The relationship between the degree of magnesium deficiency and the soil cations was investigated on Rall′s apple orchards in Akita.
1) Severe magnesium deficiency was observed on Daigo soil of which week ability to resist leaching by high rainfall.
2) The severity of magnesium deficiency was significantly correlated with the exchangeable magnesium content in the soil of 20cm, 40cm, and 20-60cm depth, but not in the below 60cm depth although there are high concentration of roots in this zone.
3) On Kamanogawa soil which was higher in a cation content than the other soil, the high potassium induced apparently magnesium deficiency.
4) The relationship between the severity of magnesium deficiency and the exchangeableMg/K ratio in each depth was lower than that for exchangeable magnesium content, but not for the ratio of exchangeableMg/K released by normal nitric acid.

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1. Tree growth, yield and fruit quality of Jonathan apples cultured in the large size pots were observed under four different conditions of soil moisture, such as“High”80-75%, “Medium”70-70%, “Low”45% and“Very low”30% of water holding capacity. And further observations were made on the morphological charactors of leaves and fruits, apparent photosynthesis, transpiration, and nutrient content of leaves with changing soil moisture.
2. Tree growth, especially top growth was markedly inferior with decreasing soil moisture, and yield and fruit size were also proportional to soil moisture.
3. Skin color of fruits in the“High”plot was inferior considerably to that of the others, and sugar content of fruits decreased with increasing soil moisture. In the“Very low”plot, fruits had no crispness. From these points, it seems that dessert quality of fruits was most superior in the“Low” plot.
4. Daily changes of fruit size and trunkgirth were checked in summer. Both of the fruits and the trunks shrunk during daytime and swelled again at night. The difference of fruit size between day and night became greater with increasing soil moisture, because the number of leaves per fruit increased conspicuously with increasing soil moisture.
5. Leaves in the lower soil moisture plot were inferior in area, thickness, cell size and the extent of intercellular spaces, however, they were superior in the thickness of cuticle layer and the density of stomata to those in the higher one. Fruits in the lower soil moisture plot had a thick skin and a firm flesh filled compactly with small cells, which had a thick wall as compared with those in the higher one. There is no significant difference in the number of cells in flesh in each plot.
6. In the“Very low”plot, many of the older leaves became yellow and abscised in summer.
7. In the“Very low”plot, almost half of the fruits produced corky core owing to boron deficiency, and also, internal breakdown occurred in some fruits after the storage for two months.
8. There was no significant difference in the rate of apparent photosynthesis between the“High”and “Medium”plots, but in the lower plots, it decreased apparently with decreasing soil moisture. The rate of transpiration is also proportional to soil moisture.
9. As the result of leaf analysis for N, P, K, Ca, Mg and B, the contents of P and B in leaves decreased considerably with decreasing soil moisture.

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Effect of N-1-naphthyl phthalamic acid (Peach-thin 322) sprays was tested on Hakuho peaches for three seasons from 1961 to 1963.
1. In 1961, four concentrations, 50, 100, 200 and 400ppm, of Peach-thin were applied two days after full bloom to the branch of four Hakuho peach trees, which were twelve years old and moderately vigorous. Two trees of them were properly thinned by 200 and 400ppm sprays, but the two others were not.
2. In 1962, the same trees as in the previous year were used. Two concentrations, 200 and 400 ppm, were sprayed two days after full bloom, and on some branches again four days after full bloom. Drop of fruits due to Peach-thin occurred from 10 to 25 days after full bloom. Differences were observed in the response to the sprays among the tested trees as in 1961, but were hardly found among the fruiting branches of various length. Once 400ppm and twice 200ppm sprays thinned fruits to the desirable level.
Vigorous young trees of four years old were also treated in this year. Concentration of 200 and 400 ppm were applied to six trees. Fruits were heavily thinned by the sprays, and almost all fruits were dropped by twice 400ppm sprays.
3. In 1963, the mature trees used in the previous years were treated with once and twice sprays of 200ppm solution. The effect was not sufficient even of twice sprays, but it was found that growth of young fruits on the sprayed branches was superior to that on the control branches.
Effect on the young trees was not so significant as in the previous year.
4. The results of experiments for three seasons indicated that thinning effect of Peach-thin was slight on the trees which were likely to set fruits heavily, and it was severe on those likely to have poor fruit setting. A very high correlation was obtained between the fruit setting percentages of control branches and those of branches sprayed with 200ppm Peach-thin at 25th day after full bloom.
Peach-thin did not cause any permanent injury on twigs, leaves and fruits.

