Miyamashikimi (Skimmia japonica Thunb.) seeds contain the following limonoids that are found in seeds of Citrus species: deacetylnomilin, nomilin, limonin, obacunone, deacetylnomilinic acid, nomilinic acid, isoobacunoic acid; and those found in seeds of Fortunella species: retrocalamin, calamin, cyclocalamin, methyl isoobacunoate diosphenol and isoobacunoate diosphenolic acid; and those found in seeds of Citrus ichangensis: ichangensin. They also contain 17-β-D-glucopyranoside of limonin, nomilin, obacunone, deacetylnomilin, calamin, retrocalamin, cyclocalamin and ichangensin. Skimmia japonica is the only plant which contains all of these limonoids. These data reveal unusual and unexpectedly high levels of citrus-like limonoids which suggest that Skimmia japonica is taxonomically closer to Citrus than previously believed.

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Inheritance of necrotic reaction from the Japanese pear cultivar 'Okusankichi', and Chinese pear cultivars 'Beijing-bai-li', 'Xiang-ya-li', 'Yuan-ba-li', and 'Zao-su' to pear scab caused by Venturia nashicola Tanaka et Yamamoto was examined, using hybrid seedlings of known parentage. The seedlings were inoculated with conidial suspension, and the resistance to scab was classified into three categories: highly resistant (HR), susceptible (S), or necrotic (N). All seedlings, derived from 'Hosui' (S)×'Beijing-bai-li' (N), were classified as S. N and S seedlings were obtained from 'Hosui'×'Xiang-ya-li' (N) and 'Hosui'×'Yuan-ba-li' (N), whereas HR, N, and S seedlings were derived from S×'Zao-su' (N). Most seedlings from S×'Okusankichi' (N) were classified as S. Progenies of N×N crosses were ranked as HR, N, and S. These results suggest that the necrotic reaction in 'Okusankichi', 'Beijing-bai-li', 'Xiang-ya-li', 'Yuan-ba-li', and 'Zao-su' to Venturia nashicola is controlled by polygenes, and that differences in the transmissibility of these genes, as parents, would significantly affect the segregation of the resistance.

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Measurements of evapotranspiration taken in the summer and winter on netted melon crops grown under glass were taken to characterize seasonal and daily changes. The data were compared to meteorological and plant-related factors to seek some relationships. Evapotranspiration followed a sigmoid curve until one week after pollination, and then decreased gradually during fruit growth. Cumulative evapotranspirations after transplanting were about 116kg and 60kg, respectively, for the summer and winter crops, whereas the peak evapotranspirations were 3.0kg plant^-1 day^-1 and 1.3kg plant^-1 day^-1. The rapid increase in the evapotranspiration during the early stage was associated with the increase in leaf area; its gradual decrease during fruit growth was associated with a decrease in the transpiration potential of leaves. Therefore, irrigation amounts should be increased with leaf development and decreased with fruit growth. The curve of solar radiation in sunny summer days peaked at noon, whereas vapor pressure deficit usually peaked in early or mid afternoon; evapotranspirations in the afternoon had higher values than had those in the morning. In winter, vapor pressure deficit was relatively high during late afternoon and early morning because of heating, whereas it was low during the remainder of the day on account of low ventilation. These fluctuations led to a weak correlation between evapotranspiration and vapor pressure deficit. Regression analyses indicated that solar radiation was a main meteorological factor affecting evapotranspiration.

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When the ethylene-enhanced degreening of radish (Raphanus sativus L.) cotyledons held in the dark was investigated, the rates of chlorophyll (Chl) catabolism decreased and the action of ethylene was blocked by inhibitors. Inhibition of the degreening of cotyledons occurred when cotyledons of seedlings were treated with cycloheximide (CHI), actinomycin D (ACD), silver nitrate (AgNO₃), silver thiosulfate (STS), and allyl-isothiocyanate (AITC), but not chloramphenicol (CAP), an inhibitor of plastid RNA synthesis. Moreover, a high negative correlation between the degree of greenness of radish cotyledons and Chl-degrading enzyme activity was obtained: Y=-11.85X+64.27, P<0.001 (r²=0.995), where X and Y are Chl a -degrading relative activity and intensity of the green color of the cotyledons, respectively. The correlation indicates that ethylene promotes the degreening process of radish cotyledons through the de novo synthesis of a Chl-degrading enzyme protein. Direct inhibition of AITC on Chl-degrading activity was not observed at the level of concentration that could completely inhibit the ethylene-enhanced degreening of the cotyledons. This finding suggests that AITC is to act as an inhibitor of Chl-degrading enzyme induction in radish cotyledons.

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Seeds of 22 onion (Allium cepa L.) cultivars were cultured on solid Murashige and Skoog (MS) medium containing 50 μM 4-fluorophenoxyacetic acid (4-FPA) and 1 μM N⁶ (2-isopentenyl) adenine (2iP). Callus formation was observed in all cultivars. Some of the calli in solid culture were transferred into liquid MS medium containing 50 μM 4-FPA and 1 μM 2iP and were cultured in suspension. After subculturing in a liquid medium of 0.2M of sucrose, light yellow and large (LL) type cell clumps were obtained. To investigate the varietal differences in plant regeneration from solid and suspension cultures, the calli in solid culture and LL type clumps in suspension culture were transferred onto solid MS medium containing 1 μM 2iP. Plantlets were regenerated directly from the calli and the LL type clumps. The frequency of plantlet regeneration from suspension cultures tended to be higher than that from solid cultures. Significant differences were observed among the cultivars in the frequencies of plantlet regeneration from solid cultures and from suspension cultures. After suspension culture, 'Kurenai' showed the highest regeneration frequency (98%).

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Prolonging the photoperiod to continuous illumination (CI) implies a longer photosynthetic period which might be ideal for better plant growth. Pepper (Capsicum annuum L.) were grown in a nutrient culture system under a 12-h photoperiod for 6 weeks. Another group of plants was grown under a 12-h photoperiod for 3 weeks and then grown under a 24-h photoperiod (12/24-htreatment) for 3 more weeks. All seedlings were exposed to a low photosynthetic photon flux (PPF) of 120μmol·m^-2s^-1. The plants in the 12/24-h treatment gained more shoot dry weight, produced more leaves with heavier specific leaf weight (SLW), and had greater fruit set than those grown under a 12-h photoperiod. In a replicated experiment, the response was enhanced when a third group of plants was exposed to CI for 9 weeks just after germination. The higher shoot dry weight, and lack of further accumulation of starch in new leaves under CI indicate that the extensive carbon fixed under CI at low PPF was utilized effectively for pepper plant growth.

