To clarify the origin of local radish variety ‘Sabaka’ in Kyoto prefecture, the presence and variations of mitochondrial male-sterile gene (orf138) and the fertility restorer gene, orf687, were investigated. Five plants of ‘Sabaka’ and 97 Japanese wild radish plants collected in Maizuru City, Kyoto prefecture, were used. After isolating total DNA from a young leaf of each plant, PCR and PCR-RFLP analyses were conducted for orf138 and orf687 gene with DNA as the template. All five plants of ‘Sabaka’ possessed a unique orf138 sequence (Type E) that has not been observed at all in cultivated radishes, and ‘Yuan hong’ type RFLP for orf687. In wild radishes, 25 plants had orf138 and three of them were classified into Type E. Whereas, 14 wild radish plants possessed ‘Yuan hong’ type orf687 similarly to ‘Sabaka’, among which two plants were Type E for orf138. These findings indicate that ‘Sabaka’ originated from the domestication of Japanese wild radish having both male-sterile cytoplasm with orf138 and the fertility restorer gene, orf687.

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To understand the mode of flesh color inheritance in loquats (Eriobotrya japonica), segregation of flesh color (yellowish orange vs. whitish yellow) was investigated in 1,643 F₁ progenies derived from 32 breeding populations. All F₁ progenies obtained from the cross between whitish yellow cultivars had whitish yellow flesh. The segregation ratio between yellowish orange and whitish yellow indicated either 1 : 0 or 1 : 1 in F₁ progenies between yellowish orange and whitish yellow cultivars. In F₁ progenies among yellowish orange cultivars, the segregation ratio was either 1 : 0 or 3 : 1. These findings indicated that yellowish orange flesh was dominant to whitish yellow flesh. The gene corresponding to yellowish orange flesh is named the Ca gene. The genotype of yellowish orange cultivars is assigned as either Ca/Ca or Ca/ca and that of whitish yellow cultivars is ca/ca. Bulk screening was carried out to find a RAPD marker linked to the phenotype of yellowish orange fresh using 280 Operon primers. In total, 28 Operon primers provided 28 polymorphic fragments between the yellowish orange and whitish yellow bulk samples. They were subjected to linkage analysis using 37 F₁ progenies between ‘Reigetsu’ and ‘Amakusagokuwase’. The 1,800 bps of RAPD fragment (OPH-01/1800) obtained from OPH-01 primer was linked to Ca gene at a recombination value of 0.081 with LOD value of 6.7. The validity of OPH-01/1800 to flesh color phenotype was evaluated among 41 loquat cultivars. The OPH-01/1800 marker was present among 78% of the yellowish orange flesh cultivars, in contrast, the OPH-01/1800 marker was absent from all whitish yellow flesh cultivars. These findings indicate that the OPH-01/1800 marker is useful to select yellowish orange flesh in a loquat breeding program.

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To discuss the sampling method for quantification of sesquiterpene lactones (SLs) in breeding of lettuce (Lactuca sativa L.) varieties with high SL concentrations, differences in SL concentrations in different leaf parts and head formation stages were investigated in three lettuce cultivars using HPLC. Significant differences in SL concentrations among the outer leaves, outer head-leaves, inner head-leaves and stem were observed. A high correlation coefficient was observed between SL concentration in the outer leaves and that in the whole head. Excision of outer leaves for sampling does not affect progeny seed production, therefore outer leaves are available as the sample for rough estimate of the SL concentration in the lettuce head. Differences in SLs concentrations were significant among three stages of head formation; beginning of heading, optimal harvesting and over-ripening. Varietal differences of SLs concentration were observed from the beginning stage of heading and a significant correlation between SL concentration at the beginning stage and that at the optimal harvesting stage was observed. This means that an earlier sampling at the beginning stage of heading is available for an estimate of SL concentration at the optimal harvesting stage.

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Effects of application time in spring on nitrogen absorption by satsuma mandarin (Citrus unshiu Marc. cv. ‘Nankan No. 20’) were investigated. Field and pot tests were performed using an ¹⁵N-tracer method in which the nitrogen was applied on March 1, April 1, and May 1. In field experiments, the absorption rate by trees was greater in April- and May-plots than in March-plots. The ¹⁵N content of one-year-old leaves showed similar changes in the March- and April-plots, which was consistently higher than that in May-plots. The ¹⁵N content in newly developed organs, such as new leaves, flowers and young fruit, was apparently greater in March- and April-plots than in May-plots between early May and early June. After late June, however, the ¹⁵N content was consistently greatest in May-plots. In pot experiments, the utilization rate of trees receiving nitrogen application in the spring was 31.5%, 34.6% and 37.1% in March-, April-, May-plots, respectively. Thus, the efficient application timing of nitrogen for spring fertilizing seems to be immediately before the bud burst in early April.

