Thirty kinds of plant hormones and other chemicals were tested for their effectiveness in thinning flowers and fruits of Satsuma orange from 1950 to 1961. The materials were sprayed at the flowering time or at the young fruit stage, 3-4 weeks after petal fall, and subsequent fruit dropping, and, in some cases, fruit growth were examined.
1. MH showed thinning effect on heavy bearing branches and its phytotoxicity was comparatively slight. Its effective concentration was 0.15% when the plants were in full bloom and 0.3% at young fruit stage.
2. Growth regulating substances, such as 2, 4-D, 2, 4, 5-T, 2, 4, 5-TP, Amidthin and Gibberellin, showed no consistent effect for thinning in their lower concentration range, while in their higher concentration range they induced severe leaf injury.
3. As to insecticides, such as DN, oil and Parathion, their effective concentrations for thinning induced severe injury to leaves and fruits, and their safety concentrations showed no effect of thinning.
4. Herbicides and other materials, such as PCP, CMU (3-(p-chlorophenyl)-1: 1-dimethyl urea), CAT (α-chloro-4, 6 bis ethyl amino-s-triazine), CIPC, DCPA (2, 4 dichlorpropionanilide), Propazine(2 chloro-4, 6-bis isopropylamino-s-triazine), OED (polyoxyethylenedocosanol) and Dessicon (potassium isopropyl xantate), seemed to have no practical value as thinning agent.

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In order to investigate soil temperature under different methods of soil management in orchard, observations on soil temperature, air temperature, humidity and radiation were made from March 4 to 7 in 1957, as shown in Table 1.
1. Soil temperature in the plot mulched with straw was the highest and that in clean cultured plot the lowest at night. But during day-time soil temperature in clean cultured plot registered the highest value and that in the mulched plot the lowest value, as shown in Fig. 1.
2. The difference in heat balance between clean cultured and mulched plot was calculated from Formula 1 and 2, as shown in Table 1. From this table, it is recognized that heat stored in the soil in mulched plot was less as compared with that in clean cultured plot.
3. It was considered that there are two factors to acount for the lower value of soil temperature during day-time and higher value at night under straw mulch. One of them is the lower value of net radiation absorbed by straw surface as shown in Fig. 3, and another is the lower heat conductivity of straw, as shown in Table 4 and Fig. 4.

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Changes which occurred in the pectic substances of Satsuma orange (Citrus unshiu) induced by gamma radiation were studied. Satsuma oranges were purchased fresh through the market. Irradiation was performed with gamma rays from the Cobalt -60 source, does being at 0, 0.9×10⁴, 9.6×10⁴, 53.2×10⁴, and 117.8×10⁴ rep.
Preparation and extraction of pectic substances: Juice, peel and pulp were separated from each other. Peel and pulp were extracted with boiling 70% ethyl alcohol to remove sugar. Extractions from sugar-free dried samples were performed successively with three agents: cold water; cold 0.4% sodium hexametaphosphate; 0.05N hydrochloric acid at 85°C (HCl-soluble A). Water soluble pectinate and pectate were extracted from cold water, water insoluble pectinate and pectate from hexametaphosphate solution, and protopectin from hydrochloric acid solution. Total pectin is the sum of the 3 fractions.
Also, extractions from sugar-free dried peel and pulp were immediately performed with 0.05N hydrochloric acid at 85°C (HCl-soluble B).
Determination of pectin content: Each of the extracts was determined by the calcium pectate method of CARRÉ and HAYNES.
Inherent viscosity measurement: Approximately 0.1% pectin solution containing 0.6% sodium chloride and 0.4% sodium hexametaphosphate at pH 6.0 ±0.2 was used for determining relative viscosity (η_γ). Viscosity was measured at 30°C by OSTWALD-CANN0N-FENSKE viscosimeter. Inherent viscosity of pectin was calculated from relative viscosity ({η}=ln η_γ/C, C is concentration of pectin in the solution [wt./vol.%]).
1. In juice, soluble pectin increased and inherent viscosity decreased by gamma radiation.
2. In peel and pulp, water-soluble and hexametaphosphate-soluble pectin contents increased by gamma radiation and that of HCl-soluble A decreased, and then inherent viscosities of all fractions decreased, especially that of hexametaphosphate-soluble fractions in peel and pulp, and that of water-soluble one in pulp. This indicated that depoly merization occurred during irradiation. Both pectin content and viscosity decreased more in pulp than in peel.
3. The pectin contents and viscosities of three fractions, especially of water-soluble and hexametaphosphate-soluble fractions, in the peel, differed from those in the pulp, and consequently it was apparent that properties of pectin between peel and pulp were different.
4. Owing to the reduction of jelly units obtained by multiplying together the yield and jellly grade calculated from inherent viscosity of the pectin in HCl-soluble B, irradiated peel and pulp were unsuitable as the material of manufacture of pectin.

