The vase life of cut flowers and foliage is often shortened by vascular occlusions that constrict vase solution supply. Reductions in stem conductivity are typically caused by blockage of cut stem ends and xylem conduits by microbes, physiological plugging, and disruption of water columns in xylem vessels by cavitation and air emboli. Cut flower and foliage longevity can be greatly affected by the chemical composition of the vase solution. Provision of biocides prolongs the vase life of numerous species. A broad range of biocides has been suggested to prevent the proliferation of microorganisms in vase solutions; however, their assumed antimicrobial action may be confounded by their other physicochemical effects. In this context, the response of cut stems to biocides may also vary according to the cut flower or foliage type, the specific microorganisms involved, and other vase solution ingredients. This paper explores the efficacy and multifunctional roles of vase solution biocidal agents used in industry and by researchers for cut flowers and foliage.

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A trehalase (EC 3.2.1.28) was purified from the cell walls of Actinidia deliciosa fruit. The purified trehalase had optimal pH of around 5, Km of 0.25 mM and Vmax of 5667 pkat/mg protein, and was relatively heat stable. The enzyme showed highly specific activity to trehalose and weak activity to maltose and maltotriose, but did not hydrolyze any other disaccharides. Trehalase activity was unaffected by Ca²⁺, Na⁺, K⁺, Li⁺, Mn²⁺, Co²⁺, and Mg²⁺ ions and EDTA, but markedly inhibited by Hg²⁺ and Fe³⁺ ions, iodoacetic acid, tris(hydroxymethyl)aminomethane (Tris), p-chloromercuribenzoate (PCMB), glucose and glucosamine. This cell wall-bound enzyme seems to degrade apoplastic trehalose. Another possibility is that this trehalase has additional functions such as defence against insects.

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To identify sources of resistance to crown gall disease and to investigate its inheritance pattern to descendants, we assessed the degree of resistance among seven apple rootstocks of ‘JM5’, ‘JM7’, ‘M. 9’, ‘M. 27’, ‘G. 65’, Malus prunifolia ‘Mo 84a’, and ‘Morioka Seishi’, two wild Malus accessions of Malus sieboldii ‘Sanashi 63’ and ‘Mo-15’, and its hybrids (147 individuals). The inoculation was tested using two Agrobacterium tumefaciens strains of Peach CG8331 (biovar 2) and ARAT-001 (biovar 1) as inocula. M. sieboldii ‘Sanashi 63’ and ‘Mo-15’ did not show any galls at the inoculated sites six months after inoculation with suspensions of the strain Peach CG8331. Galls developed on the other rootstocks with a frequency from 0.31 to 0.82. In an inoculation test with strain ARAT-001 as the inoculum, no galls were formed on M. sieboldii ‘Mo-15’, and the frequency of M. sieboldii ‘Sanashi 63’ was low, 0.19. The frequency in ‘G. 65’ inoculated with strain ARAT-001 was much lower than that with strain Peach CG8331, whereas that in other rootstocks showed similar or higher frequency compared to strain Peach CG8331. The results suggested that there is an interaction (specificity) for the frequency of gall occurrence between A. tumefaciens strain and apple rootstocks. Based on the results of our study, M. sieboldii ‘Sanashi 63’ and ‘Mo-15’ were regarded as the most resistant genotypes to the virulent strains of A. tumefaciens used in our study. Resistant hybrids with no galls were found in progeny derived from a cross between ‘JM7’ × ‘Sanashi 63’ against strains of A. tumefaciens; numbers of hybrids were 19 (16%) and 5 (4%) against strains Peach CG8331 and ARAT-001, respectively. In F₁ progeny between ‘JM5’ × ‘G. 65’, plants with no galls were not observed. These results indicate that crown gall resistance in M. sieboldii ‘Sanashi 63’ is heritable through its descendants.