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Endogenous gibberellins (GAs) were extracted from shoots with floral buds of Eustoma grandiflorum and analyzed by full scan gas chromatography/mass spectrometry (GC/MS). Consequently, five C13-hydroxylated GAs, GA₁, GA₁₉, GA₂₀, GA₄₄, and GA₅₃, were identified. The presence of these GAs suggests that one major GA biosynthetic pathway, the early C13-hydroxylation pathway, is operating in these shoots. Stem elongation of resetted plants was promoted by applications of GA₁, GA₄, GA₉, and GA₂₀. C13-hydroxylated GAs, GA₁, and GA₂₀, were more active in stem elongation than were the non-C13-hydroxylated GAs, GA₄, and GA₉. Inhibition of stem elongation on Uniconazole-P (UCZ) and Prohexadione-calcium (PCa)-treated plants was wholly reversed by application of GA₁, where the inhibition by PCa was partially overcome by GA₂₀. These results suggest that the activation steps of precursory GAs, such as 3β-hydroxylation steps from GA₂₀ to GA₁ and from GA₉ to GA₄, are functioning in the rosetted plants and that the endogenous GA₁ is physiologically important in regulating stem elongation of E. grandiflorum.

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Eighteen ginger strains were collected mainly from Asian countries from 1985 through 1989 to investigate their pollen fertility and germinability. The pollen fertility test was performed in mid-October 1990, and that for pollen germinability was conducted during November 1990. All strains displayed low pollen fertility; three strains had pollen fertility ranging from 20.9% to 21.4%, seven from 10.6% to 19.0%, and eight from 0.9% to 7.4%. In the pollen germinability test, 14 strains used had very low germination rates; four had germination rates ranging from 0.15% to 0.22%, three from 0.06% to 0.10%, and seven from 0.00% to 0.02%.

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Distribution patterns of ¹³C-photosynthates in bearing kiwifruit vines in relation to shoot growth were investigated in June and July. The amount of ¹³C from leaves partitioned into fruit was greater in naturally self-pinched shoots than it was in growing shoots at early and mid-stages of fruit development. At 120 hours after ¹³CO₂ feeding in June, ¹³C contents were 11.1 and 1.2mg per fruit, for self-pinched and growing shoots, respectively. A steep gradient in ¹³C concentration from the base to the apex of the growing shoots existed, whereas there were little differences in ¹³C levels among the nodal positions in self-pinched shoots. Furthermore, fruit had more ¹³C than did the terminal parts of shoots, including leaves in self-pinched shoots, but the reverse was true in growing shoots. These results show that shoot elongation during fruit growth adversely affects the distribution of photosynthates into fruit. Therefore, such practices as inducing natural self-pinching and manual pinching to suppress shoot extension are effective means for favoring the allocation of photosynthates to fruit so as to promote their growth and development.

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The self-incompatibility (S) genotypes of 'Tsugaru', 'Sekaiichi', 'Natsumidori', 'Akita Gold', M. 9 and 16 other cultivars and strains corresponding to each S-allele genotype were determined by controlled cross pollination. Those of 45 others reported earlier were reconfirmed. The genotypes and the corresponding cultivers and strains are: [table] Underlined cultivars and strains were newly determined in this report.

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The relationship between the nutrient status of Japanese persimmon trees cv Maekawa Jiro and the number of normal flowers and yield was studied. 1. The relationship between leaf soluble sugar in the June of the previous year and the number of normal flowers in the following spring was barely significant (r=0.48). No significant relationship existed between leaf N, starch, and soluble sugars on all other sampling dates and the number of flowers the following season. 2. A positive correlation existed between nitrogen content in 1-year-old wood and the number of normal flowers; a coefficient of correlation, r=0.57, was found between the number of normal flowers versus trunk cross-sectional area. Date for three years reveal that a small quantity of nitrogen is stored in the winter of the off-year. 3. A multiple regression equation reveal that the number of normal flowers is highly correlated with the nitrogen content in 1-year-old dormant wood and the leaf soluble sugar of the previous June. 4. Thus, we conclude that leaf carbohydrate content at the beginning of flower-bud initiation and the nitrogen level in 1-year-old wood about the time flowers are differentiating are important factors which determine the number and quality of flowers. 5. To obtain an optimum yield of good quality fruit annually in 'Maekawa Jiro', a leaf-fruit ratio of 40 is required, provided the nitrogen and carbohydrate levels are likewise optimum.

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The changes in ACC and glutathione and their effects on the breaking of bud dormancy of grapes by high temperature treatment (45°C water soaking for 4 hours) were investigated. High temperature treatment increased ACC content and ethylene production in 'Delaware' grape cuttings and their levels remained higher than that of the control for 21 days after treatment, but they decreased and became lower than that of the control after budbreak. The level of reduced glutathione (GSH) in cuttings exposed to high temperature was consistently higher than that of the control 3 days after treatment, but the situation was reversed for oxidized glutathione (GSSG). Apparently GSH broke bud dormancy, but GSSG inhibited it. These results indicate that dormancy of grapevine buds is broken when GSSG converts to GSH, and that cyanide produced during ethylene biosynthesis may stimulate the conversion.

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To clarify the mechanism of breaking bud dormancy in grapevines, the effect of substances related to ethylene biosynthesis on budbreak was investigated. When the cuttings of dormant 'Delaware' grape were treated with ACC, ethylene or ethephon, only ACC broke bud dormancy. When the cuttings of dormant 'Delaware' grape, soaked in 45°C water for 4 hours, were treated with aminooxy acetic acid (AOA), cobalt chloride (CoCl₂) or silver thiosulphate (STS), AOA and CoCl₂ inhibited budbreak but STS did not; whereas applications of 20% calcium cyanamide, 10% hydrogen cyanamide and 10% potassium and sodium cyanides broke bud dormancy; calcium and hydrogen cyanamides were the most effective. These results indicate that ethylene itself has little or no direct effect on breaking bud dormancy and that HCN, which is produced during ethylene biosynthesis may break bud dormancy in grapevines.

