Journal of the Japanese Society for Horticultural Science
Online ISSN : 1880-358X
Print ISSN : 0013-7626
ISSN-L : 0013-7626
Volume 70 , Issue 1
Showing 1-22 articles out of 22 articles from the selected issue
  • Akihiko Teragishi, Yoshio Kanbara, Hiroshi Ono
    2001 Volume 70 Issue 1 Pages 1-6
    Published: January 15, 2001
    Released: January 31, 2008
    JOURNALS FREE ACCESS
    The basal ends of cuttings of fig cv. Masui-Dauphine were imbedded into rockwool cubes on 2 December 1996 and raised in an enclosed nursery kept at 17°C or 23°C night temperatures(NT). The cuttings, raised at 17°C NT, had shorter shoot but the leaves had higher photosynthetic rates than had those raised at 23°C NT. The nursery plants were then transplanted onto a noncirculating closed hydroponic system in a greenhouse held at 11°C or 17°C NT on 16 January 1997. Shoot growth was restricted after being transplanted in the greenhouse kept at 11°C NT, regardless of the NT in the nursery ; the first fruit was formed at the 5th node approximately 50 days after transplanting, whereas on nursery plants raised at 17°C NT grown in the greenhouse kept at 17°C NT, the first fruit was formed at a lower node 5 days later than those previously raised at 23°C NT. When these plants were weighed, dried, and reweighed on 24 March, their shoot weights did not differ significantly, but the root weights of nursery plants raised at 17°C NT were heavier than were those raised at 23°C NT. Shoots of nursery plants, supplied 100 ml of nutrient solution per plant daily 30 days after transplanting, were shorter than were those supplied 150 ml of nutrient solution. However, root growth and the nodal position of first fruiting did not differ between the two plots.
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  • Kazunori Notsuka, Takekazu Tsuru, Mikio Shiraishi
    2001 Volume 70 Issue 1 Pages 7-15
    Published: January 15, 2001
    Released: January 31, 2008
    JOURNALS FREE ACCESS
    The effect of berry sampling time and genotypic difference in stenospermocarpic seedless grapes on the recovery of viable embryos through in ovulo embryo culture was examined. In 5 open-pollinated seedless cultivars, berry weight increased consistently as the fruit developed, but the ovule length did not correspondingly increase, being either constant or shrinking. The recovery rate of viable embryos significantly increased as the days after anthesis proceeded, especially on the 40th day. During the culture, polyembryony was occasionally observed in some ovules. At the micropylar end of the ovule, most multiple embryos emerged adventitously from the hypocotyl-root axis of zygotic embryo. In 5 open-pollinated selections and 6 cultivars, veraison ranged from 49 to 66 days after anthesis. Varietal difference in the recovery of viable embryos from ovules sampled at veraison was significant, ranging from 0 to 24.7%. In a total of 20 crosses between seedless accessions, the recovery rate of viable embryos significantly varied from 2.7 to 47.0%. The rate of plant recovery in vitro ranged from 0.6 to 24.9%. F1 progenies produced through in ovulo embryo culture in seedless x seedless crosses segregated as follows ; completely seedless : perceptible seed traces : seeded=24 : 56 : 21.
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  • Yoko Suzuki, Saori Odanaka, Yoshinori Kanayama
    2001 Volume 70 Issue 1 Pages 16-20
    Published: January 15, 2001
    Released: January 31, 2008
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    Fructose content and fructose-related enzyme activity based on fresh weight were measured during fruit development to characterize the metabolic properties responsible for fructose accumulation in apple (Malus domestica Borkh.) and Japanese pear (Pyrus pyrifolia Nakai). When fructose content gradually increased from 66 to 92 days after flowering (DAF) in Japanese pear fruit, NAD-dependent sorbitol dehydrogenase (SDH) and fructokinase (FK) activities decreased simultaneously. Subsequently, while fructose content rapidly increased from 92 to 126 DAF, the decrease in FK activity continued, whereas SDH activity increased. In apple fruit, FK activity throughout fruit development was lower than 10% of the maximum activity in Japanese pear fruit. Therefore, It seems that the low FK activity contributes to fructose accumulation while SDH activity increased in apple and Japanese pear fruits. Fructose-6-phosphatase (F6Pase) activity was much lower than FK activity during the fruit development of apple and Japanese pear, which indicates that FK plays a more important role than does F6Pase as a determinant of fructose level in conversion between fructose and fructose-6-phosphate. Phosphoglucose isomerase (PGI) activity was similar or higher compared with FK activity during the fruit development of apple and Japanese pear, suggesting that the isomerization by PGI is not a rate-limiting step from fructose to glucose-6-phosphate. Thus, it is not likely that PGI is responsible for the regulation of fructose levels.
