We clarified the effect of cultivation environment on the stability of picotee colored area rate and the selection efficiency. We investigated the picotee colored area of the parent lines of the market F₁ cultivar under several conditions of temperature and irrigation method. The change in cultivation environment affected the rate of picotee colored area in both lines. The rate of picotee colored area increased with an increase in vigor under a 20°C subirrigation condition, indicating that, the phenotype of the individual became apparent, while the rate decreased and the phenotype became latescent under high temperature dryness similar to condition in the breed nursery. Several individuals with different rate of picotee colored areas were selected from each set of parents under 20°C subirrigation. Selection under an environment in which the individual picotee phenotype became clear was effective for improving the stability of picotee formation in self progeny and F₁. In our research, selection of picotee formation stability in seed parents that show flavonoid type picotee is more effective for improving stability than selection of pollen parent.

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The Okinawa Islands have many wild and locally cultivated citrus genetic resources belonging to the mandarin group. However, these have decreased in recent years. It is essential, therefore, to explore the northern part of Okinawa Island and collect and study these citrus germplasm to ensure the availability of these fruit for future utilization. As a result of our exploration, we collected 30 local citrus genetic resources including wild monoembryonic Citrus tachibana (Makino) Tanaka var. attenuata, wild Citrus depressa Hayata (Shiikuwasha), and introduced and cultivated varieties; each of these exhibited different phenotypes. We thus were able to study the phenotype details and fruit quality of these citrus germplasms. Since polymethoxyflavonoids (PMFs) have been previously studied as a functional component in Citrus, we analyzed of our all samples using HPLC. As a result, we categorized the samples into 3 groups according to their PMFs constituents: ‘Shiikuwasha’, ‘C. keraji hort. ex Tanaka (Kabuchii)’, and others, which included C. oto hort. ex. Yu Tanaka and C. nobilis Lour. The ‘Shiikuwasha’ and ‘Kabuchii’ groups contained high amounts of PMFs. C. tarogayo hort. ex Yu Tanaka was included in the ‘Kabuchii’ group. Citrus tachibana (Makino) Tanaka var. attenuata and C. depressa (var. Ishikunibu) were included in the ‘Shiikuwasha’ group because of their specific constituents, despite having lower amounts of total PMFs than other cultivars in the ‘Shiikuwasha’ group.

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Common Japanese eggplant varieties are non-parthenocarpic and need 4-CPA treatment to bear fruit in forcing culture. Performing this treatment is quite time consuming, and culturing parthenocarpic eggplant requires fewer working hours. Therefore, we examined the relationship parthenocarpy and yield and yield-related traits in eggplant in forcing culture. In this study, we used parthenocarpic and non-parthenocarpic doubled haploid (DH) lines that originated by anther culture of F₁ hybrid between ‘Chikuyo’ or ‘Kokuyo’, which are Japanese common F₁ varieties, as a seed parent and AE-P03 or AE-P05, which are parthenocarpic pure lines, as a pollen parent. The numbers of flowers and fruit growth percentages of parthenocarpic lines were equal to those of non-parthenocarpic lines. However, the fruit set percentages of parthenocarpic lines were lower than those of non-parthenocarpic lines. Especially, the fruit set percentages of parthenocarpic lines between April on June were over 10 points lower than those of non-parthenocarpic lines. As a result, the yield of parthenocarpic lines was lower than that of non-parthenocarpic lines. These findings suggest that for the breeding of parthenocarpic eggplant varieties, it is important to develop fruit load ability using with hybrid vigor.

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‘Fuyuwarabe’, a bunching onion (Allium fistulosum L.) cultivar with a short thick leaf sheath, low pungency and soft-texture was bred. This is a synthetic variety derived from intercrossing of F₃ individuals and its characteristics remained stable in each generation from Syn₂ to Syn₄. The degree of individual variation of ‘Fuyuwarabe’ appears to be the same as that of open pollinated varieties of bunching onion. ‘Fuyuwarabe’ exhibited high yield when it was seeded in late June and harvested in middle or late December. This cultivar would certainly be useful for labor-saving of soil hilling for blanching and for shortening of the growing period. It could also be adapted to recent demand for a palatable and compact bunching onion.

