In growing Washington Navel orange in Japan, poor fruit set has often been a serious problem.
In order to investigate the effective means of improving fruit set, solution of urea or several growth regulators were sprayed during the flowering period or about four weeks after petal fall, and at the same time, the effect of cross-pollination with Natsudaidai pollen was examined.
1. The fruit set of Washington Navel orange was increased by the application of gibberellin or urea spray in the flowering or young fruit period. Cross-pollination with Natsudaidai pollen also increased the fruit set.
2. Combined treatment of cross-pollination and gibberellin or urea spray was more effective than each of single treatment.
3. Gibberellin spray seemed to be more effective than cross-pollination with Natsudaidai pollen.
4. Gibberellin sprayed in young fruit period was more effective than in flowering period, and there was little difference in its effect between repeated sprays in flowering and young fruit period and a single spray in young fruit period. On the contrary, urea was more effective when sprayed in flowering period than in young fruit period.
5. Gibberellin seemed to be more effective at higher concentrations till 500ppm, but the difference between 500ppm and 1000ppm was not remarkable.
6. Spraying of some growth regulators-2, 4-D, 2, 4, 5-T, 2, 4, 5-TP and etc.-showed no definite effects in increasing fruit set when they were applied both in flowering and young fruit period.
7. On the trees the fruit set of which was very poor because of much more flowers and less leaves, spraying of urea or gibberellin as well as cross-pollination with Natsudaidai showed no effect in increasing fruit set.

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In order to trace the summer dressed phosphorus in the citrus trees, 79.76 grams of superphosphate labelled with 470μc of ³²P was applied to a 19-year-old bearing Satsuma orange tree growing in a terraced orchard. Special cares were paid for protecting the workers from radiation. The soil was gravelly sandy soil. The labelled superphosphate was applied on July 16, 1959, and plant and soil samples were taken on November 20, about four months after the application. The precipitation during the experiment was 1085mm.
Plant analyses revealed that the phosphorus derived from the labelled superphosphate applied in July in various organs of the citrus tree was as low as some thousandths of the total phosphorus. It was higher in the fine roots and leaves than in fruits, trunk and coase roots. The total amount of fertilizer phosphorus absorbed during four months was 38mg, and its rate to the amount applied was only 0.5%.
Determinations of soil phosphorus, both total and citric acid soluble, revealed that the phosphorus applied in July accumulated in the surface layers, decreased in the deeper layers, and was hardly detectable in the layers deeper than 9cm. The total amount of phosphorus retained in the upper 9cm of soil layer was about 27% of the applied phosphorus. It was not clear whether the rest (of the phosphorus) was retained in the deeper layers or leached through, because radioactivity in the deeper layers was not high enough for quantitative analyses.

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Grafting congeniality between Japanese chestnut (Castanea crenata SIEB. et ZUCC.) and Chinese chestnut (C. mollisima BLUME) has been studied using Gin-yose (Japanese) and Boji (Chinese) as scions and seedlidgs of Gin-yose and Shibaguri (both Japanese) and Miyagawa No. 20 (Chinese) as rootstocks.
Percentages of “take” were not so different among the various combinations of scions and stocks.
Four year's observation on tree growth showed that Boji on the Japanese stocks made poor growth, while the other combinations made satisfactory growth.
Analyses of mineral composition of scions and stocks revealed that crude ash, potassium, and calcium contents were higher and magnesium and manganese contents were lower in the Boji top than in the Gin-yose top on either Japanese or Chinese stocks, and that Japanese stocks tended to absorb relatively larger amounts of crude ash, potassiumm and calcium, and smaller amounts of magnesium and manganese than Chinese stcck. As the result, Boji on Japanese stocks was extremely high in crude ash, potassium, and calcium contents and low in magnesium and manganese contents. Weak growth and a liability to show magnesium and manganese deficiencies of Boji variety on Japanese stocks seem to be attributable to the unbalance among the rations mentioned above.

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There are many methods of judging the nitrogen requirements of grape vines. One method examined was that in which the nutrient status of grape vine was determined through analysis of free amino acids and amides in the petiole. Among the amino acids and amides, glutamine and asparagine contents were influenced by the nutritional status of nitrogen. Nitrogen deficient vines contained less glutamine than normal ones. When nitrogen was supplied excessively, vines showed a marked increase of glutamine content accompanied by definite appearance of asparagine. The seasonal variation of glutamine was relatively small, and it was associated with the time of nitrogen application.

