Edible chrysanthemums are traditional vegetables in the Tohoku region and Niigata prefecture with a long history of cultivation. They include various indigenous cultivars with unique flower shapes, colors, tastes, flowering times and putative functional ingredients; however, the growing area of edible chrysanthemum has considerably decreased in this decade and most cultivars are threatened with extinction. Therefore, the characterization and preservation of each cultivar are urgently needed. Morphological, ecological and yield characteristics of 29 edible chrysanthemum cultivars were investigated. In comparison with a popular cultivar, ‘Kakinomoto’, various promising cultivars with potential marketability were found. They include cultivars with an early-flowering time, good texture, sweet taste or high anthocyanin content. Based on flow cytometrical analysis, the cultivars investigated were classified into 3 groups depending on the estimated chromosome number, 2n = 53−57, 2n = 63−66 and 2n = 70 or more. The DPPH test revealed that all cultivars had marked antioxidant activities and differences among the cultivars observed. Those with high antioxidant activities are also regarded as promising cultivars.

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In vitro shoot proliferation and ex vitro rooting of Japanese wild Vaccinium species and blueberry cultivars were investigated. Multiple shoot induction and proliferation were highest in medium with 5 mg·L⁻¹ zeatin and multiple shoots were obtained with a 5.6–40.6% induction rate. The most efficient proliferation was obtained by subculturing multiple shoots at 2–3-month intervals. Rooting occurred early when the plants were treated with indole-3-butyric acid (IBA), and the rooting rate increased by raising the IBA concentration. The light condition had no effect on IBA-treated shoots. The rooting rate ex vitro was higher than in vitro, although cultivar and species differences were seen. There was a rooting rate of 48% or more in Natsuhaze (Vaccinium oldhamii Miq.) after one month of acclimatization, and a very high rooting rate of 72% was shown in shoots 3 cm in length. Ex vitro rooting using mist irrigation in a glasshouse was attempted with the aim of practical implementation. The survival rate after two months of acclimatization was 95.8, 75.0 and 91.7% in Natsuhaze, ‘Berkeley’, and ‘Redpearl’, and the rooting rate was 80.6, 63.9 and 83.3%, respectively. Within 12 months, these plants were 20 to 30 cm tall and suitable for field planting.

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Effects of the grafting method, cultivars of rootstock and boron application on the causative factors and preventative measures of malformed leaves of grafted cucumber (Cucumis sativus L.) seedlings were investigated. Malformed leaves occurred in insert grafting to the cut rootstock, insert grafting with a rooted rootstock and cleft grafting, but did not occur in approach grafting, even if the hypocotyl of the scion and the rootstock were cut off just after grafting. The occurrence of malformed leaves differed by the rootstock cultivar, and tended to increase using F₁ hybrid of Cucurbita maxima Duch × Cucurbita moschata Duch. The occurrence was reduced by foliar application of borax solution at 0.05–0.1% after grafting. The rate of malformed leaves markedly decreased when boron was added to the nutrient solution for 2 days before grafting in hydroponics. The rooting of the rootstock and subsequent growth after grafting were strongly influenced by boron application. The mechanisms of the occurrence of malformed leaves after grafting were discussed.

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Methane fermentation digestion liquid (MFDL) possesses sufficient nitrogen contents to use as fertilizer and can be produced at farm sites, however, the existence of insoluble contents and high viscosity makes the application difficult in a greenhouse. Therefore, the authors first developed a trial model of a filtering device based on a screen filter and an application device using water pressure. Next, a field trial was conducted in a summer greenhouse using a drip fertigation system. The MFDL amount that was periodically applied to plants was decided by counting the number of leaves. Urea application was prepared as a control. As a result, the physical treatability of MFDL application improved for drip fertigation without any stacking problems throughout the cropping season. There were no significant differences in leaf counts, applied amount of nitrogen or yield between MFDL and urea application. Applied MFDL was considered to be absorbed in cucumber via degradation and nitrification soon after application. In conclusion, MFDL is available as a nitrogen fertilizer if applied appropriately.

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Melon (Cucumis melo L. group) plants of a resistant line and a susceptible line to viviparous sprouting, known as vivipary, were grown with three different concentrations (6.5, 13, and 26 me·L⁻¹) of nitrate nitrogen in order to clarify the relationship between viviparous sprouting in the fruit and endogenous levels of abscisic acid (ABA). Vivipary increased with the highest nitrate nitrogen treatment in the fruits of the susceptible line. No viviparous sprouting, however, was observed with any nitrogen treatments in the resistant line. Higher nitrate nitrogen treatments decreased the ABA content in juice around the placenta, showing higher content in the resistant line than in the susceptible line. These results suggest that high nitrate nitrogen application decreases ABA content in juice around the placenta and consequently increases in viviparous sprouting, and that the susceptible line has lower content of ABA in juice.

