Journal of the Japanese Society for Horticultural Science
Online ISSN : 1880-358X
Print ISSN : 0013-7626
ISSN-L : 0013-7626
Volume 67 , Issue 2
Showing 1-21 articles out of 21 articles from the selected issue
  • Fusao Mizutani, Golam A. B. M. Rabbany, Hiroaki Akiyoshi
    1998 Volume 67 Issue 2 Pages 147-152
    Published: March 15, 1998
    Released: January 31, 2008
    JOURNALS FREE ACCESS
    Peach seeds evolved ethylene immediately after their removal from pits. The ethylene-producing ability remained high during early seed development but decreased as the seeds matured. The seed coat tissues were the major source of ethylene ; endosperm and embryo produced a negligible amount. The internal gas composition of the seeds was 2.7% O2, 19.5% CO2 and 77.9% N2. Not only high CO2 but also low O2 concentrations suppressed the increase in 1-aminocyclopropane-1-carboxylate (ACC) content of peach seeds. ACC synthase and ACC oxidase pre-exist in the seeds in situ. Under high CO2 and low O2 concentrations, the ethylene biosynthetic pathway seemed to be temporarily blocked before and/or at ACC synthesis. The significance of such suppression and burst of ethylene production in peach seeds is discussed in relation to pit splitting and the normal growth, development and ripening of fruit.
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  • S. K. Kang, H. Motosugi, K. Yonemori, A. Sugiura
    1998 Volume 67 Issue 2 Pages 153-160
    Published: March 15, 1998
    Released: January 31, 2008
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    Using persimmon (Diospyros kaki cv. Hiratanenashi) buds collected in Yamagata, Kyoto, and Kochi Prefectures in Japan having different climate, the effect of bud dormancy and temperature conditionings (high temperature, 25°C ; low temperature, 4°C) on the bud cold hardiness was studied. Additionally, the same temperature conditionings were applied to 'Hiratanenashi' and 'Fuyu' buds whose dormancy release was delayed with 100 ppm gibberellic acid (GA3). Evaluation of cold hardiness was conducted on the buds using microcomputer-based thermal analysis. The dormancy release of 'Hiratanenashi' bud from Yamagata Prefecture, where mean air temperature during the winter was 2 to 3°C lower than Kyoto and Kochi Prefectures, was completed in late November, whereas that of the other locations occurred in late December. Irrespective of locations, the buds showed the same seasonal pattern, being hardiest in late January. Neither the low nor the high temperature conditionings had an effect on the bud cold hardiness during the deep dormant period at all locations. After the release from bud dormancy was induced, the high temperature conditioning decreased the bud cold hardiness by a maximum of 4°C, whereas the low temperature conditioning increased the bud cold hardiness by a maximum of 1.5°C. Two foliar applications of GA in the fall to 'Hiratanenashi' and 'Fuyu' delayed the release of bud dormancy 12 and 8 days, respectively. As with untreated 'Hiratanenashi' buds from different locations, GA-treated 'Hiratanenashi' and 'Fuyu' buds responded to the temperature conditionings only after the buds were released from dormancy. Likewise, potted 'Hiratanenashi' trees in Kyoto, subjected to the temperature conditionings, did not respond to cold hardiness conditionings until the bud dormancy release was completed.
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  • Haruyuki Kuroda, Shonosuke Sagisaka
    1998 Volume 67 Issue 2 Pages 161-165
    Published: March 15, 1998
    Released: January 31, 2008
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    Changes in levels of hydrogen peroxide (H2O2) and metabolic activities of peroxide-scavenging systems in flower buds of apple, Malus domestica Borkh., were studied with special reference to freezing injury. In the flower buds frozen at -20°C, a lethal temperature, an increase in levels of H2O2 was observed within 30 min after thawing began. H2O2 then decreased gradually even though its concentration remained high. As H2O2 accumulated, the concentrations of glucose-6-phosphate (G6P) and reduced glutathione (GSH) decreased to very low levels and both glucose-6-phosphate dehydrogenase (EC 1. 1. 1. 49) and ascorbate peroxidase (EC 1. 11. 1. 11) were inactivated. Contrarily, during freezing, little change was observed in levels of H2O2. However, the levels of GSH and G6P decreased accompanied with quantitative increases in levels of GSSG, which suggest that H2O2 is generated during freezing. These results indicate that H2O2, produced during freezing and thawing, renders the peroxide-scavenging systems dysfunctional ; that the sequence of events, which starts from the generation of H2O2, resulting in the collapse of peroxide-scavenging systems and the accumulation of H2O2, are associated with the freezing injury.