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  • Yoshinori Nakao, Kenji Kawase, Shuji Shiozaki, Tsuneo Ogata, Shosaku H ...
    2001 Volume 70 Issue 1 Pages 21-27
    Published: January 15, 2001
    Released: January 31, 2008
    JOURNALS FREE ACCESS
    Approximately 120 days passes from pollination until fertilization in Ginkgo biloba. After pollination in late April or early May, the pollen develops in the pollen chamber until fertilization. The generative cell in the pollen grain divides into two cells ; one differentiates into a spermatogenous cell, the other into a sterile one. The spermatogenous cell then divides into two sacs, separated by a membrane ; these sacs, in turn, differentiates into sperms that swim to the egg to affect fertilization in early September. With the enlargement of the endosperm, the nucellus, enveloping it at the bottom of the pollen chamber, cracks. The crack is formed concomitantly with the development of a protuberance which is produced on top of the endosperm. The growth of the keeps pace, allowing the sperm to swim to the egg.
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  • Yuhua Li, Ryozo Sakiyama, Hirobumi Maruyama, Saneyuki Kawabata
    2001 Volume 70 Issue 1 Pages 28-32
    Published: January 15, 2001
    Released: January 31, 2008
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    The expression of anthocyanin biosynthesis pathway genes was investigated in 'Nyoho' strawberry fruits during fruit development. Fruit color changed from pale-green to white about 3 weeks after anthesis (white-mature stage). At this stage, anthocyanins rapidly accumulated until the full ripe. Total soluble sugar content also increased after white-mature stage. This includes sucrose but not glucose and fructose levels that remained constant during ripening. The transcript level of phenylalanine ammonialyase (PAL) and chalcone synthase (CHS) genes did not change markedly throughout the fruit development. The transcript level of chalcone isomerase (CHI) and dihydroflavonol 4-reductase (DFR) gene was high in the young fruit, decreased to an almost undetectable level at the white-mature stage, and then increased again until the fully ripe stage paralleling mostly the accumulation of anthocyanin. The latter corelation suggests the involvement of CHI and DFR in the regulation of anthocyanin biosynthesis during fruit ripening.
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  • Hitoshi Watanabe, Toshio Ando, Tatsuya Tsukamoto, Goro Hashimoto, Edua ...
    2001 Volume 70 Issue 1 Pages 33-40
    Published: January 15, 2001
    Released: January 31, 2008
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    Cross-compatibility of Petunia exserta, a natural species having red flowers, with 46 taxa of Petunia sensu Jussieu (20 taxa of Petunia sensu Wijsman plus 27 taxa of Calibrachoa) was examined to obtain basic information for the breeding of garden petunias. Petunia exserta completely failed to set capsules when crossed with any species of Calibrachoa. Petunia exserta exhibited unilateral interspecific incompatibility with 15 taxa of Petunia sensu Wijsman : As a seed parent, it could be crossed with all taxa of Petunia except P. occidentalis, but the reciprocal crossings were successful with only five taxa. In the F2 generation of P. exserta hybrid crossed with P. axillaris subsp. axillaris having white flower, individuals having red flowers segregated. F2 progenies contained delphinidin glycosides as the major floral anthocyanin similar to P. exserta. The use of P. exserta as an additional gene resource for improving red flowered garden petunias is discussed.