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1. In the present experiments, Tenma, a cultivar of the Japanese radish, was used as material. Fertility was determined by pollen behavior on stigmas instead of by seed counts.
2. The results of self- and cross-pollinations showed that all plants tested were self-incompatible. Excepting a few incompatible matings, all other combinations were cross-compatible (Fig. 1 and 2).
3. Self- and cross-pollinations were attempted in the sister plants obtained by bud-selfing two self-incompatible plants (No. 8 and 6 in 1959).
4. In the selfed progeny of No. 8, ten plants tested were divided into three classes on the basis of cross-relations (α, β and γ). All these plants were self-incompatible. Two classes, α and β, were cross-compatible in both directions. On the other hand, class γ was cross-compatible in a combination, β×γ, but cross-incompatible in all other combinations (Fig. 3).
5. In the selfed progeny of No. 6, ten plants tested were divided into two classes (α and β). All these plants were self-incompatible. The combination between α and β was compatible, but the reciprocal was incompatible (Fig. 4).
6. The data presented in Fig. 1 and 2 may be explained if the following items are assumed:
(a) The self- and cross-incompatibility is controlled by a series of multiple alleles at one locus (S₁-S₆)
(b) No dominance relation between S genes.
(c) The reaction of the pollen is gametophytically determined (the Nicotiana-type).
By this hypothesis, however, the results of Fig. 3 remain unexplained (Fig. 5a).
7. All these results may well be explained by the following hypothesis:
(a) The self- and cross-incompatibility is controlled by a series of multiple alleles at one locus (S₁-S₉)
(b) The dominance relation between S genes in the pollen (S₁, S₄, S₇, S₈>S₉, S₆>S₂).
(c) The reaction of the pollen is sporophytically determined (the Crepis-type).
A genetic explanation for the results was given in Fig. 6 and 7.
8. Following this hypothesis, three classes (α, β and γ) were expected to appear in the selfed progeny of No. 6, while only two classes (α and β) were found as indicated above. It is thought that the plants belonging to class γ were probably ruled out during the experiments, owing to the lack of vigor and feeble growth (Fig. 8).
In short, the results of self- and cross-pollinations in variety Tenma were different widely from those reported earlier (1944, 1956 and 1958). At a glance, the genetic behavior of incompatibility seemed to be the Nicotiana-type. However, the pollination experiments of the selfed progenies suggested the more complex relations existing between them. From the results obtained it is concluded that the genetic behavior of incompatibility in variety Tenma may be the Crepis-type.

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Browning of grated Chinese yam has been one of the most serious problems in production of yam for early market. In this study, properties of the browning substances and factors affecting their content were investigated.
At first, it was acertained that the browning phenomenon of grated Chinese yam was due to Fenzymatic oxidation of polyphenolic substances. In ascending paper chromatography of 50% methanol extract of tuber, using butanol-acetic acid-water (4:1:1) as developing solvent, were found four spots with Rf. values of 0.07, 0.29, 0.43 and 0.62 (Fig. 1). In the same way, two spots with Rf. values tof 0.07 and 0.43 were isolated from the extract of aerial tuber. Among these spots, the substance with Rf. value 0.43 was considered to play the most important role in the browning phenomenon. Ultraviolet absorption spectrum of this substance has a maximum at 277mμ and a minimum at 260 mμ (Fig. 2).
Analyses of tubers harvested at different stages of maturity, from July 20 to November 30, revealed that polyphenol content was higher in young tubers than in old ones, but a slight increase was found in the last two harvests (Fig. 3). It was observed that the earlier the digging date, the greater the degree of discoloration of grated tuber (Fig. 5).
Contents of polyphenolic substances in various portions of tuber are shown in Fig. 4. In general, polyphenol content is higher in apical portion of tuber than in central portion and is intermediate in basal portion.
Influence of storage on polyphenol content of tubers dug up at different dates is shown in Fig. 7. It shows that the content increased during storage from harvesting time till November 27, but decreased on February 10. Incerase during storage was remarkable in the early digging tubers, especially in their apical portion.
Polyphenol content in aerial tubers was higher than that in tubers, and was similar in its pattern of distribution as in the tuber (Fig. 10 and 11). It decreased markedly after one month of storage in sand.
Polyphenol content in leaves was higher than that in tuber or aerial tuber, and increased regularly from basal leaves to apical ones (Fig. 12).