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  • Fusao Mizutani, Golam A. B. M. Rabbany, Hiroaki Akiyoshi
    1998 Volume 67 Issue 2 Pages 166-169
    Published: March 15, 1998
    Released: January 31, 2008
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    The effect of tropolone, hinokitiol, purpurogallin, and colchicine on ethylene production and ACC content in young excised peach seeds was investigated. Application of aqueous solution or suspension of these compounds inhibited ethylene production and suppressed the increase of ACC. Tropolone and hinokitiol at 250 ppm inhibited ethylene production by 95%, whereas purpurogallin and colchicine were less effective. Tropolone and hinokitiol are readily volatilized so that when the effect of their gaseous phase on ethylene production was examined, we found their inhibitory effects were proportionate to their concentrations. The inhibition by low gaseous hinokitiol concentration was released when the seeds were transferred to air, but it was irreversible when the concentration was high. Mechanisms of inhibition of ethylene biosynthesis by tropolones are briefly discussed.
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  • John Ofosu-Anim, Yoshinori Kanayama, Shohei Yamaki
    1998 Volume 67 Issue 2 Pages 170-175
    Published: March 15, 1998
    Released: January 31, 2008
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    To clarify how ABA and IAA may mediate sugar uptake during fruit development, the kinetics of sugar accumulation by excised discs of melon (Cucumis melo L. cv. Prince) was studied. Uptake kinetics for glucose and fructose in discs of young and premature fruit, 14 and 28 days after pollination, respectively, and for sucrose in young tissues have biphasic (curvilinear) concentration curves. This indicates the presence of both carrier-mediated and simple diffusional uptake systems. The carrier-mediated system occurs at lower sugar concentrations for the three sugars in young fruit, but for glucose and fructose in premature fruits ; it was not detectable in mature fruit 42 days after pollination. The Km value for carrier-mediated sugar uptake ranged from 6 to 14 mM and did not change with fruit development and among sugars. ABA at 10-5M enhanced the simple diffusional uptake of the three sugars, whereas IAA at the same concentration stimulated the carrier-mediated system of the three sugars but not the simple diffusional uptake system for sucrose. The roles of ABA and IAA on the carrier-mediated and simple diffusional uptakes systems for sugars seem to be very important during the growth and maturation of the melon fruit.
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  • Michio Ohi, Itaru Tsuyuki, Yuichi Yoshida
    1998 Volume 67 Issue 2 Pages 176-179
    Published: March 15, 1998
    Released: January 31, 2008
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    Localization of and changes in pectic substances in the crown cells of two strawberry cultivars during flower-bud development were investigated. Sections of crowns treated with and without 1% pectinase and stained with the periodic acid-Schiff reagent were compared. 1. At the vegetative stage, most granules in the untreated cells and pectinase-treated ones were equally stained. During the early stage of pistil differentiation, most granules in the untreated crown cells became stained, whereas those in the pectinase-treated ones did not. Thus, the granules in the cells during the early stage of pistil differentiation are composed of polysaccharides containing pectic substances which signify that pectic substances accumulate not only in the cell wall but also in the cytoplasm. 2. The total uronic acid which was traced during flower-bud development scarcely changed between the vegetative stage and the early stage of pistil differentiation. But pectic substances in the cytoplasm increased concurrent with flower-but development which we attribute to their migration from the cell walls.
