The effects of water stress on the production of sorbitol in the leaves and roots of one-year-old grafted loquat trees were investigated. Concurrently anatomical changes in the nuclei of the leaves and the root apical meristem were followed by staining with 4'-6-diamidino-2-phenylindole (DAPI) and observing the results by fluorescence microscopy. The degree of water stress was graded into three levels: a) unstressed plots (control), b) moderately stressed plots (m-plots, no irrigation period for 20 days), and c) severely stressed plots (s-plots, no irrigation period for 25 days). The degree of water stress was estimated by the water saturated deficiency (WSD) of the leaves. With an increase in WSD, the sorbitol content in the leaves and roots increased, the accumulation occurring in the roots. Although WSD for the s-plots was higher than that for the m-plots, there was no significant difference in sorbitol content in leaves and roots between the two treatments. After recovery from water stress, the sorbitol content decreased gradually in roots and leaves. Leaves of m-plots abscised little after irrigation was resumed, whereas leaves of s-plots abscised severely; only a few trees died. New roots developed in control plants, but not in stressed-plants. Water stress resulted in an acceleration of nuclear degradation and a decrease in starch accumulation in the mesophyll parenchyma and in the apical meristem from the root tip to 2-3 mm.

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The efficacy of ammonium nitrate (AMN), NH₄NO₃, as an additive to gibberellic acid (GA₃) solutions on berry growth and quality of seedless 'Delaware' grape was tested in 1995 (Expt. 1) and 1996 (Expt. 2). Clusters were dipped twice in GA₃ ± AMN solutions before and after full bloom in both years. Treatments with GA₃ alone are considered the control. The addition of AMN to 50 and 100 ppm GA₃ induced significantly larger growth rates than those of GA₃ alone during the early growth stage. At 12 days after full bloom (DAFB) cell sizes of berries that received the combined treatments were significantly larger than those that were treated with 50 ppm GA₃. At harvest, there were no significant differences in seedlessness and titratable acidity between treatments with or without AMN. However, in Expt. 1, the total soluble solids content (TSS) in berries from the combined treatments tended to be slightly lower than that in berries treated with GA₃ alone; in Expt. 2, no difference was observed, except with the treatment of 100 ppm GA₃ + 25 mM AMN. AMN, when combined with 50 ppm GA₃, produced more larger berries than did the 100 ppm GA₃ treatment. These results indicate that treatment with 50 ppm GA₃ + 25 mM AMN has the potential to produce larger berries with slightly lower TSS than do treatments without AMN or with 100 ppm GA₃ alone.

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The effects of summer-pruning (SP) and gibberellin (GA) paste treatments on fruit maturation, sugar accumulation pattern and incidences of watercore in Japanese pear (Pyrus pyrifolia Nakai) 'Akibae' were examined. Watercore increased with fruit maturation in all treatments although the SP treatment was effective in reducing and delaying the occurrence of watercore. Only 4 and 33% of the treated fruit were afflicted with the disorder .compared with 13 and 50% of the control at full maturity in 2000 and 2001, respectively. That SP alleviated GA-induced watercore shown by the decrease in watercore index during maturation period but not at full maturity. GA-pasted fruit had higher GAs content and matured earlier than did the 'untreated one, but no significant difference in endogenous GAs levels in fruits from the control and the SP plot. Fructose and sorbitol were the major sugars at the early stages of fruit maturation but sucrose was the predominant one at the mature stage. SP treatment had no effect on fruit development, maturity indices, including flesh firmness, and ground color, but somewhat delayed the accumulation of sucrose forward harvest compared with those of the untreated plots. These results indicated that SP treatment might reduce watercore disorder through by delaying sucrose accumulation in 'Akibae' fruit.