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  • Yukio Higuchi, Akiyoshi Kitajima, Isao Ogiwara, Naotoshi Hakoda
    2001 Volume 70 Issue 1 Pages 41-45
    Published: January 15, 2001
    Released: January 31, 2008
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    The inheritance of primin secretion in Primula obconica was determined by studying the F1, F2 and BC1 progenies of crosses between primin-secreting cultivars and primin-free ones. All plants in a ten-cross combination of F1 secreted primin ; thus, the primin-secreting phenotype was dominant over the primin-free phenotype. In four of ten cross combinations, the factor segregated in F2 and BC1 as Mendelian ratios of 3 : 1 and 1 : 1, respectively, indicating that primin secretion is controlled by a single gene. However, in another six cross combinations, the segregation ratios of F2 were significantly different from 3 : 1, whereas those of BC1 were 1 : 1. The results suggested that the distorted segregations observed in certain F2 might have been caused by certation or gametic selection. Given the above findings, the inheritance of primin secretion, which was characterized by distorted segregations in certain F2 was found to be controlled by a major gene.
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  • Fang yun Cheng, Noriaki Aoki, Zheng an Liu
    2001 Volume 70 Issue 1 Pages 46-53
    Published: January 15, 2001
    Released: January 31, 2008
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    Morphological development of forced tree peony (Paeonia suffruticosa) was observed in 17 Chinese and 3 Japanese cultivars (cvs) and the effects of pre-chilling on the growth and development in the Chinese and Japanese cv groups were compared. The development from bud swelling to flowering was divided into 8 stages. The leaves, stem and flower buds mainly grew during stages IV-VII, and stage VI was the longest showing the most vigorous growth. Stages III, IV and V were very complicated in morphology and varied with the cv, but could be identified easily by the leaf development. The pre-chilling promoted the growth and advanced the flowering, but the stage sensitive to the chilling in the Chinese cvs differed from that in Japanese cvs, which indicated the existence of different growth mechanisms. The pre-chilling was effective at the early stages in the Chinese cvs, but at the later stages in the Japanese cvs. The Chinese cvs grew more rapidly and responded to low temperature at an earlier stage, but their cut flower quality was inferior to the Japanese cvs. These results corresponded to a smaller requirement of cumulative temperature for flowering in the Chinese cvs. The pre-chilling decreased the stem length and foliage extension, but promoted the flower size and advanced the flowering date. Non-flowering cvs had normal leaves developed a normal stem and responded to pre-chilling as well as did the flowering cv. These results suggested that the vegetative growth is somewhat independent of the generative growth.
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  • Ayano Michishita, Kenji Ureshino, Ikuo Miyajima
    2001 Volume 70 Issue 1 Pages 54-59
    Published: January 15, 2001
    Released: January 31, 2008
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    To establish a technique of obtaining azalea (Rhododendron spp.) seedlings precociously, ovules (immature seeds) from a diallel cross among 5 species and 1 variety were cultured in vitro. Adding 50 mg·liter-1 GA3 to the medium accelerated ovule germination, so that in the fastest case, 3 months after crossing (3 MAC) ovules from 20 crosses germinated, but the germination rates were low and less than 30%. When ovules 4 MAC were cultured, seedlings were obtained from all crosses ; more than 50% of seedlings from crosses with R. kiusianum and R. kaempferi as seed parents were obtained within 1 and 2 months after culturing. These results indicate that by exposing ovules of 4 MAC to 50mg·liter-1 GA3, one can obtain hybrid seedlings precociously ; the period from crossing to the seedling stage was 1.5 to 2.5 months shorter than with 6 MAC cultured seeds.
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  • Akira Suzuki, Naoko Kawata
    2001 Volume 70 Issue 1 Pages 60-62
    Published: January 15, 2001
    Released: January 31, 2008
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    The relationship between anthesis, harvest time, and fruit quality using 840 flowers of 'Jersey'highbush blueberry was investigated. The time of flowering and berry harvest was significantly correlated (r=0.485) at the 1% level. Thus, flowers which bloom early produced early maturing berries. The highest coefficient of correlation existed between harvest date and the number of days to maturity (r=0.718), whereas that between harvest date and berry weight was negatively but highly correlated (r=-0.660). Considering this bloom characteristic, the possibility exists that harvest date can be manipulated by controlling flowering time through the application of a plant growth regulator, adjusting the cluster size, and/or the degree of pollination and seed set.