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Seasonal changes in monoterpene concentrations in the juice of Muscat of Alexandria grape were investigated. Volatile monoterpenes were analyzed by trapping them in the headspace with Tenax-TA. Reproductive results were obtained when headspace gas was trapped at 40°C for 180 min. In the headspace trapping method, the concentration of each monoterpene was slightly lower compared to those extracted with n-pentane directly from juice. Clear peak separations were obtained by gas chtomatography. Linalool increased rapidly from 30 days after veraison and reached a maximum in late September, it then declined. Geraniol increased slowly from the stone hardening stage to the overripe stage. Percentages of linalool and geraniol to total monoterpene at harvest were 66.3 and 27.0, respectively.

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The role of glutathione, which maintains protein thiol groups in the reduced state in living cells, on the onset of endodormancy (rest) of grape buds was investigated. When potted grapevines were exposed to 30°C/25°C (high), day/night, or 20°C/15°C (low), day/night, before the onset of bud dormancy, buds administered low temperature became dormant, but those treated with high temperature did not. On shoots treated with low temperature, endogeneous ABA levels increased soon after treatment, whereas ABA levels in shoots treated with high temperature remained low. Reduced glutathione (GSH) content in the shoots treated with high temperature increased, whereas in shoots treated with low temperature, it decreased gradually. Oxidized glutathione (GSSG) content in the shoots treated with high temperature remained almost constant during the experimental period, whereas under the low temperature treatment it increased. GSSG content increased in shoots induced to dormancy by the ABA treatment. Furthermore, exogenous treatment with GSSG inhibited budbreak. Therefore, we conclude that glutathione is one of the potent factors in controlling grape bud dormancy.

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The self-incompatibility genotypes of apple cultivars were determined using cross-incompatible and -compatible parents and their progenies. The existence of 6 alleles and 7 genotypes was comfirmed: the genotypes of 9 cultivars were established as follows: (S_Ja, S_Jb)='Golden Delicious' (S_Ja, S_Jd)='Toukou' (S_Jc, S_Jd)='Jonathan', 'Hlmekami' (S_Jc, S_Je)='Delicious' (S_Jc, S_Jf)='Fuji' (S_Jd, S_Jf)='Senshu', 'Iwakami' (S_Je, S_Jf)='Ralls Janet', (S_Ja, S_Je) or (S_Jb, S_Je)='Redgold', 'Kinsei' It seems that 'Indo' has a S_Jd-allele.

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The effect of soil water deficit on vitamin C, sugar, organic acid, amino acids and carotene contents in fruits of five large-fruited tomato cultivars was examined. 1. The effect of soil water deficit on vitamin C content per fresh weight varied, depending on the cultivars; in some cultivars vitamin C content increased, whereas in others it was unaffected. 2. The amounts of glucose and fructose per fresh weight in water-stressed plants were larger than those of control treatment in almost all cultivars, but they were the same on dry weight basis. This indicates that the soil water deficit merely reduced water accumulation by the fruits. 3. The amounts of organic acid and free amino acid (per fresh and dry weights) were increased by water deficit treatment. Furthermore, the effect of the treatment on the composition of organic and free amino acids was different which suggests that soil water deficit affects the metabolic pathway of organic and free amino acids in tomato fruits. 4. In red and pink type cultivars, soil water deficit tended to increase the amount of lycopene per fresh weight in the outer pericarp region but it had no effect on the amount and distribution of the yellow pigments, β-carotene and xanthophyll.

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Strawberry seedlings were inoculated with anthracnose by spraying suspensions of 5×10⁵ conidia per milliliter (±1×10⁵). Immediately after inoculation, the seedlings were placed in an inoculation chamber at 28°C and 100% RH for 24-hr. In Experiment 1, progenies from 20 hybrid crosses at the young and mature seedling stages were transferred to the greenhouse after inoculation. In Experiment 2, seedlings of 'Nyoho'×'Houkouwase' were inoculated with spore suspensions as in Exp. 1. The inoculated seedlings were placed in growth chambers set at 20, 22, 24 and 26°C for 8 days and then transferred to the greenhouse; control seedlings without inoculation were placed in the greenhouse. 1. Experiment 1. The mortality rates of progenies from 20 hybrid crosses 15 days after transplanting correlated positively with those of mature seedlings, 37 days after transplanting. This means it is possible to evaluate the resistance to anthracnose crown rot (Glomerella cingulata ) by the longevity at the early stage of seedlings. 2. In Exp. 2, the screening was clearly effective because the susceptible seedlings after the selections at various temperatures became fewer than the control seedlings. The mortality rates for young strawberry seedlings of 'Nyoho'×'Houkouwase' increased proportionately with the increase in temperature of the growth chamber.

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Risk of mutations is a serious problem in propagation in vitro. Traditional vegetative propagation by division is a genetically safe clonal propagation method, although multiplication speed is slow. To improve the multiplication rate of Cymbidium by division, effects of dark treatment of pseudobulbs on sprouting of lateral buds and subsequent growth were investigated. Dark treatment promoted new shoot development from lateral buds in all cultivars. The effect was prominent in lead bulbs which in all cultivars developed shoots. Although the effect of dark treatment was less effective in the 1-and 2-year-old pseudobulbs, these bulbs sprouted more shoots than lead ones. Effects of dark treatment became obvious four or five months later after the start of the treatment because it inhibited defoliation from two-and one-year old pseudobulbs and stimulated healthy root development. The increased number of roots could be responsible for new shoot development. Cym. Hong Gui developed flower stalks from back pseudobulbs and bloomed in the dark and light. The rate of flower stalk development was slow in plants which produced numerous shoots. These findings indicate that dark treatment of pseudobulbs could hasten clonal multiplication of Cymbidium by division.

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Seedlings of cosmos (Cosmos bipinnatus Cav.), lettuce (Lactuca sativa L.), sunflower (Helianthus annuus L.), ornamental kale (Brassica oleracea L. var. acephara), tomato (Lycopersicon esculentum Mill.), bell pepper (Capsicum annuum L.), and cucumber (Cucumis sativus L.) were irradiated by a UV-B lamp (fluorescent sun lamp) or a three-band fluorescent lamp (control) for 72 hr just after sowing. Hypocotyl elongation was repressed by all species during the irradiation with UV-B. The retarding effects of UV-B persisted when these seedlings were placed in dark or a greenhouse with 30% shade after irradiation. The most effective timing of UV-B irradiation for cosmos and ornamental kale seedlings was from 48 hr to 72 hr after sowing, when the seedlings were rapidly increasing their surface area to UV-B.

