To clarify the floral inhibition in cherimoya in warm environments, the number of flowers, floral morphology, nodal position, days to flowering, and flowering period were determined under 20/15°C and 30/25°C day/night temperature conditions throughout two years. Floral differentiation of cherimoya was more favorable at 20/15°C than at 30/25°C. More flowers were produced at 20/15°C and the flowering period was longer. Flowers were also larger at 20/15°C, however, the growth rate of floral organs was faster at 30/25°C. The temperature effects were more pronounced in the second year. The floral responses to temperature were different depending on the nodal positions, because of the different developmental processes. The number of the floral buds at the basal part of new shoot (at the 1st-3rd nodes) at 30/25°C was similar to that at 20/15°C in the first year, but it became smaller than that at 20/15°C in the second year. On the other hand, no distal buds of new shoot (at the 4th-more distal nodes) were produced at 30/25°C throughout the experiment period. The floral buds at the basal nodes differentiated almost a year previous to their anthesis, whereas the distal buds differentiated in synchronization with the shoot extension, about 5 weeks before anthesis. The axillary buds for basal flowers of the next season had already differentiated even in one-week-old leaf axils. Cherimoya produced an axillary multiple bud complex for the subsequent bloom and flush. In a 4-week-old leaf axil, a few floral buds with one or two vegetative buds usually developed at 20/15°C, while none or one floral bud with several vegetative buds developed at 30/25°C. The bud differentiation period was found to be the most temperature sensitive stage to influence flower number and morphology. Thus, exposure of cherimoya trees to a warm environment a year previous to the flowering and during shoot extension, respectively, was suggested to inhibit flowering at the basal and distal nodes.

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The effects of different amounts of nitrogen, applied in the soil, on the accumulation of nonstructural carbohydrate in leaves and roots were determined as well as on some characteristics of chloroplasts in one-year-old peach trees (Prunus persica) grown in 500-ml pots. The amounts of nitrogen, applied as NH₄NO₃, were as follows : 0 mg/pot (N-0), 75 mg/pot (N-75), 150 mg/pot (N-150), 300 mg/pot (N-300), and 600 mg/pot (N-600). The weights of stems and leaves and shoot length were greatest in N-150 and N-300 trees, whereas root weights were heaviest in N-75 and N-150 trees. Shoot and root growth was significantly reduced in N-0 and N-600 trees. Leaf chlorophyll content (μg cm^-2), total soluble sugar (% dry weight), and nitrogen content (% dry weight) of leaves and roots increased with increased application of nitrogen, whereas starch content of leaves was inversely proportional to the amount of nitrogen administered. The amount of sorbitol (% fresh weight) in leaves was proportional to the growth rate of the trees. Chlorophyll was stained more heavily by 4', 6-diamidino-2-phenylindole in N-600 leaves than in N-0 leaves ; the staining concentrated at the periphery of chloroplasts, indicating an accumulation of starch. The level of the enzyme, ribulose-bisphosphate carboxylase-oxygenase (RuBisCO), increased with increased applied nitrogen, reaching maximum at N-300 and N-600. Total soluble sugar in roots was high in vigorous trees, where root starch content was inversely proportional to root growth.

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Phenolic compounds extracted from the graft union of heterograft trees (Prunus persica/P. tomentosa) were analyzed by histochemistry and HPLC methods and compared with those on homograft trees (P. persica/P. persica). A DMACA (p-dimethylamino-cinnamaldehyde) staining method showed that at early stages after budding the phenols were localized mainly in the callus cells, in the new xylem and in the cortical tissues of the heterograft combination and persisted even 6 months after budding. These phenolic compounds frequently surrounded necrotic tissues which seemingly impeded the union between the scion and rootstock. From the HPLC analysis, four phenolic compounds were found as major components in both rootstocks, but two of them were not detected in the phloem of dwarfing P. tomentosa. The chemical nature of these peaks was unknown, except one was identified as catechin ; however, based on their UV spectrum, behavior in TLC and retention time, our assignments are tentative. In general, the phenolic content in the phloem tissues was higher in homograft than in heterograft trees, particularly peaks # 1 and # 3, which we suppose are prunin and naringenin respectively. However, in the xylem tissues on heterograft trees the phenolic concentration was much smaller and the patterns from the stock to the scion were different from those observed on homograft trees. Peak # 1, prunin and Peak # 2 accumulated in the phloem above the heterograft union ; whereas in the xylem, Peak # 1, prunin, and Peak # 3, naringenin, were present at low amounts. Catechin, a low molecular weight flavan occurred in similar amounts in the xylem of both combinations, accumulating at the graft union, whereas the phloem, of the homograft contained a larger amount of catechin.

