Callus formation, organogenesis and somatic embryogenesis from root section of gladiolus cormels grown in vitro were observed on MS medium containing NAA with and without BAP, respectively. The regeneration rate of adventitious buds showed a high frequency on MS medium containing 5 mg·liter^-1 NAA and 5 mg·liter^-1 BAP. Regenerated shoots were transferred to MS medium, and subsequently roots developed and corms were formed at the base of the shoots. The corms were released from their dormancy by low-temperature treatment and transplanted into pots, then developed shoots, roots and flowers. The regenerated plants had the same characteristic flower shape and color as the mother plant. Varietal differences were observed in the rate of adventitious buds formation. In conclusion, we showed the most suitable culture condition, for organogenesis and somatic embryogenesis of gladiolus in using root explant.

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To obtain the seedless sudachi of a triploid, 297 flowers were crossed between tetraploid sudachi and diploid sudachi, and 50 triploids were established in 1992. Flowcytometer was used for selection of triploid hybrids. When diploid sudachi were used for seed parents, undeveloped seeds were obtained, and triploids were hardly obtained. When tetraploid sudachi was used for seed parents, developed seeds were formed, and although the rate of establishment was low, a certain number of triploids could be obtained. ‘Tokushima 3X No.1’ was selected from these and has been submitted for registration under the Law of Seedlings. The flesh color of ‘Tokushima 3X No.1’ is a pleasant green, and it has no seeds but an abundance of juice. Furthermore, it can be to shipped early after open-field culture of sudachi. It is expected be an early crop cultivar in which quality fruit production is possible. In order to breeding a seedless cultiver, it is thought that production of a triploids is one of the most effective methods not only for sudachi but for other sour citrus plants as well.

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Rooting growth and cut flower quality of Gypsophila paniculata L. cuttings grown in cell medium hardened by heat fusion polyester fiber was investigated. Rooting percentages of hardened media were not affected by medium compositions and were higher than those without hardened media. Moreover, the hardened media did not break down whenever root-ball was not formed. Regardless of transplantation age, hardened medium had little effect on transplant growth and cut flower quality. Hardened medium had no effect on the formation of succulent roots. Therefore, we developed a method of transplanting young cuttings before the root-ball formed using the harden cell medium.

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The procedures for tissue culture to establish a mass propagation method for Primula sieboldii E. Morr., were examined. Young expanding leaves were taken from potted plants. After sterilization, leaf segments were cultured on 1/2 MS medium (Murashige·Skoog, 1962) supplemented with 4.44×10^-6 M benzyladenine (BA), 5.37×10^-7 M α-naphthalene acetic acid (NAA), 3% sucrose and 0.8% agar. There were differences in the potential of leaf segments to induce calli and adventitious shoots among the tested cultivars. To obtain a number of clones, root segments excised from a donor plant in vitro were used as explants. Calli from the root segments were easily induced on MS medium supplemented with BA and NAA. Adventitious shoots were induced easily and then transferred to hormone-free MS medium for 30 days. These adventitious shoots successfully developed into plantlets. The best results for inducing calli in root segment culture were obtained using MS medium with 10^-6 M BA incubated under 3,000 1x, a 16 hr photoperiod at 20 or 25°C. Thus, plantlets were easily regenerated from calli. The regenerated plantlets were incubated on vermiculite, and growing plants were then transferred to soil and successfully acclimated.

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We investigated the effect of localized deep application of compost using a labor-saving excavation machine on the yield and root growth of the Japanese pears tree, ‘Kousui’, which shows decreased yield with aging of the trees.
1. A significant positive correlation between fruit yield and weight of fine roots with a diameter of 1 mm or less was observed in 10 alluvial soil fields of matured Japanese ‘Kousui’ pear trees in Saitama Prefecture.
2. Twenty liters of compost was applied without mixing the soil in eight holes dug 1.5 m away from the trunk of ‘Kousui’ trees, which had shown reduced yield and root growth. Holes were created using a hole digger machine (tractor-attached type). The fruit size and yield of the treated trees were increased one year after compared with those of control trees. The same results were obtained two and three years thereafter. The root growth after treating with compost was analyzed using root analysis software ‘RHIZO’ (Regent Instruments inc). The total length of roots with a diameter of 0.5 mm or less was increased about 3 times compared with that of control trees, 1, 2 and 3 years after treatment.
3. After digging a hole near the rooting zone using the hole digger machine, the application of compost to the hole replacing the soil dug out sharply increased the total length of the fine roots ten-year-old ‘Kousui’ trees after two years.
4. Spot application of compost using the labor-saving hole digger machine to Japanese pear trees showing lower yields, sharply increased the quantity of the fine roots, resulting in increased fruit size and yield.

