Journal of the Japanese Society for Horticultural Science
Online ISSN : 1880-358X
Print ISSN : 0013-7626
ISSN-L : 0013-7626
Volume 40 , Issue 1
Showing 1-15 articles out of 15 articles from the selected issue
  • Ryuji NAITO, Mikio NAKANO
    1971 Volume 40 Issue 1 Pages 1-9
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    The activity of fractionated gibberellin (GA)-like substances extracted from the seeds and pericarps of seeded and GA-induced seedless berries of Delaware grapes collected at 21 days after full bloom was determined, and the main active components in pericarp tissue were identified by means of selected bioassays and thin-layer chromatography.
    In the seeds the highest activity was detected in the basic ethyl acetate fraction with the barley endosperm assay, whereas in the pericarps of seeded and seedless berries the basic and acidic ethyl acetate fractions, especially the acidic ethyl acetate fraction, were predominant in activity among the four fractions of basic ethyl acetate, neutral chloroform, acidic ethyl acetate, and acidic butanol. Moreover, the active components in basic ethyl acetate fractions from seed and pericarp were completely different in Rf on the paper chromato grams.
    The higher level of total GA-like substances was found in pericarp of seedless than seeded berries.
    The GA-like substances in acidic ethyl acetate fractions from pericarp of seeded and seedless berries exhibited strong activity in dwarf pea, dwarf rice, and barley endosperm assays, but not in a cucumber assay, and they were very similar to GA3 in Rf on the thin-layer chromatograms. These substances therefore seem to be identical with GA3.
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  • Motoichi TERABUN
    1971 Volume 40 Issue 1 Pages 10-16
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    This experiment was carried out to clarify the photoenvironmental condition of short-day on the bulbing of onion plants that previously received stimulus of long-days, using the cultivar of Kaizuka-wase.
    1. The onion plants were daily exposed to sunlight for 8 hours, followed by supplementary incandescent light at intensity of about 1000 lux for 16 hours, and then transferred to short-day exposure.
    2. When the 2-, 4- and 6-long-days plants, which received stimulus of long-day exposure for 2, 4 and 6 days, were grown under short-day exposure for 30 days, the 4- and 6-long-day plants began to bulb noticeably several days, but 2-long-days plants failed to bulb. The length of lag periods between stimulation and response in relation to bulbing ranged from 7 to 10 days, and the increase of bulbing-ratio was rapid between 6th and 16th day after transfer to short-day exposure (Fig. 1).
    3. The 6-long-days plants receiving short-day exposure accumulated sugars in their leaf-sheath accompanied with bulbing, as well as the plants receiving long-day exposure (Table 1).
    4. When 6-long-days plants were grown under 2-, 4- and 8-hours day-length, only 8 hours daylength plants continued to swell, but no bulb developed on plants exposed to less than 8-hours day-length (Table 2).
    5. The 8-long-days plants were transferred to short-day exposure in the growth chamber with light intensities maintained 10000 (H) and 2500 (L) lux, and were exposed alternately to high and low intensities.
    The plants previously exposed to high intensity well developed their bulb than ones previously exposed to low intensity, even in the cases that the plants received the same amount of light. After a sequence of high and low intensity the intensity of first irradiation determines whether the bulb will develop or not (Fig. 2).
    6. Exposed to red light of 16 hours after sunlight of 8 hours, the 4-long-days plants were not suppressed their bulbing by red light, like the plant exposed to sunlight alone (Table 3).
    7. When the 8-, 6-, 4- and 2-long-days plants were transferred to dark condition for 8, 4, 2 and 0 days, followed by 8 hours day-length, the longer the duration of darkness, the less the bulbing-ratio (bulb/neck).
    From these results, it is assumed that the stimulus for bulbing will be extingushed or decreased by darkness or weak light.
    8. The onion plants previously received stimulus of long-day exposure, even in short-day exposure, elongated their leaf-sheath (Table 6).
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  • Motoichi TERABUN
    1971 Volume 40 Issue 1 Pages 17-22
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    This experiment was carried out to ascertain the photo-environmental factors except light quality on bulb formation of onion plants using cultivar Kaizuka-wase. Plants were grown under short-day condition until the start of the treatment.