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γ-aminobutyric acid (GABA) is a four-carbon non-protein amino acid that is present in a wide variety of prokaryotic and eukaryotic organisms. Because of its antihypertensive effect on the human body, the demand for naturally occurring GABA has increased recently in the Japanese food industry. In this study, we evaluated the GABA content of tomato fruits of 61 commercial cultivars, wild species, and wild derivatives in 2005 and 2006 to screen for resources to breed a GABA-rich cultivar. GABA contents in tomato fruits greatly varied among the tested varieties and were poorly reproducible between the tested years. GABA-rich candidates selected from the screening were then subjected to salinity-stressed cultivation using the NFT system to assess their suitability for cultivation to produce GABA-rich fruit. Based on the results of two screenings and the salinity-stress cultivation test, ‘DG03-9’ was selected as a GABA-rich cultivar. The accumulation profiles for GABA, glutamine, and glutamic and aspartic acid during fruit development were also investigated in ‘DG03-9’ and ‘House Momotaro’ under salinity stress. The GABA content peaked at 24 days after flowering (DAF) in ‘DG03-9’ and 36 DAF in ‘House Momotaro’, and then declined during ripening. Salinity stress apparently promoted GABA accumulation during the early developing stages, but its effect on GABA decrease was different between the varieties. Although the GABA content in red mature fruits of ‘DG03-9’ was higher than that in fruits of ‘House Momotaro’ under normal and saline conditions, the maximum contents were almost the same in both cultivars. These results suggest that the lower reduction rate of GABA during the ripening stage causes high GABA accumulation in ‘DG03-9’ fruit. This variety will be a useful resource in the breeding of new GABA-rich cultivars. Additionally, we utilized an enzymatic assay with GABase to quantify GABA content in tomato fruit. This method will be a powerful screening tool for breeding.

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The present study was conducted to clarify the possibility of high soluble solid content tomato production in soilless culture with a small volume of substrate under water stress conditions, which was separate from salinity stress and controlled by matric potential for fertigation using a tensiometer. Treatments consisted of 2 set point levels of matric potential (−2 and −4 kPa) for fertigation in Experiment 1-1, 3 application rates (20, 80, and 180 mL/time/plant) in Experiment 1-2, and a combination of 2 set points of matric potential (−2 and −6 kPa) and 2 application rates (40 and 70 mL/time/plant) in Experiment 2. In Experiment 1, tomato plants and fruit production seemed to be affected by higher water stress treatment, but salinity stress was also applied simultaneously, in spite of leaching of salts into medium. In Experiment 2, it assumed that water stress treatment was mostly achieved by keeping the EC of medium solution below 5 dS·m^-1. The matric potential in the medium fluctuated −0.5 to 2 kPa at −2 kPa and −1 to −6 kPa at −6 kPa during the day. The proline content of leaves is considered an index of stress degree. It tended to increase with time during the experiment and to be higher at −6 kPa than −2 kPa treatment, although there seemed to be no distinct difference in the EC of medium solution among treatments. Therefore, according to the above proline content, it is suggested that water stress itself can stress the plant to some extent in soilless culture, but it may be difficult to induce sufficient stress intensity, which is comparable to the salinity stress producing high soluble solid content tomatoes, by water stress itself.

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In order to investigate the effect of the amount of NH₄-N applied (hereafter referred to as the “NH₄-N application amount”) on the growth and nutrient uptake of Chinese chive (Allium tuberosum Rottler ex Spreng.) plants in hydroponic culture, seven different NH₄-N application amounts using a free drainage system were examined between transplantation and harvest. To exactly evaluate the absorption of nutrients, all of the drained fluid was collected and analyzed. NH₄-N was applied with irrigation once for each 1 MJ of accumulated solar irradiation per square meter. The NH₄-N application amount for each irrigation event was 0, 5, 11, 21, 42, 84, and 168 μg/plant/MJ/m² (expressed as μg/plant/MJ in this paper) respectively. The results showed that the amounts of K, Ca, and Mg taken up by the plants decreased with the increase of the NH₄-N application amount. The amount of NH₄-N taken up by the plants (hereafter referred to as the “NH₄-N uptake amount”) increased significantly with the increase of the NH₄-N application amount, while the absorption of NO₃-N was not influenced. There was a significant positive relationship between the NH₄-N application amount and NH₄-N uptake amount, based on the law of diminishing returns. When the NH₄-N application amount ranged from 0 to 84 μg/plant/MJ, the yield of Chinese chive plants increased gradually with the increase of the NH₄-N application amount. The highest yield was obtained when the NH₄-N application amount was 84 μg/plant/MJ. The corresponding uptake amounts of NH₄-N, NO₃-N, P, K, Ca, and Mg were 10.7, 14.6, 6.0, 22.5, 3.3, and 2.0 mg/plant, respectively. When the NH₄-N application amount increased up to 168 μg/plant/MJ, the yield of the Chinese chive plants significantly decreased. Comparison of the results obtained in the previous and present studies suggested that the critical amount of NH₄-N for the growth of Chinese chive plants should be in the range of 33–35 mg·g^-1 DW, as excessive absorption damaged growth. For the cultivation of Chinese chive plants, the NH₄-N uptake amount of Chinese chive plants appeared to be more important than its concentration in the nutrient solution.