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To avoid problems, such as lifting soil and soil borne diseases, when growing tomatoes on hillside fields, we developed a hydroponic system for sloped land. First, we investigated an irrigation system. The drip tubes were set on contour line. After the water valve was closed, a considerable amount of drainage leaked from the lowest line. We changed the type of drip tube to that providing drainage shut off below a certain pressure and inserted check valves into the line. As a result, drainage from the lowest line stopped. Second, we developed a hydroponic system by application of the irrigation system. The supply of nutrient solution and fertilizer injectors were powered solely by water pressure, without the use of electric power or pump. As a result of growing tomatoes using the system, the yield of higher positions on the sloped greenhouse was less than that of the lower positions because of the insufficient water pressure. However, after securing the water pressure, there was no difference in yield at different positions. Finally, we developed a closed hydroponic system by improving the system. Drain of the nutrient solution was collected by slant of the ground into a reservoir tank. During the supply of nutrient solution, the collected drain in the tank was injected into the fresh solution by an aspirator that was powered by a current of water. Tomatoes were grown for about 7 months and the yield was 12.8 ton 10a^-1 using this system.

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Characteristics of tree growth, yield efficiency and dry matter production (DM) were studied using the columnar-type apple tree ‘Maypole’ grafted on Marubakaido (Malus. prunifolia Bork. var. ringo Asami), M.26 and M.27. Tree growth was largest in trees grafted on Marubakaido followed by that on M.26 and M.27, then the expansion of M.27 slowed down beginning with 4-year-old trees. Trees grafted on to M.26 and M.27 had many flower buds. Leaf lengths of the middle of shoot of 5-year-old trees grafted on M.27 were shorter than those grafted on Marubakaido and M.26.
Total length and leaf area of lateral shoot at each height increment of trees were largest in trees grafted on Marubakaido followed by M.26 and M.27. The percent instantaneous incident photosynthetic photon flux density at each height increment of trees was largest in trees grafted on M.27 followed by that on M.26, and Marubakaido. Yield per tree and cumulative yield per 10a were largest in trees grafted on Marubakaido followed by M.26 and M.27.
Yield efficiency was highest in trees grafted on M.27 followed by M.26, and Marubakaido. Fruit weight on trees grafted on to M.26 and M.27 was heavier than on trees grafted on Marubakaido.
Total DM per year of M.26 and M.27 trees compared to that of Marubakaido trees was 40% and 23%, respectively. Assimilation partitioning rate of the fruit increased in proportion to the high dwarfing rate ability of the rootstock, and the assimilation partitioning rate of branches decreased except for that in shoots and thick-root (>2 mm). Total DM per leaf area, fruit DM perleaf DM and area were largest in trees grafted on M.27 followed by M.26 and Marubakaido.
In conclusion, the present results clearly indicated that the reaction of the tree growth, yield efficiency and dry matter production in columnar-type trees grafted on dwarf rootstock resembled that of normal-type trees.

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Fertilization techniques using carbon dioxide with liquid CO₂ and an exhaust of oil-burner were investigated for preventing decreased flower formation in forcing-cultured ‘Tone-wase’ persimmon.
In both open-field and forcing culture, flower bud development rapidly progressed from 5-6 weeks to 8 weeks after full bloom. Thereafter, flower bud development scarcely proceeded.
CO₂ fertilization from full bloom to the end of heating (just before fruit coloring), with both liquid CO₂ application for 5 hours early every morning, which raised the CO₂ concentration in the greenhouse to 1,500 ppm, with oil-burner exhaust all day long, improved flower bud formation, fruit weight and yield per tree. These methods lowered the cost of CO₂ application to one-half or one-third of the cost for conventional treatment.

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Effect of the nitrogen fertilizer level on growth and bolting of cv. ‘Kincho’ was investigated to clarify the involvement of nitrogen nutrition in flower initiation of bunching onion (Allium fistulosum L.). A low nitrogen level retarded the growth and promoted leaf sheath bulbing. Low nitrogen decreased both the nitrogen and carbon concentrations, but increased the C/N ratio. Low nitrogen promoted bolting when the plants were exposed to a low temperature for 21 days. However, the nitrogen level did not affect bolting when plants were exposed to a sufficiently low temperature for 35 days. In conclusion, low nitrogen is considered to be a supplementary factor for flower initiation of bunching onion.

