We investigated the characteristics of onion bulbs in relation to workability and productivity of peel processing. In this study, we peeled onions by cutting off the top and bottom of the bulb and then peeling away the outer skin. Peeled and unpeeled bulb weights were strongly correlated, but the working times for peeling onions did not relate to any specific traits. It is considered that heavy bulbs improve workability in peel processing of onion and that a greater yield of product could be achieved within a given time by using heavy bulbs. However, model analysis of the peel processing yield of onion using a formula for a spheroid showed that, peel processing yield correlated only with bulb height; therefore, the productivity of peeling onions are improved by using bulbs with a greater height. Prediction equations of peel processing yield are derived from model analysis using the formula for a spheroid. Estimates based on prediction equations for an independent two-year study using several varieties have fit well with the experimental data and we concluded that the prediction equations obtained can be used to evaluate the peel processing yield of onion cultivars. We can evaluate the peel processing yield of onion varieties without actually peeling them, which allows efficient selection and breeding of onion varieties for the processing of peeled onions.

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A shoot with leaf color mutation in a Japanese pear (‘Osa-Gold’) was found among trees treated by chronic gamma-ray irradiation. Seven nurseries raising plants from mutated specimens were surveyed in 2004 and 2009. In 2004, shoots with yellow-green leaves and with yellow-green margin variegation leaves were observed. The comparisons of observation in 2004 and 2009 showed that yellow-green mutant was stable and five types of shoots sprouted from the branches with variegated leaves in 2004 were observed in 2009. These findings showed that the variegated mutant was apparently unstable; however SAM structure in the yellow-green variegations was also stable and the development of L2 and L3 were merely different depending upon leaves. Furthermore, the results of microscopic observation, the phenotypes of cross pollinated seedlings, twin sector variegations showing the yellow-green variegated leaves indicated that the leaf-color mutant was heterozygous and showed a semi-dominant gene. Furthermore mutant cells in the SAM of the variegated shoot occupied the L2 layer. The methods of utilizing these mutants are discussed.

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Flowering cherries utilized as tourism resources in Izu, Japan are presumed to be interspecific hybrids. In this study, we investigated the genetic relationships among these flowering cherries using 9 nuclear SSR markers and 2 regions of chloroplast DNA sequences. According to the genetic identity based on nuclear SSRs, flowering cherries in Izu were divided into two groups. One was the Prunus lannesiana var. speciosa group, and the other was the P. campanulata group. However, many hybrids and P. campanulata shared the same sequence type of chloroplast DNA. These findings suggested that natural crossing among hybrids of P. lannesiana var. speciosa and P. campanulata often occurred in Izu. Therefore, we hypothesized that hybrid varieties in Izu developed near a human settlement near which P. lannesiana var. speciosa and P. campanulata were often planted in. Then, it was thought that these hybrids were valuable genetic resources for breeding to promote the large petals of P. lannesiana var. speciosa, dark red petals of P. campanulata and so on. Moreover, it was suggested that ‘Minato-zakura’ originated with a tetraploid (4n) of P. pseudocerasus as the mother, and that there are some individuals that were seedlings of ‘Kawazu-zakura’ and extremely closely related to ‘Kawazu-zakura’.

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Interspecific hybridization between carnation (Dianthus caryophyllus) lines with a long vase life and D. superbus var. longicalycinus, a wild Dianthus species native to Japan, was carried out in order to combine early flowering, high productivity and long vase life. Although the interspecific hybridization of this combination was very difficult, seed was set in 4 of 22 crosses. Moreover, all obtained seeds were abnormal; the seeds were imperfectly solid and had a wrinkled brown surface. However, 15 F₁ seedlings were obtained using normal cross-breeding techniques, without depending on in vitro culture. Selected F₁ lines showed fertility in both seed and pollen parent. SSR analysis proved that all 9 selected F₁ lines were interspecific hybrids. In backcrosses between selected F₁ or BC₁ lines and carnation lines with long vase life, the percentage of seed setting was markedly increased, and germination percentage of obtained seeds was also high. The mean vase life of the F₁ generation was 7.0 days; in contrast, vase life of the BC₂ generation, after two cycles crossing and selection using carnation lines with long vase life, had improved to 14.7 days, a net increase of 7.7 days. Carnation breeding using D. superbus var. longicalycinus was effective for selecting early flowering progenies. The F₁ generation showed a very early flowering habit; average number of days to flowering in 15 F₁ seedlings was 135 days. In BC₁ and BC₂ generations, segregation of seedlings with early flowering was also observed. Our findings suggest that flower vase life is not linked early flowering habit. Several selected BC₂ lines with long vase life, early floweing and high productivity could be developed, even when using D. superbus var. longicalycinus, which has a very short vase life, as breeding material.