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Callus formation and plant regeneration from flower bud organs in Gladiolus were studied. The results were as follows: 1. Callus was not inducible from upper parts of the perianth, but was obtained from their lower parts and from ovaries at frequencies of 56.0% and 94.0%, respectively; about 64.0% of these calli regenerated shoots. 2. Among ovaries at different developmental stages, those samples 2∼3 days before anthesis were most efficient in callus formation and shoot regeneration. 3. Calli were induced from all explants of ovaries on MS medium containing 5mg·liter^-1 NAA and 5mg·liter^-1 BAP. 4. Shoots were regenerated most efficiently from the calli on MS medium containing 2mg·liter^-1 BAP. 5. Callus formation from ovaries varied little among varieties, but shoot regeneration from the calli varied a great deal, e.g. regenerating frequency of cv. Traveler was much higher than that of cv. Hector. 6. When regenerated shoots were transferred to the MS medium, shoots and roots developed and subsequently corms formed at the base of the shoots. After corms were released from their dormancy by a low temperature treatment and transplanted into the field, they developed shoots and roots and then flowered. Flower shape and color of the regenerated plant had the same characteristics as the mother plant.

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Stem segments of 23 chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura) cultivars were cultivated on MS medium containing NAA 2.0mg·liter^-1 and BA 0.2mg·liter^-1. Among which 11 cultivars had high adventitious shoot regeneration potentials. Three of these cultivars, 'Shuhonochikara', 'New Summer Yellow' and 'Yamabiko' which were selected for transformation experiments had their regeneration potential suppressed by kanamaycin at 7.5∼10.0mg·liter^-1. The stem segment explants were co-cultivated at 25°C for 3 days with Agrobacterium tumefaciens strain LBA4404, containing pBI121 plasmid. After co-cultivation, the explants were placed on regeneration medium, containing 7.5∼10.0mg·liter^-1 kanamycin. The presence of the NPTII gene in the regenerated plants was confirmed by PCR-southern analysis. The transformation efficiency increased to 2.46% when the Agrobacterium suspension was diluted with a regeneration medium, containing 100μM acetosyringone.

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Flowering responses of 'Regina', 'Carmen' (syn. 'Cana') and 'Wilhelmina' Alstroemeria to air and soil temperatures were studied for producing cut flowers in a soil cooling system. 1. Chilling requirements for flowering shoot production were 3∼6 weeks at 2°C for 'Wilhelmina', 6 weeks for 'Carmen' and more than 10 weeks for 'Regina'. 2. 'Regina' plants stopped producing flowering shoots when rhizomes were kept at 25 and 18°C but continued to produce flowers at 14°C, irrespective of air temperatures. 3. Rhizomes of 'Regina' plants, subjected to 15°C or lower for at least 6 hr per day, continued to produce flowering shoots although the number of vegetative shoots increased as compared to rhizomes exposed to a continuous chilling treatment. 4. Chilled 'Regina' and 'Carmen' plants ceased flowering subsequently when they were exposed to 28/22°C (12 hr day/12 hr night) for 4 and 10 weeks, respectively.

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To elucidate the relationship of polyamine content to ethylene evolution in fruit ripening of Japanese pear cv. Kosui, aminooxyacetic acid (AOA) or methylglyoxal bis-(guanylhydrazone) (MGBG) was administered to intact fruits about one month before harvest. After treatment, changes in ethylene evolution from the fruits and their 1-aminocyclopropane-1-carboxylic acid (ACC) and polyamine contents were compared to those of the control. Treatment with 5mM AOA, which is known to block the conversion of S-adenosyl-methionine (SAM) to ACC, decreased ethylene evolution just before harvest, although ACC content hardly changed. This treatment gradually increased spermidine (SPD) and spermine (SPM) contents for 20 days after which they subsequently decreased, accompanied by lower levels of putrescine (PUT) during ripening. Treatment with 1mM MGBG, which blocks the conversion of SAM to SPD or SPM, sharply increased ethylene evolution and ACC content just before harvest. The treatment also increased PUT content for 20 days after treatment and tended to lower SPD and SPM contents. These results indicate that a competitive relationship exists between ethylene and polyamine biosyntheses, using SAM as a substrate during the ripening process of 'Kosui' fruit.

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Graft transmissible diseases of fruit crops are very important because of the large production losses and the transmission of pathogens to propagated clones. Virus, viroid and prokaryote organisms have been found as the causal agents of many diseases. However, unidentified pathogens still remain in many fruit crops. ELISA, electrophoreses and PCR can detect the characterized pathogens rapidly, but plant indexing is necessary for undermined pathogens. To obtain pathogen-free plants, a heat-treatment is effective to eliminate various pathogens from infected plants, but usually not viroids. Apical shoot-tip-culture or grafting can eliminate viroids as well as other pathogens, except for capillovirus. Methods combining pre-heat treatment and subsequent shoot-tip culture/grafting have been demonstrated for the elimination of known pathogens. Pathogen-free stock plants are usually preserved in protective screen houses. However, additional propagation and nursery production have been accomplished in fields in Japan. Thus, periodic checks or indexing of the mother stocks are needed. Pre-inoculation of bud-sources with protective mild strains of virus has been proved effective to control citrus stem pitting disease caused by aphid-vectored CTV. Disinfection of cutting tools is recommended to prevent viroid transmission, especially in nursery production.

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The cultivation of grafted vegetable is one of the essential cultural techniques for certain vegetables in many parts of the world where intensive and successive cropping is routinely practiced. More than 95% of the watermelons and oriental melons in Japan, Korea, Taiwan are being grafted on squash and gourd rootstocks before transplanting. The number of vegetables being grafted is estimated to be 540 million seedlings per year in Korea and 750 million in Japan. The benefits of grafting are well recognized so that illustration on vegetable grafting has become the key portion of the crop production guide pamphlets published by the government. Even though several grafting robots have been introduced to Korea from Japan, none of them are used now for practical grafting, possibly because of several unexpected limitations. In addition, most of these robots are too big to be handled and too expensive to be purchased by individual growers. Reasonably priced and easy-to-handle grafting machines are also urgently needed for the individual growers. Growing highly uniform seedlings in tray is vital for efficient grafting operation, especially for grafting by robots. Research relevant to seed germination and ways to obtain fast and uniform seed germination should be conducted to maximize the efficiency of vegetable grafting.