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  • Yohichi Matsubara, Takashi Harada
    1998 Volume 67 Issue 2 Pages 180-184
    Published: March 15, 1998
    Released: January 31, 2008
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    The relation between pectic substances level and arbuscular mycorrhizal (AM) fungus infection in seedling roots of asparagus (Asparagus officinalis L. var. altilis, cv. MW500W) Welsh onion (Allium fisturosum L., cv. Green-negi), and petsai (Brassica campestris L., cv. Harumaki-gokuwase) was investigated to seek an effective inoculating method for AM fungus infection in host roots. The levels of total pectic substances were higher in storage roots of asparagus, root tips of both asparagus and Welsh onion, and both the secondarily branched root and main root of petsai, which are difficult to infect, than in the easy-to-infect primary feeder root of asparagus and both the primarily branched root and main root of Welsh onion. Pectic substances in the cortex of the storage root of asparagus and the secondarily branched root of petsai, and in the root tips of both asparagus and Welsh onion become heavily stained with ruthenium red, whereas the cortex of the primary feeder roots of asparagus and both the primarily branched root and main root of Welsh onion did not. The middle lamella and primary cell walls of root tissues are ruthenium red-sensitive. The lack of infection in asparagus storage roots and petsai branched roots is attributed to rich pectic substances in their thick middle lamellae and primary cell walls, so that the roots were infected with AM fungus (Gigaspora margarita) after pectinase treatment prior to the inoculation. These facts suggest that pectic substances in root tissues influence infection of AM fungus.
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  • Keita Sugiyama, Tsuguo Kanno, Masami Morishita
    1998 Volume 67 Issue 2 Pages 185-189
    Published: March 15, 1998
    Released: January 31, 2008
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    Watermelon cultivars with high female flower bearing ability bore the first female flower at a lower node than those with low female flower bearing ability, when sprayed with silver thiosulfate, STS, at the cotyledonary stage or at the first true leaf stage. Also, watermelon seedlings sprayed with STS produced more female flowers than did the unsprayed control plants. Correlation between the number of female flowers in the F2 population sprayed with 6 mM STS and the node order of the first female flowers is high. In a progeny selected from the F2 population, the female flower was borne at a lower node order of the main stem, whereas in another, the first female flower differentiated at a higher node order ; the former had more female flowers than had the latter. These results indicate that we are efficiently able to select the plants with high female flower bearing ability by STS treatment before transplanting.
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  • Michio Kanechi, Junko Yamada, Noboru Inagaki, Susumu Maekawa
    1998 Volume 67 Issue 2 Pages 190-197
    Published: March 15, 1998
    Released: January 31, 2008
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    The effects of water stress on the photosynthesis (Pn) of potted sunflower Helianthus annuus L. plants were examined by monitoring the photosynthetic O2 evolution rates under saturated CO2 (10 kPa). These conditions eliminate stomatal limitation and partitioning of the recent assimilates into sucrose and starch in leaves was measured with decreasing leaf relative water content (RWC). Water-stressed leaves at RWC lower than 60% required at least 8 min pre-illumination at a saturated irradiance to reach the maximum O2 evolution rate (Pmax), compared to 2 min for non-stressed leaves, suggesting slower light-activation of enzymes involved in CO2 fixation in the Calvin cycle. Light-saturated photosynthesis and apparent quantum yield decreased with decreasing leaf RWC, but the former was inhibited more than the latter by the water stress. Pmax of both non-stressed and ABA-fed leaves required a very high CO2 pressure of 10 kPa to overcome stomatal closure but Pn never completely recovered in dehydrated leaves at RWC lower than 65%. We concluded that a non-stomatal inhibition played an important role in reducing photosynthesis of severely dehydrated leaves. Water stress increased sucrose content and decreased starch content in dehydrated leaves, leading to an increase in sucrose/starch ratio with decreasing RWC and Pmax. These results suggest that photosynthesis of water-stressed sunflower leaves was depressed on account of stomatal and non-stomatal limitations, which might be a feedback regulation of sucrose and starch syntheses influenced by water stress.