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Melon (Cucumis melo L. group) plants of two resistant lines and one susceptible line to viviparous sprouting were grown with three different concentrations (2.4, 4.2, and 6.0 me·L⁻¹) of potassium to investigate the relationship between viviparous sprouting and endogenous abscisic acid (ABA). Seed yield per fruit was considerably decreased with decreasing potassium application in the susceptible line. In the resistant line, however, no influence on seed yield was observed. Potassium concentrations both in the petiole and in the juice around the placenta were higher in the resistant line than in the susceptible lines. Vivipary increased with decreasing concentration of potassium applied to the susceptible lines. No viviparous sprouting was observed in any potassium treatments for the resistant line. ABA content in the fruit juice decreased with decreasing potassium concentration. A germination test was carried out with different concentrations of ABA, and resulted in sharp decline of seed germination with increasing ABA concentrations in the resistant line. These results suggest that lower potassium application may cause a decreased ABA content in fruit juice, may cause a increase of viviparous sprouting in the fruit, and that the resistant line showed an inhibitory effect of ABA on sprouting at a lower threshold value of ABA concentration.

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To establish high plant density production of strawberry (Fragaria × ananassa Duch) using a movable bench which circulates the planting bed by longitudinal and lateral movement horizontally, three experiments were conducted. Subirrigation combined with supplementary surface irrigation was suitable as the nutrient solution supply method of the movable bench in experiment 1. For row spacing on the movable bench, we found that 0.50 m was the most efficient for fruit yield per m² in experiment 2. In experiment 3, based on the results from experiment 1 and 2, we designed and installed an experimental movable bench system of 9.6 m × 10.8 m. Three strawberry cultivars (‘Akihime’, ‘Mouikko’, ‘Tochiotome’) were grown using the movable bench system for forcing culture from September 2008 to May 2009. Marketable fruit yields of strawberries grown using the movable bench (MB) were compared to those grown using a conventional elevated bench (CB). In ‘Akihime’, the marketable fruit yield per plant of CB was higher than that of MB. In ‘Mouikko’ and ‘Tochiotome’, there was no significant difference in marketable fruit yield per plant between MB and CB. These results show that twice the number of strawberry plants per m² at CB can be grown at MB. They also show that MB can produce almost twice as much fruit yield per m² as CB.

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We examined the effect of bourse shoot length on the quality of 6 cultivars of apples. Fruit with a long bourse shoot was larger than with a short shoot in ‘Jonagold’ and ‘Mutsu’, but there was no practical effect of the bourse shoot length on fruit quality in other cultivars. The effect of bourse shoot pruning during summer on fruit quality was also examined in ‘Fuji’ apple trees. Pruning in June had no effect on fruit quality, independent of the extent, but the number of fruit branches about 10–15 cm length were increased by half cutting the bourse shoot. Moreover, the rate of flower bud formation of the apical bourse shoot was not decreased by the treatment; therefore, strong bourse shoots developing on vigorous trees should be pruned.

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We developed occupational gloves with a color chart on the surface with three grades of color (CC gloves) for persimmon fruit. Compared with the conventional color chart plate (CC plate), CC gloves were more useful because harvesting and color evaluation could be performed simultaneously. Moreover, harvesting practices were not obstructed by branches or leaves; therefore, time for color evaluation was reduced by 40% or more compared to the CC plate. When a first-time harvester used CC gloves, errors in harvesting persimmon fruit fell from 12 to 4%; thus, the CC gloves developed here would improve a farmer’s harvesting practices considerably.

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Effects of different first bearing years (3, 4, or 5 years after planting) on the tree growth, yield and fruit quality of satsuma mandarin (Citrus unshiu Marcow. cv. ‘Otsu-No. 4’) trees grafted on dwarf rootstock ‘Hiryu’ (Poncirus trifoliata (L.) Raf. var. monstrosa) were investigated. No relationship was found between the first bearing age and fruit quality. The later the first bearing, the larger the canopy volume became, however, trees that began to bear from 5 years after planting were large and higher alternate bearers. On the other hand, trees that began to bear from at 3 years after planting showed less growth and production. In consequence, trees that began to bear from 4 years after planting (tree height 172 cm, canopy volume 3.2 m³) had the best productivity and work efficiency.

