Artificial cross experiments were carried out to determine cross-compatibility within and between 38 accessions from natural populations of Lilium japonicum. Results of the cross experiments showed that plants from the Kyushu district and the eastern part of the Shikoku district, and those of L. japonicum var. abeanum, native in the eastern part of the Shikoku district, are less compatible with plants from other districts. To examine flowering characteristics of the progenies derived from artificial crosses, seedlings were established from the obtained seeds through aseptic culture. Only one progeny derived from a cross within an accession from the southern Kinki district reached flowering during the first year of cultivation. Progenies from crosses between accessions from the southern Kinki district and eastern Shikoku district tended to differentiate more flowers than other progenies during the third year of cultivation. Flowering time of parents used in the crosses seemed to be quantitatively reflected in that of their progenies.

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Two new rootstock cultivars of melon (Cucumis melo L.) resistant to race 1,2y of Fusarium oxysporum f.sp. melonis were released. ‘Dodai No. 1’ was selected from a cross between ‘Melon Parental Line 1’ ((C. melo var. reticulatus Naud. × C. melo var. makuwa Makino) × C. melo var. reticulatus Naud.) and ‘Tokyo-wase (maruba)’ (C. melo L. var. conomon). ‘Dodai No. 1’ showed remarkable quantitative resistance to race 1,2y, moderate quantitative resistance to race 2 and true resistance to race 0 and race 1. The F₁ cultivar ‘Dodai No. 2’ was developed as a hybrid of two melon cultivars, ‘Barnett Hill Favorite’ and ‘Dodai No. 1’. ‘Dodai No. 2’ showed moderate resistance to race 1,2y, true resistance to race 0, race 1 and race 2. Both cultivars can be effectively used as rootstock to control Fusarium wilt in melon fields infested by race 1,2y in Hokkaido.

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A rootstock cultivar of melon (Cucumis melo L.) ‘Dodai No. 1’, which shows remarkable quantitative resistance to race 1,2y of Fusarium oxysporum f.sp. melonis. was developed from a cross between ‘Melon Parental Line 1’ ((var. reticulatus Naud. × var. makuwa Makino) × var. reticulatus Naud.) and ‘Tokyo-wase (maruba)’ (var. conomon Makino). To clarify the selection effectiveness of resistance, both parents, F₁ line (‘Melon Parental Line 1’ × ‘Tokyo-wase (maruba)’), F₂ line and F₃−F₆ lines were evaluated for resistance by inoculation with F. oxysporum f.sp. melonis race 1,2y. Resistance was remarkably improved from F₂ to F₃, and moderately improved from F₄ to F₆. These findings indicate that F. oxysporum f.sp. melonis race 1,2y resistance is controlled by several additive genes derived from both parents. Observation using KOH-aniline blue technique for fluorescent staining of fungi demonstrated that the infection rate and extension of hyphae were suppressed in resistant cultivars and lines. These findings imply that the mechanisms in expression of additive genes are related to suppression of entrance and extension of F. oxysporum f.sp. melonis race 1,2y hyphae. Furthermore, it seemed that these mechanisms are common among C. melo cultivars that have different genetic backgrounds.

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We analyzed fruit and seed sets after self-pollination in 3 apple cultivars. Between 1998 and 2001, we carried out self-pollination of cultivars ‘Megumi’, ‘Orin’ and ‘Fuji’, which exhibit different levels of self-incompatibility. In addition, we carried out self-pollination of ‘Fuji’ using X-ray irradiated pollen. Self-pollination of ‘Fuji’ showed percentages of fruit sets ranging from 0 to 4.5% over 4 years. In contrast, self-pollination of ‘Megumi’ and ‘Orin’ showed higher percentages ranging from 40 to 48% in the 2^nd year and from 16.3 to 38% in the 3^rd year. There were no differences in fruit set between experiments using X-ray irradiated pollen and non-irradiated pollen. ‘Megumi’ showed the production of seeded fruits, however, most of ‘Orin’ resulted in the production of fruits without seeds. We carried out self- and non-pollination of ‘Orin’, resulting in a high percentage of fruit set on average in all cases. All trees showed fruit but no seed. These results demonstrated that ‘Orin’ possess autonomic and/or stimulative parthenocarpy. From self-pollination of ‘Fuji’, we obtained many progenies from fruits containing seeds by the application of embryo culture, however, the percentages of seed set in ‘Fuji’ were less than those in ‘Megumi’. PCR amplification using S-allele-specific primers showed the possibility that some progeny were derived from self-compatible fertilization. These self-pollinated plants were grown in green house, however, some plants showed abnormal phenotypic appearances.