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1. In Muscat of Alexandria grapes, strong fruiting shoots each of which had been allowed to bear only one blossom cluster, were pinched one to three weeks before blooming, so as to have 5 or 10 leaves at their basal part. Then, pollen germination and berry set were both greatly promoted, being accompanied with a marked increase of B leaf content near the cluster.
2. When boron (H₃BO₃ 0.2%) was sprayed instead of pinching on the strong fruiting shoots before blooming, pollens germinated more actively and berries set better, their leaves containing more abundant B.
3. In the paper chromatography of anther extracts for amino acid and sugar, asparagine was determined only in the untreated plot, and proline and alanine were found more quantitatively both in the pinched and the boron sprayed plots.
4. Total sugar content of anthers increased much in either plot of pinching or boron spray. In the pinched plot both sucrose and glucose increased, while in the boron sprayed plot sucrose disappeared and glucose increased greatly.

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The respiratory and ripening behavior of the oleificated fig fruit during ageing were studied following the treatment with rape seed oil.
1. The treated fruit showed a typical climacteric rise in the respiratory drift. That is, respiration rate increased rapidly from the next day of the treatment, reaching a maximum 2 days after treatment. Thereafter the rate sharply declined. Respiratory quotient of the treated fruit at the climacteric maximum was 2.1. The fruit began to color in the skin on and after the climacteric period and matured 6 days after treatment.
2. The content of starch in the treated fruit increased for 2 days after treatment and then decreased, in which the content was relatively low. Gradual increasing of the content of reducing sugar was observed. The content attained a maximum at maturity in both treated and untreated fruit, being determined as 12.5% and 13.8% on fresh weight basis respectively.
3. The content of malic acid in the treated fruit increased rapidly, attained a maximum 2 days after treatment, and then decreased abruptly. The malic acid content in the treated fruit at maturity was as low as 0.02% on fresh weight basis.
4. Net contents of acetaldehyde and ethyl alcohol in a treated fruit increased late in the maturing period of the fruit. However, typical sigmoidal curves were observed as expressed in mg per 100g fresh matter. Namely, the drift rose up rapidly, reaching a maximum 2 days after treatment, followed by the sharp depression and second rising just before maturity.
5. Ethylene content in the treated fruit also increased rapidly and reached a maximum 5 days after treatment, just before the maturation of the fruit, afterwards the content decreased.
6. Nitrogen and phosphorus contents in the treated fruit decreased gradually as the fruit matured. While, potassium content showed slight increase from 4 days after treatment to maturity, although the content decreased at the early stage after treatment. The contents of the three major elements in the treated fruit at maturity were slightly larger as compared with those in the untreated fruit.
7. In both treated and untreated fruits, several endogenous growth substances, such as IAA, IBA, IAN and GA₃ like substances, were identified by paper chromatographic method. Moreover, two different unknown inhibitors were also detected. The activities of IAA and IBA were great at the stage of noticeable coloring in the skin, while the activity of IAN was great at maturity.
8. From these data mentioned above, it may be concluded that the duration of the metabolic process is shortened when the fruit is treated with the rape seed oil, and the treated fruit attains maturity more promptly than untreated fruit.

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1. The growth and fruiting behavior of Satsuma orange trees planted on the various soils originated from different rocks were compared over 9 years from 1957 to ′65. In June, 1957, a 4-year-old treewas planted in each concrete frame of 3.3 square meters in area and 1.2 meters in depth. Soils examined were collected from citrus raising areas in Ehime Pref., and the origins of them were as follows:
Sekizen soil: Paleozoic graywacke and lime stone
Futami soil: Chlorite schist
Ohira soil: Biotite andesite
Yoshida soil: Mesozoic sand stone
Ono soil: Diluvial
Idai soil: Granodiorite
2. Judging from the result of trunk enlargement, Satsuma orange on Sekizen soil showed best growth, following that on Futami soil, and Ohira or Yoshida and Ono or Idai soils in the order. The trees on Sekizen and Futami soil produced much fruits than that on Ono and Idai soil. High significant correlation (r=+0.90) was found between the total yield for 7 years and trunk diameter in 10th year.
3. The qualities of fruits were investigated for 4 years from 6th to 9th year after planting. Matured fruits on Idai soil which colored early showed light orange, and those on Sekizen soil which colored remarkably late showed yellowish-orange. The coloring of fruits on Ono soil showed the tendency of some delaying. The fruits on Futami and Ohira soil colored deeply at the maturity. Those on soils other the above varied the tone of color year by year.
4. In the brix and soluble solids in juice, no difference was observed among fruits on 6 kinds of soil in 1962 and ′63. However, in 1964 and ′65, the contents were high in fruits on Ohira and Futami soil, medium on Sekizen, Yoshida and Ono soil, and low on Idai soil. The content of acid (as citric) in juice throughout the years was high in fruits on Ohira and Futami soil, medium on Sekizen. Yoshida and Ono soil, and markedly low on Idai soil.
5. In the investigation on the three different orchards, whose soils derived from sand stone, chlorite schist and biotite andesite respectively, Satsuma orange showed noticeable differences in the growth of trees, and the yield and qualities of fruits among them, alike the above results in frame experiment.