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1. Examination of pollen fertility of male plants and seed fertility of female plants in wild and cultivated butterburs revealed that most of wild butterburs were fertile (Figs. 1, 5, 12-right, 14), while most of cultivated varieties and some wild plants were partially or completely sterile.
In wild butterburs, percentages of normal pollen grains in fertile and partially sterile male plants were about 90 and 50, respectively (Figs. 1, 2). Completely sterile male plants produced empty pollen grains of various sizes (Fig. 3), or disintegrating microspores (Figs. 4, 6, 7, 8). Sterile female plants produced empty seeds (Fig. 12-left).
In cultivated varieties, male plants of“Mizubuki” produced no viable pollen, and female plant of“Aichiwasebuki” and“Mizubuki”did not bear seeds even when artificially pollinated with viable pollen. In“Akitaôbuki”, however, female plants bore plump seeds and pollen fertility of male plants was about 70 per cent.
2. The inflorescence and florets of completely sterile plants were morphologically different from those of fertile plants. In male sterile plants, the style was markedly shorter than that in fertile plants (Figs. 9, 10, 11), and anthers were film-like and brownish and did not open. In sterile female plants, florets turned brown gradually, the ovary and pappus did not develop at all (Fig. 12), and finally seed stalks withered bearing empty seeds on their heads. Completely sterile plants were characterized by earlier sprouting and more vigorous growth habit than fertile plants.
3. Sterility of butterburs was ascertained to be inherent to stocks. It is highly probable that completely sterile plants are triploid.
It was assumed that the sterility of“Aichiwasebuki” and“Mizubuki”, two cultivated varieties, originated in sterile wild stocks from which cultivated plants have been derived by vegetative propagation (crown division).

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“Natuhusinari”, which has been bred in the Station in Kurume, produces female flowers at more than 80% of the nodes in spring and early summer sowings. Some lines of“Natuhusinari”, which segregate gynoecious plants, have been developed and are used as female in some commercial F₁ hybrids and as breeding material.
This variety was found to be highly resistant to powdery mildew caused by Sphaerotheca fuliginea (SCHL.) POLLACCI. In order to study the inheritance of powdery mildew resistance, the F₁, F₂ and backcross plants between“Natuhusinari”and“Kurume-otiai No. 1”, a susceptible variety, were grown in the field in summer of 1958. Since heavy natural infection of powdery mildew occurred, it was easy to distinguish the resistant individuals from susceptible ones in the late stage of their growth.
The F₁ plants as well as the susceptible parent were severely infected. The F₂ and backcross data are presented in Table 1. It clearly show that the powdery mildew resistance is a recessive and monogenic factor.
The parents of the cross also differ in their fruit-Spine color:“Natuhusinari”has white spine, while “Kurume-otiai No. 1”has black spine. The F₁ plants had black spine. The F₂ and backcross data are given in Table 1.
The results show that a single gene difference exists between the parents for fruit-spine color, and further that there is no linkage between powdery mildew resistance and fruit-spine color.