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Bacterial wilt, which is a serious problem for Solanaceae crops, is caused by Ralstonia solanacearum (Smith, 1896) Yabuuchi et al. 1995. To protect against this disease, planting a resistant cultivar and using biological pest control have been considered effective. However, because the trait of resistance to bacterial wilt is assumed to be influenced by multiple genes, selective breeding of the resistant cultivar is very difficult. Therefore, we attempted to breed a new rootstock cultivar with resistance to pepper bacterial wilt disease. First we carried out inoculating test to the resistant line (MZC-180) and six newly inbred potential lines (Shikou Nos. 1–6). Inoculation test with R. solanacearum race 2-d showed MZC-180 and its six breeding lines possessed obviously higher resistance to the disease than the sweet pepper cultivar used for comparison. Furthermore, MZC-180 and Shikou Nos. 3, 4, 5 and 6 showed higher resistance than the resistant rootstock cultivar of sweet pepper ‘Daisuke’. On inoculation tests with five strains of the disease, MZC-180 and Shikou Nos. 3, 4, 5 and 6 also showed higher resistance than ‘Daisuke’ to all strains. In comparison with several Solanaceous plants, MZC-180 and Shikou No. 3 showed higher resistance than all the other tested plants.

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Limited fertilization treatment (LFT) was applied to cabbage plug seedling stored for more than two months. The cabbage seedling was only supplied with water after sowing in a soil mixture with fertilizer. The stem length, leaf number, and largest leaf length were maintained at similar levels for three weeks after sowing. The plug seedlings receiving LFT showed a morphology similar to that of the control (fertilized, CL) three weeks after sowing (optimum planting time). However, limited morphological changes were observed over a nine-week observation after the optimum planting time. Leaf chlo2rophyll content of LFT decreased during storage, but reached a level similar to that of CL within the first week after planting. The dry matter ratio of plug seedling in LFT_6,9,12 (6, 9 and 12 weeks after sowing) showed a two-fold increase in comparison to that of CL. However, one week after their planting, the dry matter ratio decreased to a level similar to that of CL. The relative growth rate of LFT_6,9,12 was less than that of the control at one week and higher than that of the control at three weeks after planting. However, the relative growth rate was similar to that of the control at two weeks after planting. The leaf number and largest leaf length of the LFT three weeks after planting, and also the yield and quality of the head from the LFT at harvesting time were similar to those of CL. The present findings suggest that plug seedling storage period could be increased by more than two months through application of the limited fertilization treatment to cabbage plants.

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Soil types of a Japanese apricot farm in Wakayama prefecture are generally classified into brown earth, yellow soil, gray lowland soil and lithosol. This experiment investigated the characteristics of nutritient eluviation in these soils to develop guidelines for good management according to the soil type. In any soil type, the higher the concentration of inorganic nitrogen in soil was, the higher the nitrogen concentration in percolated water became. The nitrogen concentration in percolated water increased in order from gray lowland soil, brown earth, yellow soil to lithosol. The amount of cation eluviation (ionic concentration in percolated water × percolated water volume) was higher in lithosol and gray lowland soil. Total cation equivalent correlated well with total anion equivalent regardless of soil type. This positive relationship suggested that cation was leached in the order of the amount of anion such as nitrate ion and sulfuric acid ion in percolated water. These findings suggested that considerable cation was leached due to the high concentration of nitrate ion in gray lowland soil or due to the amount of percolated water in lithosol.