    1. Plants were shaded to reduce the daylight of natural day-length (astronomical day-length 14h 20 m-14h 30m). One group was grown in full sunlight, two others under one layer of white or black cheesecloth, and the 4th under two layers of black cheesecloth. Those admitted 100, 70-75, 30-40 or 10-20 per cent of the full light respectively.
    Not only their bulb formation was retarded by 10-20 per cent of full light, but also failed to bulb by 30-40 per cent of light. Moreover, by 10-20 per cent of light, the symptoms of long-day induction did not appear in the pore of innermost leaf (Table 1).
    2. Plants were exposed to the reduced sunlight for 8 hours, followed by suppelementary incandescent light of about 2000 lux for 16 hours. Plants grown in full sunlight had the highest bulbing-ratio, followed by plants grown under 70-75, 30-40 and 10-20 per cent of full sunlight, the plants that received the lowest intensity, also, developed their bulb (Table 1).
    3. Plants were exposed to full sunlight for 8 hours and followed by incandescent light of about 2000, 750 or 240 lux for 16 hours. The higher the supplementary lighting became, the higher the bulbing-ratio became, and even under the lowest intensity their bulb well developed (Table 1).
    4. Onion plants were exposed to 16-, 20- and 24-hours day-length (sunlight of 8 hours, followed by supplementary incandescent light) for 10, 12 or 15 days and then followed by 8 hours day-length. Measurements were made at 20, 22 and 25 days after the beginning of long-day exposure.
    When total duration of light given during long-day was ′240 hours′ as follows: 24 hrs-10 days, 20 hrs-12 days and 16 hrs-15 days, at same duration after the beginning of long-day, the longer the day-length became, the more the bulb developed, in spite of same duration of given light.
    But, at same duration after the beginning of short-day or at 10 days after the beginning of short-day exposure, such as 20, 22 and 25 days after the beginning of long-day exposure for 24, 20 and 16 hours day-length respectively, there was no difference between the reciprocity (day-length times duration of long-day) (Fig. 1).
    5. Plants were given 8 hours of sunlight and 16 hours of darkness, the dark periods being interrupted with incandescent light of 1000 lux at different times after the beginning of dark period for 8 hours. Plants interrupted at 2 hours after the beginning of dark period had the highest value of bulbing-ratio, on the contrary, plants interrupted at 4 hours (middle of night) had the lowest value (Fig. 2).
    6. Plants were given 8 hours of sunlight and 16 hours of darkness, the dark periods being interrupted with incandescent light of 1000 lux for 50 per cent of the time in light-dark cycles of various lengths. Plants received additional light of 16 hours served as 24 hours day-length control.
    The light-dark cycles are as follows: 30-32, 60-16, 120-8, 240-4, 480-2 and 960-1 (length of one light-dark cycle, in minutes-number of cycles) In secondary experiment, plants were given 12 hours each of light and darkness, the light-dark cycles are as follows: 30-24, 60-12, 90-8, 120-6, 180-4, 240-3, 360-2 and 720-1.
    The shorter the cycles became, or the more the number of cycle became, the more the bulb formation was induced, besides, it was found that relation between length of cycles or number of cycle and bulb formation was linear logarithmic (Fig. 3 and Fig. 4).
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  • Satoru TOKUMASU
    1971 Volume 40 Issue 1 Pages 23-28
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    Seeds of cruciferous vegetables including Brassica and Raphanus have more or less dormancy after harvest. When dormant seeds are stored in either dry or wet condition, the removal of dormancy is delayed as compared with air-dry condition. The effect of desiccation and moistening of seeds during storage is not to“induce”or“deepen”dormancy, but only to“prolong”or“maintain”it. The effect of desiccation and moistening is temporary in most species but semipermanent in Brassica japonica. In Brassica napus, as an exception, the removal of dormancy is hastened by dry storage. It is imagined that each species has its own optimum humidity for the removal of seed dormancy. In most species the optimum might be in air-dry condition, but in B. napus in more desiccated one. From the data of interspecific and intergeneric hybrid seeds, the prolongation phenomenon is genetical and presumably due to the action of multiple genes.
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  • Toshio MORITA
    1971 Volume 40 Issue 1 Pages 29-34
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    Experiments on the application time of nitrogen fertilizer were carried out to clarify the mechanism of the formation and thickening of tuberous roots in sweet potato. Four types of soil classes, that is, sand, sandy loam, loam and clayey loam were used.