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This study was carried out on the manganese deficiency of Citrus unshiu in relation to soil and tree conditions, growing on volcanic soils in Kanagawa Pref.
Both soil and leaf samples were obtained from 7 orchards located on gravelly clay loam and 34 orchards on volcanic silty clay loam in September of 1956. Field surveys of root distributions were made in September of 1957, in 8 orchards located on volcanic gravelly loam and 16 orchards on volcanic silty clay loam, when both soil and leaf samples were obtained in each orchard. In March of 1963, the fresh weight of feeder roots in a given volume of soil beneath of four trees, two manganese deficient trees and two normal trees, were compared.
Hot-HCl soluble manganese content of this area was remarkably lower than those of the other areas in Japan.
Manganese deficiency symptoms in leaves were not found in the trees growing on the soils which contained more than 10ppm of exchangeable Mn, more than 150ppm of easily reducible Mn, and more than 50ppm of 3N ammonium dihydrogen phosphate soluble Mn. But both of manganese deficient trees and normal trees were found in the orchard soils which contained less than these critical levels. About 90 per cent of orchards in this survey (50 orchards during 1956 to 1957), however, contained less than above values of each manganese fraction in their soils. These critical values are higher than those obtained with oat or upland rice plants.
Soil reactions were relatively acidic in all soils. Soil pH was a little higher in manganese deficient orchards than normal orchards. However, the differences of soil reactions between manganese deficient soils and normal soils varied in significancy year by year.
There was a difference between manganese deficient trees and normal trees in the developmental patterns of feeder roots in the surface 0 to 20cm depth of soil. The fresh weight of feeder roots in a given volume of soil was less in the former than the latter. This difference may be due to the soil management system and to the fruiting of trees.
Basing on the above results, the mechanism of development of manganese deficiency in citrus trees is discussed.

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The investigation was undertaken to study the effect of different Ca levels and sources of nitrogen supplied on the growth and the inorganic composition of natsudaidai (Citrus natsudaidai HAYATA) seedlings in solution culture.
On the Ca deficient seedlings in both NaNO₃ and NH₄NO₃ series, the growth was reduced, and their upper leaves turned to dull yellow green from the margin, finally left normal green only in the areas of the inverted V shape around the midrib. The interveinal parts outside the areas of the inverted V shape were dotted with many, small, light brown specks. In severe case, affected leaves dropped, and shoot apex exhibited the appearance of die back. Roots turned to brown, and rotted. Especially, in NH₄NO₃ series, deficiency symptoms were severer, and appeared even in the higher Ca level than in NaNO₃ series.
In NH₄NO₃ series, the higher Ca level was necessary for their maximum growth than in NaNO₃, but the growth of seedlings in NH₄NO₃ series was inferior to that of NaNO₃ in every Ca level.
In the leaves of NaNO₃ series, N, P and Ca contents increased, while K and Mg decreased with increment of Ca concentration in the medium. In NH₄NO₃ series, only Ca content increased, while K, Mg and N (beyond Ca 2ppm) decreased with the increasing concentration of Ca in the medium. In the roots of both sources of N, the contents of P, Ca and K increased, while Mg decreased, with increasing Ca supply.
In both leaves and roots of seedlings supplied with NH₄NO₃, N content was generally higher, but contents of cations were lower than those of NaNO₃ series.