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Eggplants, variety“Kitta”, were grown in three different localities in 1955 and 1957 to study the effect of climatic conditions on seed production. These localities and their elevations are as follows:
Locality Height above sea level
Hiratsuka (Dept. Hort., Nat. Inst.
Agr. Sci., Kanagawa Pref.) 8 meters
Ryuo (Yamanashi Agr. Exp. Sta.,
Yamanashi Pref.) 260 "
Yatsugatake (Yamanashi Agr. Exp.
Sta., Yamanashi Pref.) 703 "
All plants used in the experiments were raised from the same seed source each year, planted in seed bed at Hiratsuka, and the seedlings were transported to the other localities from Hiratsuka on the same date in late May, about 70 days after planting, and then they were planted in Wagner pots (1/2000 are). To reduce the effects of difference in soil conditions, the soil used was prepared at Hiratsuka and transported to the other localities with the seedlings. The same amounts of fertilizers were applied to each pot according to the fixed schedule. The plants were trained to three main stems. Fruits were thinned to three per plant in one plot and were unthinned in the other.
The vegetative growth of plants, especially the height of plants and number of leaves in both thinned and unthinned plots at Ryuo were far superior to those at the other localities every year. Similar trends were observed on the weight and number of ripe fruits and seed yield per plant in both plots.
During the experiment periods for these years, Ryuo had wider daily temperature ranges than the other localities, and daily mean temperatures at Ryuo and Hiratsuka were approximately the same, while they were lower at Yatsugatake than at Ryuo and Hiratsuka.
Thus the favorable effect on the growth and seed production of eggplant at Ryuo may be attributed to higher day temperatures and lower night temperatures, or wider ranges of daily temperature during the growing season. Yatsugatake has a wider daily temperature range than Hiratsuka, but the daily mean temperatures are lower and unfavorable for eggplant growth. This seemed to be the reason why the growth of plants, fruiting, and seed yield at Yatsugatake were inferior to those at Ryuo and Hiratsuka. The daily temperature ranges at Hiratsuka, the coastal area, are small, and the climatic conditions are fairly favorable for the growth and seed production of eggplant, but the plants at this locality showed generally less growth and seed yield than those at Ryuo.
These differences in fruiting and seed yield of eggplant among localities are indicated to be more marked in the unthinned plants than in the thinned. The results at Ryuo in 1955 showed that the weight and germination percentage of the seeds produced from earlier three fruits on each plant in unthinned plot were approximately the same as those in thinned plot. However, the seeds produced from later three fruits in unthinned plot were inferior to those from earlier three fruits in unthinned plot and in thinned plot.
These results suggest that, if daily mean temperature is optimal, wide daily temperature range is favorable for the growth and seed production of eggplant.

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Experiments were carried out to compare the concentrations of cations and pH favorable for plant growth, in culture solution supplied with different forms of nitrogen. Several vegetable crops were cultivated in sand or solution under glass. Forms of nitrogen supplied were NO₃-N, NO₃+NH₄ or NH₄-N (10m.e. as N).
1. Cabbage plants supplied with NO₃+NH₄ or NH₄-N required more calcium than plants supplied with NO₃-N, for better growth. And in the NO₃+ NH₄ treatment, growth of plants which were given more calcium (6-18m.e.) caught up with growth of NO₃ plants, but not in the case of NH₄ plants. In turnip, however, growth of NO₃+NH₄ plants was also behind that of NO₃ plants, notwithstanding higher calcium supply (4-12m.e.). On the other hand, in spinach, growth of plants supplied with any form of nitrogen did not increase so much, even when calcium level was raised up to 4-12m.e., and growh of both NO₃+NH₄ and NH₄ plants were fairly below that of NO₃ plants.
2. In cabbage, in spite of increased magnesium or potassium supply, growth of NO₃+NH₄ or NH₄ plants was inferior to that of NO₃ plants.
3. Calcium deficient symptoms of cabbage and turnip were rather severe in the plants supplied with NO₃-N, but in spinach, severer symptoms emerged in the plants supplied with NO₃+NH₄ or NH₄-N. Moreover in cabbage, there were some differences in the magnesium or potassium deficient symptoms among the forms of nitrogen supplied.
4. Total calcium coucentration in the leaves of turnip was fairly higher than that of spinach, its greater portions being in the soluble forms, and with increasing the calcium supply, the proportion of soluble calcium increased slightly in plants supplied, with any form of nitrogen. In the leaves of spinach also, the proportion of soluble calcium was fairly high in the lower calcium supply, but with increasing calcium supply, greater portions of calcium became insoluble, its tendency being most remarkable in the NO₃ plants.
5. Growth of cabbage or bean plants which were given NO₃-N showed no greater difference in the range between pH 4 and 7, but turnip plants developed chlorosis and lowered their growth at pH 7. In every test plant supplied with NO₃+NH₄ or NH₄-N, its growth increased with rise of pH level, and at pH 7, NO₃+NH₄ supplied plants made equal growth to NO₃ supplied plants, but, NH₄ plants made less growth.
6. As for the interaction between pH and calcium, growth of cabbage plants supplied with NO₃-N increased with increment of calcium supply in both solution mediums with pH adjusted at 4 and 7. On the other hand, growth of NO₃+NH₄ or NH₄ plants did not increase in spite of calcium supply at pH 4, but at pH 7 their growth increaed with rise of calcium level, and growth of NO₃+NH₄ supplied plants came up with that of NO₃ supplied plants.