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Covering plants with plastic film has been common practice in vegetable growing for early and late markets. Temperature inside of the cover rises higher than 40°C in clear days if ventilating is neglected. Therefore injuries due to high temperature are frequently observed in vegetable crops under the plastic coverings.
In this preliminary study on high temperature injury in fruit vegetables, young plants of tomato, cucumber and egg-plant were exposed to artificially controlled high temperatures and their subsequent behaviors were observed.
High temperature about 50°C induced necrosis in leaves and stems of these fruit vegetables, especially in their young portions, in relatively short time.
Plants exposed to 45°C for 3 hours each in successive five days showed no visible injury in their leaves and stems, and their growth was as well as that of the control plants, though their leaf color was slightly lighter than that of the control plants, and in egg-plant, development of purple pigment in flowers and leaves was depressed. Nevertheless, in tomato, percentage of fruit setting was significantly lowered, while hormone spray was effective to counteract this disorder. In cucumber, male flowers had not come to bloom since a few days after the end of the treatment.
Germination tests of pollen on artificial media revealed that percentage of germinating pollen of these fruit vegetables was decidedly decreased by the treatment. This is assumed to be one of the causes of poor setting of fruits and deformed fruit-formation which are often found in the plants growing under plastic covers.

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The authors studied the effects of maturity and after-ripening on the germinability of seeds, using the dwarf variety “Masterpiece”. The bean seeds were sown on April, 5, 25 and May 5, 1955.
Germination tests of the seeds which were harvested from pods of 15, 20, 25, 30 and 35 days after anthesis were carried out. These lots of seeds were after-ripened for 5, 10, 15 and 20 days, so that the maximum period from anthesis would reach 35 days.
1. The seeds harvested 15 days after anthesis did not germinate at all, but those harvested 20 days after anthesis showed germination to some degree. Germination percentages of seeds harvested more than 25 days after anthesis increased gradually as the period between anthesis and seed harvesting became longer, and the seeds harvested 35 days after anthesis showed almost 100% germination.
2. The effects of after-ripening on the germinability of bean seeds were very remarkable. For example, even the seeds harvested 15 days after anthesis which would not germinate at all in the fresh condition showed germination to some degree by 5 days after-ripening and almost 100% germination by 20 days after-ripening. Also, the seeds harvested 20 days after anthesis which would show only less than 10% germination in fresh state reached 100% germination by 10 days after-ripening.
3. There was a tendency that although the total number of days from anthesis was the same, seeds which were harvested early and after-ripened had better germinability than fresh seeds. But there were some exceptions with the seeds which were harvested 15 days after anthesis.

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The experiments were carried out to ascertain the influence of nutrition on the growth of plant, and on the yield, quality and pigment contents of fruit in 1958 and 1960. Sand culture was conducted in 1958 and field culture in 1960 at the Faculty, Shinshu University. Varieties used were Aichitomato in the former year and Sekai-ichi in the latter.
1. Deficiency of nutrient elements (nitrogen, potassium, phosphorus or magnesium) restricted the plant growth. Especially, nitrogen deficiency resulted in the greatest suppression of growth in sand culture, while phosphorus deficiency caused the greatest suppression in field culture. Potassium and magnesium deficient plants were as healthy as control plants.
2. In the sand culture, the fruit yield was smaller in nutrient deficient plants. In the field culture, phosphorus deficiency reduced the yield, whereas magnesium and potassium deficiency had no effect on the yield.
3. Total acidity in phosphorus deficient fruit was higher than that of fruits lacking the other elements. On the contrary, in nitrogen deficient fruits the sugar contents were higher than those of control fruits or fruits lacking the other elements.
4. Plants supplied with nutrient solution lacking a certain element resulted in lower contents of the element in their fruits. This tendency was especially marked in fruits produced in sand culture.
5. As to pigment content, phopshorus deficient fruits contained less lycopene, carotene and xanthophyll, but nitrogen deficient fruits contained more lycopene than control. It is considered that in order to harvest fruits of good color, the amount of nitrogen should be as small as possible so long as the yield is not decreased, while phosphorus should be applied sufficiently to avoid its deficiency.