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In recent years, many highly productive lines of transplants including the virus-free lines have been produced through vegetative propagation. In Japan, however, commercial supply of the vegetatively propagated transplants is less than that of seed propagated transplants. Meanwhile, international trade of propagated materials is increasing as the number of multi-national companies increases. This trend will be intensified worldwide by the UPOV-treaty which strengthens the patents for plants. As a result, there will be an increase in importation of vegetatively propagated transplants. Problems and future prospects of vegetatively propagated transplants are discussed.

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There are more than 75, 000 ha of cruciferous, solanaceous and curcurbitaceous crops that are using transplants in production and a total amount of over 1.2 billion transplants are needed each year in Taiwan. Providing good quality seedlings to farmers is important for successful crop production. After the introduction of using plug trays for growing seedling in early 1980, it has been widely adopted by growers. Due to its advantage, many farmers prefer to purchase plug transplants rather than grow their own. More than 30 nursery centers providing transplants to farmers have been established in Taiwan. In the past 15 years, public and private sectors have conducted much research work concerning plug culture practice, which is the leading factor for successful development of plug growing in Taiwan.

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Diurnal temperature fluctuation interacts with light quality and photoperiod to affect plant stem elongation. Stem cell elongation but not division increases as day temperature increases relative to night temperature and as day length increases for many species. The effect of diurnal temperature fluctuation and photoperiod on stem elongation are mediated via phytochrome where stem elongation increases as %P_fr decreases. The basis for diurnal temperature and photoperiod effects on stem elongation is associated with temperature fluctuation when stimuli occur during the period of most rapid stem elongation during a 24-hour cycle, i.e., the end of the scotoperiod and beginning of the photoperiod. The basis for thigmotropic inhibition of stem elongation is associated with endogenous stimulation of ethylene synthesis. Application of this information to commercial plant production and potential future research directions will be discussed.

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Excessive stem elongation in transplants hinders mechanical transplanting and reduces plant survival in the field. Mechanical stimulation is an effective method for reducing stem elongation during transplant production. This investigation determined how to optimize the treatment and the consequences it has on subsequent field performance. This research examined the effects of varying the dose, the interval between brush strokes during stimulation, the time of day that stimulation was applied and the time application was started. Tomato seedlings and grown at 2, 100 plants per m² were reduced in height by 20% when brushed with 10 strokes per day from canopy closure until they were ready to set out. More intense treatment did not further reduce the height. The interval between strokes could range from none to 10 minutes with no difference in the effect. The treatments were similarly effective whether applied in the morning or in the afternoon. Treatments begun at different canopy heights were shorter in direct proportion to the number of days of treatment. The plants grew 6 mm per day when they were not treated and 3 mm per day during treatment. In the field, treated and untreated processing tomatoes recovered from transplant shock equally based on the resumption of elongation growth. Leaf area development and yield were also equal. Furthermore, fresh-market tomatoes were unaffected in earliness, and no treatment-related defects were noted in the fruits. Treated plants were more tolerant of wind. In wind-tunnel tests, treated plants resisted wind speeds about 4 km·h^-1 higher. A field planting subject to 70 km·h^-1 wind had 12% mortality in untreated plants but only 2% in treated plants. Mechanical conditioning with brushing and impedance produced transplants with desirable qualities without adverse effects on field performance.

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Tree size and harvest season might be designed and controlled in growth chambers or by elevation in the field. By means of higher temperature, thousands of hectors of Japanese pears in Taiwan are being cultivated to produce off-season fruit year around, mainly from spring through fall months. The height of a Japanese pear tree with setting fruit might be 30 cm if the tree is kept in 15 : 25 : with full light intensity through out the year until the flower buds are initiated and begin to develop. Like banana trees, papayas are susceptible to wind damage. Papaya is also susceptible to the papaya ring spot virus (RSV) prevalent in Taiwan and other tropical and subtropical areas. Nethouses were constructed to prevent aphids from transferring the virus. In the nethouse, decreased light intensity induced vigorous vegetative growth of the papaya. When the tips of the papaya touched the net, the canopy could not spread, forcing farmers to remove the net. The papaya soon became infected by RSV resulting in higher cultivation costs. In order to increase the life span of papaya in nethouses, a mechanical stimulus was applied to the papaya by cleaving and bending the trunk to various heights. This technique facilitated evaluation of wind damage, disease susceptibility, and duration of the harvest. Research shows papaya trunks can be trained to a tunnel-type growth form extending the duration of the harvest for an additional year or more. This suggests that the plastic recovery property of the papaya trunk allows cultivation economically in greenhouses or nethouses, and eventually in the field with greatly reduced affects from wind damage.

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For over 50 years it has been known that the chromoprotein phytochrome has a fundamental role in photoperiodic timing mechanisms. However, exactly how phytochrome is involved in measuring the length of the dark period has eluded all attempts by researchers to elucidate biochemical and molecular mechanisms. This predicament can be partly explained by the recent discovery that phytochrome is actually a family of a number of related photoreceptors with separate, but overlapping functions. We have been engaged in an attempt to delineate the roles of individual phytochromes in photoperiodic timing in both a LDP and a SDP through reverse genetics. We are using transgenic plants of Nicotiana sylvestris (a LDP) and Nicotiana tabacum cv. Maryland Mammoth (a SDP) that have been engineered to overproduce or underproduce either Phy A or Phy B using a double 35S promoter to enhance expression of the transgenes. To date three homozygous antisense tobacco PHYA lines of N. sylvestris have been obtained ; PCR analysis showed the integration of the transgene, and these lines displayed longer hypocotyls under continuous far red light. A total of five N. sylvestris lines expressing PHYB in the sense orientation have also been identified by PCR analysis. Seedlings of four of these putative PHYB overexpressing lines had significantly shorter hypocotyl lengths under continuous red light. Interestingly, one overexpressing PHYB line exhibited a phenotype consistent with co-suppression : under red light, hypocotyls of this line were much longer than those of wild type seedlings. We are now in the process of examining the photoperiodic responses in both classes of transgnic plants. We are also in the process of characterizing plants of N. sylvestris transformed with PHYB in the antisense orientation, as well as N. tobacum cv. Maryland Mammoth plants transformed with PHYB in both the sense and antisense orientation, and with PHYA in the antisense orientation. Further progress on the molecular characterization of these additional transgenic lines is reported.