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The purpose of this study was to examine the effects of summer pruning on the improvement and uniformity of the quality of fruit hedgerow-trained sweet cherry trees. The photosynthetic activity and translocation and distribution of photosynthates before summer pruning were compared with those after summer pruning to identify changes. Photosynthetic activity was measured in the basal part of current shoots 30 days after summer pruning. Photosynthetic activity did not change in response to weak sunlight, but it responded to changes in the photoenvironment to a 32% increase of strong sunlight from the level before summer pruning. The amount of ¹³C translocation to fruit from various parts of the current shoots was in the following descending order: basal part > middle part > tip. The basal part provided the largest amount of ¹³C translocation to fruit. Summer pruning further increased the rate of translocation to fruit from leaves in the basal part of current shoots. These data clearly show that current shoot management by summer pruning is an effective method to produce mass in sweet cherry.

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The effect of atmospheric relative humidity during water stress was studied to determine the cause of the fluctuations in the number of first-flush flowers affected by water stress in Meiwa kumquat trees. Water stress at around 10% of soil water content was started 2 weeks after termination of shoot elongation in a greenhouse humidified by mist, and maintained for 10 or 20 days. Another two treatments were established in a greenhouse that was not humidified: withholding water for 10 days (dry soil and air) and no treatment (dry air). The number of first-flush flowers increased significantly with 20-day water stress, as did the ABA content of the root. ABA contents of the leaf at the end of treatment with 10- and 20-day water stress were not different from untreated control trees. Further, with dry soil and air, the number of first-flush flowers and the ABA content of the root were increased significantly compared to those in the control and treated with dry air. These results indicated that the ABA content of the root was an appropriate index to evaluate the increasing effect of first-flush flowers by water stress. Further, low atmospheric relative humidity seemed to amplify the effect of water stress on increasing the number of first-flush flowers.

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We studied the effects of GA (GibberellinA₃; KYOWA Co. Ltd.) treatment on parthenocarpic seedless berry formation and cytokinin-like plant growth regulator CPPU (Forchlorfenuron; KYOWA Co. Ltd.) treatment on berry enlargement in Japanese wild grape, Vitis coignetiae Pulliat. The goal of our research is the development of stable fruit production, inducing parthenocarpy by chemical control in a single variety orchard of female trees. Two adult vines of the same strain in the orchard of Yamagata Field Science Center at Yamagata University were used to elucidate the optimal times and concentrations for these treatments. Two GA treatments of a cluster bagged during flowering against pollination at the beginning of flowering (100 ppm) and after flowering (50, 100 or 200 ppm on 5, 10 or 15 days after full bloom) led to 99% seedless berry formation; however, the parthenocarpic seedless berries formed were quite smaller and had a lower soluble solid concentration and higher organic acid content than normal seeded berries. We next examined the effects of CPPU treatment on seedless berry enlargement. When treatment with 100 ppm CPPU at full bloom, 5, 10 and 15 days after full bloom, was applied, the earlier the treatment, the larger the number of berries per fruit cluster. When dipping treatment of the fruit cluster in 50, 100 or 200 ppm CPPU solution 10 days after full bloom was tested, a significant berry weight increase was observed only with treatment at 100 ppm, although the berry quality remained lower than that of seeded berries. These results showed the optimal times and concentrations of GA and CPPU treatment for obtaining seedless berries from the strain of Vitis coignetiae in a single variety orchard of female trees, but further studies are needed to obtain larger berries of better quality.

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A preservative preparation containing extract from Artemisia capillaries THUNB.(SK-202) has antifungal effects on satsuma mandarin fruit during storage. Effects of post-harvest treatment of SK-202 on ethylene evolution, respiration rate, fruit quality and shelf life of ‘Okitsu wase’ satsuma mandarin (Citrus unshiu Marc.) were investigated. Fruit were gently wiped with a cloth which had been dipped in SK-202 solution. The treated fruit showed a significant rapid reduction in ethylene evolution 3 days after treatment compared with the control, although there was no difference up to the first 2 days after treatment. Thereafter, the level of ethylene evolution was maintained at approximately 50% of the non-treated fruit until 16-day storage. The respiration rate of treated fruit decreased significantly 4 days after treatment, followed by consistently lower levels than the control during the experiment. The rind color of treated fruit was enhanced by treatment in terms of Hunter Δa and C values. Thus, the treatment increased the total carotenoid content in the flavedo tissues. The weight loss of treated fruit as well as peel wilting was lower than the control. There were few differences in soluble solids and titratable acid content in the fruit juice between treatment and control groups.