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We examined physiological- and chemical-characteristics of watercored fruits induced by gibberellin (GA) paste treatment in Japanese pear (Pyruspyrifolia Nakai) 'Akibae' and 'Housui'. 'Akibae' was more susceptible to the development of watercore induced by GA treatment during fruit maturation than was 'Housui'. 'Akibae' fruit accumulated sucrose during its fruit maturation, reaching a level two times higher at maturity than did 'Housui'. Analyses of watercore tissues in two cultivars showed marked drops of firmness and total lipid contents concomitant with increases in electrolyte leakage and sugar content in both cultivars. Ethanol insoluble solids (EIS) contents in watercore fruit consistently decreased with the extent of the disorder in 'Akibae' but they remained nearly constant in 'Housui'. The amount of water- and trans-1, 2-cyclohexanediamine-N, N, N', N'-ielra-acetic acid (CDTA)-soluble pectic polysaccharides increased as watercore extended in both cultivars. 'Akibae' had more hemicellulose and cellulose (FW basis) fractions than did 'Housui', their weights decreased continuously as the watercore zone expanded. Therefore, we conclude that the physiological and chemical changes, corresponding to watercore development, induced by GA treatment progressed faster in 'Akibae' than they did in 'Housui'.

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To understand the relationships among the genomes of Diospyros kaki (persimmon) and its wild relatives, we performed genomic in situ hybridization (GISH) on somatic metaphase chromosomes of D. kaki, using digoxigenin (DIG)- 11-UTP labeled DNA of eight Diospyros species. In a series of GISH, it appeared that the D. glandulosa probe hybridized to D. kaki chromosomes resulted with the strongest signal intensity. When comparable GISH was conducted, using unlabeled DNA of D. kaki as a blocking DNA, the highest concentration of blocking DNA was necessary to block hybridization of the D. glandulosa probe. These results suggest that the genomes of D. kaki and D. glandulosa share many common DNA sequences, and that the genome of D. kaki is most closely related to that of D. glandulosa among the species tested.

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Shoot apices in young, facultative, short-day strawberry plants (Fragaria × ananassa Duch. cv. Tochiotome) were removed to examine the role of apical dominance in the development of axillary buds into branch crowns and stolons. At planting, plants had 3 fully-expanded leaves associated with visible axillary buds and 2 expanding leaves. Young, expanding leaves were removed along with shoot apices one day after planting. Plants were grown in a glasshouse maintained at 25°C from 6:00 to 18:00 and 19°C from 19:00 to 5:00; day length was extended to 15 hr. Within a few days, new stolons were formed on the primary crowns in the intact control plants, whereas new stolons on treated plants formed on developing branch crowns 3 weeks after removal of their apices. Treated plants formed 3 branch crowns, while control plants formed single branch crowns just below the primary inflorescences. The results indicate that the lower axillary buds can develop into branch crowns even under long days and warm temperatures if the buds are released from aoical dominance.

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The possible involvement of ABA and polyamines in the thermal acclimation process of photosynthesis in cucumber (Cucumis sativus L., cv. Nankyoku No. 2) was investigated. Photosynthetic activity was measured in the photosynthetic oxygen evolution rate and photosystem (PS) II chlorophyll fluorescence yield (Fv/Fm). Raising the growth temperature from 25/25°C to 38/38°C (day/night) caused gradual reduction in heat damage to photosynthesis from the prior exposure of intact leaves to 45°C. Thylakoids isolated from acclimated leaves were more thermostable than those from non-acclimated leaves, as judged by a lesser degree of reduction in PS II and PS I electron transport activity and the loss of 33-kDa polypeptides and manganese after exposure of isolated thylakoids to 40°C. The enhanced thermostability of the photosynthetic apparatus is probably attributable to the decrease in lipid unsaturation of thylakoid membranes. Exposing the plants to 38°C caused a rapid decrease in ABA content in leaves, which may exclude the possible involvement of ABA in increased thermostability of photosynthesis during the acclimation treatment. However, acclimation treatment caused a gradual increase in spermidine and spermine titers in leaves. Application of 5 mM spermidine or spermine to non-acclimated leaves made the photosynthetic apparatus more thermostable. Spermine treatment to isolated thylakoids from non-acclimated leaves also alleviated the heat-inactivation of photosystems. The results suggest that polyamines play a role in thermal acclimation of photosynthesis in cucumber.