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  • Takashi Onozaki, Hiroshi Ikeda, Takashi Yamaguchi
    1998 Volume 67 Issue 2 Pages 198-203
    Published: March 15, 1998
    Released: January 31, 2008
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    The effect of calcium nitrate addition to α-aminoisobutyric acid (AIB) on the vase life of cut carnation flowers (Dianthus caryophyllus L.) in continuous treatment and pretreatment was investigated. In the continuous treatment, the addition of 2.5 mM calcium nitrate to 10 mM AIB significantly prolonged the vase life of 'Soana' cut flowers, relative to the control or 10 mM AIB or 2.5 mM calcium nitrate alone. This combination treatment was as effective as 20 mM AIB solution in extending vase life of carnations. In the pretreatment trials, an exposure to 60 mM AIB for 21 or 24 hours significantly extended the vase life of 'Nora', relative to the control. Exposure of cut flowers to 60 mM AIB+10 mM calcium nitrate solution for 21 or 24 hours enhanced the vase life by 20% or 14%, respectively over 60 mM AIB alone, but the calcium nitrate effect was not significant. The results of this study suggest that the addition of calcium nitrate to AIB promotes the AIB uptake in cut carnation flowers.
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  • Zhong Chuan Xu, Yoshinori Ikoma, Masamichi Yano, Kazunori Ogawa, Hiros ...
    1998 Volume 67 Issue 2 Pages 204-209
    Published: March 15, 1998
    Released: January 31, 2008
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    Large varietal differences in ethylene production in Chinese kiwifruits were found, especially between 'Kui mi' and 'Hong xin', based on the sensitivity and responsiveness of the cultivars to exogenous ethylene, which could induce autocatalytic ethylene production in fruit. The difference in the potential to induce ethylene production is attributed to the greater gene expression of ACC synthase in 'Kui mi' than in 'Hong xin'. In contrast, no distinct differences were found in the transcript levels of ACC oxidase gene between these cultivars. 'Kui mi' having a high rate of ethylene production also had a high ACC content compared with 'Hong xin'. When endogenous ethylene production reached a peak at 96 hr after 24 hr-ethylene treatment, the transcript levels of ACC synthase gene were most prominent. However, the transcript level of ACC oxidase gene was clearly detected in all samples of 0 hr and more after a 24 hr-ethylene treatment. These results suggest that a key enzyme which controls the rate of endogenous ethylene production in kiwifruit is ACC synthase, not ACC oxidase.
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  • Hiroshi Hamamoto, Yoshihiro Shishido, Shigeki Furuya, Kenichiro Yasuba
    1998 Volume 67 Issue 2 Pages 210-212
    Published: March 15, 1998
    Released: January 31, 2008
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    Effect of 2, 3, 5-triiodobenzoic acid (TIBA) on growth of pollinated tomato (Lycopersicon esculentum Mill. cv. Momotaro) fruits was investigated. Lanolin with and without TIBA was applied to peduncles of tomato trusses and the flowers pollinated by vibrating them. In TIBA-treated plants, indole-3-acetic acid (IAA) level was maintained higher in fruits up to 21 days after pollination, the seeds weighed less than those from normally pollinated fruits, the degree of puffiness was more severe, and many fruits had symptoms of a physiological disorder, blossomend rot.
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  • Golam A. B. M. Rabbany, Fusao Mizutani
    1998 Volume 67 Issue 2 Pages 213-215
    Published: March 15, 1998
    Released: January 31, 2008
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    Effects of tropolone and hinokitiol on ethylene production, ACC content and in vitro activities of ACC synthase and oxidase were investigated by using wounded mesocarp tissues of winter squash fruit (Cucurbita maxima Duch. cv. Ebisu). Tropolone over the range from 1 to 500 ppm inhibited ethylene production by 33 to 98% and reduced ACC content by 48 to 83%, whereas hinokitiol treatment reduced them by 17 to 97% and by 34 to 83%, respectively. Both tropolone and hinokitiol were found to inhibit ethylene production through suppression of activities of the two key enzymes.