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Effects of overhead liquid fertilizer application on tree nutrition, yield and fruit quality of satsuma mandarin (Citrus unshiu Marc.) were investigated. Liquid fertilizer was prepared by dissolving solid fertilizer containing 15% nitrogen in water at 300-fold dilution. Fourteen-year-old ‘Nichinan No. 1’ trees top-grafted on ‘Nankan No. 20’ (interstock)/trifoliate orange rootstocks were used. The soluble fertilizer was applied eighteen times between March and November. As controls, pellet-shaped solid fertilizer containing 10% nitrogen, 8% phosphorus and 7–9% potassium was applied on soil surfaces at a rate of 70 kg (middle March or early April), 80 kg (early October) and 50 kg (early November or middle November) per ha as nitrogen equivalents. In addition, plots in which the nitrogen content was reduced by 30% in both liquid and solid fertilizer were allocated. Both plots with reduced liquid fertilizer and solid fertilizer plots demonstrated equal yields, nitrogen centrations in the leaves, brix and citric acid concentrations in the fruit juice. When liquid fertilizer was sprayed on the trees 18 times annualiy, it was thought that reduction by 30% was better. This indicates cost efficient overhead application of liquid fertilizers in satsuma mandarin orchards.

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Absorbance at 280 nm in soil extracts with 0.4 M sulfate solution was highly correlated with the concentration of total N in the extracts of different soils. Therefore, we proposed an easy detection procedure for evaluating available N in soil. To estimate the total N uptake of spinach grown triannually under a rain shelter, the amount of 0.4 M sulfate-extractable organic nitrogen in the soil was determined before cultivation in the Andosol area in Iwate prefecture, Japan. Total nitrogen uptake of spinach grown without fertilizer in 8 experimental sites showed a tendency to increase when the amount of 0.4 M sulfate-extractable organic nitrogen in soil was increased, while N uptake efficiency tended to decrease when there was over 540 mg•kg⁻¹ of the extractable organic N in soil. Application of manure compost was2 effective in increasing the yield, while reducing internal nitrate concentration of spinach. However, the internal nitrate concentration in spinach exceeded the criterion value (3,000 mg•kg⁻¹) when there was over 540 mg•kg⁻¹ of 0.4 M sulfate-extractable organic nitrogen in soil. These findings indicate that the determination of 0.4 M sulfate-extractable organic nitrogen in soil might contribute to the fertilization of rain shelter house-grown spinach.

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Diploid seedless watermelons are presently produced by pollination with partially inactivated (soft X-ray irradiated) pollen. Bud pollination on the day preceding flowering was tested as a means of reducing labor in seedless watermelon production. The fruit set rates by pollination in the afternoon, as well as those on the day of flowering, were higher than those in the morning. There was no difference in fruit weight, fruit shape, rind thickness, soluble solids (Brix), flesh color, rind hardness, and number of empty seeds between the fruits resulting from bud pollinations and the fruits produced by pollination on the flowering date. These results were almost similar to those of partially inactivated pollen preserved for about one year. Our previously established seedless watermelon production method involved making the soft X-ray irradiated pollen, covering the female flower with a bag before flowering, artificial pollination, and covering the female flower after pollination. With bud pollination, the work involved in covering the female flower before flowering could be omitted, and since preserved inactivated pollen could be used, the total working hours were reduced by about 63.5%.

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Effects of winter night temperature (5, 10, 15 or 20°C) on the flowering, yield and quality of spray-type carnation (Dianthus caryophyllus L.) ‘Light Pink Barbara’ and ‘Cherry Tessino’ were investigated. In both cultivars, secondary lateral shoots sprouted after the second decapitation (second pinch lateral shoots) grew more rapidly at higher night temperature, whereas the length of second pinch lateral shoots at anthesis was the longest at the lowest night temperature (5°C). In both cultivars, the number of days from pinching to flowering decreased, and the yield of cut flowers increased with increasing night temperature. The lowest (5°C) night temperature adversely affected flower quality, resulting in increased second florets. In ‘Cherry Tessino’, the red color pigmentation of white marginal variegation of flowers increased up to completely red petals with increasing night temperature. The chromatic component L* value showed a tendency to decrease with increasing night temperature, and a* value showed a tendency to decrease at 5°C. In conclusion, from the perspective of achieving a good balance between productivity and the quality of cut flowers, suitable night temperatures in winter for cut flower production of spray-type carnation ‘Light Pink Barbara’ and ‘Cherry Tessino’ are suggested to be 10 to 15°C.