    In sandy soils, the application of nitrogen at about 30 days after planting was unfavorable to tuberous root formation during the one month period, mid-July to mid-August, because the higher rate of nitrogen absorption produced the vines growing vi gorously. However, the marked nitrogen absorption during the period of thickening growth after tube rous root initiation was favorable to the increase of yield of tuberous roots.
    In clayey soil, the application of nitrogen until 10 days after planting was favorable to both formation and thickening of tuberous roots due to the vigorous growth of vines having the high rates of nitrogen absorption throughout the growing season. Such a nitrogen status caused a higher yield of tuberous roots.
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  • Tadashi ITO
    1971 Volume 40 Issue 1 Pages 35-40
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    This study was carried out to examine the apparatus in measuring the photosynthetic activity of vegetable plants and to discuss some problems in relation to the methods of measurement and plant materials.
    Whole plant or single attached leaf was placed in the“Plexiglass”assimilation chamber in which the light intensity, the carbon dioxide concentration, the leaf temperature and the air humidity could be controlled over a wide range. The carbon dioxide concentration in the air of the inlet and outlet of the chamber was measured with infrared gas analyser, Hitachi-Horiba Type EIA-1 A (0-600ppm, 0-2, 000ppm).
    In order to reduce the resistance against carbon dioxide transfer at boundary layer of leaf surface, an air circulating fan was installed in the plant assimilation chamber. The leaf assimilation chamber was also well constructed to distribute the air uniformly over entire leaf surface.
    Photosynthetic activity of the tomato plant in the assimilation chamber increased with increased air supply up to the order of 0.8l/cm2 leaf area/hr. Without operating air circulating fan, however, air supply of 2.0l/cm2/hr was not enough for adequate photosynthesis in the plant. This would suggest that the resistance of boundary layer of leaf surface against carbon dioxide transfer was one of the serious problems to achieve the sufficient photosynthesis in the assimilation chamber.
    As the gas analyser used in this study has maximum error of 1 per cent of the carbon dioxide concentration over a given range, it is of considerable importance to define the lowest limit of air supply. In this apparatus the photosynthetic activity should be measured with the air supply of approximately 1.0l/cm2/hr and with carbon dioxide depletion of not more than 20 per cent of inlet air.
    The photosynthetic activity of the tomato plant was almost independent of the leaf temperature at a normal carbon dioxide supply. However, in the atmosphere enriched with carbon dioxide, the rate of photosynthesis was greatly influenced by the leaf temperature within the range of 15°C to 35°C.
    Considerably large standard deviation of photosynthetic activity was found in the tomato plants which were placed under natural conditions and sampled immediately before the measurement. Therefore, the plant materials should be selected in the evening and kept under controlled conditions for certain hours in the dark so as not to disturb the internal equilibrium.
    When the photosynthetic rate was measured in a single cucumber leaf, the rate was slightly increased by darkening of young leaves outside assimilation chamber. By lowering the root temperature from 18°C to 13°C, the photosynthetic rate in the leaf dropped to 76 per cent of the normal. The steady state of the photosynthesis under given conditions was obtained after about 50 minutes of the exposure to the light. So it is suggested that the leaves outside assimilation chamber and root should be kept under the controlled conditions during the measurement of photosynthesis.
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  • Tadashi ITO
    1971 Volume 40 Issue 1 Pages 41-47
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    Tomato plants were placed in a plexiglass chamber in order to determine the time course of photosynthetic activity both under natural and artificial-ambient conditions. External and internal factors which might affect the rate of photosynthesis were examined and discussed in this paper.
    The rate of carbon dioxide exchange was linearly proportional to the light intensity. In the afternoon, however, the rate was slightly depressed as compared with the rate at the same light intensity in the morning. Photosynthetic rate is known to be greatly influenced by external factors of radiant flux density, ambient carbon dioxide concentration, leaf temperature, and wind speed over the leaf surface. When carbon dioxide content was depleted to 0.55mg/l in this study, the photosynthetic rate was evaluated to be 90 per cent of the normal.
    In the successive experiment, tomato plants were placed in the glasshouse under natural conditions and sampled at hourly intervals to measure the photosynthetic activity under consistent external conditions. The fall in the photosynthetic activity during afternoon suggests that the rate of photosynthesis was dependent on internal factors.