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  • Toshihito Tabuchi, Shinji Ito, Noriko Arai
    2001 Volume 70 Issue 1 Pages 63-65
    Published: January 15, 2001
    Released: January 31, 2008
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    The abscission process in emasculated tomato flower pedicels was investigated anatomically. Six days after emasculation, cells in the epidermal tissue in the abscission zone initially enlarged ; two days later, cells in the cortical region enlarged. Ten days after emasculation, cell enlargement spread toward the vascular bundles and then to the inner cortical parenchymatous region and to the pith. Finally, the enlarged cells separated from each other and formed large intercellular cavities ; the unpollinated flower abscised along this line from its weight 14 days after emasculation.
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  • Katsuhiko Matsuura, Kenji Tanabe, Fumio Tamura, Akihiro Itai
    2001 Volume 70 Issue 1 Pages 66-71
    Published: January 15, 2001
    Released: January 31, 2008
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    When leaves on two-year-old 'Masui Daufine' fig (Ficus carica L.) trees were exposed to 13CO2 in mid-October, analysis showed that 13C-photosynthates were stored during dormant season and remobilized in the following spring. The 13C atom % excess during dormant season was highest in small roots and was followed in descending order by fine roots, middle-sized roots, large-sized roots, trunk, two-year-old branches, and one-year-old branches. However, new shoots and roots exhibited relatively higher 13C atom % excess than did the old organs 25 days after bud burst. The new roots retained high levels of 13C atom % excess more than 45 days after budbreak, but the 13C atom % excess in the one- and two-year-old branches and large-sized roots dramatically decreased during 25 days after bud burst. Furthermore, a significant decrease in 13C atom % excess levels in the trunk and middle-sized roots occurred between 25 and 45 days after budbreak ; 13C atom % excess in new shoots was lower in the upper parts than in the lower parts 45 days after bursting. Thus, it seems that the growth of new shoots and roots in the spring depends mainly on carbohydrate reserves in adjacent older branches and large-sized roots for at least 25 days after bud burst. Subsequently, for the next 20 days, new growths rely on the stored food in the trunk and middle-sized roots ; eventually, parts of the elongating shoot apices import photosynthates from the lower new leaves.
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  • Daijiro Yahata, Hitoshi Nogata
    2001 Volume 70 Issue 1 Pages 72-77
    Published: January 15, 2001
    Released: January 31, 2008
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    Effects of fruit thinning on characteristics and sugar accumulation by the 'Masui Dauphine', Common fig (Ficus carica L. var. hortensis Shinn), syconia on different nodal positions were investigated. Fruits from the 1st to the 7th nodes on all shoots were thinned when they were 4mm in diameter ; fruit development and characters of the second crop on the 8th and 13th nodes were compared with those on an unthinned tree. 1. On thinned and unthinned trees, the fruit development period from budbreak to harvest of the second crop on the 8th and 13th nodes was 73∿74 days. Fruit thinning had little or no effect on the final weight and diameter of fruits on the 8th node, whereas the fruits on the 13th node were larger and heavier. 2. On the unthinned trees, the diameter and weight of the fruits on the 3rd node were significantly larger than those on the 8th and 13th nodes at harvest. Peel coloring and Brix values of fruitlets and receptacles of fruits on the 3rd node were higher than those on the 8th and 13th nodes. No difference in firmness of fruits located on different nodal positions was detected. 3. Diameter and weight of the fruits on the 13th node on thinned trees were larger than those on unthinned trees at harvest ; the weight of receptacular tissue was markedly heavier than those of fruitlets. The thinning treatment fostered better peel color of fruits on the 8th node but not those on the 13th node ; it had no effect on fruit firmness. 4. On the thinned trees, the fruitlets and receptacles of the fruits on the 8th and 13th nodes had higher glucose and fructose contents than had comparable organs on unthinned trees ; the total sugar contents, on fruit weight basis, consequently, were also higher. Fruit thinning treatment accelerated growth (weight) as well as sugar accumulation by the receptacles of fruits on the 13th node.
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  • Katsuji Noda, Hitoshi Okuda, Takeshi Kihara, Isao Iwagaki, Kenji Kawas ...