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Transgenic plants of trifoliate orange (Poncirus trifoliata Raf.) possessing chimeric genes, a promoter of cauliflower mosaic virus (CaMV) 35S RNA and structural gene of rolC of the Ri plasmid (35S-rolC) or promoter region (5' upstream of non-coding DNA) of rolC and the structural gene of rolC (rolC-rolC) were obtained by Agrobacterium-mediated transformation. The stable integration of the genes was confirmed by polymerase chain reaction (PCR) and Southern blot analyses. The transformed plants are dwarfed, but the degree of dwarfing differed among individual plants and between plants with 35S-rolC and those with rolC-rolC. The internodal lengths of the transformants with 35S-rolC were much shorter than those of nontransformed control plants. Eighteen out of 20 transformants with 35S-rolC were 40% shorter than the control. The internodal length of plants with rolC-rolC, in contrast, ranged from 10-120% of control plants. Almost all transformants possessed higher rooting abilities than did the control plants.

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Using potted peach (Prunus persica Batsch.) trees at the fruit maturation stage, fruiting effects on sorbitol and starch contents in leaves from day to night as well as before and after fruit removal were examined. Sorbitol content per unit fresh weight in leaves before fruit removal increased significantly during the day ; it decreased at night. Within one day after fruit removal, sorbitol increased to a level greater than that before fruit removal, whereas the decrease at night did not differ significantly between before and after fruit removal. The diurnal changes in starch content of the leaves exhibited a similar pattern to those of sorbitol before fruit removal. Likewise, within one day after fruit removal, starch content increased during the day to a higher level but the decrease at night was smaller compared to the level before fruit removal.

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An understanding of plant-nutrient relationship is essential if the production of soybean in the saline soils of the world is to be made viable. Radiophosphorus (³²P) and radiosodium (²²Na) were administered to greenhouse-grown soybean plants (average height : 25 cm) cultured in Hoagland solution to investigate the uptake of phosphorus (P) and sodium (Na) as a function of increasing salinity from zero to 120 mM NaCl. P uptake depends on the concentration of inorganic P (Pi) in the nutrient medium. The addition of 8 mM Pi to the saline medium enhanced P accumulation significantly (p<0.01) by all plant parts. Polynomial regression equation expressed the relationship between ²²Na activity and increasing salinity in leaves to be cubic (r²=1); a quadratic relationship prevcailed for the stem. The ³²P activity versus increasing salinity was linear with a positive slope for the roots, but a negative slope for the the stem. Shoot and root dryweights decreased with increasing salinity. Leaf-chlorophyll content increased at low but decreased at high salinity levels. It is recommended that saline soils are fertilized with Pi to ameliorate salt-stress in soybean.

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Seventy-four sweet pepper accessions (Capsicum annuum L.), 59 hot pepper accessions (C. annuum), and 63 other Capsicum spp. accessions were screened for resistance to bacterial wilt (Ralstonia solanacearum (Smith 1896) : Synonym Pseudomonas solanacearum E. F. Smith) to find the resistant materials. After the plants were transplanted to a field infested with R. solanacearum at NIVOT, then an inoculum suspension of R. solanacearum was poured around them. For evaluation of resistance, each accession was scored by using a disease index ranging from 0= symptomless to 4= death. Resistance of highly resistant accessions whose disease index was less than 1 was evaluated again by a seedling test. Highly resistant accessions were found in sweet peppers, hot peppers, and other Capsicum spp., particularly in sweet pepper, and their commercial F₁ cultivars. Therefore, bacterial wilt infection can be controlled by the use of the resistant cultivars identified in this study. 'Mie-Midori' and its progenies were used as parents for the breeding nearby all resistant Japanese green pepper cultivars identified in this study. In sweet and hot pepper which originated in Asia i.e., Japan, China, etc., exhibit high or moderate resistance to bacterial wilt, whereas those from other areas such as North and South America, Europe, etc. did not possess this characteristic.