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Spinach, Chinese cabbage, celery, turnip, and carrot were grown in sand culture under glass and were supplied with NO₃ (a mixture of nitrates of K, Ca, and Mg), NH₄+NO₃ (ammonium nitrate), or NH₄ (ammonium sulfate) in the absence and presence of NaCl, to study the sodium chloride injury of these crops in relation to the form of nitrogen supplied. The nitrogen concentration of any nutrient solution was equally 10m.e./l (140ppm), and the concentration of NaCl added to the solution was 8000ppm for spinach and Chinese cabbage, 6000ppm for celery, 2500ppm for turnip, and 4000 ppm for carrot. The pH of the solutions was adjusted to 6.2-6.4 in all cases.
1. Both in the absence and presence of NaCl, plant growth was much better with NO₃ than with NH₄. And NH₄+NO₃ plants showed growth similar to or less than that shown by NO₃ plants. Effect of NaCl on the yield of crops was not always constant with each nitrogen form.
2. The dry weight percentage of plants generally incresed with the increasing supply of NH₄-N.
3. In the absence of NaCl, plants supplied with NO₃ developed no specific symptoms; but NH₄+NO₃ plants produced darker green foliage than NO₃ plants in some crops, and produced uneven or leathery leaves in Chinese cabbage. The supply of NH₄ alone generally caused various specific symptoms, such as entire or interveinal chlorosis, burn, or withering of leaves. The rate of dead leaves increased as the amount of NH₄-N increased. Some crops supplied with NH₄ alone had brownish or purplish rootlets.
In the presence of NaCl, the supply of NH₄-N crops caused serious symptoms of malnutrition more markedly than in the absence of NaCl with NH₄ alone chlorosis was developed markedly in general, and leaves of some crops were fragile. In Chinese cabbage, NH₄+NO₃ caused marginal rot of younger leaves, symptom of Ca deficiency, more markedly than NO₃; and plants supplied with NH₄ alone were severely stunted in growth showing entire chlorosis, marginal rot, and burn of leaves. In carrot, branched roots occurred to a high degree with NH₄+NO₃ or NH₄.
4. In the absence of NaCl, as the proportion fo NH₄-N in the solution increased, N content of both leaves and roots tended to increase; and P content of leaves similarly increased, while that of roots showed an irregular tendency. Content of K, Ca, or Mg of both leaves and roots generally decreased with the increasing supply of NH₄-N.
In the presence of NaCl, similar tendencies as mentioned above were obtained for each element, except for N in leaves which mostly decreased with the supply of NH₄-N, and the content of any essential cation was generally depressed by the interaction with Na. Moreover, Cl or Na content of leaves increased with the increasing supply of NH₄-N, while that of roots showed a variable tendency with crop species.
5. It is concluded that NO₃-N is much more favourable than NH₄-N as the nitrogen source for the crops tested, especially in the presence of excess NaCl. Application of NH₄-N in the presence of excess NaCl may cause marked interference in absorption of essential cations, especially of Ca, and increased accumlation of Cl or Na in leaves.

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1. Influences of photoperiod, especially light break, given before or after flower bud differentiation, on the initiation and development of flower bud in strawberry were studied using variety Red Star.
2. Flower bud differentiation was markedly delayed by long day treatments (15_??_161/2 hours and 24 hours) or a fairly long light break (8+3 hours) given before the differentiation (September 1). Effect of light break could hardly be seen when it was short (7+1/2 hours).
3. Light break of 8+3 hours was nearly as effective as the 15_??_161/2 hour long day treatment in terms of the delaying effect on flower bud initiation.
4. Increase in foliar length and the number of runners was observed in plants given long day or three-hour light break.

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Amaryllis bulbs of high-quality clones are propagated practically by the fractional scale-stem cuttage method. Studies were carried out on the regenerative response of cuttings at different times of the year taking consideration of the seasonal change of organic and inorganic contents in their parent bulbs. Parent bulbs of a clone were dug out in March, and one half of them were planted in the field early in April prior to use, while the other half were stored indoors. At sampling dates, each of the bulbs from field or storage was cut vertically into 16 fractions, each of which was then divided into two parts, inner and outer, of equal weight. For sprouting, the fractions were placed close together in a slanting position in flats in vermiculite at room temperature or 32°C constant.
The report in this paper is presented after compiling the results of the following three separate experiments. Experiment I in 1955 was made to clarify the bulbil-forming capacity of fractional scale-stem cuttings at room temperature or 32°C constant at different times of the year. In Experiment II in 1956-57, the contents of organic and inorganic matters in bulb fractions were determined at intervals of a month, and the seasonal regenerative capacity of the fractions was also observed using the same bulb as used for chemical analysis. Experiment III in 1958 was done with the purpose of estimating the respiration rate of bulb tissues monthly. In these experiments, fractions from the inner part of bulbs and those from the outer part were treated separately.

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