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Ascorbic acid content is an important factor in spinach (Spinacia oleracea L.) quality. In this study, we investigated the effects of the amount of solar radiation and temperature on the ascorbic acid content of spinach. Experiments were carried out under rain shelters on four sowing dates. Spinach plants were harvested when they reached marketable size, and ascorbic acid contents were measured. The ascorbic acid content of spinach on a fresh-weight basis increased or decreased within each day and also changed with similar tendency to the integrated amount of solar radiation on the day before harvesting. This result suggests that the ascorbic acid content on a fresh-weight basis is strongly affected by the total amount of solar radiation received by the plants one day before harvesting. Diurnal changes in the ascorbic acid content on a fresh-weight basis were largely affected by the ascorbic acid content on a dry-weight basis and partly affected by the water content of the plants.

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We investigated the influence of the amount of applied nitrogen on cold hardiness and lipid content of Japanese pear ‘Nijisseiki’ and ‘Hosui’. ‘Hosui’ was more sensitive to excessive nitrogen application than ‘Nijisseiki’ as shown by the increase of nitrogen contents in the shoot, decrease of cold hardiness and growth inhibition the next spring. Total lipid content and phosphatidylcholine (PC) content of ‘Hosui’ were lower than ‘Nijisseiki’. An increase in lipid PC and unsaturated lipid content induced by chilling were inhibited by excessive nitrogen application in both cultivars. Thus, excessive nitrogen application may induce a decrease in cold hardiness by decreasing the lipid content and the unsaturated index.

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Heating costs have become a problem for greenhouse tomato production because of the rapid increase in fossil fuel prices in recent years. To reduce fuel consumption without decreasing crop yields, it may be effective to provide only local heating for organs sensitive to low temperatures, such as shoot apexes and flower clusters. In this study, we used a small electric heater to provide local heating around the shoot apex and flower clusters of tomato, and examined differences in surface temperatures and fruit yield. We measured the surface temperature of tomato plants using thermography, and examined various characteristics related to fruit yield. Tomatoes were grown using two local heating treatments (“high”, with an average night temperature of 13.0°C for the surface around the shoot apex, and “low”, with a surface temperature of 11.5°C) under the lowest night temperature of 8°C, as well as a control condition, with a surface temperature of 9.6°C. The surface temperature of the shoot apex was increased by local heating, although the lower leaf temperatures ware not. Pollen fertility (measured as the proportion of pollen that accepted an acetocarmine stain), fruit set percentage, and intervals between flowering days of adjacent clusters were improved by local heating, although cultivars appeared to differ in their responses. The yield of ‘Momotaro-haruka’ was increased by the local heating treatment.

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Effects of pinching positions (just above the first, second, third and fourth node) on the growth and flowering of snapdragons (Antirrhinum majus L.), ‘Maryland Pink’ and ‘Light Pink Butterfly II’, were investigated. Seeds were sown in July and seedlings were raised without temporary planting. The main shoots were pinched at different node positions in September. The results were compared with those of the conventional cultivation with temporary planting. First flowering of lateral shoots in the third and fourth node pinching was earlier than in other pinching positions. The number of cut flowers was increased with upper pinching positions. The length of cut flowers in the primary lateral shoots from the fourth node was shorter than those from the other nodes. When cut flowers from the same node positions were compared, the length was shorter in ‘Light Pink Butterfly II’ than in ‘Maryland Pink’. Although second node pinching is conducted in the conventional commercial cultivation of snapdragons in Japan, we suggested that upper node pinching might be suitable for higher productivity in the cultivation without temporary planting. Pinching at the first, second, third and fourth nodes without temporary planting all resulted in more cut flowers than second node pinching under conventional cultivation (with temporary planting). These findings showed that suitable positions for pinching the main stems were just above the second or third node for ‘Maryland Pink’, and the second node for ‘Light Pink Butterfly II’.