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Tomato, cucumber, and kidney bean were grown in sand culture under glass and were supplied with NO₃ (mixed nitrate of K, Ca, and Mg), NH₄+NO₃ (ammonium nitrate), or NH₄ (ammonium sulfate) in the absence or presence of NaCl, to study the sodium chloride injury of these crops in relation to the form of nitrogen supplied. Nitrogen concentration of any nutrient solution was equally 10m.e./l (140ppm), and the concentration of NaCl added to the solution was 3000ppm for tomato and cucumber, and 2000ppm for kidney bean. All of the solutions were adjusted to pH 6.2-6.4.

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Intending an ecolo-physiological study on branching in pea (pisum sativum L.), the authors have first tried to examine influences of photoperiod and seed -vernalization on branching.
Varieties used were GW (early-flowering), Shirobana-Zairai (middle-flowering) and Aka-Endo (late-flowering) for the strain of arvense and Alaska (early-flowering), Alderman (middle-flowering) and Usui (late-flowering) for the strain of hortense.
Seeds were sown in the field of Kusatsu City, Shiga Prefecture, on May 24, September 5, and October 20 in 1960 and on April 25 in 1961. The photoperiodic treatment (long and short day) was started as soon as the seedlings expanded their first leaves.
In the experiment beginning in April or May, plants receiving a short photoperiod (SD) were given 8 hours of day light between 9.00 a. m. and 5.00 p. m. They were covered with light-tight white-vinyl screen from 5.00 p. m. to 9.00 a. m. Plants receiving a long photoperiod (LD) were given the natural long-day in the spring. In the experiment from September or October, a long photoperiod of 16 hours was made supplementing the natural daylength with artificial lighting in the evening. Plants receiving a short photoperiod were placed under the natural short-day in the autumn.
Besides, in April and September, vernalized seeds (V20 or V30) were sown along with untreated (V0). The seed-vernalization was performed at 1-3°C for 20 or 30 days in a dark electric refrigerator.
Each treatment with two replications contained 20 plants, and some 7-8 plants out of them were sampled for measurement. The further details of the experiment are arranged in Table 1.
1. Under short-days, the internode elongation of main shoot and branches of pea is remarkably inhibited. Influence of seed-vernalization on the growth of main shoot was not verified.
2. Generally, the total number of branches per plant increases under short phtoperiod, and hereby the increase is more remarkable in the secondary than in the primary branches. Further, varieties belonging to the strain of arvense, in particular its late varieties respond more decisively to the photoperiod than those belonging to the strain of hortense. Their response is, however, makedly weakened when they are grown in a warmer season.
The influence of seed-vernlization on the total number of branches per plant is so varied with varieties and the sowing time that any conclusive remark is hard to make.
3. Branches of pea may be divided into two groups with reference to their position on main shoot, that is, groups of low- and high-nodal branches. These two groups are separated from each other on the main shoot by some blank nodes inserted between them.
Our experiment has made it clear that photoperiod and seed-vernalization produce a considerable influence on the distribution of branches. Short-days encourage the branching at basal nodes, while under long-days high-nodal branches are always more than under short-days.
The influence of seed-vernalization on the distribution of branches is comparable to that of long-day in the way that plants grown from vernalized seeds produce more high-nodal branches than control plants.
4. With all the varieties used in our experiment, the influence of photoperiod and seed-vernalization on the position of the first flower on main shoot is quite evident. The number of nodes to the first flower decreases on long photoperiod and by seed-vernalization. Here also, the response is more remarkable in late varieties than in early ones.