    2001 Volume 70 Issue 1 Pages 78-82
    Published: January 15, 2001
    Released: January 31, 2008
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    The performance of very early ripening satsuma mandarin (C. unshiu Marc.) 'Yamakawa' grafted on 7 different rootstocks in 1988 was examined from 1994 to 1998. The growth of the scion grafted on Shiikuwasha, Rangpur lime, 'Citrumelo' and Volkameriana was superior to that grafted on trifoliate selections (trifoliate orange, rubidoux trifoliate and 'Flying Dragon'). 'Citrumelo' had the highest cumulative yield from 1994-8. Although the highest Brix was found in fruits borne on 'Flying Dragon' and 'Citrumelo' rootstocks, fruit quality was slightly higher but the yields were lower on trifoliate selections. In trees on 'Citrumelo', the mean top/root (T/R) dry weight ratio was 1.77, indicating that a disproportionate amount of the total dry matter was partitioned to the aerial parts of the tree. Based on tree vigor, yield, and fruit quality, 'Citrumelo' is considered to be the most suitable rootstock for very early satsuma mandarin 'Yamakawa'.
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  • Mayumi Befu, Akira Kitajima, Kojiro Hasegawa
    2001 Volume 70 Issue 1 Pages 83-88
    Published: January 15, 2001
    Released: January 31, 2008
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    Chromosomes which were derived enzymatically from young leaves of the following species and cultivars were sequentially stained with Giemsa, chromomycin A3 (CMA), and quinacrine mustard (QM) : 'Suisho-Buntan', 'Banpeiyu' and 'Ban-okan' pummelo (Citrus grandis [L.] Osb.), fingered citron (C. medica L. var. sarcodactylis), 'Okitsu-Wase' satsuma mandarin (C. unshiu Marc.), koji (C. leiocarpa hort. ex Tanaka), and 'Duncan' grapefruit (C. paradisi Macf.). The chromosome compositions are : 3A+3C+3D+9E in 'Suisho-Buntan', 2A+1B+3C+3D+9E in 'Ban-okan', 2B+8D+8E in fingered citron, 1A+1C+8D+8E in 'Okitsu-Wase', 1C+8D+9E in koji and 2A+1B+1C+6D+8E in 'Duncan'. In 'Banpeiyu', the composition of the 17 chromosomes was 1A+2B+2C+4D+8E ; the remaining chromosome could not be discerned whether it was A or B. In all species and cultivars except fingered citron, some chromosome CMA bands are not paired, indicating that some exist as partial homologue chromosomes. Type-D and type-E chromosomes are predominant types in species or cultivar, such as fingered citron, 'Okitsu-Wase', and koji. They are considered to have differentiated earlier during their phylogeny. Therefore, it is thought that type-D and type-E chromosomes are the basic types in citrus.
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  • Naohiro Kubota, Makoto Ohno, Fumio Fukuda
    2001 Volume 70 Issue 1 Pages 89-94
    Published: January 15, 2001
    Released: January 31, 2008
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    The effects of daylength and its extension (Exp.1) and a light interruption at night (Night Break, NB : Exp.2) at different times on shoot growth and flower bud differentiation in potted 'Pione' grape (Vitis vinifera x V. labruscana) were investigated in a greenhouse (forced conditions). Both experiments were conducted for 13 weeks beginning at the end of December when the natural daylength corresponded to about 9hr and 50 min. The primary shoot was pinched to 15 nodes and all lateral shoots were repeatedly pinched, leaving just one leaf at the node. In Exp.1 an additional lighting was supplied with a homolux lamp as follows : 6 hr after sunset, 6 hr before sunrise, 3 hr after sunset and 3 hr before sunrise, and from sunset to sunrise. The elongation of the primary shoot, the number of leaves on lateral shoots per main shoot and leaf area per shoot were significantly increased when the daylength was extended as compared to the control vines grown under natural daylight. The mean number of bunch primordia per lateral bud in vines exposed to lamp increased three to four-fold compared with the control. No significant difference in shoot growth and flower bud differentiation was observed among the three plots for which daylength was prolonged to 16 hr. Night interruption for 2 hr from 8 p.m., 11 p.m., and 2 a.m. with a homolux lamp (Exp.2) promoted shoot growth compared to the control vines ; the number of bunch primordia was almost the same. There was no significant difference in shoot growth and the flower bud differentiation among the three night break treatments. Among the plots the most vigorous shoot growth and the largest number of bunch primordia per bud occurred in vines exposed to constant (24 hr) light.
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  • Kyojun Imai, Shuji Shiozaki, Tomomi Tsuda, Yoshinori Nakao, Tsuneo Oga ...