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We assessed runner production in everbearing strawberry cultivars (Fragaria × ananassa Duch.) ‘Natsuakari’ and ‘Dekoruju’, which exhibit poor ability to produce runners, thus limiting their propagation and use. Both cultivars required 1,000 h of chilling (< 5°C) to induce runner production when grown under a long day length (LD); however, they required longer chilling under a short day length (SD). Plants chilled for 2,000 h tended to produce more runners under SD than under LD. During spring and summer, the overwintered ‘Natsuakari’ plants produced the fewest runners under SD. In contrast, the overwintered ‘Dekoruju’ plants produced the fewest runners under LD. Thus, a longer day length did not always enhance runner production in these cultivars. In autumn, 90-day cold storage at −2°C was substituted for natural chilling for plants that were rooted in summer. For both cultivars, the production of runners by plants that were rooted in July was similar to or greater than that by plants that were rooted in May. The rooting of mother plants in July, which are more available than plants rooted in May, did not have a detrimental effect on runner production during the next early summer period. Considering total runner production till July, we concluded that it is appropriate to initiate cold storage in December for the ‘Natsuakari’ cultivar and in November or December for the ‘Dekoruju’ cultivar.

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In tomato culture, low-node-order pinching system at high planting density, combined with an increased number of cropping times per year and an extended nursery period, are important for obtaining high yields. The production of flowering transplants that are as advanced as possible by the time of transplanting is necessary because of the limited area available in the nursery, and it is important to control excessive stem elongation of transplants during this stage. The height of seedlings increased more during the day than at night, and this stem elongation was correlated with elongation of epidermal cells. As seedlings were grown by quantitative nutrient management and stopping the nutrient supply at night during this stage could decrease plant heights compared with the heights of seedlings grown in an electric conductivity-based control using a root-zone limiting hydroponic system. The dry matter ratio and root: shoot ratio of the transplants grown with quantitative nutrient management and without supplying nutrient solution at night were both higher than those in the control. After transplanting into an NFT system, there was no significant difference in the yields of transplants grown among under those treatments. Based on these results, we propose using an approach based on quantitative nutrient control and suspension of nutrient supply at night in order to control excessive stem elongation during subsequent nursery stages.

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We studied the effects of water stress from summer until harvest time on the fruit quality of the medium-late maturing citrus cultivar ‘Harehime,’ [(‘Kiyomi’ × ‘Osceola’) × ‘Miyagawa wase’]. During the dry treatment, we induced water stress of −0.7 to −1.2 MPa leaf water potential (φmax) from mid August until harvest time. We did not induce water stress using wet treatment. Following dry treatment, the Brix value of the fruit juice at harvest time was about 3 degrees higher than that following wet treatment, and the fruit lateral diameter decreased to about 1.3 mm. In particular, since the Brix value following these two treatments differed by 2.9 degrees by the beginning of October, water stress from August to September probably has a large effect on the increase in Brix of the fruit. Regarding the fruit quality at harvest time following the dry treatment, the fruit weight was about 10% lower than that following the wet treatment, and the reddish color of the fruit epicarp became darker. There was no difference in the sugar component ratios of the fruit juice following these treatments, but after the dry treatment, fruit had about 1.6 times higher total sugar content than those after the wet treatment. Regarding organic acids in the fruit juice, the citric acid content after the dry treatment was 1.3 times that after the wet treatment, and the malic acid content after the dry treatment was about 0.7 times that after the wet treatment. The content of 9 amino acids in the fruit juice was higher after the dry treatment than that after the wet treatment. Furthermore, the dry treatment achieved increases of about 3 times as much aspartic acid and about 2.1 times as much glutamic acid compared to those after the wet treatment. The total amino acid content after the dry treatment was about 1.7 times that after the wet treatment. These findings suggest that water stress after summer causes the fruit to be somewhat smaller, but makes its juice components more concentrated, thereby enabling the production of a highly marketable fruit.