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The effects of organic acids on protoplast culture in spinach were investigated. Protoplasts obtained from young leaves were cultured in a modified 1/2 Murashige and Skoog's inorganic medium, containing KM8p vitamins, 1.0 mg·liter^-1 BA, 1.0 mg·liter^-1 2, 4-D, and 0.5 M mannitol or 0.5 M glucose supplemented with sodium pyruvate, citric acid, malic acid, fumaric acid, succinic acid, maleic acid, or several combinations thereof. When 0.5 M glucose was present in the medium as an osmoticum, the organic acids (except for malonic acid) stimulated protoplast division, but when 0.5 M mannitol was present instead of glucose, they inhibited the division of protoplasts. Citric acid was most effective in protoplast division, the highest frequency being obtained in the medium supplemented with 0.1 mM citric acid and 0.5 M glucose. The growth of the colony followed a trend similar to that of protoplast division, yielding numerous micro-calli. Citric acid in the protoplast culture medium also induced maximum shoot regeneration. Division of protoplasts obtained from leaves of different plant ages was enhanced by citric acid ; a high frequency of cell division was maintained in seedlings up to 25-day-old. The addition of citric acid to the medium promoted protoplasts division in the density range of 3.0 to 20×10⁴ protoplasts·ml^-1, but it was more effective at lower plating densities. Therefore, our results confirm the usefulness of citric acid for spinach protoplast culture.

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Anthers of three male sterile mutants of tomato plants and their original cv. First were subjected to several factors which affected callus induction and shoot regeneration. Callus induction capacity was significantly improved by the presence of ms genes which disrupt microsporogenesis at meiosis in the anthers of Fms-2 line. Fms-1 and Fms-3, which block microsporogenesis at microspore and tetrad formation respectively, were inferior to Fms-2 in callus induction. Experiments carried out with the Fms-2 line demonstrated that the developmental stage of the explant was a crucial factor in callus formation and that optimum stage was between pre-meiosis and metaphase I, which corresponds to the stage just after the blockage of microsporogenesis. Callus was efficiently induced from anthers, pretreated at 4°C for 3 days, on MS medium, supplemented with 5.0 mg·liter^-1 IAA and 2.5 mg·liter^-1 zeatin, under a 16-hr photoperiod. The highest frequency of shoot differentiation was achieved on MS medium, supplemented with 0.2 mg·liter^-1 kinetin.

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Ploidy levels of the seedlings derived by crossing diploid accessions (2n=28) of wild taro [Colocasia esculenta (L.) Schott] from Bangladesh were analyzed to seek the origin of triploids (2n=42). Six and two triploids were detected among 1041 hybrids and 354 selfs, respectively, although most hybrid and selfed seedlings were diploid. These results indicate that triploids in taro originated both in hybrid and selfed seedlings of diploids. Isozyme analysis at the Aat-1 of aspartate aminotransferase of the six hybrid triploids revealed that the seed parent was the double genome donor in five, whereas the pollen parent served as the donor in one. Therefore, both seed and pollen parents are able to serve as a double genome donor of the triploids.

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The possible involvement of oxygen radical generation in chilled leaves in the different chilling tolerances of cucumber (Cucumis sativus L.) cultivars was investigated. Plants with their first expanded leaves were exposed to 3°C or 15°C in the dark for 24 hr ; they were warmed for another 24 hr at 28/22°C (day/night) with a 12-hr photoperiod. Chilled leaves subsequently developed chilling injury symptoms (marginal and inner necrosis) and accumulated malondialdehyde (MDA). Both chilling injury and rate of MDA accumulation were largest in 'Suyo', intermediate in 'Sharp I', and smallest in 'Jinchun No.3'. In leaves of chilling-sensitive 'Suyo'; NADPH-dependent superoxide and hydrogen peroxide-generating activities increased markedly during chilling. Hydroxyl radical-generating activities as indicated by methane sulfonic acid formation increased rapidly upon warming, with a concomitant decrease in activities of superoxide and hydrogen peroxide generation. The NADPH-dependent superoxide-generating activity increased again during the later warming period. In contrast, chilled leaves of chilling-tolerant 'Jinchun No.3' showed only a slight increase in the oxygen radical generation activities during both chilling and warming periods. In chilled leaves of 'Sharp I', activities of hydrogen peroxide and hydroxyl radical generation increased during the early warming period, whereas those of NADPH-dependent superoxide generation occurred later. The NADPH oxidase activity in chilled leaves changed with time similarly to the activity of NADPH-dependent superoxide generation in all cultivars examined. The results indicate that chilling injury of cucumber leaves is caused by the increased oxygen radical generation under chilling and subsequent warming conditions. This increase in oxygen radical generation may be triggered primarily by the increased NADPH oxidase activity, the rate of which determines the degree of chilling tolerance in cucumber cultivars.