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Ovule and seed abortion in Japanese morning glory (Ipomoea nil (L.) Roth.) was investigated to seek the causes for low seed production. Fruit sets in open-pollinated plants were 31% and 36%; numbers of seeds per mature fruit were 3.9 and 2.7; and percentages of mature seeds in total ovules were 17% and 16% for 'Akatsukinomurasaki' and 'Sunsmile Pink', respectively. Aborted ovules or seeds collected at 30 days after pollination (DAP) were smaller than normally developing seeds, although they were larger than unfertilized ovules at anthesis. Success or failure in fertilization could be determined by the presence of pollen tubes in the sections of ovules or developing seeds sampled at 3 DAP, but even unfertilized ovules without pollen tubes enlarged in developing capsules. In aborted ovules or seeds sampled at 4 DAP or later, the structures in embryo sacs degenerated. Observation of sections of aborted ovules or seeds revealed that 64% and 71% of ovules in 'Sunsmile Blue' and 'Akatsukinokurenai', respectively, were not fertilized, and that 5% and 2% of the fertilized ovules in the respective cultivars aborted. In each cultivar, about 4% ovules with a nucellus lacked the embryo sac. We conclude from our data that the high percentage of abortion that leads to low seed production in Japanese morning glory is attributable to the lack of fertilization and zygote formation.

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Embryogenic suspension cultures of Japanese morning glory (Ipomoea nil (L.) Roth.) cv. Violet were established from immature embryos by using a liquid N6- based medium (N6 inorganic salts and MS organic constituents) with 3 mg·liter^-1 NAA and 60 g·liter^-1 sucrose. Suspension cells showed a 1.5 to 2.5-fold increase in packed cell volume in one week. When suspension cell clusters were transferred to MS media, containing 0-0.5 mg·liter^-1 NAA, 60 g·liter^-1 sucrose, and 3.2 g·liter^-1 Gellan gum, 3.57-3.90 somatic embryos/cell clusters were produced. For shoot formation, these somatic embryos were transferred to MS medium with 0.2 mg·liter^-1 IAA, 2 mg·liter^-1 BA, 30 g·liter^-1 sucrose and 10 g·liter^-1 agar. The developing shoots were transferred to 1/2MS medium (half-strength MS inorganic salts) containing 30 g·liter^-1 sucrose and 10 g·liter^-1 agar for rooting. As many as 40 plantlets were obtained from a 0.1 ml packed cell volume of suspension cell clusters in 3-4 months. That the regenerated plants were successfully transferred to pots demonstrates that this plant regeneration system may facilitate micropropagation of mutant Japanese morning glory via embryo culture and transformation in I. nil.

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The European pears, 'Bartlett' (Ba), 'Aurora' (Au), 'Conference' (Co), and 'La France' (LF) were less susceptible to browning than were 'General Leclerc' (GL), 'Grand Champion' (GC), 'Beurre Hardy' (BH), and 'Josephine de Malines' (JM). The acetone extracts (AE) of Ba, Au, Co and LF had less phenolics than did GL, BH, GC and JM. The ratio of the phenolics in AE to total phenolics was also bigger in the latter 4 cultivars. The amount of monomeric and/or oligomeric flavan-3-ols (procyanidin) in methanol extracts (ME) was larger than that in the AE of Ba, Au, Co and LF, whereas the amount of procyanidin in the AE was similar to or higher than that in the ME of GL, BH, GC and JM. The relative degree of polymerization (RDP) of procyanidin assessed by the butanol-HCI method and the vanillin-sulfuric acid method showed that RDP of procyanidin in Ba and Au was low, RDP in LF, GL, BH, GC and JM was high in both ME and AE. Polyphenoloxidase (PPO) activity of 8 cultivars varied, the highest activity occurred in LF and the lowest in GC. Highly polymerized procyanidin in AE did not react with PPO directly in a test solution, whereas browning of the mixture occurred in the presence of PPO and chlorogenic acid. The resulting brown color was darker than it was in the mixture of chlorogenic acid and PPO only, indicating that highly polymerized procyanidin plays an important role in tissue browning and its level is strongly related to the potential browning in pear fruits.