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We investigated the effects of various substrates on growth and yield in tomato forcing-culture using a root-proof capillary wick. Three-phase distribution, i.e. liquid, gas and solid, considerably differed among substrates in pre- and post-cultivation. In some substrates, there was also considerable difference between pre- and post-cultivation. Marketable fruit yield was highest in the substrate consisting of paddy soil : bark compost : peatmoss : perlite = 2 : 4 : 1 : 1, and lowest in crushed rice husk, while the soluble solids content remained almost the same in all substrates. Liquid and gaseous phase distribution in pre-cultivation showed a greater relation to marketable fruit yield than those in post-cultivation. Liquid phase distribution showed a greater relation to marketable fruit yield than gaseous phase distribution. In bark compost and crushed rice husk, EC and the concentration of inorganic nutrient solution, except for PO₄³⁻, in substrates were sometimes higher than those in other substrates. However, EC and the concentration of inorganic nutrient solution in substrates seemed not to affect the fruit yield, because there was no symptom of damage due to nutrient excess or deficiency. These findings suggest that liquid phase distribution of substrates would be an indicator of suitable substrate selection for this culture method. The value around 45-55% indicated that the substrate consisting of paddy soil : bark compost : peatmoss : perlite = 2 : 4 : 1 : 1 was suitable.

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The effects of low light intensity treatment and period of treatment on the flowering and cut flower quality of Limonium sinense hybrid were investigated. In an experiment using phytotron, low light intensity treatment (photosynthetic photon flux density (PPFD) 163 μmol·m⁻²·s⁻¹) from 21 or 28 days after planting (16 or six days before bolting, respectively) increased the number of days from bolting to flowering and cut flower length as compared to those of plants grown under standard light intensity (PPFD 359 μmol·m⁻²·s⁻¹). It seemed that the delayed flowering allowed greater elongation of the stalk by increasing the growing time. In the field experiment, treatment of 50% shading for four weeks from 30 or 32 days after planting (five or two days before bolting, respectively) also increased the days from bolting to flowering and cut flower length. Shading from five days before bolting was more effective than that starting two days before. In conclusion, shading for four weeks in summer from five to 15 days before bolting may be a method of improving cut flower quality in autumn.

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To investigate the effects of gibberellic acid (GA) on the suppression of physiological fruit drop, experimental GA treatment (dipping fruit in 50 ppm GA₃ aqueous solution) combined with seed injury (SI) treatment were conducted using ‘Shimizu Hakuto’ peach. In experimental GA treatment (Exp. 1) 30 (G30) and 50 (G50) days after full bloom (DAFB), enlargement of fruit thickness was enhanced and rates of split-pit fruit were higher in G50 compared with G30. Suppression of embryo growth and browning of the seed coat, which were not observed in G30, occurred in G50. However, fruit drop was decreased in both G30 and G50 compared with that in the control. Next, SI was performed at 55 (SI55) and 65 (SI65) DAFB for fruit treated by G30 or G50, and control (Exp. 2). Fruit drop was delayed in G30 + SI55 and G50 + SI65 but was not decreased in G30 + SI65 or G50 + SI55 compared to control + SI55 or control + SI65. Furthermore, SI was performed at 70 (SI70) DAFB, and GA treatments were performed one day (SI70 + G71) and three days (SI70 + G73) after SI treatment (Exp. 3). Fruit drop were temporarily decreased by both GA treatments and the effect was obviously higher in SI70 + G73 than in SI70 + G71. Activation of GA content in flesh was higher in SI70 + G73 than in SI70 + G71 but there was no difference in the GA content of seed between these two treatment groups. Results of Exp. 3 indicate that GA contents of flesh might rapidly disappear following SI treatment and retention of fruit on the tree was not maintained. Based on the above results, GA3 treatment during Stage 1 of fruit growth effectively decreases physiological fruit drop.

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A capillary watering system for Japanese pear production in a soil mound rhizosphere restricted culture was evaluated for reduction in initial introduction expenditure by investigating the effects of water level and the width of the watering mat on tree growth, fruit yield and quality. When the water level was set to 2, 5, and 8 cm below the level of the soil mat, with a watering mat 100 cm wide, the water consumption by trees in the −5 cm and the −8 cm plots decreased to less than that for the trees in the −2 cm plot. Leaves in the −8 cm plot wilted. The fruit yield and quality from trees in the −2 cm plot were higher than those from trees in the −5 and −8 cm plots. When the width of the watering mat was set to 20, 50, and 100 cm, with a water level of −2 cm, water consumption in the 20 and 50 cm plots decreased to less than that in the 100 cm plot. Leaves in the 20 cm plot wilted. In the 100 cm plot, fruit yield and Brix were as high as 61 t·ha⁻¹ and 12.7%, respectively. When the water level was set to −8 cm from 91 to 105 days after flowering, Brix rose to 13.5% without reducing the yield at all. A capillary watering system can supress the initial irrigation expenditure to 36% of that for a conventional drip irrigation system.