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Pharbitis nil has been widely used as a typical short-day plant in studies of flowering. It can be induced to flower by a single dark treatment even in seedling with just unfolded cotyledons. This plant is also capable of inducing to flower under continuous light by giving various treatments such as poor nutrition (PN), high-intensity light (HL), low-temperature (LT) and physical or chemical inhibition of root elongation etc. Furthermore, the responses to these treatments were different among strains. Therefore, it is a suitable experimental material to study the mechanism of floral induction. We are investigating to elucidate the mechanism of floral induction under various conditions by using Pharbitis nil, strain Violet, Kidachi and Tendan. In this symposium, we will report two subjects on flowering in Pharbitis nil, (1) the mechanism of floral induction of long-day (LD) flowering by PN, HL and LT, (2) our recent works on short-day flowering. Pharbitis nil, strain Violet, is induced to flower under continuous light by PN, HL and LT, but strains Kidachi and Tendan were not by PN and HL, though they initiated floral buds under LT. HL has interesting effects on flowering, that is, (1) induction, (2) promotion of LT flowering, (3) inhibition of short-day flowering. The cotyledons are necessary for flowering under these conditions. Therefore, we widely analyzed the extracts from the cotyledons by using HPLC equipped with various detectors. As the results, we found several substances which closely correlated with flowering. Floral induction under PN and HL is closely correlated with the accumulation of some phenylpropanoids such as chlorogenic acid (CGA), p-coumaroylquinic acid (CQA) and pinoresinol-β-D-glucoside (PRG), sugars such as glucose, fructose and sucrose, and polyamine such as putrescine (PUT). Under LT, feruloylquinic acid (FQA) and ascorbic acid instead of CGA and PRG increased preceding floral initiation. Promotive and inhibitory effects of HL on flowering can be explained by the action of ascorbic acid. High level of sugars is necessary condition and the accumulation of CGA, PRG, FQA and/or PUT seems to be sufficient condition, that is, floral initiation under long-day condition always occurred when necessary-sufficient condition was fulfilled. In order to elucidate the physiological roles of these phenyl-propanoids, we remarked PRG, which is known as an inhibitor of phospho-diesterase (PDE). Inhibitors of PDE such as papaverine, theophyline and caffeine promoted flowering under PN. Moreover, FQ and some benzoic acid derivatives which promoted LD flowering inhibited the activity of PDE, suggesting the involvement of c-AMP in LD flowering. It will be described about the endogenous level of c-AMP in relation to PN flowering. In pattern analysis by using HPLC, it was difficult to find out florigen-like substance in extracts from photoperiodically induced leaves. Recently, we found that the inhibitors of biosynthesis and degradation of catecholamines (CA) inhibited floral initiation when they were applied before and during the dark period. Thus, we introduced a coulometric array system (ESA-Coulochem), which can measure CA at f mol level, for the quantitative measurement of CA. Unexpectedly we failed to detect CA, but we found many substances which seem to be florigen. It will be referred to their results.

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The developmental program in animal is controlled by homeotic genes which share a unique and homologous sequence, the homeobox sequence. And the gene product of homeobox, the homeodomain protein, is thought to work as a gene regulator protein which binds to target DNA by its helix-turn-helix motif. And thus effect as regulators on developmental program. Whether homeobox genes control the development and differentiation of plants like in animals or not, is one of the interesting questions. To understand the effect of plant homeobox genes, we isolated a homeobox containing gene, OSH1 from rice and introduced it into several plant species including kiwifruit and tobacco. OSH1-transformed plant species exhibit similar morphological changes such as dwarfism, abnormal shaped leaves and loss of apical dominance. These observations suggest that the OSH1 gene product may regulate the expression of genes related to plant morphogenesis. However, the molecular mechanism(s) by which OSH1 regulates plant morphogenesis, such as the target gene(s) are still unknown. So, we analyzed the plant hormones which have distinct influences on plant growth and development. We discussed about the hormonal changes related to OSH1 expression and possible effect site of OSH1 in development.

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The gametophyte-sporophyte interactions govern the reproductive strategy of higher plants by forming different barriers to self-pollination in pollen-pistil system. Self-incompatibility, barrier was studied in the experimental system including 2 clones of petunia : (a) self-compatible (self-pollination results in adhesion, hydration and germination of pollen grains, growth of pollen tubes and fertilization), (b) self-incompatible (with the S-gene of incompatibility, the expression of which inhibits pollen tube growth in sporophyte style tissues). Thus, our experimental model permitted us to study signal systems capable of transmitting not only positive information favoring the growth of compatible pollen tubes to the ovary, but also a negative information preventing the penetration of incompatible pollen tubes. A concept of multilevel system controlling gametophyte-sporophyte interactions was put forward. Here, we provide evidence for the participation of sporophytic proteins and ethylene in the regulation of male gametophyte growth and development. The protein specificity in pollen-pistil system during floral organogenesis is characterized by common antigens to male and female systems, as well as by pollen-and pistil-specific antigens, which are synthesized at the late stages of flower development (including a unique S-antigen in sporophyte tissue of pistil). The pattern of lectin activity observed in pistil transmitting tissue is related to the lectin molecule functioning in the interactions between the cells of male gametophyte and those of pistil sporophytic tissues. We have shown that two enzymes are related to the operation of the gametophyte-sporophyte interactions : style RNase takes part in the gametophytic selfincompatibility mechanism, whereas cholinesterase is the most likely candidate for the specific recognition and signal transduction in pollen-pistil system. It is demonstrated that the sporophyte stigma tissues are the source of ethylene production during pollen tube growth in the pistil in the case of both compatible and incompatible pollination.