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  • Katsumi Ohta, Kenji Tsurunaga, Takashi Hosoki
    1998 Volume 67 Issue 2 Pages 216-218
    Published: March 15, 1998
    Released: January 31, 2008
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    Control of fruit cracking in cherry tomato (Lycopersicon esculentum Mill.) 'Sun Cherry Extra' grown in hydroponics was attempted by light treatment during the night. The rate of fruit cracking in the untreated control was about 10%, whereas under a high light intensity (81.1μmol·s-1·m-2 PAR) and low light intensity (8.1μmol·s-1·m-2 PAR), it was 4 and 8.5%, respectively. Diffusive resistance of stomata at 4 AM was 5 g·1-1 under high light intensity, compared to 17 g·1-1 in the untreated control. The rate of solute flow into the peduncle during the high light intensity treatment decreased to negative values, whereas that into the petiole increased. This result indicates that solute flowed into the leaves when they were exposed to light, lowering the water potential to below that in the untreated control. Based on these results we conclude that the treatment with high light intensity at night diminished the frequency of fruit cracking by decreasing the solute flow into the fruit.
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  • Masahiko Fumuro
    1998 Volume 67 Issue 2 Pages 219-227
    Published: March 15, 1998
    Released: January 31, 2008
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    The effects of girdling the trunks of 6- to 9-year old, close-planted Japanese persimmon (Diospyros kaki L. cv. Nishimurawase) trees during early shoot elongation period on tree growth and root functions were determined. Girdling (1 cm width) trunks 10 cm above the ground level in early May (23 days before full bloom, DBFB) inhibited current shoot and trunk growth and decreased leaf number per tree. Shoot growth inhibition continued into the next season but had little or no effect on yield and fruit quality in the two years. Girdling the trunks in late April or early May, 34 and 23 DBFB, respectively, revealed that the earlier the tree trunks were girdled, the greater was the inhibition on shoot and trunk growth. Both treatments reduced leaf number per tree and leaf growth. The trunk girdling decreased the respiration rate of fine roots, the nitrate nitrogen and potassium conc. in the xylem sap as well as that and magnesium in the shoot. However, it had a negligible effect on leaf and stem water potential. These results indicate that trunk girdling during early shoot elongation period has a dwarfing effect on close-planted Japanese persimmon trees. Furthermore, it revealed that the growth inhibition was caused by a reduction of dry matter production attributable to the smaller number and areas of leaves and by inhibition of root functions, such as nutrient absorption and accumulation.
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  • Manabu Nishiyama, Wataru Ohkawa, Koki Kanahama
    1998 Volume 67 Issue 2 Pages 228-235
    Published: March 15, 1998
    Released: January 31, 2008
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    Effects of temperature and photoperiod on vegetative and reproductive growth were investigated in everbearing strawberry (Fragaria×ananassa Duch. cv. 'Summerberry') plants. Runner plants grown in a nursery field until November were transplanted to clay pots, and were grown in growth chambers at a 12-hr day/night setting of 20/15°, 25/20°, and 30/25°C, under either constant light (24-hr, long-day) or an 8-hr (short-day) photoperiod. The treatments were started on December 1. 1. At 30/25°C, the appearance of an inflorescence was inhibited under short-day. By contrast the number of inflorescences was remarkably increased until 10 weeks after the start of the long-day treatment. The production rate of axillary inflorescences which developed from subtended axillary bud without a foliage leaf was increased remarkably under long-day. These results were similar to those of non-dormant plants. 2. At 20/15°C and 25/20°C, more inflorescences were initiated under the long-day than under the short-day treatment. At 20/15°C, the photoperiod was not effective on the development of inflorescences. 3. Under the 8-hr photoperiod, the petioles grew longer at 25/20° and 30/25° than those on plants kept at 20/15°C ; conversely, under the 24-hr photoperiod, the average length of the petioles became shorter at the higher temperatures with time compared to that of plants kept at 20/15°C.