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Radial fruit cracking (RFC) can contribute to serious economic losses in tomato production under rain shelter in cool uplands. In order to investigate the effects of translocation and distribution of photosynthate to the fruits during the occurrence of RFC, tomato plants were grown under treatments with fruit thinning and CO₂ enrichment, which regulate the strength of sink and source, and treatments with covering of the fruit truss, which decreases solar radiation incident on the fruit surface. The occurrence of RFC was increased by fruit thinning and CO₂ enrichment, and decreased by covering of fruit truss. Time course of the percentage of RFC to total harvest showed a remarkable rise toward the end of August and toward the end of October in 2004, when harvested fruit weight was increasing. These finding suggest that RFC is attributed to excessive enlargement of the fruit by promotion of translocation and distribution of photosynthate from leaves (source) to fruits (sink) and the solar radiation incident on the fruits. In addition, the relation between RFC and the generation of a cork layer is considered.

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Four everbearing strawberry (Fragaria × ananassa Duch.) cultivars, ‘Kaho’, ‘Ohishi-shikinari’, ‘Miyoshi’ and ‘Yamato-shikinari’, which were overwintered, were grown at day (6:00–18:00)/night (18:00–6:00) temperatures of 30/25°C under 12-, 13-, 14- and 15-h photoperiods for 16 weeks. ‘Yamato-shikinari’ was also grown under a 16-h photoperiod. Under such a high temperature condition, these cultivars were found to be qualitative long-day plants. Flower bud initiation was inhibited under 14-h or shorter photoperiod in ‘Kaho’, under 13-h or shorter in ‘Ohishi-shikinari’, under 12-h in ‘Miyoshi’ and 15-h or shorter in ‘Yamato-Shikinari’. Non-chilled ‘Kaho’ and ‘Ohishi-shikinari’ plants were also tested. The photoperiods under which their flower bud initiation was inhibited were the same as those of overwintered plants. The critical photoperiod for flower bud initiation in everbearing strawberry plants grown under high temperature varied among cultivars.

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Effects of thermal conditions during seed ripening on bolting of Eustoma grandiflorum (Raf.) Shinn. seedlings grown at high temperatures were studied by preliminarily applying thermal treatments to immature capsules. A high temperature of 38/28°C (day/night) during ripening reduced the bolting rate compared to that under a cool temperature of 23/18°C. Bolting rates of seedlings subjected to 23/18°C treatment were almost equal to those of seedlings from ambient temperature in a rain-protection house from summer to autumn in a warm region of Japan. Immature ‘Aya-no-sakura’ capsules with peduncles were harvested three weeks after pollination, inserted into a preservative solution containing sugar, and incubated at temperatures of 10, 15, 20, and 25°C for three to eleven weeks. Three- to nine-week incubation at 10°C and three- to seven-week incubation at 15°C effectively increased the bolting rates of seedlings. Immature ‘Aya-no-sakura’ capsules gathered seven or nine weeks after pollination were held at 5.5, 9.5, 13.5, 17.5, or 21.5°C until dry. Seedlings dried at 5.5 to 17.5°C exhibited high bolting rates. These findings demonstrated that seeds could memorize thermal conditions applied during ripening and that chilling applied during seed ripening could promote bolting of seedlings. Cut immature capsules could respond to chilling, and consequently the seeds exhibited increased bolting rates, although cutting immature capsules from plants slightly reduced rosetting of seedlings.

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The present study investigated the anatomical and chemical factors causing the internal browning (IB) in Ipomoea tuberous roots cv. Kokei No. 14. The experimental results demonstrated that roots exhibiting IB were more prevalent during the maturation period and an increase in the severity of IB symptoms was accompanied by a parallel increase in tuberous root weight. Heating treatment during maturation period inhibited optimal root growth during this period, reducing IB occurrence. Destroyed parenchyma cells were often observed in tuberous roots with severe browning compared with those in normal roots. A pronounced increase in polyphenol oxidase (PPO) and decrease of glutathione reductase (GSHR) was detected in the former cells as compared with the latter. These observations suggest that activation of the H₂O₂ detoxifying pathway derived from PPO accompanied a decline in H₂O₂-decomposing capacity of the ascorbate-glutathione cycle by cell destruction is one of the main reasons for the occurrence of IB.