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Young, non- induced to flowering cuttings of the non-branching chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura) 'Iwanohakusen' were exposed to 30/20°C (day/night) to test whether the treatment inhibited differentiation of axillary buds from the shoot meristem. For comparison, comparable cuttings were grown at 20/15°C (control). Axillary bud initiation on plants, grown at 30/20°C, occurred, and the initials developed to a shell zone and a small mound of meristematic tissue in the leaf axils. However, they did not progress to the prophyll and leaf primordial stages as did the axillary buds of the control plants. Thus, the elevated temperature treatment did not affect the initiation of axillary buds, but it inhibited the meristem to differentiate further. Therefore, we consider that exposure to high temperature prevents differentiation of the prophyll and leaf primordium.

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Heterozygosity and the mode of inheritance of various characters within selfs (S₁) of the Japanese taro, 'Mizu-imo' and a wild Thailand taro, 'Tha-1', and their F₁ and F₂ progenies, respectively, were investigated. 'Mizu-imo' has petioles with anthocyanin pigments and a low density of idioblasts with raphids, whereas 'Tha-1' has green petioles with numerous idioblasts that contain the needle-like calcium oxalate crystals. The idioblast densities in petioles of Si of 'Mizu-imo' and 'Tha-1' were lower than those of the parents; the heritabilities of idioblast density were, respectively, 0.487 and 0.511. The idioblast densities in petioles of F₁ and F₂ progenies segregated widely; their mean values, however, were intermediate between the parents, indicating that the heritability of idioblast is controled by polygenes. From segregation ratios of F₁ and F₂ generations, anthocyanin pigmentation in petioles of taro was presumed to be controlled by a single dominant gene. Therefore, the genotypes of 'Mizu-imo' and 'Tha-1' are postulated to be heterozygote and recessive homozygote, respectively, but the anthocyanin content is supposedly a quantitative character controlled by polygenes. Anthocyanin pigmentation in rachis of taro was presumed to be controlled by a single dominant gene. Therefore, the genotypes of 'Mizu-imo' and 'Tha-1' are postulated to be heterozygote and recessive homozygote, respectively. Development of the stolon was presumed to be controled by a single dominant gene. Therefore, the genotypes of 'Mizu-imo' and 'Tha-1' are postulated to be recessive homozygote and dominant homozygote, respectively.

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A comparison was made between broadcast application and row application with mulching in respect of efficiency of nitrogen fertilizer uptake and on the yield of carrots. The row fertilizing, sowing and mulching were managed in one cultural system utilizing improved combination of fertilizer applicator, seeder and mulcher. Carrot seeds were sown in an Andosol field in February 1999 and 2000, and a Cambisol field in February 2001. The plants were grown in plastic tunnels until rnid-April at which time they were uncovered; they were harvested in June. No significant difference in the yield was observed between broadcast application (N: 2.0 kg·a^-1) and row application (N: 1.0 kg·a^-1) but the nitrogen fertilizer efficiency was 61% in the row application, compared to 35% for broadcast application. Residual nitrate nitrogen in field subsoil after harvest in the row application was only 25% of in the broadcast application. It is concluded that for carrot production, a row application of 1.0 kg·a^-1 resulted in a good yield with low amount of residual nitrate nitrogen in the soil.

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We investigated the effects of the age of cabbage plug seedlings on the initial growth and carbohydrate partitioning after transplanting. Seedlings grown in 9-ml cells were transplanted into 350-ml pots 14, 21 or 28 days after sowing. Analyses for soluble sugar and starch revealed that they accumulated more in leaves than in roots. Starch concentration in leaves was higher than that of soluble sugar; it increased with seedling age. During seven days after transplanting, the relative growth rate decreased with increasing seedling age; this decrease was greater in shoots than in roots. Lower leaves enlarged more slowly after transplanting than did leaves at upper positions. The accumulated starch in the 1st leaf decreased rapidly after transplanting. Root growth of 28-day seedlings after transplanting was retarded less by shading of the 1st leaf than by leaf removal, while that of 14-day seedlings was retarded equally by both treatments. In 21-day seedlings, the distribution rate of ¹⁴C-photoassimilates from the 1st leaf to roots increased after transplanting. These results indicate that starch, accumulating in leaves before transplanting, hydrolyzed to sugars that rapidly translocated to the roots after transplanting.