    2001 Volume 70 Issue 1 Pages 95-101
    Published: January 15, 2001
    Released: January 31, 2008
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    Kaki-shibu is a fermented product made from the juice of immature Japanese persimmon fruit ; it has been traditionally used for painting and dyeing in Japan. Recently, it has attracted much interest as a deproteinizer during the brewing of sake. The properties of the kaki-shibu extracted from 'Tamura' and 'Tennou' persimmon and changes in the course of fermentation were studied, focusing largely on the non-tannic components. The soluble tannin content in the extract from immature fruit of 'Tennou' was 1.3 times higher than that of 'Tamura' ; the colloidal titration value and Baume degree were also higher 6 months after preparation. In both cultivars, the fructose content in the kaki-shibu, 3 days after the preparation, was higher than that of glucose. Sucrose was barely detected in the extracts of both cultivars. Sugars decreased rapidly during fermentation and disappeared 8 and 15 days after preparation of kaki-shibu from 'Tennou' and 'Tamura', respectively. Glycerin was detected in the 'Tennou' extract only 8 days after the preparation, but that from 'Tamura' persisted for 6 months after its preparation. Fermentation, which is an essential aging process for kaki-shibu, proceeded most actively from 3 to 29 days after the juice was extracted in both cultivars. The involatile acids, succinic and lactic, and the volatile acids, acetic, butyric and propionic, were formed during organic acid fermentation. Succinic and lactic acid contents rose rapidly for 3 days, whereas acetic acid increased for 15 to 29 days after the juice were extracted in both cultivars. Butyric acid was detected only in 'Tennou' 8 to 15 days after the samples were prepared. The total acid content, 6 months after the samples were prepared was 1.4 times higher in 'Tamura' than it was in 'Tennou'. These results indicate that kaki-shibu extracted from 'Tennou' contains an abundance of tannins, whereas that from 'Tamura' had greater organic acid content.
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  • Takashi Fudano, Takahiro Hayashi, Susumu Yazawa
    2001 Volume 70 Issue 1 Pages 102-107
    Published: January 15, 2001
    Released: January 31, 2008
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    Photosynthetic rate and partitioning of photosynthate in sweet pea (Lathyrus odoratus L.) 'Early Lavender' whose leaves were administered 13C during the flowering period were investigated. 1. The apical portion was a strong sink for 13C-photosynthates under 100% and 50% full sunlight. Partitioning of photosynthates to the apical portion increased significantly when the young flower buds were removed from the inflorescences on the first and second nodes above the inflorescences which had two open flowers. 2. The photosynthetic rate was the highest in the leaflet on the same node as the inflorescence which had two open flowers. The photosynthetic rate of the leaflet was decreased by removing the young flower buds of the inflorescence. The photosynthates from the treated leaves were translocated preferentially to the inflorescence on the same node. 3. The photosynthetic rate was kept high even in leaves on lower nodes. More photosynthates were partitioned to the apical portion of a shoot from lower leaves than those from the upper ones.
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  • Ikuo Miyajima, Katsuyuki Kurose, Shikanori Matsuda, Shunpei Uemoto, Yu ...
    2001 Volume 70 Issue 1 Pages 108-114
    Published: January 15, 2001
    Released: January 31, 2008
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    The variations in flower morphology and flavonol pigment composition in the petals of Rhododendron kiusianum endemic to Kuju and Aso Mountains and their surrounding areas were investigated. A typical R. kiusianum plant which grows in the Kuju Mountains seems well-adapted to severe climatic conditions, such as alpine temperatures and strong winds, as well as acid soil and the presence of sulfurous acid gas. Although the species is also distributed at the top of Mt. Yufudake and Aso Mountains, the distributional areas of this species are separated from the other crosscompatible azalea species, such as R. kaempferi, by a summergreen forest or an open field, respectively. Flower colors of individuals growing on Mt. Haneyama varied widely, nearly all having prominent blotches on their petals. The composition of flavonols in their petals also ranged widely. From these findings, we conclude that the population at Mt. Haneyama seems to be the result of natural crossing between R. kiusianum and R. kaempferi.
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  • Hiroyuki Yamamoto, Yoshihiro Takahashi, Keishi Shimokawa, Munenori Fur ...