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We previously identified and characterized a predominantly pollen-expressed gene of Petunia inflata that encodes a receptor-like kinase named PRK1. The extracellular domain of PRK1 contained leucine-rich repeats, and the cytoplasmic kinase domain was found to autophosphorylate on serine and tyrosine. To investigate the function of PRK1 in pollen development, we transformed P. inflata plants with a construct containing the promoter of a predominantly pollen-expressed gene of tomato, LAT52, fused to an antisense PRK1 cDNA. Three transgenic plants produced approximately equal amounts of normal and aborted pollen. Progeny analysis revealed that the transgene cosegregated with the pollen abortion phenotype. The mutant microspores of the transgenic plants developed normally until the uninucleate stage, but were not able to carry out microspore mitosis and eventually disintegrated. Northern blot analysis suggested that the pollen abortion phenotype most likely resulted from down-regulation of the PRK1 gene by the antisense PRK1 transgene. Progeny analysis in two of the transgenic plants, ASRK-13 and ASRK-20, showed that the transmission of the antisense PRK1 gene was also greatly reduced through the female. Light microscopic examination revealed that embryo sac development of approximately half of the ovules of ASRK-13 was abnormal. The majority of the affected ovules were able to progress through most of megagametogenesis to produce a seven-cell embryo sac, but they failed to complete the maturation stages of the embryo sac development when cell expansion, nuclear migration, and differentiation take place. These ovules could not achieve fertilization and subsequently degenerated, resulting in abortion of half of the seeds. RNA gel blot results showed that the PRK1 gene is expressed in the ovary. These results suggest that PRK1 plays an essential role in a signal transduction pathway that mediates post-meiotic development of microspores as well as embryo sac.

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The first step of clonings of genes expressed in pollen mother cells (PMCs) is to isolate living PMCs. In the procedure of isolating PMCs from cabbage (Brassica oleracea var. capitata) and Chinese cabbage (B. campestris ssp. pekinensis), 1%&acd;30% sucrose, 2%&acd;10% mannitol, CPW medium (Frearson et al., 1973) and B5 medium (Gamborg et al., 1968) were used to maintain the cell vitality. The result showed that 7% sucrose was better in maintaining the cell vitality of PMCs. Percoll gradient density centrifugation was used to separate PMCs from tetra stage microspores and unicellular microspores by two steps. The first steps, 0% / 10% percoll, can separate unicellular microspores from PMCs and tetra microspores ; the second step, 0&acd;10% / 20% percoll, could isolate PMCs from tetra microspores. The isolation of PMCs of cabbage was effective than Chinese cabbage. The 0.7mg PMCs and 3.3mg tetra microspores were obtained from one gram buds. The total RNA was extracted from PMCs and tetra microspores. There were two major ribosomal RNA bands (18S rRNA and 28S rRNA) after total RNA agarose gel electrophoresis. The poly(A)+ RNA was purified from total RNA by the way of oligo(dT)-cellulose affinity column chromatography.

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The factors inducing the formation of style- and stigma-like (SSL) structures by ovule culture in tobacco were investigated. In juvenile ovules which were excised from flower buds containing pollen grains at unicellular stage, the key to the formation of these structures seems to be isolation of the ovules with placenta from surrounding tissues and organs. Plant growth substances were not necessary for these formations in the ovules. However, kinetin was necessary for these formations in more advanced ovules which were excised from flower buds containing pollen grains at bicellular stage. In media containing kinetin, ovule-like structures were also observed on the basal part of style-like structures. The ability of pollen germination on the stigma-like tissues and pollen tube penetration into style-like structures was confirmed. This observation seems to indicate that these structures have the same functions as normal stigmas and styles. Moreover, the morphological characteristics of the SSL structures were similar to those of normal tissues.

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The greatest constraint to get high beneficial commercial production of lychee and longan is their irregular flowering. There are two ways to solve this problem ; first is to breed new cultivars (with regular flowering). There has been a little progress for this way, however, some success was reported as a selection of seedling from natural open pollination. The second way is to study their physiology of flowering and try to modify the response by cultural practices. More progresses have been done in lychee than longan. It was found that available carbohydrates analysed as total non-structural carbohydrates or starch were found to be accumulated before flower initiation and leaf flushing both in lychee and longan. Cincturing and plant growth regulators such as paclobutrazol, ethephon and SADH were reported to improve flowering and restrict vegetative flushing in lychee, although the results can often be inconsistent, while there are only few experiments had been done in longan, which provided negative results. Many researchers reported that water stress is required to induce dormancy, which promotes flowering. But some researchers did not agree. The effect of pruning and fertilizer application on flowering have been studied as only a few experiments, which suggested that they may play some roles in flowering of lychee and longan.

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Quality problems which diminish the competitiveness of ASEAN fruits in target export markets include decay and physiological disorders. Latent diseases originate in the field, but become evident only after harvest. Factors which induce physiological disorders, on the other hand, are principally postharvest in origin. However, predisposing conditions might occur during fruit growth and development. Fruit crops important to ASEAN include the banana, pineapple, mango, rambutan, papaya and durian. Although disease problem, principally, anthracnose and stem end rot constitute a major problem in these fruits, causative organisms have been identified and control measures formulated. In contrast, physiological disorders, which lead to quality deterioration and limit the marketable life of these fruits, are not as well understood. Hypoxia, particularly if combined with threshold levels of ethylene and temperature extremes can lead to a variety of these disorders. Quality problems arising from physiological disorders of mango, rambutan, papaya and durian, as well as etiological aspects are discussed.

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Strawberries were subjected to air or 20% CO₂ + air at 2.2°C for 2 days. Firmness of strawberries increased under high CO₂ treatment by 20-30%. Cell wall analysis showed lower water soluble pectin and higher chelating soluble pectin in CO₂ treated strawberries. Viscosity of water soluble extract from alcohol soluble solids was lower in CO₂ treated strawberries, and could be influenced by the change in pH. The enhanced firmness effect was also observed in mature mangoes, but not in immature and fully mature mangoes. The mechanism of firmness enhancement by CO₂ was possibly due to the change in intercellular pH and its solute composition.

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The purpose of quality evaluation is to assure a product quality to subsequent processes or the customer. If the quality can be judged by the appearance, product is easily evaluated by the senses or mechanical sensors. There are often items requiring a destructive test among those considered to influence quality, especially taste. The research has been tried for these cases using the methods of visible light, near infrared spectroscopy, acoustics or NMR. Now, internal qualities of many fruits have been inspected nondestructively. Still, there is no indication of the sugar content of individual fruits at shops. Consumers hope to find some indication of the sugar contents and a label guaranteeing the quality of given fruit. Furthermore, it would be expected to develop a technical method to find any difference between real organic products and usual products.