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Cattleya (Sophrolaeliocattleya Estella Jewel 'Kazumura') and Cymbidium (Cymbidium Sazanami 'Harunoumi') orchids were grown under strong and weak solar UV radiation for 80 days from August 1 to test the effects of radiation on foliar pigment contents and antioxidative enzyme activities in two-year-old leaves. Foliar chlorophyll and carotenoid contents in both Cattleya and Cymbidium leaves grown under strong UV radiation were lower than those under weak UV radiation. Flavonoid content in Cattleya leaves grown under strong UV radiation was also lower than that under weak UV radiation, but that in Cymbidium leaves grown under strong and weak UV radiation was the reverse. Activities of ascorbate peroxidase after 10 days and catalase from 20 to 40 days in Cattleya leaves exposed to strong UV radiation were higher than those grown under weak radiation. In contrast, activities of superoxide dismutase and catalase after 20 days in Cymbidium leaves grown under strong UV radiation were lower than those of leaves exposed to weak radiation. Thus, our results revealed that the intensity of UV radiation differently affected the leaves of antioxidative substances and enzymes activities of the two orchid species.

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The effect of onion oil on the prevention of browning of shredded letuce was examined and its inhibitory components sought. It is not necessary for the oil to be in direct contact with shredded lettuce to inhibit browning, the active components are believed to be volatile. GC-MS analysis revealed that the main components of the onion oil were dipropyl trisulfide, dipropyl disulfide and methyl propyl trisulfide. Although the active fractions were widely dispersed in the high performance liquid chromatogram when the browning inhibitory effect of each fraction was tested by the fractionation of the onion oil, the dipropyl trisulfide fraction was the most inhibitory, followed by methyl propyl trisulfide fraction, dipropyl disulfide fraction and propyl propenyl disulfide fraction in the weakening order. Among the tested components, dimethyl trisulfide possessed the strongest specific activity, but its quantity was very small. These results suggest that inhibition of browning of shredded lettuce is mainly due to the main components of onion oil and that trisulfides are more inhibitory than disulfides.

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Effects of shading and soil moisture on formation of the idioblasts containing calcium oxalate raphides in petioles of three taro cultivars, Egu-imo, Takenoko-imo and Mizu-imo were investigated. The densities of the idioblasts containing calcium oxalate raphides, which are the cause of acridity in taro, decreased in proportion to the amount of shading in all cultivars. The frequencies of idioblasts with raphides under 100 and 60% shading decreased to about 30 and 60-78% in comparison to those in full sun. In relation to soil moisture content, the petioles of taro plants grown in moist soil contained less idioblasts than petioles of grown in a relatively drier soil. Shading and soil moisture resulted in large differences in idioblast densities in 'Egu-imo' and 'Takenoko-imo' but not in 'Mizuimo'. Under similar environmental stresses, petioles of young, upper leaves produced more idioblasts than those at lower nodal positions. These results indicate that the amount of raphides formed in the idioblasts is a sensitive response of taro plants to external environmental factors, in this case, the degree of shading and soil moisture content. Apparently, light and dry soil conditions promote the production of oxalic acid in taro petiole and the uptake of calcium ions by the corm and/or roots.

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Ethylene production and activities of three cell wall degrading enzymes [polygalacturonase (PG), α-L-arabinofuranosidase (AF-ase) and β-D-galactosidase (GA-ase)] during rapid softening of Japanese persimmon 'Saijo' fruit were investigated. Ethylene production and activities of PG and GA-ase in fruit picked at the late mature stage were 1/100, 1/10 and 1/2 of young immature fruit, respectively. The late mature fruit softened somewhat slower than young fruit. Activity of AF-ase both in green immature and fully mature fruit during rapid softening increased twice as much as the fruit at harvest, indicating that the enzyme plays an important role in the softening process. That AF-ase was already active in firm fruit at harvest suggest that another, more direct factor, might also be associated with the softening. These results suggest that the degradation of non-cellulosic neutral polysaccharide by AF-ase is at least related to the rapid softening of Japanese persimmon 'Saijo' fruit.

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