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The level of active oxygen species and antioxidative enzymes were investigated in broccoli florets of cultivars (‘Youxiu’ and ‘Patriot’ which have high storability, and ‘Cuiguang’ and ‘Heights’ which have low storability) with different storability. ‘Youxiu’ in spring and ‘Patriot’ in autumn have low respiration rates at the beginning of storage compared with those of ‘Cuiguang’ and ‘Heights’. The superoxide anion and hydrogen peroxide content in ‘Youxiu’ was less than in ‘Cuiguang’, while the activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase were low at the beginning of storage. The hydrogen peroxide content in ‘Patriot’ was less than that in ‘Heights’, while the activities of catalase, ascorbate peroxidase and peroxidase were low at the beginning of storage. The change in the value of the quality indicator −a*/b* for ‘Youxiu’ and ‘Patriot’ was greater than for ‘Cuiguang’ and ‘Heights’ after 4 days of storage at 20°C. Therefore, it is suggested that active oxygen species and antioxidative enzymes have low physiological properties in broccoli cultivars with high storability.

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Influences of duration and storage temperature between harvest and 1-methylcyclopropene (1-MCP) treatment on the storability of ‘Fuji’ apple (Malus pumila Mill.) fruit were investigated. Fruit were treated with 1 μL·L⁻¹ 1-MCP for 18 hours at 20°C on the day after harvest or at 8, 15 or 22 days after harvest (DAH), following storage at 2 or 20°C. Fruit were then stored at 2°C until 209 DAH. Titratable acidity decreased more rapidly at 20°C than at 2°C until treatment. Flesh firmness changed little at either 20 or 2°C. Until 22 DAH, internal ethylene concentration (IEC) at 2°C remained lower than the level at 8 DAH at 20°C because IEC rose more rapidly at 20°C than 2°C. When fruit were stored at 2°C from harvest until treatment, delaying treatment until 22 DAH had no influence on the efficacy of 1-MCP treatment. However, when fruit were stored at 20°C until treatment, suppression of ripening by 1-MCP treatment decreased with increases in treatment delay. The results indicated that ‘Fuji’ apple fruit should be placed in cold storage immediately after harvest until 1-MCP treatment in order to maintain fruit quality during long-term storage.

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Recently, the various functions of kaki-tannin have been the focus of attention in many fields. The common and traditional method of preparing kaki-tannin as Kakishibu requires considerable time, usually more than 3 years, because this method includes a fermentation process in the preparation. Therefore, a novel method of quickly preparing kaki-tannin is described in this paper. Immature and mature fruits of ‘Tone-wase’ persimmon were harvested respectively and then treated with ethanol for removal of astringency, and homogenized by a juicer. These homogenates were centrifuged at 1,630 × g for 15 mins to show 3 or 4 layers in the centrifuging tubes, depending on the harvest time. Each layer was separated, removed from the tubes, and then freeze-dried. The dried powders were then solubilized to extract kaki-tannin by heating in water (121°C for 15 mins), respectively. Most of solubilized kaki-tannin was obtained from layer No. 3 in the case of immature persimmon fruit and from layer No. 2 in the case of mature fruit. The maximum recovery of kaki-tannin after astringent removal from fruit tissues was about 2% per fresh weight of the immature fruit. This method requires only 8 days to prepare kaki-tannin from immature persimmon fruits after harvest, in contrast to the traditional method. As indicated above, this method is considered very useful for preparing a large amount of kaki-tannin and it may open the door to the industrial utilization of kaki-tannin.

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