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1. The effects of temperature, phtoperiod and gibberellin spray on developmental phases (bolting, budding and flowering) of head lettuce plants were observed. The plants were grown in the growth cabinet in which temperature and photoperiod was controlled strictly.
2. All of the combinations of air temperature of 10, 15, 20 and 25°C with long and short day induced bolting in head lettuce.
3. Bolting of head lettuce was more prevented under short than long day at the same treatments of temperature. Thus, the bolting of head lettuce was delayed by short day.
4. Budding and flowering of head lettuce was more promoted under high temperature and long day than low temperature and short day. High temperature and long day accelerated budding and flowering in head lettuce.
5. Bolting, budding and flowering of head lettuce were more promoted under high temperature and long day than low temperature and short day.
6. The effects of gibberellin on the reproductive phase of head lettuce treated at 10°C, as influenced by photoperiod are recorded in Figure 3 and illustrated in Figure 4. No significant differences were observed between gibberellin treated plants and non-treated plants in flowering date.
Gibberellin promoted bolting in head lettuce grown under short and long day, but it failed to hasten budding time of head lettuce.
7. The favorable conditions of temperature for fertility were from 15 to 20°C. The plants treated at 25°C fertilized slightly. In contrast, the plants treated at 10°C under both photoperiods resulted in sterility without normal flowering.
These results suggested that critical evaluation of low temperature to fertility was the range of 10 to 15°C.
8. The favorable conditions of temperature to growth responses of head lettuce were from 15 to 20°C.
The number of leaves and branches was higher under conditions of high temperature and short day than low temperature and long day.
Green color of the leaf under conditions of low temperature and long day was deeper than that under high temperature and short day.

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The changes of carbohydrate, nitrogen, auxin, gibberellin and nucleic acid metabolism associated with the transition of tomato plant from the vegetative to the reproductive state in response to the environmental and cultural treatments were investigated in this report, with the aim of finding the causal physiological factors for the flower formation.
1. Relationships between nitrogen and carbohydrate metabolism and the flower formation.
Carbohydrate and nitrogen compounds gradually increased with the progress of plant growth and reached to their peaks just before the flower bud differentiation of plant grown at each condition, and then decreased with the development of flower bud.
2. Relationships between auxin metabolism and the flower formation.
The content of auxin in the apical parts of plants grown under the natural conditions was large at the vegetative stage and temporarily decreased just before the flower induction, and then increased considerably after the flower induction.
3. Relationships between gibberellin metabolism and the flower formation.
Seasonal trend of gibberellin-like substances in the apical parts of plants grown under the natural conditions was the same as that of auxin.
4. Relationships between nucleic acid metabolism and the flower formation.
DNA content was fairly constant in the apical parts of plants grown at various conditions during the course of vegetative growth, but thereafter gradually increased following flower induction, while RNA content in the apical parts of plants grown at various conditions increased rapidly with the progress of the plant growth, reaching to a peak immediately before flower initiation, corresponding with the time of a temporary decline of auxin, and then decreased after flower induction.
5. Relationships between the various constituents and the flower formation.
From the previous papers and the present results it may be explained as follows:
Auxin and gibberellin in the apical bud and/or the immature leaves exerted an effect to pull the stream of the flower forming substances from the mature leaves, and the amount of the flower forming substances supplied to the meristematic tissues varied being controlled by the level of auxin and gibberellin in the apical bud and/or the immature leaves. The lower level of auxin and gibberellin in the apical bud and/or the immature leaves affected to promote the accumulation of the flower forming substances in the meristematic tissues. The reproductive DNA (gene for flower formation) in the meristematic tissues had to duplicate and was activated by the flower forming substances accumulated in the meristematic tissues, and the activated reproductive DNA transcribed the genetic code to the reproductive RNA, and the specific reproductive protein was produced in the meristematic tissues under the guiding auspices of the messenger RNA, and the cell division in the meristematic tissues caused by the action of the reproductive protein and induced the flower formation.