    One of the internal factors was water content in the leaf. Without any symptom of wilting, water content dropped from 85 to 81 per cent of fresh weight, showing the lowest value at noon. The plant with water deficit leaves always gave lower carbon dioxide absorption value, approximately 80 to 90 per cent of the normal. Since the water deficit causes the hydro-passive and hydro-active stomatal closing, higher stomatal resistance may restrict the rate of photosynthesis during afternoon.
    The accumulation of assimilates could be assumed to be one of the internal factors affecting the photosynthetic activity in the afternoon. Starch grain especially, highly accumulated in the leaf sampled at 13.00 and 15.00, had high degree of negative correlation with the rate of photosynthesis. The possible mechanism for reduction in the rate of photosynthesis by accumulated starch grains might be through an increase in the mesophyll resistance for the carbon dioxide diffusion to chloroplast, and a decrease in the light absorption by chloroplast.
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  • Norio SHIRAKAWA
    1971 Volume 40 Issue 1 Pages 48-55
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    These studies were designed to obtain some informations on the mode of action of a selective herbicide, CMMP (solan) for tomato, carrot and mitsuba (Cryptotaenia japonica HASSK.).
    1. As CMMP-chloroplast complex was formed readily, CMMP was made to react with chlorophyll, one of the chloroplast components. The reaction of CMMP with chlorophyll took place apparently.
    2. CMMP may be able to react with the porphyrin ring of chlorophyll, because the reaction of CMMP with chlorophyllin was recognized.
    3. Reactions of CMMP with extracts from several resistant and susceptible etiolated plants were investigated. It was therefore assumed that CMMP reacted with protein or protochlorophyll in plants. Besides, CMMP apparently reacted with bovine alubumin from blood.
    4. The selective action of CMMP for some plants was examined by detecting the difference of combining ability of crude enzyme solution with CMMP or CMA (3-chloro-4-methylaniline). It was reaffirmed that the detoxic hydrolysis of CMMP in the enzyme solution did not take place at all even in resistant plants.
    5. The recovery of injury by application of chlorophyllin after spraying with CMMP was much more remarkable for resistant plant (tomato) than for susceptible plant (egg plant).
    6. The application of chlorophyllin after spraying with CMMP was more effective than the application of glucose, sucrose or glucuron for recovery of injury by CMMP.
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  • Yoshiji NIIMI
    1971 Volume 40 Issue 1 Pages 56-63
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    In vitro culture of just fertilized ovules with placenta of P. hybrida, W166H× K146BH (each of clone is of self-incompatible), was conducted on some inorganic nutrient medium. Normal and abnormal seedlings developed from ovules with placenta at the stage of just fertilized ovules on MURASHIGE and SKOOG′s inorganic medium containing large quantities of KNO3 and NH4NO3, but no seedlings on other inorganic media.
    To obtain many normal seedlings, effects of concentration of inorganic nitrogen KNO3 and/or NH4-NO3 on the growth of ovules were examined on NITSCH′s nutrient medium. The medium of NITSCH′s nutrient plus KNO3 500ppm and NH4NO3 80ppm was better for growth of embryo than other media containing high nitrogen salts added to NITSCH′s nutrient medium.
    In conclusion, there were combined effects of NO3-N and NH4-N on the growth and development in vitro of P. hybrida embryo. Nitrogen salt solution for better growth was in a concentration of 12 mM and in ratio of NO3-N to NH4-N in molar unit of 11:1.
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  • Yasushi HONDA, Osamu ISHIGURO, Hirotsugu NUMAGUCHI
    1971 Volume 40 Issue 1 Pages 64-67
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    It was carried out CA storage of Satsuma orange with semi-practical CA plant, described previous papers. In order to store Satsuma orange, the plant was modified to control the humidity (85-90%RH) in the cold room, which was designed to attach prolonged air-pipe and heater in front of unit cooler.
    Experimental material was used Fujinaka line of Satsuma orange harvested on the 23rd of November, 1968. After pre-treatment (curing) for one month, the orange (758.7kg) was stored in CA room (occupied 9% of room capacity) for 122 days. Atmosphere in the CA room was controlled 3.5±1.5 °C temperature, 86±5% RH, 5±1% oxygen level and 1.1±0.5% carbon dioxide level. The results were summarized as follows:
    1. With this plant, atmospheric conditions in the room were maintained stably during the storage.
    2. After 122 days, total losses of the orange were 24.43% (weight loss, 7.23%: decay loss, 17.20%). Most of decay was Brown-rot and Stem-endrot.