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To develop the male sterile line of Allium fistulosum L., cytoplasmic substitution by continuous backcrossing was performed using A. galanthum Kar. et Kir. as a cytoplasm donor. Pollen and seed fertility in F₁ hybrid and the backcross progenies were examined. In backcrossing, progenies were selected in the direction of high seed fertility from B₁ generation and in the directions of low and high pollen fertility from B₂ generation. The pollen fertility in F₁ hybrid was 65% ; that in B₁ and B₂ generations varied from 10 to 77%, 0 to 98%, respectively. Almost all plants in B₃, B₄, and B₅ generations selected in the direction of low pollen fertility were pollen sterile. The decrease of pollen fertility in F₁ hybrid is attributed to the hybridity of nuclei. However, it is difficult to relate pollen sterility observed in the backcross progenies to the hybridity of nuclei because the nuclei of those plants are mostly composed of genomes of A. fistulosum. Therefore, it is concluded that the pollen sterility observed in the backcross progenies is attributed to incompatibility between the cytoplasm from A. galanthum and the nucleus from A. fistulosum. In each of B₃, B₄, and B₅ generations selected in the direction of high pollen fertility, pollen fertile and pollen sterile plants segregated at a ratio of approximately 1 to 1. This finding strongly indicates that the pollen fertile plants had a single dominant fertility restoring gene which originated from the nuclear genome of A. galanthum and that the pollen sterile plants had not this gene. Although the seed fertility somewhat varied among the progenies at each backcross generation, it could be improved with frequency of backcrossing, and some plants had higher seed fertility than A. fistulosum. Analyses of chloroplast and mitochondrial DNAs proved that all the backcross progenies examined inherited the cytoplasm from A. galanthum. From these results, we conclude that the cytoplasm of A. galanthum is useful for developing the male sterile line of A. fistulosum.

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Treatments with sodium benzoate and n-propyl gallate as free radical scavengers slightly delayed the wilting of perianth in detached gladiolus florets. Superoxide dismutase (SOD) activity of the perianths sharply decreased in 2 days after their full unfolding (DAU) when they commenced to wilt. The decrease of SOD activity was alleviated by treatments with 300μM cycloheximide (CHI) which prevented perianths from wilting. Specific activity of catalase (CAT) of perianths did not markedly change, but CAT activity on the basis of perianth decreased concomitant with their wilting. CHI slightly decreased specific activity of CAT. Peroxidase (POD) activity of the perianths sharply increased 1 DAU. This increase was almost completely suppressed by CHI treatments. These results indicate that the free radicals are involved with the decline of SOD activity, increase of POD activity, and in the wilting process of gladiolus perianths.

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A sexual incompatibility mechanism prevents reciprocal crosses between Hydrangea macrophylla f. hortensia (Lam.) Rehd. and H. arborescens L. No viable hybrid plants have been produced by conventional hybridization because the progenies exhibit hybrid lethality at a young seedling stage. For circumventing hybrid lethality, we cultured cotyledonary segments of embryos derived from crosses of H. macrophylla and H. arborescens. The cotyledonary segments formed callus. Fifteen callus lines, which regenerated plantlets, were established from crossings of H. macrophylla 'Blue sky'×H. arborescens 'Annabelle'. However, only a single callus line among them regenerated plantlets which could be transplanted to soil. Hybridity of the regenerated plants was examined by morphological, cytological characteristics, and RAPD markers : morphologically, the regenerated plants appeared intermediate to the parents ; the regenerated plants were aneuploids having a chromosome number, 2n=42 ; whereas those of the parents H. macrophylla 'Blue sky' and H. arborescens 'Annabelle' were 2n=52 and 2n=38, respectively ; the RAPD banding patterns of the regenerated plants exhibited the same hybrid bands as the parents. The hybridity of the regenerated plants was probably confirmed by the above methods.