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1. The present study has been conducted to investigate the effect of short day treatment during the bulbing period on the number of new leaves, growth of leaves, number of composing leaves in bulb, and date of sprouting, and to elucidate the relation between bulb formation and dormancy in onion.
2. The short day treatment (8.5-hour photoperiod) given during the bulbing period accelerated the growth of leaf and increased the number of leaves. When the treatment was proceeded over 20 days new foliage leaves sprouted from bulbs about 25 days after the beginning of the treatment.
3. The short day treatment given in the early stages of bulb formation caused delay of falling of tops, decrease in bulb size, and increase of decay in bulbs, and the longer the treatment period, the more striking the effects.
4. Storage leaf formation in onion (a characteristic of bulb formation) was found to start about May 15 under natural conditions.
The short day treatment after May 20 and 30 reduced the number of storage leaves and accelerated the growth of sprout-and foliage-leaves. The treatment after June 9 showed no effect on the number of component leaves in bulb, but accelerated the growth of sprout- and foliage-leaves.
5. Sprouting of bulbs in storage and those planted in the field was observed every 5 days. The results were as follows:
Short day treatment until the harvesting time accelerated sprouting in response to the length of treated period.
Plants grown in B field, which ceased leaf growth earlier than plants in A field, sprouted sooner than those grown in A field.
In plants exposed to natural day length (approximately 14-hour photoperiod) for about 30 days after the short day treatment, the time of sprouting was later than plants grown under natural day length alone throughout the period.
6. Defoliation on and after June 5 increased the number of new leaves and accelerated sprouting and decay of bulb, those responses being similar to those found in onion grown under short day.
7. In onion under long day and warm temperature condition, metamorphosis of leaves, inhibition of growth of leaf blade and thickening of leaf sheath, are observed.
In plants exposed to short photoperiod during the bulbing period, however, bulb formation was ceased, though storage leaves once formed did not develop into foliage leaves.
8. Desirable harvesting time of onion was discussed basing on the relation between bulb formation and dormancy in onion.

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1. The response of strawberry plant (var. Red Star) to day-length treatments under constant temperatures (20°C and 30°C) was examined.
2. The vegetative growth was much inhibited at 30°C, while it was normal at 20°C. Long daylength promoted the growth of crown, especially the length of leaf and of first cluster.
3. Although flowering was observed at 20°C irrespecitive of day-length, only the plants treated with long day-length after November 1 flowered at 30°C.
4. It was reaffirmed that the long day-length inhibits and promotes the flowering when given before and after the flower bud differentiation respectively. Therefore, the later the long-day treatment in autumn, the sooner the flowering.

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1. The studies were carried out to examine whether the cultural conditions of the seed bulbs would affect the growth and the formation of droppers of tulips in the following generation when they were grown under the same field conditions.
The seed bulbs were selected from the bulbs produced in the previous studies, namely their produced conditions were differed in depth of planting of seed bulbs, soil moisture, soil nature, soil reaction, day length, and supplying amounts of nitrogen, phosphate, and potassium fertilizers, as mentioned in the previous report.

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It has been observed in an ordinary culture that adventitious buds of Bryophyllum tubiflorum were formed in June, but not in winter. The new adventitious buds developed at the apical ends of the leaves. The process of adventitious bud formation is shown in Fig. 3.
In May, 1957, the experiment was carried out to know what factors are concerned with the formation of adventitious buds.
Several young plants were grown under 8, 12, 13, 14, 15 or 24 hour day length. Although these plants grew normally, the short day plants (8 or 12 hours) began to differ from the long day plants (13, 14, 15 or 24 hours) as time elapsed. Finally, the short day plants were unable to produce new adventitious buds, whereas the long day plants produced a great number of them. The results are summarized in Table 1, from which it was considered that the critical day length for the adventitious bud formation in Bryophyllum tubiflorum was 13 hours.
The next experiment was carried out in May, 1958. Young plants which had been in short day condition (8 hours day length) were planted under three temperature conditions (13-18°C, 11-25°C or 7-35°C). The result is shown in Table 2. The formation of the adventitious buds at the higher temperature was earlier than at the lower temperature. The adventitious buds were produced even at the low temperature, when the favorable condition of day length was given. However, the short day inhibited the bud formation, even if the temperature was favorable for bud growth

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