    3. Sound fruits were had good appearance, taste and flavor, too.
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  • Masutaro OKUBO, Katsu ISHII, Keiji UMEDA
    1971 Volume 40 Issue 1 Pages 68-73
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    In order to elucidate the retardation of color development of tomato fruits packaged with polyethylene bag, changes of carotenoids in fresh fruits, especially colorless intermediates, were investigated.
    1. During the ripening of tomatoes after harvest, chlorophyll content in tomato fruit decreased, while lycopene content increased sharply.
    2. When coloring of tomatoes was controlled by packaging with polyethylene bag, both of the decreasing of chlorophyll and the formation of lycopene were suppressed, but carotene contents slightly increased as well as in unpackaged fruits.
    3. In the packaged fruits containing little lycopene, abnormal accumulation of colorless carotenoids, phytoene and phytofluene, were not observed, although much content of them were found in unpackaged fruits which contained much content of lycopene.
    4. From the above results, it is assumed that the suppression of lycopene formation in tomato fruits packaged with polyethylene bag is not controlled by inhibition of dehydrogenation of phytoene and phytofluene, colorless carotenoids, but by the lack of intermediates which might have formed in the pathway from terpenyl pyrophosphate to phytoene.
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  • Takao MURATA, Sachio MIYASHITA
    1971 Volume 40 Issue 1 Pages 74-80
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    Changes of respiration and ethylene production of Satsuma orange (Citrus unshiu MARCOVITCH, cv. Ishikawa) and Natsudaidai (Citrus Natsudaidai HAYATA) picked at different stages of development were determined at 22±1°C.
    1. Respiratory patterns of young, small Satsuma oranges were similar to those displayed by tipical climacteric fruits. The height of the respiratory rise was decreasing during development of fruits. Young Natsudaidai fruit did not show the clear climacteric like rise of respiration after harvest.
    2. The initial respiratory rate of 22±1°C of detached Satsuma orange and Natsudaidai fruits decreased during development.
    3. A dramatic increase in ethylene production was observed in small and young Satsuma orange after certain lag period during storage at 22±1°C. The rise in ethylene production was after 4 days in the fruits picked on 24th in July, after 6 days in the fruits picked on 24th in August, and after 14 days in the fruits picked on 24th in September, respectively. The rise in ethylene production was not accompanied by the rise of respiration and by abscission of stem end.
    4. The rate of ethylene production at 22±1°C of Satsuma orange picked on 24th July (fruit weight 12.9g) was larger than those of fruits picked on 24th in August (fruit weight 39.7g) or in September (fruit weight 89.9g).
    5. Respiratory rate at 30°C of tissue slices of peels or of pulp vesicles prepared from the Satsuma oranges picked at early in August was higher than those of fruits picked at early in September or in October.
    6. Ethylene production rate by cut fruits (1/2, 1/4, 1/8) increased after 2-3 hours after cutting. By increasing the surface of cutting area, ethylene production was increased and its ratio was in proportion to the surface area. The rate of ethylene production from cut surface was 347-394mμl/cm2/25 hours.
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  • Hiroyuki YAMANAKA, Kazuo CHACHIN, Kuniyasu OGATA
    1971 Volume 40 Issue 1 Pages 81-84
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    The experiment was carried out to determine the changes of free amino acids during the ripening of tomato fruits and in parthenocarpic tomato fruits induced by auxins (4-chlro-2-hydroxylmethylphenoxyacetic acid and p-chlorophenoxyacetic acid). The tomato fruits used were‘Fukuju No.2’grown in the field, and‘Yozu’and‘Fukuju No.2’grown in the greenhouse. Ripening test was made with the fruits which were harvested at mature green stage and stored at 20°C. Auxins were sprayed on the fourth cluster of greenhouse grown‘Fukuju No.2’ and the fruits were harvested at table ripe stage and analyzed.
