiation that began in mid-June, and it differentiated 2 or 3 scaly leaves and several normal leaves, which reached their completion shortly before harvest. The scaly leaves and the bottom parts of normal leaves remaining in the bulb developed to new scales with the progress of growth.
3. Leaves attained to their maximum length and weight in mid-May, after which the weight decreased gradually. The moisture contents of leaves indicated no apparent changes all through the growing period, except the time of shooting when it increased a little. The circumference of bulbs somewhat decreased in mid-April as the result of stretching of inflorescence out of bulb, followed by a continuous increase up to harvest in mid-June.
4. The weight of old scales decreased gradually from the planting and rapidly from the shooting to the flowering time in mid-April, and the moisture content of old scales became a little higher. Later on, the weight continued to increase, and the moisture content to decrease.
5. The changes of scaly and normal leaves into scales by thickening and increasing their weight started in the period from late April to early May. The increase of weight continued without pause till harvest accompanying the gradual lowering of the moisture content.
6. The nitrogen amount in tops showed a rapid increase till the end of April, and little change during the first half of May, followed by a rapid decrease. In old scales, on the other hand, it fairly decreased for a short time after planting and then maintained that level till the end of April, then increased continuously through the period from early May to harvest. New scales generally showed the same increase of nitrogen amount as that of old scales.
7. The changes of the amount of phosphorus in each part of plant indicated nearly the same trends as those of nitrogen. And magnesium amount also showed approximately the same type of changes.
8. Potassium concentration in each part of plant, except a sudden drop in new scales in mid-April, kept almost a constant level. Therefore the changes of potassium amount in each part of plant nearly coincided with the changes of dry matter weight.
9. The changes of calcium amount in tops and new scales remarkably differed from those of the other elements in respect to that it constantly increased throughout the nearly whole growing period. In old cales, calcium amount did not show any noticeable change throughout the growing period except a temporal rapid increase in mid-May.
10. Reserved carbohydrates in the hyacinth bulb were non-reducing sugar of approximately 40% on dry matter basis and starch of about half of that amount. In old scales, the amount of non-reducing sugar decreased remarkably in the period from the planting to the flowering, and starch disappeared utterly in this period, which were restored again thereafter. In new scales, the accumulation of carbohydrates began a little later than in old scales starting early in May. In general, concentrations of carbohydrates were higher in new scales than in old scales.
11. Considering the progress of growth from the nutritional view point, the growth period of hyacinth may be divided into the following six stages:
I. Stage of root system development (planting-thawing),
II. Stage of earlier top-growth (thawing-mid-April),
III. Stage of later top-growth (late April-early May),
IV. Stage of earlier bulb weight increase (early May-mid-May),
V. Stage of later bulb weight increase (mid-May-early June),
VI. Stage of maturity (early June-harvest).

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