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It was investigated whether the daughter tubers formed from tubers that were formed from the protocorms of Habenaria radiata gel covered and inoculated with orchid mycorrhizal fungi grew larger than the tubers formed from seedlings, and whether these daughter tubers had the possibility of forming flower buds or reaching bloom in habitat. Whether the orchid mycorrhizal fungi in habitat was effective in promoting larger tuber formation. It was considered that half of tubers could form flower buds or reached bloom when the tuber weight of H. radiata enlarged beyond 150 mg. The daughter tubers grew larger than the tubers formed from seedlings, and the growth rate of the daughter tubers in habitat were two-fold larger. Therefore, the daughter tubers were thought to have the possibility of forming flower buds or reaching bloom after about five years. Because orchid mycorrhizal fungi which promotes tuber formation of H. radiata was recognized in habitat, it is considered desirable to inoculate this fungi on gel covered protocorms. Further, it was thought that environmental conditions must be investigated in order to enlarge the daughter tuber in habitat by methods in addition to the growth promoting effect of mycorrhiza which also lives in habitat.

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We investigated the effects of temperature and light conditions on germination of Lilium × formolongi. The optimal germination temperatures were 20°C in early flowering cultivars ‘F₁ Augusta’ and ‘Raizan No. 1’, 18°C in the medium flowering cultivar ‘Raizan No. 2’, 15°C in the late flowering cultivar ‘Raizan No. 3’. ‘F₁ Augusta’ and ‘Raizan No. 1’ showed a high rate of germination at 5°C compared with ‘Raizan No. 3’. Seed germination of the all cultivars tested was inhibited by high (≧24°C) temperatures. Pre-chilling treatments, at 3, 5, or 10°C for more than 10 days, accelerated seed germination at 20°C. Germination at 30°C was accelerated by pre-chilling treatment at 10°C for more than 10 days, whereas pre-treatment at 3 or 5°C had no promotive effects. In conclusion, pre-chilling treatment at 10°C for more than 10 days is recommended to achieve uniform germination of Lilium × formolongi under high temperature conditions. There was no effect of light conditions on germination.

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This experiment aimed to establish a method for diagnosing potassium deficiency in ‘Delaware’ grape using petiole extract. It is considered that potassium concentration in petiole extract could be used for diagnosis of potassium deficiency in ‘Delaware’ grape, because there was a significant positive correlation between potassium concentration in the petiole extract and potassium content in leaves. When potassium concentration in the petiole extract which was measured by a simple reflection photometer system at the flowering stage was found to be lower than 2,400 ppm, potassium deficiency would definitely occur at a later stage, even if none of the symptoms were observed at that time. However, it is suggested that potassium deficiency could be avoided by the application of potassium after diagnosis.

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The effects of 0, 25 or 100 mM NaCl treatments on ion uptake and gas exchange of the Japanese pear ‘Akibae’ grown on the rootstocks P. betulaefolia, P. calleryana and P. pyrifolia were investigated. The leaf Na and Cl concentrations and the decrease in the photosynthetic rate for P. betulaefolia rootstock were lower than those for other rootstocks. ‘Akibae’ grown on P. betulaefolia exhibits a higher salt tolerance than those grown on P. pyrifolia and P. calleryana. These findings suggested that P. betulaefolia have a salt exclusion mechanism in the root, and this characteristic is maintained even if scion cultivars were grafted. Therefore, P. betulaefolia is a useful rootstock for Japanese pear cultivation under saline conditions.