    In‘Fukuju No.2’fruits grown in the field, γ-aminobutyric acid, serine, glutamic and aspartic acids were present predominantly at the start of the experiment (breaker stage). γ-Aminobutyric acid decreased about 1/3 of the initial content during ripening, and glutamic and aspartic acids increased approximately 3.5 and 2.5 fold respectively. Leucine, iso-leucine and valine decreased slightly, and a small amount of proline and methionine was detected in over ripened fruits.
    In‘Yozu’fruits grown in the greenhouse, the amounts of amino acids were generally less than in ‘Fukuju No.2’fruits.‘Yozu’fruits have a smaller amount of γ-aminobutyric acid as compared with ‘Fukuju No.2’fruits grown in the field and the content was almost constant during ripening, while glutamic and aspartic acids increased considerably as the fruits ripened.
    The parthenocarpic tomato fruits were found to contain less amino acids than the control ones with, the exception of glutamic acid and serine fraction.
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  • Toshiharu KUROSAKI, Kuniyasu OGATA
    1971 Volume 40 Issue 1 Pages 85-90
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    This paper presents the results of experiments on the effect of low-dose radiation of γ-rays on the storage life of early (November 16th) and late (December 16th) harvest Satsuma oranges.
    1. The irradiations were carried out with a Co-60 source at the Radiation Center of Osaka Prefecture. Satsuma oranges were irradiated at the doses of 50, 100 and 200 Krad at the rate of 1×105rad/hr. Subsequent to irradiation, they were stored at room temperature (2°-17°C) and at low temperature (2°-6°C).
    2. Irradiation above the dose of 100 Krad caused the partial browning of peel of both early and late harvest fruits. In the fruits irradiated at the dose of 50 Krad, the browning was not observed. The 50 Krad-fruits stored at low temperature were favorable in appearance, showing little shrinkage of peel, and they had less microbial growth. The rotting of the fruits irradiated at the doses of 100 and 200 Krad was caused by the infection of Alternaria citri PIERCE et ELLIS. However, no symptom of Alternaria citri was observed in the control fruits and the 50 Krad-fruits, and their rotting was caused by the infection of Penicillium.
    3. The titratable acidity decreased with high doses immediately after irradiation, and this tendency was greater immediately after irradiation than during the storage. The organic acids were fractionated the stepwise elution chromatography on silica gel (100 mesh). It was found that the concentrations of citric acid and malic acid were lower in irradiated fruits than in unirradiated ones and that in irradiated samples succinic acid accumulated.
    4. The content of ascorbic acid in irradiated fruits decreased with high doses, and while that of dehyroascorbic acid in irradiated ones increased with high doses, immediately after irradiation. The rates of decreasing of ascorbic acid and of increasing of dehydroascorbic acid during storage were slightly higher in the fruits of 100 and 200 Krad than in unirradiated fruits. The content of ascorbic acid in the 50 Krad-fruits was more than in other lots at the end of the experiment. No change in sugar content by gamma irradiation was noted.
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  • Kazuo CHACHIN, Toshiharu KUROSAKI
    1971 Volume 40 Issue 1 Pages 91-97
    Published: 1971
    Released: July 05, 2007
    JOURNALS FREE ACCESS
    This experiment was undertaken to determine the effects of gamma irradiation on sprout-inhibition, some chemical constituents and the growth of organisms of Shonan red onions. The onions were irradiated at the doses of 15-250 Krad of 60Co γ-rays and stored at room temperature. The sprouting of Shonan red onions was prevented at a dose of 15 Krad completely. The percentage of rotting and weight loss during the storage was higher in the onions of 250 Krad than in other lots. The softening of the scale texture occurred by irradiation with the doses of 125 and 250 Krad, but there was found the recovery of firmness to a level of unirradiated onions in the onions of 125 Krad thereafter. The texture of sales of unirradiated and 15 Krad onions was crispy throughout the experiments. The activities of pectinmethylesterase were slightly higher in irradiated onions than in unirradiated ones at 50 days after irradiation. The decreases of ascorbic acid, anthocyanins, sugars and some volatiles contents were greater in the 250 Krad-onions than in other samples immediately after irradiation and during the storage. The some microorganisms, Penicillium sp, Aspergillus sp, bacteria and etc. were observed in Shonan red onions. The growth of molds on agar were suppressed at the doses of 125 and 250 Krad, but there was found more growth of bacteria in the onions of 125 and 250 Krad in comparison with that of 15 Krad and unirradiated.
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