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The present study elucidated varietal difference in the content of vitamin C among 22 pollination constant non-astringent (PCNA) and 9 non-PCNA persimmon cultivars including leading cultivars, in addition to changes during the fruit development and maturation stage. We also showed the possibility of improvement in vitamin C content by modification of the cultivation methods. The results suggested that PCNA cultivars contained significantly higher vitamin C content both in fruit flesh and peel than non-PCNA cultivars. The average value of vitamin C content in fruit flesh and peel was 218 mg and 84 mg per 100 g in the PCNA cultivars, while that in non-PCNA cultivars was 125 mg and 47 mg respectively. The ratio of dehydro-ascorbic acid per vitamin C was generally higher in non-PCNA cultivars than in PCNA cultivars. Vitamin C content in fruit flesh decreased continuously from the young developmental stage until the fully matured stage in ‘Fuyu’, ‘Sosyu’ and ‘Tonewase’, although the degree differed depending on the cultivar. Water impermeable mulching treatment of ‘Fuyu’ trees since September 6 and 10 in 2007 and 2008, respectively, significantly increased the vitamin C content of fruit. Vitamin C content at fruit maturation was 134 mg per 100 g in both years in contrast to 117 and 111 mg per 100 g for untreated control trees in 2007 and 2008, respectively. This would be due to the vitamin C biosynthesis activated by water stress, as well as due to the effect of the concentration of vitamin C in fruit.

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This study evaluated tree growth, yield and fruit quality when the Japanese pear ‘Kousui’ was grown on 1) a two-scaffold Y-shaped dense-planting system on soil-mounds of 150 L (2SY/SM); 2) a two-scaffold Y-shaped dense-planting system in an open field (2SY/OF); and 3) a conventional four-scaffold pergola training system in an open field (4SP/OF). The yield in the 2SY/SM was 18 t·ha⁻¹ in the second year, then reached 61 t·ha⁻¹ in the fifth year. The first yield in the 4SP/OF was 4 t·ha⁻¹ in the fourth year and reaching 13 t·ha⁻¹ in the fifth year. The sum of the yield in the 2SY/SM was 854% to the 4SP/OF. Average fruit weight was greater and Brix was higher in the 2SY/SM. Adequate irrigation, best-matched to the water absorption abilities of the trees may have resulted in a high yield and high fruit quality by trees grown by 2Y/SM. Probably due to adequate irrigation, those trees also featured high density, more abundant absorbing roots and better vegetative growth after transplanting, as well as more bearing branches with more floral buds and leaves.

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We investigated the effects of applying a water curtain system on the environmental factors and fruit yield of strawberry during the summer season of 2008 and 2009. Two (in 2008) or three (in 2009) tunnel-shaped neighboring greenhouses of equal size were used in these experiments. The water curtain system was installed in one of the greenhouses (WC greenhouse). During the tests in 2009 only, shading film (30% shade) was installed in another greenhouse (shaded greenhouse). The last of the greenhouses was used as the control greenhouse. In the WC greenhouse, the leaf and growing media temperatures were lower than those in the control greenhouse. The decrease in solar radiation caused by the water curtain system was within several percentage points of that in the control greenhouse. As a result, the strawberry yield was higher than that in the control greenhouse (by 13–14%). Solar radiation of the shaded greenhouse was 64% of that in the control greenhouse, but the leaf and growing media temperature was almost the same as that in the control greenhouse, and the yield was lower than that in the control greenhouse. These findings indicate that the application of the water curtain system was effective for decreasing the leaf and growing media temperature without reducing solar radiation, and for increasing the strawberry yield during the summer season.

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In this study, we examined the effects of UV-C irradiation, light condition of the fruit bearing part, removal of the fruit bag and changing of the harvest period on the resveratrol content of table grape berry skins cultivated in Mie. The resveratrol content in ‘Kyoho’ was increased by UV-C irradiation and that in ‘Aki Queen’ showed a significant positive correlation with photon flux density of the fruit bearing part. The resveratrol contents were increased both by removal of the fruit bag in ‘Aki Queen’ and ‘Muscat Bailey A’ and by delaying the harvest time in ‘Kyoho’ and ‘Muscat Bailey A’. Our finding showed that the cultivation techniques to increase solar irradiation are effective to produce grape berries with a high level of resveratrol.