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Effects of tunnel covering plastic films and fertilization methods on growth, bolting, and yield were investigated in welsh onion (Allium fistulosum L.) harvested in early summer. Polyolefine plastic film (PO) induced the highest mean air and soil temperatures, while dripped polyethylene plastic film (DP) showed the lowest temperatures. Coefficient of variance on soil water content was higher in PO and non-dripped polyethylene plastic film (NDP). Application of an overall layer of fertilizer produced a lower bolting rate than application of fertilizer in a planting furrow only when using DP, but opposite results were demonstrated with PO and NDP. Effects of covering films and fertilization methods on bolting rate and yield showed significant interaction. Higher thermo-keeping films suppressed flower initiation. When higher thermo-keeping films were used to cover tunnels, management to control nitrogen concentration is required to inhibit bolting in this culture.

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To realize seedless fruit production in ‘Tosa Buntan’ pummelo (Citrus grandis Osb.), the effects of streptomycin (SM) spraying, open pollination and fruit thinning time on seedless fruit set and development were investigated in a commercial orchard consisting almost entirely of a single cultivar. Three spray applications of 500 ppm SM to whole trees at 1–5%, 50% and 100% flowering time produced completely seedless fruit. Seedless fruits were not only easy to eat due to the minimal length of unfertilized ovules, but also easy to separate segments due to an undeveloped core. Fruit thinning with a leaf/fruit ratio of 120 4 weeks after full bloom increased seedless fruit size and over 30% of seedless fruit were the most commercially desirable 3L size. The number of fruit set per secondary scaffold branch, the proportion of edible portions and citric acid concentration were similar to those of hand-pollinated control fruit. These findings demonstrate that three spray treatments of SM and early fruit thinning 4 weeks after full bloom in a single cultivar produced a desirable size of seedless fruits in ‘Tosa Buntan’ pummelo.

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When cucumber plants are grown in a greenhouse kept at 25°C with 40% RH in the forenoon to improve working environment, the occurrence of bottle-gourd-shaped fruits increased. We tried some cultural management practices to decrease the occurrence of such fruits. As a result, removing several first lateral branches after their cucumber fruits were harvested reduced the proportion of bottle-gourd-shaped fruits induced by rising soil temperature. Pinching the alternate lateral branches of the 11, 13 and 15th node on the main stem improved the number of fruiting nodes and prevented a decrease in the number of harvested fruits. Treatment with 0.1% potassium sulfate solution also decreased the proportion of bottle-gourd-shaped fruits, and increased the proportion of marketable cucumbers.

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Fruit growth of ‘Maekawa Jiro’ persimmon (Diospyros kaki Thunb.) grown in either a heated plastic house or open field was analyzed in relation to changes in air temperature during the period from 50 days after full bloom to fruit harvest. Air temperature in the plastic house was lower than that in the open field during fruit growth stage I, but the reverse conditions were observed thereafter. Both the plastic house- and field-grown fruits reached the end of the fruit growth stage I when the cumulative mean air temperature after full bloom reached 2,300°C·days, and the linear regression equations describing the relation between the daily increment of fruit diameter and the cumulative mean air temperature was quite similar. After fruit growth stage II, both plastic house- and field-grown fruits showed negative correlations between the daily increment of fruit diameter and mean air temperature, and the period when the growth of the plastic house-grown fruits was inhibited by high temperature was longer than that of the open field-grown fruits.

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Qualities of fruits harvested at different sites and developmental stages were investigated in ‘Nanko’ Japanese apricot (Prunus mume Sieb. et Zucc.). Qualities of the processed Japanese apricot liqueur (ume liqueur) were also investigated. We regarded the time, when qualitative components reached a high level as the optimal time of harvest, and examined the common index of the optimum time of harvest among the places where progression to maturity differed. The time of sharp decrease in fruit firmness coincided with the time when citric acid concentration reached a high level regardless of the site and year. Citric acid content and extracted volume from fruit in the ume liqueur increased with a later harvest time at all sites. These findings showed that fruits at the time of a sharp decrease in fruit firmness were most suitable for ume liqueur, because browning strength, contents of citric acid and phenolics, antioxidant activity were high. In conclusion, fruit firmness can be utilized as a maturity index for making ume liqueur.