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Capsicum frutescens is known as a highly pungent chili pepper species, but an accession of C. frutescens showed very low capsaicinoid content. This few-pungent trait is novel and unique to ‘S3212’ in C. frutescens. To investigate the inheritance of the few-pungent trait, segregation of capsaicinoid content in F₂ and backcross populations (BC₁) crossed with high pungent C. chinense ‘S3010’ were observed. The segregation ratio indicated that few-pungency was controlled by a single recessive gene designated as the cf gene. Isolocus test between cf locus and C locus controlling capsaicinoid production was carried out using cleaved amplified polymorphic sequence (CAPS) marker SCY-800 linked to the C locus. CAPS pattern and few-pungency were not related, so the cf locus is different from the C locus. The single cf gene controlling few-pungency found in this study is expected to be used to develop new cultivars stable in few-pungency.

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Cardamine yezoensis Maxim., an edible wild Brassicaceae plant, is mainly found along river banks in the mountains of Hokkaido, Japan. For the purpose of domesticating this plant as a novel vegetable, an asexual propagation method for C. yezoensis nursery plants utilizing in vitro culture and appropriate hydroponic culture conditions was investigated. Leaf sections from wild plants were successfully regenerated in vitro using a combination of 0 to 1.0 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1 to 1.0 μM 6-benzylaminopurine (BA) as growth regulators. Nursery plants of uniform size were obtained using the following 2-step in vitro culture process. Asexual propagation was achieved by incubating approximately 1 × 1 mm leaf blade and petiole sections excised from in vitro plantlets in a medium containing 0 to 0.1 μM 2,4-D and 0.1 μM BA as growth regulators. This was followed by successive subculture of axillary buds of propagated plants in a medium containing 0.04 to 0.44 μM (0.01 to 0.1 mg·L^-1) BA as a growth regulator. Well-grown edible plants were harvested after 60 days of hydroponic culture with liquid fertilizer at an electrical conductivity of 0.5 to 1.0 dS·m^-1.

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We obtained somatic hybrids between Arabidopsis thaliana Columbia, and a cabbage variety, ‘Chusei Succession’ (Brassica oleracea L.), in addition to our previous success using the cabbage variety ‘Fujiwase’. All hybrids of the two combinations possessed the chloroplast genome of cabbage, while the mitochondrial genome was recombined. PCR primers specific to each of the five chromosomes of A. thaliana were designed and used to analyze the hybrids. It was found that the hybrids had all five chromosomes of A. thaliana. Somatic hybrids between Columbia and ‘Chusei Succession’ flowered and showed extremely low pollen fertility, producing no seeds by spontaneous self-fertilization, whereas seeds were obtained by crosses between somatic hybrids and three cultivars of B. oleracea. The seeds could be useful materials for the transfer of genes of A. thaliana to cabbage and to establish cabbage lines with novel mitochondrial genomes.

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In order to increase seed production of a pat-2 parthenocarpic tomato cultivar, we attempted to enable fertilization by applying an inhibitor of gibberellin (GA) biosynthesis to the whole plant to prevent pseudoembryo formation prior to anthesis. The pat-2 parthenocarpic tomato cultivar ‘Severianin’ was cultured with hydroponics, and the GA biosynthesis inhibitor, uniconazole-P, (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol, was added to the culture solution at 0, 0.01, 0.05, and 0.25 mg·L^-1 about two weeks before the first flower anthesis. Stigmata were removed to prevent pollination from half of the plants of each concentration before anthesis, and the other half were tapped by a finger at anthesis for pollination. For pollinated fruits, there were no differences in fruit weight and seed number between the different concentrations of uniconazole-P. A significant positive correlation was observed between seed number and fruit weight in pollinated fruits treated with uniconazole-P that was not observed in the absence of uniconazole-P. There were no significant differences in the germination rate at any concentrations tested compared to the control. Seedlings grown from uniconazole-P-treated plants appeared to develop normally and did not differ from the control. Hence, uniconazole-P treatment of the whole plant was useful for increasing the efficiency of seed production for a parthenocarpic pat-2 cultivar. This was augmented by choosing large fruits at harvest, which contain sufficient amounts of true seeds based on the strong positive correlation between seed number and fruit weight.