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1. To clarify the suitable application amounts of ureaform (Uf), a slowly available form of synthetic organic nitrogen, four plots which consisted of four levels of actual N (6, 8, 10, 12g per plant) were established. Furthermore, three plots whose plants received 8g of actual N with rape-seed cake (R), ammonium sulphate (A), and urea (U), respectively, were also made for comparison. Var. Earl′s Favourite for fall cultivation was used, and effects of these fertilizer treatments on the growth, the fruit weight and quality, and the concentration of various forms of nitrogen in the leaves of muskmelon were investigated.
2. The fruit weight both in the plots of Uf-8 and Uf-10 was greater than that in the plot of Uf-12 as well as both in the plots of A and U. On the other hand, the external appearance of fruit in the plot of Uf-6 as well as in the plot of R, as measured by the net, and the days of post-ripening of the fruit, was superior to that in the plot of Uf-12 as well as both in the plots of A and U.
3. With increasing the application amounts of ureaform from 6 to 10g per plant, the concentrations of NH₄-N and NO₃-N in the leaves, the electrical conductivity and NO₃-N of the soil were increased.
Judging from these results, especially, from the concentration of NO₃-N in the leaves both in the plots of Uf-10 and Uf-12, the suitable application amounts of ureaform for muskmelon seemed to be 6 to 8g per plant as actual N.
4. To clarify the trend of the mineralization of several nitrogen sources, the rates of ammonification and nitrification of ureaform, rape-seed cake, ammonium sulphate and urea incubated at the soil temperatures of 20°C and 30°C were measured.
5. The ammonification rate of ureaform incubated at the soil temperature of 20°C increased up to 69% of the added nitrogen on the 28th day after incubation, and then gradually decreased down to 30% on the 63rd day after incubation. On the other hand, the nitrification rate of ureaform incubated at the same soil temperature increased up to 52% on the 63rd day after incubation.
The ammonification rate of rape-seed cake incubated at the same soil temperature increased up to 60% on the 28th day after incubation, and then gradually decreased down to 27% on the 63rd day after incubation. On the other hand, the nitrification rate of rape-seed cake incubated at the same soil temperature increased up to 37% on the 63rd day after incubation.
The trend of the nitrification rate of urea incubated at the same soil temperature was similar to that of ureaform.
The nitrification rate of ammonium sulphate incubated at the same soil temperature only increased up to 10% on the 63rd day after incubation. This low nitrification rate seemed to be caused by the comparatively low soil pH brought by the added ammonium sulphate.
6. Though the nitrification rates of ureaform and rape-seed cake incubated at the soil temperature of 30°C were much greater than those of the same nitrogen sources incubated at the soil temperature of 20°C, the nitrification rates of urea and ammonium sulphate incubated at the soil temperature of 30°C were slightly greater than those of the same nitrogen sources incubated at the soil temperature of 20°C.

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Studies on the maturing process and the growth phases of the onion plants were carried out in the years 1957 to 1960. Material used in this experiment was cultivar Sapporo-ki, a local variety of Sapporo district, grown under two cultural methods. One of the cultural condition was the direct seeding and another was the transplanting method. In the direct seeding procedure, the plants seeded in late April and thinned in late June, and in the transplanting procedure, the plants raised in a frame in late March were transplanted in mid May.

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This paper reports the physical factor in onion juice.
1. It was clearly shown that ether-insoluble fraction in onion juice remarkably depressed the seed germination.
2. It was also shown that the same concentration of NaCl or KNO₃ solutions as that of onion juice inhibited both germination of seeds and growth of onion seedlings, and that the addition of ether extracts obtained from onion juice to Nacl solution enhanced the inhibition of seed germination more than NaCl solution only.
3. Refractometer index of onion juice increased with bulb thickening and reached a maximum value a month later followed by a gradual decline.
The inhibition of seed germination by onion juice was significantly correlated with the refractometer index of it.
4. Ohshu, a late variety, showed higher value in refractometer index of juice and more strong inhibition of seed germination than Senshu-Ki, a middle one.
5. The effect of concentration of reducing sugar and sucrose as substrate on the respiration metabolism of terminal part of stem disk or crude enzyme with Warburg manometer suggested that the same concentration of substrate as that of onion juice depressed considerably the respiration.
6. On the basis of foregoing results it was concluded that sugar accumulation accompanied with bulbing induces the depression of respiration metabolism, resulted in rest in bulb, and that the gradual decline in sugar concentration by respiration in bulb during storage allows the terminal bud to renew the growth.

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Nutritional studies including field experiment were carried out to clarify the suitable time for nitrogenous fertilizer application on sweet potato culture with regard to the soil properties.
Application of nitrogen in sandy soil at about 30 days after planting of cuttings resulted vigorous top growth from mid-July to mid-August and rather small number of tubers was produced.
However, the final yield of tubers was great probably resulted from the great extension of leaves. Top growth on clayey soil was slower and retarded throughout the growing season in comparison with that on sandy soil, and it is recommended to apply nitrogenous fertilizer in clayey soil somewhat earlier than in sandy soil.
When a given quantity of nitrogen was divided into two, one half was applied at the planting time and another half was applied 30 daysafter planting, good results in the formation and development of tuber were obtained. It may be due to the following fact that the above application, especially in poor clayey soil, brings the moderate top growth during the tuber forming period and the enhanced growth during the tuber development period.