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Enzyme for degrading pheophorbide a (Pheid a), a chlorophyll (Chl) catabolite, was found in a crude extract prepared from tomato fruit. Application of 10mM CaCl₂ strongly enhanced the enzyme activity. In the presence of EGTA, the enzyme activity was low and activation of enzyme by CaCl₂ did not occur. An inhibitor of calmodulin, trifluoperazine (1mM) inhibited the enzyme activity, and CaCl₂-activation of the enzyme. ATP (5mM) enhanced the enzyme activity as strongly as did CaCl₂. Effects of ATP and CaCl₂ were not additive. Inhibitors of protein kinases, H-7 and KN-62, fully reversed the activation of the enzyme by CaCl₂. We conclude that the effects of ATP and CaCl₂ on the enzyme activity are mediated with protein kinases that are activated by calcium, utilizing ATP as the phosphate donor. Calmodulin is likely to be involved in the process (es). In addition, this enzyme is inactivated by 2, 2'-bipyridyl and salicylic acid. The products of Pheid a degradation in our system were fluorescent compounds according to a rapid scanning of 3-D fluorescent spectrum measurement. We designated them Tom-FCCs (Tomato fluorescence chlorophyll catabolites). Tom-FCCs have strongest intensity of fluorescence near 300nm, and emission wavelengths at 355 and 435nm. In the presence of CaCl₂, production of Tom-FCCs was enhanced which provides the evidence that the final step in Chl degradation is regulated by calcium and protein kinase in vitro.

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The degradation of chlorophyll (Chl) α in crude extracts of ethylene-treated Citrus unshiu (C. unshiu) fruit was examined by reverse phase HPLC analysis. In the present condition, a new Chl derivative (new pigment), C13²-carboxyl-pyropheophorbide (Pyrophed) α, chlorophyllide (Chlide) α and Pyrophed α were eluted as Chl α derivatives. The new pigment was formed when Chl α or Chlide α was incubated with the crude extracts, but not the substrates, pheophorbide (Phed) α, Pyrophed α and pheophytin (Phytin) α. Analysis by reverse phase HPLC revealed that the new pigment was Mg-C13²-carboxyl-Pyrophed α, which was also formed in crude extracts of non-treated C. unshiu fruits. These results indicate that the novel catabolic pathway of Chlide α into Pyrophed α could exist in C. unshiu fruit.

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The mechanism of ethylene (C₂H₄) action on type I reactions (the loss of phytol, the loss of magnesium, and the modification of the side chains of an isocyclic ring of the chlorophyll (Chl) structure) during Chl catabolism in Citrus unshiu (C. unshiu) fruit was investigated by using inhibitors of protein synthesis. C₂H₄ treatment promoted the degreening through increased chlorophyllase (Chlase) activity of C. unshiu fruit peel held in the dark. Cycloheximide (CH), an inhibitor of cytoplasmic protein synthesis, inhibited the C₂H₄-enhanced degreening. Chloramphenicol (CP), an inhibitor of plastid protein synthesis, did not inhibit the effects of C₂H₄. On the other hand, C₂H₄ treatment did not significantly increase chlorophyllide (Chlide)-degrading enzyme (CDE) activity nor C13²-carboxyl-pyropheophorbide (Pyrophed) forming enzyme (CPFE) activity of C. unshiu fruit peels. Likewise, CDE and CPFE activities in C₂H₄-treated C. unshiu fruit were unaffected by CH-and CP-treatments. A high positive correlation between the degree of greenness of C. unshiu fruit peel and Chlase activity was obtained : Y=1.368 X-16.038, (r=0.992), where X and Y are intensity of the green color of the peel and Chlase activity, respectively. However, correlations between the degree of greenness of the peel and 1) CDE activity (Y=0.024 X+98.030, r=0.460) and 2) CPFE activity (Y=0.015 X+103.581, r=0.424) are low. These results indicate that C₂H₄ appears to enhance the degreening of the peel through de novo synthesis of Chlase, and that Chlase is the "key" enzyme in the degreening process.