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  • Shigeru Mizuguchi, Masanori Ohkawa, Tomohiro Ohshiro
    1998 Volume 67 Issue 2 Pages 236-241
    Published: March 15, 1998
    Released: January 31, 2008
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    In vitro experiments were conducted to clarify the process of forming the vascular bundle system in regenerated bulblets from the mother scale of Lilium japonicum Thunb. cultured on MS medium. The medium contained 0.2mg·liter-1 α-naphthaleneacetic acid (NAA) and 0.01mg·liter-1 benzyladenine (BA) or 0.01mg·liter-1 NAA and 2.0mg·liter-1 BA or no plant growth regulators. There were one major and two minor vascular bundles in the scale of the bulblets cultured for 8 weeks in vitro. A collateral vascular bundle (CVB) exists in the scale and in the basal plate of the bulblets ; a radial vascular bundle (RVB) differentiated in the roots developing from the basal plate of the bulblets. Major vascular bundles of the bulblet scale were connected to those of the scale two nodes below ; minor ones were connected to the vascular bundle of the scale one node below. Root primodia were formed from the ring tissue at the basal plate of the bulblet. The regular system of vascular bundle was established in the regenerated bulblets cultured for 4 weeks on the medium without plant growth regulators, but it did not form on the medium containing 0.01mg·liter-1 NAA and 2.0mg·liter-1 BA. Many vascular bundle interlinkages are present in the central part of the bulblets grown on the medium with 0.01mg·liter-1 NAA and 2.0mg·liter-1 BA. Thus, a high concentration of benzyladenine (BA) results in irregular vascular bundle system in regenerated bulblets.
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  • Masanori Ohkawa, Jyunya Kitajima
    1998 Volume 67 Issue 2 Pages 242-248
    Published: March 15, 1998
    Released: January 31, 2008
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    Wild black lily bulbs were planted in pots and grown for 8 months in a glasshouse. The bulbs produced scapes with 1∿2 terminal flowers and 5∿6 leaves with a verticillate phyllotaxis. Tow new bulbs were formed on the mother-bulb as it was consumed and eventually rotted. Morphological characteristics matched those of Fritillaria camtschatcensis Ker-Gawl. Small globule-scales of the bulbs were excised and cultured on MS-media without plant hormones in the dark or under light of 40μmol·m-2·sec-1 at 15, 20, and 25°C for 8 weeks. The optimum condition for bulblet formation was a MS-medium containing a combination of 0.1 mg·liter-1 NAA and 0.1 mg·liter-1 24-epibrassinolide (EB) at 20°C in the dark.