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We developed a simple method for presumption of the bud break stage in forced culture of Japanese persimmon (Diospyros kaki Thunb.) ‘Tonewase’ by the Developmental Rate Model (DVR model). Developmental Index (DVI) at the start of heating (8–24°C) related to the number of days necessary for bud burst of cuttings. Based on this relation, we tried to estimate the bud burst stage in forced culture, with minimal air temperature maintained above 8–12°C in a greenhouse at Nara Fruit Tree Research Center, using the DVI at the start of heating from late December to late January, mean air temperature and heating days. By this method, presumed error was within 3 days between estimated and observed bud burst stage. This suggested that the bud break stage of ‘Tonewase’ in forced culture could be simply assumed using the DVR model and minimal air temperature in the greenhouse.

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To produce tomato in summer and autumn seasons in hilly and mountain areas steadily, we developed a sloped greenhouse and a fertigation system suitable for use on sloping land. We installed and tested the greenhouse and the fertigation system in three tomato-growing farms in Mikamo, Tokushima (about 300–370 m above sea level, 4–20° inclination). Cost of materials of the greenhouse and the fertigation system were ¥3,000,000 and ¥500,000 per 1000 m², respectively. Between 2002 and 2005, we compared tomato cultivation using a sloped greenhouse and fertigation system to cultivation under the conventional rain shelters. The number of times using insecticides under the greenhouse with an insect screen were lower than that under the conventional rain shelters. There was no consistent tendency in the number of times germicides were applied in the greenhouse compared to that under conventional rain shelters. Tomato yields from greenhouse cultivation with fertigation system for all years and all three growers were higher than those under the conventional rain shelters. Compared to the greenhouses, tomato yields under the conventional rain shelter demonstrated sharp fluctuations because of damage due to typhoon or plant diseases. We considered that installing a sloped greenhouse and fertigation system increased the tomato yield and income of the grower, although the initial costs were more expensive than those of installing conventional rain shelters.

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Pre-harvest fruit softening, so-called “On-tree early softened fruit”, in which maturation is abruptly accelerated and over-ripened prior to harvest for certain physiological reasons, was compared among 6 strains of the “Early B” types of Japanese persimmon ‘Saijo’. We also examined the cause and methods of preventing this phenomenon. Pre-harvest fruit softening was less frequently observed in the “Endo”, “Yamasaka”, and “Abe” strains than in “Koto” strain, even in years with heavy rain during July to September. In these strains, relatively higher activities were found in the fine roots, and except in “Koto”, there were lower levels of ethylene evolution in the fruit during early September to late October. A remarkable ethylene evolution was observed in fruit on about day 10 of flooding treatment, then heavy falls of leaf and fruit were observed. On the contrary, however, shaded trees did not show increased ethylene production in fruit, and caused few or no falling leaves and fruit. This was also observed in untreated trees. Accordingly, the disorder might be promoted not by shortage of sunshine, but by high moisture in the soil. Soil moisture in late July to October was little changed by a “White porous water proof sheet” covering the soil under the tree crown, the pF value of soil at a depth of 15 cm was 2.3 through out the period. Ethylene release from fruit, and the occurrence of pre-harvest fruit softening were considerably reduced by mulching with a water proof sheet. From the above results, it was considered that the pre-harvest fruit softening was induced mostly through the following 2 process; ① At the late stage of fruit maturity, flooding condition by continuous rainfall blocks aeration in root, and the ethylene precursors (ACC) are accumulated in fruit. ② Thereafter, waters are actively vaporized from fruits by exposure to high temperature during the following fine and windy days, and ethylene release in fruit under water stress, resulting in rapid fruit softening.