    2001 Volume 70 Issue 1 Pages 115-120
    Published: January 15, 2001
    Released: January 31, 2008
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    Acetone powder extracts (APE) prepared from broccoli flower buds, contained a soluble pyropheophorbide a cleavage enzyme. The enzyme catalyses pyropheophorbide a cleavage in the presence of H2O2 and p-coumaric acid (PCA). The optimum pH was 5.0 with an acetate buffer. Linearity between the rate of the cleavage and protein concentration range from 0∿450μg protein per 3.0 ml of the reaction mixture. The Km for the pyropheophorbide a, PCA and H2O2 was ca. 10.6μM, ca. 382μM, and ca. 352μM, respectively. The enzymatic cleavage of pyropheophorbide a was inhibited by ascorbate, n-propyl gallate, tiron, potassium cyanide (KCN) and hydroquinone. We confirmed that the enzymatic cleavage of pyropheophorbide a is involved with free radicals. The cleavage by PCA-H2O2-APE was accompanied by the opening of the chlorophyll-ring and a decrease in the red and Soret bands of the UV/VIS differential spectrum of the reaction mixture. These results indicate that the peroxidase-catalysed oxidative cleavage reaction systems of pyropheophorbide a participate in the pyropheophorbide a degradation process in broccoli flower buds. Moreover, ethylene-induced chlorophyll catabolism in broccoli flower buds is discussed.
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  • Yoshihiro Takahashi, Masaru Adachi, Munenori Furuta, Hiroyuki Yamamoto ...
    2001 Volume 70 Issue 1 Pages 121-125
    Published: January 15, 2001
    Released: January 31, 2008
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    To elucidate the mechanism of degreening in flower buds of broccoli (Brassica oleracea L.), high performance liquid chromatography (HPLC) was used to separate chlorophyll derivatives in acetone extract derived from broccoli flower buds. Low levels of chlorophyll a derivatives, i.e. chlorophyllide a, pheophorbide a, pyropheophorbide a, C132-hydroxy-chlorophyll a, and pheophytin a were detected in extracts with or without treatment with ethylene for 48hr. Chlorophyll degrading reaction, the conversion of chlorophyllide a to pheophorbide a, was catalyzed by soluble enzyme in the acetone powder extract from flower buds in the presence of chlorophyllin, Mg-chlorin prepared from chlorophyll a as a substrate. The release of Mg2+ is associated with a shift of absorption from 658 to 687 nm. Changes in absorption at 687 nm are taken as a measure of Mg-dechelatase activity. Heating the extract prevented the reaction from proceeding, indicating that the protein/enzyme in the extract was inactivated. Mg-dechelatase did not catalyze the releasing reaction of Cu2+ from Cu-chlorophyllin as substrate. Hence, Mg-dechelatase of the flower buds appears to recognize Mg-chlorin specifically. Moreover, a high negative correlation which existed between the total chlorophyll contents in flower buds and Mg-dechelatase activity is expressed as : Y=-0.73X+97.37, r2=0.94, where X and Y are Mg-dechelatase activity and the total chlorophyll contents, respectively. These findings indicate that chlorophyll degradation in the flower buds is caused by the enhancement of Mg-dechelatase activity.
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  • Masakazu Kasumi, Yasumasa Takatsu, Toru Manabe, Mikio Hayashi
    2001 Volume 70 Issue 1 Pages 126-128
    Published: January 15, 2001
    Released: January 31, 2008
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    The effects of gamma irradiation to cormel explants on callus formation, somatic embryogenesis, and flower color variations of the regenerated plants were examined in gladiolus (Gladiolus × grandiflora hort.) 'Traveler' and 'Topaz'. The rate of somatic embryogenesis decreased as the exposure dosage was increased. The total dosages of 100-200 Gy at 10 Gy·hy-1 caused a 50 percent reduction in the rate of callus formation and somatic embryogenesis (RD50). The flower color variants occurred in 'Traveler' but not in 'Topaz'. The frequency of flower color variants increased, resulting in the appearance of extremely deep colors and morphological variants when tissue culture technique was used in combination with gamma irradiation. Most flower color variants were solid (i. e., nonsectorial-chimeric) variants. These results show that the application of tissue culture technique in combination with gamma irradiation could lead to a high frequency of variants, diversifying the germplasm pool for breeding of other vegetatively propagated ornametal plants.
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