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Effects of the fruit set position and training method on Brix of fall-cropped muskmelon fruit (cv. ‘Rupia Red’) were examined. Plants were topped at the 3^rd node and two primary lateral shoots were grown as the main stems. Two bearing shoots were left at the 6-7^th, 8-9^th, 10-11^th or 12-13^th node of each primary lateral shoot and one fruit was set at the 1^st node of each bearing shoot. Secondary lateral shoots except the bearing shoots were removed up to the 15^th or 20^th node of the primary lateral shoots. As the node order of the bearing shoot rose from the 6-7^th to 12-13^th, Brix decreased from 13.1% to 11.6%. However, the total yield decreased as the node order of fruit set lowered. Topping of the main stem had a large effect on Brix. The average Brix was 10.9% when topped at the 25^th node, while it was 12.2% for non-topped plants. The parameter that had the greatest effect on Brix was the fresh weight of the leaf blades above the fruits, and the effect was significant. These results suggest that the number of healthy leaves above the fruits is critical for stabilization of the fruit quality of fall-cropped muskmelon.

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Using 11 or 15 year-old ‘Saijo’ trees, trained to a modified leader system with 4 scaffold limbs, renewal of the trees suffering slightly from a sprouting disorder to a new healthy ‘B type’ strain was attempted by side-grafting on each main scaffold limbs. Two scions were grafted about 50cm above the trunk on each limb. In order to enlarge the shoots from scions as early as possible, girdling and bark inversion were applied to each limb with a 0.8∼1.0 cm width, just above the grafting portions.
Scion shoot growth was promoted by girdling or bark inversion treatment. In the first year of grafting, total contents of carbohydrate in the scion shoot were significantly increased by girdling or bark inversion treatment. The rate of scion shoot enlargement, compared to the old limbs at 2 years after grafting, reached 70∼80% with girdling or bark inversion treatment, which was higher in 20∼30% to control. No significant difference was observed in scion shoot growth between girdling and bark inversion treatments, however, fruit growth on the old limbs to which bark inversion was applied was superior to that on the limbs to which girdling was applied. For promotion of scion shoot growth, the flowering period (early June) seemed to be suitable for the girdling treatment.

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Tomato plants (Lycopersicon esculentum Mill., cv. House-Momotaro) were grown for 9 months from September to June in a conventional open rockwool system or in a similar system equipped with a solution-recycling unit that we devised to reduce environmental pollution with drained nutrient solution. Concentrations of nutrients in the rockwool slub solution differed with the systems; P, K, Ca and Mn concentrations were lower and B and Na concentrations were higher in the solution-recycling system than in the open system. Nevertheless, concentrations of major nutrients and Na in leaves did not greatly differ between systems. Furthermore, plant growth and crop yield in the solution-recycling system were similar to those in the open system. These findings show that the solution-recycling unit attached to a commercial open rockwool cultivation system makes it possible to reduce environmental pollution by discarded nutrient solutions without reducing the yield on long-term cultivation of tomato plants.

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The effects of artificial shading in summer on photosynthesis, carbohydrate accumulation and fruit set in sweet cherry grown in warm areas were studied. Potted trees were grown in steel frame structures covered with woven shade cloth made of silvered polyethylene and providing 53% light reduction. Shading slightly increased the daily leaf net photosynthetic rate compared to control. Shading delayed leaf abscission. In another experiment, 1-year-old trees were grown under the same level of shade. Although dry weight was not influenced by shading, reserve carbohydrate concentration of the tree under shaded conditions was higher than that under unshaded conditions. Five-year-old trees were subjected to the same level of shading. Shading prolonged embryo sac longevity the following spring and resulted in increased fruit set. These findings suggest the possibility of applying artificial shading in summer to increase assimilate accumulation and fruit set the following spring in sweet cherries grown in regions with hot summers.

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With the aim of elucidating the cause of the occurrence of radial fruit cracking in tomatoes cultivated in summer and fall under plastic canopies, we examined the effects of the differences in soil moisture with four irrigating methods and the effects of the differences in two training systems.
When foliage and fruits were exposed to scarce solar radiation, changes in soil moisture did not demonstrate and effect on the incidence of radial fruit cracking. However, it was observed that refuse radial fruit cracking tended to occur in enlarged fruits. When the foliage and fruits were exposed to abundant solar radiation under the same irrigating conditions, radial fruit cracking and refuse radial fruit cracking evidently tended to occur more frequently than that under limited solar radiation, irrespective of fruit size.
These facts suggest that radial fruit cracking in tomatoes cultivated in summer and fall occurs mostly in response to the solar radiation reaching the foliage and fruits, while changes in soil moisture affect the occurrence of radial fruit cracking relatively less.