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  • Isamu Hayashi
    1998 Volume 67 Issue 2 Pages 249-260
    Published: March 15, 1998
    Released: January 31, 2008
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    The effects of organic amendments on the chemical and physical properties of soil and the productivity of greenhouse-grown 'Bridal Pink' roses were studied for four years. This trial consisted of seven synthetic soil mixes plots and were combined with two fertilizer treatments. Three plots contained 70, 50, and 30% (by volume) of an equal amount of well fermented cow manure and wood chips ; the remainder was made up of volcanic black ash soil. Three plots had similar percentage compositions of amendments except that they consisted of hemlock bark manure. The seventh plot consisted of 50% Danish sphagnum peat moss and volcanic soil. The fertilizer treatments were : A) a mixture of organic fertilizers and liquid fertilizer and B) a mixture of a soluble and slow release chemical fertilizer. Six 'Bridal Pink' plants grafted on seedlings of Rosa multiflora were planted per wooden box (72×90×30cm depth) lined with a plastic net to retain the soil. The leachings were collected periodically after watering and analyzed for nutrients. Flowers were harvested annually for four years and graded for quality. 1. No difference in yield and stem length of cut flowers was observed in the first year ; the stem lengths were shorter in the second year, especially in the 70 and 50% wood : manure mixtures.2. In the third and fourth years, a severe decrease in soil volume occurred in the 70 and 50% mixtures. The soil was replenished in these plots at the beginning of the third year ; none was added to the 30% mixture of the wood : manure and 30% bark manure plots, and 50% peat moss plot. In the third and fourth years, a slight reduction in yield occurred in the plots without soil replenishment.3. No difference in yield was noted in the first year between fertilization plots ; yield was higher in the third year in the chemical plot compared to the organic fertilizer plot.4. While large accumulations of nutrients in the soil occurred in soils containing high amounts of cow manure, analysis of the leaching showed that many nutrients were being lost by the daily watering. Hence, at replanting time, the soils were leached with excessive irrigation. The trial showed that the physical conditions of the soil could be kept favorable by the addition of peat moss, followed by that of bark manure addition. Though cow manure in large volume can improve the physical property of a synthetic soil, temporarily, for growing roses in the greenhouse, it would not suitable for long term growing because of significant decrease in gaseous phase in soil.
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  • Xu Wei Ma, Keishi Shimokawa
    1998 Volume 67 Issue 2 Pages 261-269
    Published: March 15, 1998
    Released: January 31, 2008
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    Ethylene enhanced degreening of intact banana (Musa sapientum L.) peel in the dark. Enzymes from ethylene-treated fruits of banana were isolated which catalyzed the degradation of chlorophyll a in the presence of H2O2 and 2, 4-dichlorophenol. Its pH optima are 5.2, 5.8, and 6.4 with potassium phosphate buffer. Reaction was strongly inhibited by hydroquinone, Tiron, Mn2+, L-sodium ascorbate, n-propyl gallate, salicylhydroxamic acid, KCN, and NaN3 and weakly by 2.2'-bipyridyl and 1, 10-phenanthroline. The participation of Fe2+⇄Fe3+ and O-2 in the reaction is discussed. Chlorophyll degrading peroxidases are clearly distinct from guaiacol peroxidase in its inhibition properties upon NaN3. Linearity between the rate of the its degrading activity and protein concentration was obtained over the range 0.04∿0.33mg protein per 3.0 ml of the reaction mixture. Km for chlorophyll a and H2O2 is approximately 16.5μM and 20.44μM, respectively. The possible in vivo participation of this in vitro system is briefly discussed. Visible adsorption spectrum of the reaction mixture during chlorophyll a degradation indicated a shift of the red band near 670 nm to a shorter wavelength and a shift of the Soret band near 430 nm to a longer wavelength. Difference spectrum of the reaction mixtures showed a peak near 450 nm. The yellow peak indicates the presence of open-ring catabolites and the lack of the Soret and red bands. The appearance of a fluorescent chlorophyll catabolite (Ex 350nm, Em 465nm) was recognized.
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  • Hitoshi Sekimoto, Katsue Matsuura, Takeru Yoshino
    1998 Volume 67 Issue 2 Pages 270-272
    Published: March 15, 1998
    Released: January 31, 2008
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    The relationship between the greening of leaves by the treatment with a gibberellin-biosynthesis inhibitor, uniconazole-P (U), and leaf area, and leaf mineral (N, Mg and Fe) contents in Cucumis sativus L. was examined. U induced greening of leaves and the reduction of leaf area but not in all cases. Thus, the greening was not always accompanied by the reduction in leaf area. The treated leaves were restored to their natural green color after the treatment with U was discontinued. Total nitrogen content of leaves was proportional to the degree of green coloration, but Mg and Fe contents were not. According to the previous reports, U enhances the level of endogenous cytokinins which increases the chlorophyll content of leaves. Thus, the leaves treated with U may be responding to cytokinins rather than to the inhibition of gibberellin biosynthesis.
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