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Among strains of ‘Saijo’ Japanese persimmon (Diospyros, kaki, Thunb.) in Shimane prefecture, the genotypes with early fruit ripening were selected as “B-type”. The “B-type” included some genetically different strains based on tree growth and fruit traits. We investigated differences in tree growth, fruit quality and yield among six strains from different origins: “Abe”, “Endo”, “B dwarf”, “Yamasaka”, “Koto” and “Wada” strains, and selected the strain with excellent the fruit production. A tendency toward dwarfing was observed in “Koto” strain. Also, as a physiological disorder of bud sprouting often occurred in the “Abe” strain, tree growth of “Koto” and “Abe” strains were inferior to the others. The “Wada” strain showed succulent shoot growth and vigorous growth of the trunk, while the yield was inferior to that of other strains and its fruit had a late ripening period. The “Yamasaka” strain showed a mean value in tree growth of all strains. The area percentage of tree canopy and leaf area index per field area (LAIf) were high in “Endo” and “B dwarf” strains. Carbohydrate production in these strains was superior, and the distribution rate of carbohydrates was high in fruit and rootlet. It is thought that the fruit yield of about 3 t per 10 a every year with high quality can be expected in each strain of “Endo” and “B dwarf”. It is thought that the “Endo” strain is the most excellent in “B-type” strains of ‘Saijo’.

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Tomatoes were grown on substrates made of cedar bark to investigate the effects of decomposition changes in physiological and chemical properties of substrates, the concentrations of the components in the solution within the substrates, and the growth and yield of tomatoes. The substrates were fixed in a closed hydroponic system with a capillary uptake method. The liquid and gaseous phases of the substrates did not differ, while the solid phase decreased as decomposition proceeded. As decomposition progressed, the annual weight loss in the substrates grew smaller, CEC of the substrates increased, nitrogen absorption by the substrates decreased, and the NO₃-N level in the solution within the substrates tended to fluctuate higher. K, Ca, Mg levels in the solution within the substrates were higher in substrate used for five years than in substrates used less than three years. There were no difference in stem diameter of tomato plants at the first and third clusters, except that plants showed thinner stems on the one-year-old substrate. The yield of tomato fruits tended to be higher on two-year-old substrate than on one-year-old substrate. The yield was lowest on the five-year-old substrate. It was suggested that the substrate be replaced after five years.

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The mechanism of enhanced fruit softening on the tree following natural disaster was investigated in ‘Saijo’ persimmon (Diospyros kaki Thunb.) by girdling, defoliation and flooding treatments. The highest rate of fruit softening on the tree occurred after girdling treatment (20%). It is possible that ethylene production caused by girdling treatment may be involved in the subsequent fruit softening. Postharvest investigation also indicated that flooding or girdling treatments yielded the highest incidence of fruit softening. These results indicate that flooding caused by natural disaster or girdling induces physiological stress that results in fruit softening of ‘Saijo’ persimmon. It was clear that fruits with black spots below the calyx easily softened before and after harvest.

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Studies were carried out to elucidate the effect of harvesting time and low-temperature treatment on germination of corm in taro (Colocasia esculenta Schott). Corms of cvs. Eguimo, Wase-Hasuba, Akame, Takenokoimo and Malaysia No. 1 were harvested on 21 September and 23 November. They were planted in a growth chamber at 25°C just after harvesting. In cvs. Eguimo and Wase-Hasuba, the germination rate of corms harvested on 21 September was much lower than that of those harvested on 23 November. In cv. Akame, the germination rate of corms harvested on 21 September was slightly lower than that of those harvested on 23 November. In cvs. Takenokoimo and Malaysia No. 1, corms germinated rapidly irrespective of harvesting time. Corms of cv. Eguimo were harvested on 3 October and stored at 3, 10 or 25°C for 0-60 days. The germination rate was low in corms planted just after harvesting or after storage at 25°C for 60 days. Low-temperature treatment at 3°C for 15 days or at 10°C for more than 30 days strongly promoted germination. Low-temperature treatment also promoted germination of corms in cvs. Yatsugashira, Ohnoimo and Ishikawa-wase. Based on these findings, it was deduced that taro corm remains dormant from late September to early October, that the depth of dormancy varies with variety, and that dormancy is broken with low-temperature treatment at 3°C for 15 days or at 10°C for 30 days.