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Effects of dwarf rootstocks on tree growth, yield and fruit qualities of young ‘Amakusa’ and ‘Amaka’ trees were compared with common Trifoliate orange and ‘Flying Dragon’ trifoliate orange rootstocks in order to improve fruit qualities and to maintain a small canopy for easy cultural operation.
For both cultivars, the volume of the tree crown four years after planting was significantly smaller on ‘Flying Dragon’ (FD) rootstock than on the common trifoliate orange (P) rootstock. Overgrowth of rootstock was observed in the cultivars on both rootstocks 6 years after planting. The degree of rootstock overgrowth was greater for trees on FD than for those on P rootstock. Both soluble solid and acid contents of the fruit juice were higher on FD rootstock than on P rootstock for both cultivars. Although yield per tree was greater on trees with P rootstock, yield per unit canopy volume (kg/m³) was greater on trees with FD rootstock. FD rootstock was considered a suitable rootstock for maintaining compact canopies and produced higher quality fruit for both ‘Amakusa’ and ‘Amaka’.

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The development of ovule and embryo sac was investigated in relation to double seed formation in peaches. Among 15 cultivars, ‘Juseito (red flower)’ showed the highest percentage of double seed formation at 75.1% on average for five years. ‘Hakuho’ had a relatively higher rate of 11.1%, while others including ‘Hakuto’ had less than 5.2%. Development of ovule and embryo sac, elongation of pollen tube in the pistils were determined among ‘Juseito (red)’, ‘Hakuho’ and ‘Hakuto’. In all cultivars, the pollen tube reached the micropile more than 7 days after pollination. By this time, most of the primary ovules were viable. However, the secondary ovules had aborted in ‘Hakuho’ and ‘Hakuto’ at a rate of 85.7% and 100.0%, respectively, while in ‘Juseito (red)’ only 18.2% of ovules had aborted. These findings suggest that the potentiality of double seed formation is determined before fertilization, and when the secondary ovules avoid abortion and persist until fertilizations, the possibility of double seed formation increases.

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Effects of the GA inhibitor ‘Uniconazole P’ were tested to decrease fruit cracking of the netted melon ‘Ams’ in open culture.
Application of 30 ppm Uniconazole P significantly decreased fruit cracking with the inhibition of shoot elongation.
Excessive fertilization with 20 kg/10 a nitrogen increased fruit cracking, but fruit cracking was obviously decreased with growth inhibition and increase of fruit weight following Uniconazole treatment. Further fertilization with 30 kg/10 a nitrogen, however, did not induce any growth inhibition and decreased fruit cracking by the same treatment.

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It is necessary to decrease the concentrations of nitrate and oxalate in spinach for human health. This analytical method was developed to simultaneously determine nitrate, oxalate and other major organic acids in spinach using capillary electrophoresis. The essence of the analytical conditions were as follows; the electrolyte used was a mixture of methanol and buffer (pH 5.6, 10 mM 2, 6-pyridinedicarboxylic acid, 5 mM ethylendiamine-tetraacetic acid disodium salt and 0.5 mM cetyltrimethylammonium bromide) at a ratio of 8:92 (V/V) and non-absorbing analytes were detected indirectly at 275 nm. The time needed for the analysis of one sample was 15 min. It was possible to separate nitrate, oxalate, malate, citrate and succinate from the spinach extract. This method could be applicable to tomatoes and other vegetables.

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Ultraviolet (UV) radiation induced production of phytoalexin scoparone (6,7-dimethoxycoumarin) in the leaves and flavedo of various citrus cultivars. Using high performance liquid chromatography (HPLC) measured scoparone in the citrus leaves and fruits after radiated with UV. The amounts of scoparone in young leaves and fruits (harvested in August) were less than those in mature specimens (harvested in December). Among the cultivars, abundant scoparone was induced in young leaves of lemon (Citrus limon (L.) Burm. f.), Meiwa kumquat (Fortunella crassifolia Swingle) and Ponkan (C. reticulata Blanco). Matured leaves of lemon, Hyuganatsu (C. tamurana hort. ex Tanaka) and ‘Seminole’ tangelo also produced abundant scoparone. In August, Meiwa kumquat and lemon, and in December, Meiwa kumquat, ‘Tsunokaori’ and ‘Robinson’ fruits were induced to produce abundant scoparone by UV radiation. Duration of changes in scoparone synthesis differed among citrus cultivars, organs and growth phases.

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