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Studies on nondestructive methods for fruits and vegetables started in the early 1970s in Japan. The main goal of the studies was measurement of surface color of the products using visible light. After that, many studies using delayed light emission (DLE), near infrared (NIR), fluorescence, sound response, and impact force response have been carried out to develop ways of detecting maturity, firmness, surface defects and other properties. Since the late 1980s, NIR spectroscopy has been studied for determining the chemical composition of many kinds of products such as peaches, Japanese pears, apples, satsuma mandarins and other products. In my presentation, new application of nondestructive quality evaluation of fruits and vegetables, including (1) firmness measurement, (2) internal void and disorder detection, (3) color grading, (4) maturity detection, (5) sweetness sorting, and (6) other topics is explained.

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Most of the mapping work in Brassica has taken place during the past 10 years. This activity has been focused mostly on rapeseed B. napus and on all three diploid cultivated species, B. nigra, B. oleracea and B. rapa. More recently, mapping has been expanded to include B. juncea. The maps produced in Brassica crops are based mainly on F₂ progenies developed independently by various laboratories, which will require in the future their integration for a more efficient use. The marker maps are being used to locate genes determining traits of economic interest, including quantitative trait loci for utilization in applied genetics and breeding of the numerous Brassica crops. Another important application of the maps, which is quite active at the present time, is on the study of the structure, origin and evolution of the Brassica genomes. The Arabidopsis sequencing genome program puts the Brassica crops in an advantageous position because of the immediate application of this information.

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DNA markers for marker-assisted selection of vegetable crops were reported. A resistant gene for clubroot disease of Chinese cabbage was mapped and three markers linked to the gene were obtained using a doubled haploid population. A marker for a late-bolting character which is valuable in Chinese cabbage embryogenic activities in F₂ plants and frequency distribution of DNA markers in a doubled haploid population regions having effect on the embryogenesis were identified. DNA markers for bacterial wilt of tomato were also obtained.

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DNA markers based on PCR are becoming increasingly important in a wide range of applications including cultivar identification, phylogenetics and the construction of linkage maps for marker assisted breeding and map-based cloning of genes. We have investigated the utility of the microsatellite sequence-tagged site marker type because of the high level of associated polymorphism and simple genetics. For grapevine cultivar identification the marker type has been very successful. For phylogenetic analysis, studies with Citrus and related genera suggests that microsatellite length variation may be better suited to construct relatedness over small genetic distances rather than large genetic distances. The integration of trinucleotide microsatellite markers into a linkage map of Citrus has demonstrated the utility of this marker type for genetic analysis within wide intergeneric crosses and the potential to act as "anchor loci" to align linkage maps from different crosses and laboratories.

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The classification of fruit trees and other cultivated plants has become an active field in agronomy, especially after the development of molecular markers, e.g., isozyme, RFLP, RAPD, AFLP, etc. However, some researchers do not understand the nature and limitation of these markers and they erroneously infer so-called "genetic distance" or phylogeny from them. In addition, some characters of cultivated plants like network phylogeny and lack of natural population confuse their classification with the methodology of wild interspecific or higher taxa. The research problems that we are confronted with are not necessarily resolved by genetic distance or inference of phylogeny. It is important to use the methods of orthodox genetics for pedigree levels and to use those of population genetics for higher but infraspecific levels.

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We have tried to apply the molecular techniques on the phylogenetic relationships, genetic diversity, cultivar identification and hybrid detection of several ornamental plants including azaleas and orchids. In azaleas, RAPD profiling was a useful tool for cultivar identification and hybrid selection. A natural hybridization or introgression event between two wild species was clarified by PCR-RFLP of cpDNA. This PCR-RFLP of cpDNA also revealed the origins of old cultivars. To clarify the phylogenetic relationships in genus Rhododendron, we examined all 8 subgenera and 12 sections of Rhododendron along with 3 genera Ledum, Menziesia and Elliottia for the sequence analysis of matK and trnK introns. The results showed interesting cladistics that will be informative for the next breeding program. In slipper orchids, intergeneric hybrids could be identified by RAPD analysis. Some RAPD bands were subgenus-specific or species-specific. The specificity of the bands was confirmed by Southern hybridization analysis and used for SCAR markers. These SCAR markers will be useful for rapid detection of the hybrid seedlings in orchid breeding.

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The gene silencing by sense and antisense transgenes in plants is an effective method to breed new cultivars. Torenia fournieri Lind. is an ornamental plant in the family Scrophulariaceae. We have established a transformation system for Torenia and modified flower longevity and color by transformation-mediated gene silencing. The introduction of a fragment of the ACC oxidase gene, in sense or antisense orientation, allowed the production of transgenic Torenia plants with extended flower longevity. The extended flower longevity was linked to the existence of the transgene. The introduction of a chalcone synthase (CHS) or dihydroflavonol-4-reductase (DFR) gene, in sense or antisense orientation, allowed the production of transgenic Torenia plants whose flower color had been changed. Some transformants showed a pastel flower color, and one showed a wavy pattern on the flower lip. These characters do not exist in normal cultivars.

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In general, plants synthesize sucrose for translocation of photosynthate. However, some horticultural crops of Rosaceae family are known to translocate sorbitol. Both types of crops are important in horticultural science. Although sucrose metabolism in source and sink tissue is well-known, regulation of sugar composition has not been investigated yet. Fruit generally contains three major sugars i.e., sucrose, glucose and fructose. As the sweetness of these three sugars is quite different, the manipulation of sugar composition in fruit could be useful for improving fruit quality. Thus genes encoding fructokinase that might be related to the level of fructose in fruit were cloned and analyzed. In contrast to sucrose, there are fewer studies on sorbitol metabolism in source and sink tissue. Therefore cloning and expression analysis of the gene encoding sorbitol-6-phosphate dehydrogenase (S6PDH) that may play a key role in sorbitol biosynthesis are also reported here. Two fructokinase cDNAs, Frk1 and Frk2, were isolated from tomato and identified using transformed yeast with those genes. The response of both genes to sugar and their expression patterns shown by northern and in situ hybridization suggest that Frk1 responds to carbon availability and plays a primary role in fructose metabolism in plant cells while Frk2 is localized specifically in cells that import and store carbohydrate. On the other hand, S6PDH cDNA was cloned from apple seedlings. The levels of S6PDH activity and protein were high in source tissue such as cotyledons and leaves in apple seedlings. Besides the S6PDH transcripts were induced during germination corresponding to sorbitol synthesis. On peach trees, the levels of S6PDH transcripts were also higher in more developed leaves compared with folded young leaves. The results strongly suggest that the S6PDH gene is expressed for biosynthesis of sorbitol in source tissue. Now some groups are executing mapping and overexpression of S6PDH.

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