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We developed a simple and rapid extraction method of soluble carbohydrates from petals for analysis by high performance liquid chromatography (HPLC), using a centrifugal filter device in a test tube without homogenization. Rose ‘Sonia’ petals were immersed in 99.5% ethanol solution in a test tube and kept at 75°C for 20 min. Sorbitol was then added to the solution as an internal standard, and the petals were transferred to the centrifugal filter device and centrifuged at 12000 × g for 10 min. Following removal of the filtrate, 99.5% ethanol was added to the filter device and a second round of centrifugation performed. Filtrated solution obtained from both centrifugations was combined with the ethanol solution remaining in the test tube, heated to dryness at 80°C, and used for HPLC analysis. Few differences in soluble carbohydrate content were observed between the new method and a conventional method in which soluble carbohydrates are extracted by homogenization. We confirmed that most carbohydrate was extracted by the new method. Moreover, the soluble carbohydrate content of samples extracted from ‘Sonia’ petals using the new method did not change during one week of storage at −30°C, indicating the stability of the samples. Marked differences in soluble carbohydrate content were not observed among ‘Chanel’, ‘New Bridal’, ‘Rote Rose’, or ‘Saturn’ rose petals, carnations or Tweedia caerulea petals or Delphinium sepals, using either the new or conventional method. Marked differences in soluble carbohydrate content were also not observed among leaves and stems in carnations, Delphinium or rose ‘Sonia’ using either the new or conventional method. These results suggest that the new method, which does not require homogenization, appears to be a more simple and rapid method of extraction of soluble carbohydrates from various organs of floricultural plants.

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Eustoma grandiflorum (Raf.) Shinn. was subjected to long-day treatment using four types of light sources with a high red (R; 660 ± 30 nm) to far-red (FR; 730 ± 30 nm) light ratio to improve cut flower quality for early-autumn shipping. The R:FR ratios of a red-light fluorescent lamp, a color fluorescent lamp (R-type), a bulb-type red-light fluorescent lamp, and a bulb-type daylight fluorescent lamp were 62.0, 100.0, 8.8, and 8.5, respectively. As a control, plants were grown under ambient daylight. Flower budding of ‘Double Pink’ seedlings, planted on July 11 and treated with night-break treatment from planting to budding using these four light sources, was delayed 2–5 days compared with the control. Night-break treatment using each light source increased the number of nodes on the main stem, number of lateral branches, and number of flower buds, and increased the cut flower length of plants at anthesis of the first floret, compared with the control. Three cultivars were treated with night break using a color fluorescent lamp (R-type) and a bulb-type red-light fluorescent lamp. Although these two light sources did not delay the flowering of ‘King of Snow’ compared with the control, the mean flowering date of ‘Double Pink’ and ‘Piccolosa Snow’ under both light sources was 3–6 days later than that of the control. These light sources increased the number of nodes of the main stem, and increased the stem length and cut flower length compared with the control in each cultivar. As the most practical application, the bulb-type red-light fluorescent lamp was used for long-day treatment of ‘Double Pink’ under four lighting periods: pre-dawn lighting for 6 h, end-of-day lighting for 6 h, all-night lighting, and night break for 6 h during the night. All-night lighting delayed flowering more than the other treatments. Cut flower length of the plants at anthesis of the first floret was longest in the pre-dawn lighting treatment. We concluded that long-day treatment using a bulb-type red-light fluorescent lamp from 0:00 to 6:00 just after planting until flower budding is most effective to improve cut flower quality for early-autumn shipping of Eustoma cultivars.