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To discuss the effect of ethylene pre-treatment on the heat tolerance of fresh agricultural produce, we investigated external and physiological quality changes in ethylene pre-treated leaves of mung bean (Vigna radiata) sprouts after incubation at high temperature. Postharvest ethylene pre-treatment for 3 days at 50 ppm induced a delay and reduction of necrosis generation (external quality decrease) at the surface of the leaf after incubation under a high temperature stress condition at 50°C for 120 minutes. Moreover, postharvest ethylene pre-treatment induced suppressed the ion leakage rate in the leaf, which is a physiological quality index showing the permeability of the membrane, under a high temperature stress condition at 50°C for 60 minutes. However, the respiration rate and lipid peroxidation extent of the leaf were not influenced by postharvest ethylene pre-treatment. These results showed that ethylene pre-treatment after harvest generate high temperature stress tolerance in the leaf, suggesting that ethylene has the potential to reduce membrane impairment, which is related to high temperature injury.

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We investigated inhibitory activities on angiotensin I-converting enzyme (ACE) and sugar content, which affect taste, during different growing seasons and in different sizes, parts, and cooking methods of ‘Yamato-mana’. Although the ACE inhibitory activity did not differ among different growing seasons, it was about twice as high in the leaf blade than in the petiole. ACE inhibitory activity in an individual plant increased with leaf age in the leaf blade and petiole. In the flower bud, the activity was as high as that in the leaf blade. Regarding the ACE inhibitory activity in relation to various cooking methods, it became higher than the baseline level after steaming and boiling with seasoning, although this activity was decreased by boiling (discarding the cooking water), and only slightly changed by pickling in salt or pickling with seasoning. The sugar content was higher in the crop that had been exposed to low temperatures for a long period during the growing season. The sugar content in the leaf blade and petiole decreased with leaf age, and the residual ratio of sugars was high after steaming. Coupled with the fact that steaming increased ACE inhibitory activity, steaming is considered suitable for preparation of ‘Yamato-mana’. That ACE inhibitory activity and sugar content of a large plant and flower bud, which was previously discarded, were the same as that in the leaf blade and petiole. This information will be useful in new product development.

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The leaves, fruits and dry pericarps of Japanese pepper (Zanthoxylum pipertum (L.) DC.) have been utilized as foods and Chinese medicines for a long time. We report here that polyphenol components, proanthocyanidins (PANs), from pericarps of Japanese pepper inhibit the growth of subacute respiratory syndrome-coronaviruses (SARS-CoV) in cultured Vero cells. “Cytostatic states” were induced in Vero cells, i.e. following cell growth was inhibited 5% without any sign of cell death by 5.5 μg·mL⁻¹ PANs treatment. Simultaneously, the virus growth was inhibited 50% [50% inhibitory concentration (IC₅₀ = 5.5 μg·mL⁻¹)] in those cells. The anti-viral activity of PANs might be due to strong inhibition of protein synthesis (macromolecular synthesis) and more than 3-fold induction of intracellular anti-oxidants, manganese superoxide dismutase (Mn-SOD) in the cells. As the anti-viral effects were dependent on cellular conditions induced by PANs treatments, the inhibition of viral growth does not seem to be virus-specific. These findings suggest that PANs from Japanese pepper have a potential to be developed into a chemotherapeutic material to treat viral diseases.

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For the development of a palatable cultivar and appropriate sales strategies, research into preferences of Japanese bunching onion (welsh onion) among general consumers and various types of restaurants were carried out. Research methods involved a distribution table for the general consumer and individual interviews for restaurants. For the general consumer, stronger flavor and sweetness of fresh and heated (boiled or grilled) bunching onions were preferred. Softer texture of grilled bunching onion was also preferred. Preferences regarding pungency, stickiness and texture for fresh, boiled and grilled Japanese bunching onions varied depending on the consumer’s individual attributes. For restaurants, softer pungency and stronger sweetness of Japanese bunching onions were preferred, while preferences for flavor and texture varied according to the restaurant type. Freshness and domestic production were considered important items when restaurant owners choose Japanese bunching onions. Japanese food restaurants tended to value taste and flavor, while other types of restaurants tended consider the price and size of Japanese bunching onion important. In the demand for the Japanese bunching onion breeding, the Japanese food restaurant owners frequently expressed hope for the development of Japanese bunching onion cultivar with specific features, while other restaurants hoped for improvement of its appearance, price and stable quality.

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A new Eustoma grandiflorum ‘Komachi white dress’ is an F₁ hybrid with a double flower and white fringy petals. It was produced by crossing between a single flower line with white petals as the seed parent and a double flower line with white malformed petals as the pollen parent. The harvest period is late July through early November. The 80 cm-long cut flower can be harvested even during October and November under shade culture and disbudding of both the lateral and the terminal buds. A good posture is maintained with leaves at the top of the plant even after disbudding. The concentration of large ovary-shaped flower buds at the top of plants is labor saving because of easy preparation of the flower cluster.

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