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Hamabofu (Glehnia littoralis Fr. Schm.) is one of the traditional blanched vegetables in Japan. Rootstocks were grown for one month under darkness or natural daylight condition to compare plant characteristics. When plants were grown under darkness, the petiole elongated remarkably compared to that of the plants grown under natural day light. The leaf blade did not expand in darkness, and the number of leaves and dry matter percentage were smaller than those of plants grown in the light. The concentrations of chlorophyll, anthocyanin, crude fibre and hardness of petiole were less in dark grown plants than in light grown plants. Results of organoleptic test indicated that plants grown in darkness were whitish, had a mild flavour and was soft, compared with plants grown in natural daylight. Furthermore, test subjects favoured the mild flavour and softness, but not the whitish colour of plants grown in the dark. Essential oil concentrations in shoots were not significantly affected by light. Anatomical characteristics such as the number and area of collenchyma and vascular bundle, and the number, the area and the occupancy area rate in the petiole cross section of oil ducts and the number of secretory cells did not different between plants grown in the dark and those grown in the light.

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To establish a nondestructive method of measuring astringency in peach fruit, near-infrared spectroscopy (NIRS) was attempted. In the organoleptic test, significant correlation existed between astringency and polyphenol concentration which ranged from 30 mg to 220 mg·100 g⁻¹FW. Strong astringency was sensed when the polyphenol concentration in the fruit was higher than 110 mg·100 g⁻¹FW. In analysis of the model solution of catechin and chlorogenic acid which are the main components of polyphenol in fruit using the second derivative transmittance spectra from 1100 nm to 2500 nm, it was found that there was a high correlation between absorbance around 1664 nm and 1730 nm and concentration of the solution. Then measurement of intact fruit by NIRS was performed using the second derivative reflectance spectra scanning from 1100 nm to 2500 nm. As a result of performing multiple regression analysis, the absorbance at 1720 nm showed high correlation with polyphenol. In the calibration equation development, the highest predicted correlation coefficient (r) was 0.80 and the bias-corrected standard error of prediction (SEP) was 14.7 mg·100 g⁻¹FW for polyphenol. It can be concluded that NIRS is a promising method for determining the astringency of peach fruit.

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We established a four-year management system that decreased the population of Meloidogyne incognita to avoid injury due to continuous cropping of Japanese bunching onion by combination with soil disinfection and an antagonistic plant. In the first year, chemical treatments (chloropicrin + 1,3-dichloropropene, dazomet and oxamyl) were added to the soil before cultivation, the population of root-knot nematodes decreased after these treatments, resulting in an increased yield of Japanese bunching onion. Soil disinfections (chloropicrin + 1,3-dichloropropene and dazomet) had a higher effect on decreasing the population of root-knot nematodes. Positive effects of soil disinfection persisted for two years. In the third year, a leguminous antagonistic plant Crotalaria spectabilis was planted. There after, the population of root-knot nematodes greatly decreased, so the yield of Japanese bunching onion recovered the next year. The four years management system with soil disinfection and growth of an antagonistic plant crop was shown to be effective for reducing economic loss and the times of soil disinfection. This system should contribute to maintaining stable production of Japanese bunching onions.

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The DPPH radical scavenging activities of different parts (leaf, stem, immature fruit, mature fruit and seed) of red bayberry were analyzed by extraction with hot water and 80% ethanol. The highest activity was obtained in the current leaf. Effects of leaf collection time and sex of donor tree on radical scavenging activity of the current leaf were examined. The highest radical scavenging activity was obtained in July. And the activity of leaves from male trees was higher than that of those from female trees.

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