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The flower of hydrangeas, as generally known, turns blue in its color, when cultivated in acid soil.
This, according to the report from Allen(1), is explained as a large quantity of aluminium absorption in acid soil, and is also confirmed subsequently by Asen(3)(4)(5) as a result of experimental analyses. Furthermore, it is reported by Post(8) that the acid soil with an acidity of approximately pH 5.5 is the most optimum condition for the cultivation of hydrangeas, and alkaline soil is least suitable for its cultivation.
From what mentioned above, it may be concluded that the successful culture of hydrangeas will be performed in acid soil, but when wanted to have its color in clear red or pink, the soil with neutral or weak acidity will be required.
Therefore, with a view to observe some prospective reactions in the color depending on the acidity of soil, the present experiment was made using a variety of hydrangeas with pink colored-flowers as explained hereunder:
The experiment was carried out through observing several of hydrangeas with pink colored-flowers transplanting from acid to alkaline soil or from alkaline to acid soil on the occasions as those of August 20 (at their full growth period), September 19 (right before the dormant period) and January 13, 1965 (when they were put into a greenhouse after chilled).
As a result, all of the hydrangeas formerly with pink colored-flowers turned into blue colored-flowers, including those of hydrangeas cultivated in the weak acid soil in the early stage of growing period and also those transplanted into acid soil in a greenhouse on January 13, as well as those controlled in alkaline soil throughout the growing season. The hydrangeas, grown throughly in alkaline soil after the potting, gave naturally clear pink colored-flowers. Besides, even those of hydrangeas, which were cultivated in the standard soil with a weak acidity until the growing period or the stage exposed to low temperature and transplanted thereafter into the alkaline soil in a greenhouse, had clear pink colored-flowers. Those of hydrangeas controlled in strong acid soil during the vegetative period of one or two months and transplanted thereafter into alkaline soil, as well as those cultivated in acid soil until the period exposed to low temperature and transplanted thereafter into the alkaline soil in a greenhouse, gave purplish blue colored-flowers.
As the results of chemical analyses of leaves and flowers, phosphorus was found in flowers more densely than in leaves, and those of hydrangeas grown in acid soil contain less phosphorus as compared with those in alkaline soil. Aluminium, on the other hand, was proved to be plentiful in leaves and flowers of hydrangeas cultivated in acid soil during their vegetative period, and less plentiful aluminium was found as those grown in alkaline soil.
As for the relation between the quantiy of aluminium and the color of flower, blue is corresponding to the aluminium amount of 950-2, 900ppm, purplish blue to 300-400ppm, pink to nearly 200ppm.
Anthocyanins, which were extracted by methanol containing 1% of HCI from those of colored flowers with blue, purplish blue, and pink, was developed by means of paper chromatography. As the result the Rf value appeared to be constant without relation to the kind of colors.

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In the previous papers, the authors reported the possibility of dahlia culture for the cut flower in winter by controlling the day-length. The young plants must be prepared by the end of autumn for this type of forcing, using cuttings taken from the mother plants or tuberous roots formed newly in autumn. However, the new tuberous root shows dormancy, deepness of which varies depending on the varieties. The present study deals with the dormancy in tubers of dahlia.
1. When crown-tubers normally produced in the field were dug up and planted in greenhouse on October 25, November 4, 14 or 24, some of them did not sprout even if favorable conditions were given. As the planting time was delayed within this period, the sprouting per cent was decreased. The shoots sprouted from the crown-tubers which were planted during the period from early October to mid-December, did not elongate normally. In many cases, their growth stopped at the stage of two leaves. However when crown-tubers were planted in greenhouse after the end of December, they sprouted well and their shoots grew normally.
Dahlia crown-tuber seems to rest from the beginning of October to the middle of December. However, judging by the facts that at least 40per cent of crown-tubers sprouted throughout this period, it seems that early rest is followed directly by after-rest in dahlia crown-tuber.
2. The degree of rest in dahlia crown-tuber varied among the varieties. There were the following three types in regard to the degree of rest. In the first type, all crown-tubers sprouted and their shoots grew comparatively well. In the second type, about half of crown-tubers sprouted, and their sprouted shoots grew little. In the third type, none of crown-tubers sprouted.
3. Crown-tubers obtained from the plants which were propagated from cuttings after June rested weaker than those obtained from the mother plants. However, when cuttings were taken before May, their crown-tubers rested as deep as those produced by the mother plants. The earlier the cutting time, the deeper rest of crown-tuber.
4. The rest of dahlia crown-tuber was broken by low temperature treatments. When dahlia crown-tubers were dug up on November 20 and treated for 40 days at 0°C, they sprouted well, and their shoots grew normally.

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