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The Japanese persimmon cultivars ‘Taiten’ and ‘Taigetsu’ are both astringent-type cultivars with large fruits of excellent quality, however, they differ greatly in terms of the time taken for various treatments to remove astringency. In this study, we measured and compared changes in the chemical constituents of the two cultivars during ethanol treatment, Constant Temperature Short Duration (CTSD) treatment with CO₂ gas, and nitrogen gas treatment. In each treatment, the tannin-print value of the flesh decreased faster in ‘Taigetsu’ than in ‘Taiten’, indicating a more rapid loss of astringency in ‘Taigetsu’. With CTSD treatment, acetaldehyde accumulated in the flesh after treatment; the acetaldehyde content in ‘Taigetsu’ decreased rapidly after 2 days, whereas in ‘Taiten’ it decreased after 6 days. With nitrogen gas treatment, the changes in acetaldehyde content were similar to those seen with CTSD treatment, but the tannin-print values showed that loss of astringency was achieved more slowly with nitrogen gas treatment than with CTSD treatment. In ‘Taiten’ fruits, malic acid accumulated during the astringency removal treatments, particularly CTSD treatment and nitrogen gas treatment at 30°C. A significant correlation was observed between acidity scores based on sensory tests and malic acid concentration in the flesh, indicating that acidity in ‘Taiten’ fruits was due mainly to malic acid.

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Attenuated mutants of Lily mottle virus (LMoV), which caused severe mosaic on the leaves and flowers of lily plants, were obtained by tissue culture of the lily bulb. The bulb scales of ‘Morino-otome’ derived from Lilium × formolongi and L. rubellum, infected with the virulent LMoV isolate ML61, were cultured on MS medium containing 1 g·L⁻¹ picloram for 0, 1 and 2 months and transplanted to MS medium for regeneration. Eleven regenerated plants, which showed markedly milder symptoms than the plants infected only with ML61, were selected. To assess the pathogenicity of the virus population in each selected plant, sap from their leaf was inoculated in seedlings of L. × formolongi ‘White Lancer’, which is sensitive to ML61. Two virus populations, LMm76-2 and LMm93, caused no or extremely mild symptoms in ‘White Lancer’. LMm76-2 and LMm93 showed a certain ability to cross-protect plants from infection by LMoV-ML61. Comparison of the 1,374 bp nucleotide sequence of HC-pro (helper component proteinase) gene among clones of each virus populations revealed some nucleotide mutations. There were three nucleotide mutations in the common sequence of each clone between LMm76-2 and LMm93. The mutation from C to U at the 808th position in the HC-pro gene was unique to attenuated mutants, resulting in one amino acid substitution from Cys to Arg at position 270 in the HC-pro protein.

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This research was conducted to establish a practical method of heat shock treatment to induce disease resistance in cucumber seedlings. To achieve this purpose, short treatment at a higher temperature than in our previous report was tested and a prototype hot water sprayer was developed for treatment. At a result of the hot water dipping test, treatment at 50°C for 20 seconds showed the same effect as 40°C for 120 seconds, which was the optimum condition in the previous experiment for inducing resistance to gray mold (Botritis cinerea). Based on this result, a prototype hot water sprayer was assembled using an LP gas boiler as the main component. A thermal cover was effective for maintaining leaf temperature at 50°C stably. When hot water was used to treat the leaves appropriately using this machine, salicylic acid concentration and the expression level of the peroxidase gene increased in the leaves. An inoculation test of gray mold showed the same protective effect as treatment with saccharine sodium, known as a plant activator. As a result, we concluded that the hot water spray is a possible practical method for inducing disease resistance to grey mold in cucumber seedlings.

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We developed a rapid method for crop load adjustment on the basis of the leaf area index (LAI) from a case study of 18 open cultivated table grape cultivars for two successive years. Quadratic regression was significant at p < 0.01 for the relationship between horizontally projected LAI (PLAI) and LAI for 40 to 50 days after full bloom, resulting in the rapid estimation of LAI by the measurement of PLAI. Parameters of LAI per canopy area, canopy area, presumed bunch weight and crop load per leaf area (red-skinned cultivar, 0.6 to 0.8 kg·m⁻² < black- and violet-skinned cultivar, 0.8 to 0.9 kg·m⁻² < white-skinned cultivar, 1.0 to 1.1 kg·m⁻²) were used and formulated to estimate crop load per canopy area. All cultivars showed higher market preferences by crop loading on the basis of LAI from the field trial.

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