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This study was carried out to investigate the effect of inoculation of bacteria, contact of caly with the pericarp and high humidity on the incidence of warty fruit of Okra (Abelmoschus esculentus Moench). Although certain bacteria were found in the wart region, inoculation of those did not affect the incidence of warty fruit. When caly were in contact with the pericarp, the incidence increased. When the caly were removed, the incidence tended to decrease. When fungicide or pure water was sprayed onto the fruit, the incidence was very high. High humidity treatment caused increases in the warty ones. However, when the caly were removed in advance, the incidence was very low under high humidity conditions. In conclusion, we could consider that the primary cause of the incidence of warty fruit was contact between the caly and epidermis, and that the effect of contact was increased by high humidity.

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The effects of using media hardened by heat fusion of polyester fibers on yields and quality of cut flower stems ‘Asami·Red’ (syn. ‘Rote Rose’) rose and on the composition of nutrient solutions for a year under closed hydroponic culture were investigated. The yields of cut flower stems grown in vermiculite medium (grain diameter: 6–7 mm) and coconut coir medium (fiber length: 3 mm) were remarkably higher than those grown in rockwool and perlite medium (grain diameter: 0.6–1.5 mm or 2.5 mm). The weight of a cut flower stem did not differ among the media, however stem lengths from both grain perlite media were shorter than those from other media. Eighteen months after transplanting, the length and width of each medium were the same as those just after planting, and the thickness in rockwool and coconut coir media decreased slightly. The solidity of each medium remained almost the same at the termination of the project. The pH of the nutrient solution in the rockwool medium changed the most, becoming higher than that of the other media for most of the time. The EC in coconut coir medium tended to be high throughout the project. The concentration of NH₄-N decreased, while other inorganic components increased gradually. In conclusion, the vermiculite or coconut coir media hardened by heat fusion of polyester fibers is the most favorable of alternative media tested in comparisons with rockwool medium under closed hydroponic culture.

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This study produced white asparagus (Asparagus officinalis L.) spears by covering plants with a shading film during semi-forcing spring harvest cultivations of asparagus. White asparagus spears with no anthocyanin pigment were produced in plastic houses, when a 2.0 m-highwalk-in tunnel covered with a shading film was set up in the houses before the spears sprouted. The number of marketable white spears was smaller than that of marketable green spears. However, the weight of white spears was greater than that of green spears. Consequently, there was no difference between white and green asparagus production with regard to marketable yield. The characteristics of white asparagus spears produced in plastic houses with a shading film covering differed from those of green spears. Their tips were tighter and mid-section diameters were greater. Further, white asparagus spears that had been boiled for 10 minutes tended to be tougher than similarly treated green spears.

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We investigated the effects of differences between day and night air temperatures (DIF) during 40 days after full bloom on shoot elongation and fruit growth of Japanese pear ‘Gold-Nijisseiki’. Although the average air temperature was almost the same throughout the period, a higher DIF increased the percentage of new shoot growth from the lateral buds on one-year-old branches. A higher DIF also reduced fruit growth and maturation. These findings indicate that controlling air temperature during the early growing stage can control new shoot and fruit growth of Japanese pear.

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The main objective of this research was to elucidate the flowering, fruit drop patterns and fruit set in Tankan (Citrus tankan Hayata) ‘Tarumizu 1 go’ to determine the physiological and environmental effects and how they relate to tree productivity. Fruiting shoots were separated on the basis of the number of subtending leaves, (leafy and leaf-less flowers) and data on flower emergence and fall patterns were collected. The results obtained showed that normal distribution curve of flowering, starts at end of April and peaking in mid-May. Tankan has flower types that range from those that have no new leaves subtending them (leaf-less flowers) to those that have up to 7 leaves. In terms of flowering, leaf-less flowers and flowers having up to 3 leaves flowered much earlier than flowers having 4 or more leaves. Two flower/fruit drop peaks were observed. The first one occurred from end of April and peaking in mid-May and the second one was of less intensity and occurred 40 to 60 days after anthesis and peaking in mid-June. The drop of flower bud was reduced to very low values. Although leaf-less flowers made up more 50% of the total flower number most of them abscised and less than 1% of the leaf-less flower set fruit. For leafy flowers, fruit set increased with increase in number of leaves. Comparatively more flowers dropped in the first fruit drop cycle than in the second fruit drop cycle. The results illustrated the importance of leafy flowers in ensuring high fruit set and productivity.

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The effects of foliar spray with white sugar (containing more than 98% sucrose) during the growing period on the quality of Eustoma grandiflorum for cut flowers and snapdragon for bedding plants were investigated. Foliar spray with 0.1% white sugar four times significantly increased the number of flowers of Eustoma grandiflorum, and increased the class quality index based on the cut flower length and the number of flowers. Foliar spray with 0.1% white sugar twice reduced the discoloration of leaves under dark conditions and increased the number of open snapdragons flowers in an unheated glasshouse. These findings indicated that foliar spray with white sugar during the growing period was also effective for quality maintenance or improvement in both plants.