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We tried to establish an evaluation technique for the varietal characteristics of lavender oil to compare their fragrance components. Nine cultivars of Lavandula angustifolia and 6 cultivars of lavandin (L. angustifolia × L. latifolia) plants were cultivated in Tsukuba, Ibaraki and 3 cultivars of lavandin were cultivated each in Kitahiroshima, Hokkaido, and Unzen, Nagasaki in Japan. The fragrance ingredients were extracted with ether by immersing from their calyces, which were adjacent to flowers. The extract solution was analyzed with gas chromatography–mass spectrometry. The concentration data were then converted into the ratio between the precursor and the product which relate to the estimated fragrance ingredient formation. The precursor and products of two types of reaction were analyzed: linalool and linalyl acetate, and lavandulol and lavandulyl acetate as the characteristic alcoholic fragrances and their acylated derivatives in L. angustifolia and lavandin, and borneol and camphor as the alcoholic fragrance and its specific oxidized derivative in lavandin only (precursor and its product, in that order). The analytical results of different sampling dates of every variety showed a similar fluctuating pattern of ratios during flowering periods in a cultivation location in different years. The relative positions of ratios among varieties were nearly constant and also showed similar results in different cultivation locations in different years. This result suggested that differences in the component ratios among varieties by testing same-stage calyces in the same cultivation area sampled on the same day showed varietal characteristics.

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Lilium formosanum Wallace has remarkable traits such as ‘precocious flowering’ ability, i.e., it reaches anthesis within 12 months from seed germination, with multiple shooting of flower stalks. To verify the possibility of the usefulness of these traits in lily breeding, nine combinations of interspecific crosses (L. formosanum as the seed parent; L. auratum, L. speciosum, L. regale, ‘Lollypop’, ‘Pink Tiger’, ‘Zaza’, ‘Le Reve’, ‘Marco Polo’, and ‘African Queen’ as pollen parents) were carried out with cut-style pollination and ovary-slice culture. Germination was observed in all nine interspecific crosses and 53 hybrids were obtained. Thirty (56.6%) of the 53 hybrids and two self-pollinated progenies of L. formosanum reached anthesis within 24 months from germination through ovary-slice culture. Multiple shooting of flower stalks was recognized in 11 (36.7%) of those flowered hybrids. Four hybrids, the pollen parents of which were Asiatic hybrid lilies with colored flowers, expressed ‘precocious flowering’ ability, multiple shooting of flower stalks, and entirely colored flowers simultaneously. These results suggest the possibility of breeding new types of cultivars with triple favorable traits from the cross between L. formosanum and Asiatic hybrid lilies with colored flowers.

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Strawberry, belonging to the Rosaceae family, translocates sucrose as the main carbohydrate to fruit, although many Rosaceae fruit trees use sorbitol as translocated sugar; however, we have found that strawberry has genes encoding sorbitol-metabolizing enzymes. In this study, the property of NAD⁺-dependent sorbitol dehydrogenase (NAD-SDH) and the effect of sugars and phytohormones on NAD-SDH activity and its mRNA accumulation were investigated to elucidate sorbitol metabolism and its regulation. The K_m values of NAD-SDH for substrates of fructose and sorbitol were 78.7 and 7.3 mM, respectively, similar to those of maize, which synthesizes sorbitol by the reduction of fructose by NAD-SDH. This result suggested that NAD-SDH in strawberry fruit can catalyze the reduction of fructose, but the activity is not enough to accumulate sorbitol in fruit. Therefore, we investigated the effect of sugars and phytohormones on NAD-SDH activity and the transcript level by adding various sugars and phytohormones to sliced fruit discs. Tissues incubated in 100 mM fructose or sorbitol stimulated NAD-SDH activity by about 2.5-fold compared with the control. Sucrose also stimulated NAD-SDH activity, but the increase was not as high as sorbitol or fructose. Of the phytohormones treated, 100 μM indole-3-acetic acid (IAA) had a marked stimulatory effect on NAD-SDH activity, but the other phytohormones (abscisic acid, gibberellic acid and 6-benzyladenine) had no stimulative effect. The mRNA transcript level in all sugar and phytohormone treatments showed no marked increase compared with the control. Thus, the kinetics and induction profiles by phytohormones of NAD-SDH showed that sorbitol metabolism in strawberry fruit was different from that in apple and Japanese pear fruits.

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