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The effects of the duration of covering treatment and the period of using a far-red-intercepting film (FR-intercepting film) while raising seedling on the future growth and flowering of certain bedding plants were investigated. The plant heights of scarlet sage (Salvia splendens Sell ex Roem. & Schult.), cupflower (Nierembergia hippomanica Miers. var. violacea Millan.), Madagascar periwinkle (Catharanthus roseus (L.) G. Don), French marigold (Tagetes patula L.) and pansy (Viola × wittrockiana Gams) and the flower stalk length of pansy kept under the FR-intercepting film for 3 weeks after potting were significantly shorter than those of the control plants. Flowering of scarlet sage, cupflower and French marigold kept under the FR-intercepting film for 3 weeks after potting was delayed. The plant height of snapdragon (Antirrhinum majus L.) kept under the FR-intercepting film for 4 weeks after potting was significantly shorter than that of the control plants. A decrease in the internode length between the 3rd and 5th nodes was considered the cause of the shorter plant height. These findings indicated that in certain bedding plants (scarlet sage, cupflower, Madagascar periwinkle, French marigold, pansy and snapdragon), covering treatment using the FR-intercepting film for only 3–4 weeks after potting tended to prevent succulent growth.

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For efficient research into breeding, cultivation, storage and marketing of vegetables, objective methods of quality evaluation are needed. Texture (Firmness) is the most important factor in evaluating the quality of Japanese radish (Raphanus sativus L.) root. We proposed a firmness evaluating method of fresh and lightly-pickled radish roots using a Texture Analyzer in the following way. Disks (10 mm in diameter and 5 mm thick) were obtained from the defined positions of radish roots of various cultivars and compressed using a cylindrical probe, then the destructive force was measured by the texture analyser. The measured forces correlated with firmness scores in the sensory evaluation. When there was more than 13 N difference in the destructive force needed for disks prepared after pickling radishes of different cultivars, the difference in firmness was also detectable by the sensory test. There was a considerable difference in the destructive force needed for the disks between cultivars, which was correlated with the concentrations of pectin and alcohol insoluble solids in radish tissue.

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The frequency of second resonance and the elasticity index (a relative value of the shear modulus measured by the vibration response technique) of fruit during ripening in ‘Le Lectier’ pears were monitored by a new nondestructive measurement device. In addition, the changes in fresh weight, flesh firmness and soluble solid concentration were determined, and the relationship between elasticity index and those characteristics was demonstrated. The elasticity indices in fruits at harvest time ranged from 48 to 65 (×10⁶), and those indices decreased during ripening. The decreasing patterns of elasticity indices differed with the type of fruit, and those indices ranged from 18 to 25 (×10⁶) when fruits reached the edible ripe stage 40 days after treatment (DAT). Changes in the physical properties of various fruit could be continuously traced by the elasticity index, and it was suggested that the differences in fruit quality at harvest time and softening patterns during ripening were attributed to the dispersion of differences in ripeness at the time when fully ripe (40 DAT). The fresh weight and flesh firmness decreased during ripening, although the soluble solid concentration was increased, and those characteristics correlated with the elasticity index. These findings suggest that the edible ripe stage of ‘Le Lectier’ pears during ripening can be estimated by the elasticity index, which was affected by both water concentration and soluble solid concentration.

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A new grape cultivar, ‘Nagano Purple’ is triploid selected from the cross combination of ‘Kyohou (tetraploid)’ and ‘Rosario Bianco (diploid)’ at the Nagano Fruit Tree Experiment Station, and released in 2004. The crossing was conducted in 1990, and young embryos were excised from cultured ovules and grown. Its maturation time in Nagano is early September (about 85 days after full bloom). The fruit clusters of ‘Nagano Purple’ weigh 160–170 g with a loose berry set. The berries are round, weighing 5–6 g. The skin color is purple black. Some grapes develop seeds in the berries. The character of the flesh is crisp, and peeling of the fruit skin is difficult. The fruit is sweet with a low acidity. The flavor is foxy. Fruit cracking has been observed. Two applications of gibberellic acid in 25 ppm solution, at full bloom and 14 days after the first treatment, effectively promote seedlessness and improve the size of clusters and of berries, reaching a weight of 480–490 g and 13–14 g, respectively. The gibberellic acid treatments effectively reduced the occurence of fruit cracking. Because it is easy to develop flower clusters on shoots, ‘Nagano Purple’ is considered to be a suitable cultivar for the short cane pruning method.

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