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Ethylene biosynthesis and expression of 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) and ACC oxidase (ACO) genes were investigated in immature [harvested at 10 days after anthesis (DAA)] and mature (harvested at 35 DAA) cucumber fruits. During storage or in response to exogenous ethylene, ACS activity in fruit harvested at 35 DAA remained at low levels resulting in very little ethylene production, although ACO activity was markedly enhanced by the treatment. Northern blot analysis revealed that transcripts for CS-ACS1, a cucumber ACS gene highly homologous to CMe-ACS1 which is expressed during melon fruit ripening, did not accumulate in any mature cucumber tissues. Exogenous ethylene did not induce accumulation of CS-ACS1 transcripts but suppressed CS-ACS2 mRNA accumulation in the peel and mesocarp tissues. CS-ACO1 transcripts were increased by exogenously applied ethylene, but CS-ACO2 was constitutively expressed regardless of the treatment. The results confirm that cucumber belongs to non-climacteric fruits because CS-ACS1 expression was not induced during fruit ripening or in response to exogenous ethylene.

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AVG (2-aminoethoxyvinylglycine) applications to flower clusters of 'Kyoho' grapes before anthesis were investigated with respect to berry set, seeded berries and berry quality from 1994 to 1997. Flower clusters were dipped in AVG at 25, 50, 75, 100, or 300ppm 1 to 3 weeks before anthesis. At 50 to 300ppm AVG increased the rates of berry set and seeded berries. Higher concentrations applied before anthesis and a lower concentration applied toward the end of anthesis also were effective in increasing berry set and seeded berries. There were no significant differences in soluble solid content and titratable acidity between the control and AVG-treated berries, but the treated berries were somewhat heavier. ACC content in AVG-treated florets was lower : the ethylene evolution rate from florets correlated positively with ACC content. Water soluble growth inhibitors of pollen tube growth in the pistils decreased significantly after AVG treatment, compared to the untreated control. AVG treatment also increased the numbers of ovules per ovary and seeds per berry.

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Differences in berry set between primary flower clusters formed on primary shoots and secondary flower clusters formed on lateral shoots of 'Kyoho' grape were investigated. The set was examined in relation to : a) developmental stages of florets, pollen, and ovaries, b) activities of pollen tube growth inhibitors in pistils, c) endogenous plant hormones in florets, and d) growth of pollen tube in the pistils. The sizes of florets and pistils in secondary flower clusters at anthesis were smaller than those in primary flower clusters. This difference was related to the suppression of cell division in pericarps in flowers of the secondary clusters. However, there was no significant difference in ovule size. Pollen from florets of secondary flower clusters was smaller, but the percent germination on agar was higher than that from florets of primary flower clusters. The percent berry set, the number of seeded berries per cluster, and seeds per berry in secondary flower clusters were significantly higher than those in primary flower clusters. Compared to florets of secondary flowers, the levels of IAA and cytokinin tended to be higher in florets of primary flower clusters, whereas the levels of GA and ABA were always lower. Water soluble inhibitors of pollen tube growth in pistils of primary cluster florets were higher than those in the secondary flowers. Thus, the growth of pollen tubes in pistils of primary flower clusters was slower than in that of secondary flower clusters, so that no tube reached the micropyles of ovaries of primary flowers within 24 hr after pollination. From these findings, we attribute the increase in berry set of secondary flower clusters to : 1) the low levels of IAA and cytokinin, 2) high concentrations of ABA and GA in florets and pollen tube growth inhibitors in the pistils.

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Growth inhibiting substances of unknown origin found in the nutrient solution nourishing growing cucumber plants were isolated and identified. The growth inhibitors were absorbed on activated charcoal and extracted therefrom by an organic solvent. These extracts were partitioned into four fractions with different solvents. 1. The inhibiting activity for cucumber plants was detected in the acidic diethyl ether soluble fraction, but not in others. 2. The active substances in the above fraction analyzed by GC/MS method were identified as : benzoic acid, p-hydroxybenzoic acid, 2, 4-dichlorobenzoic acid and phthalic acid. 3. The above substances were assayed for their activity on cucumber seedlings by adding various concentrations to the nutrient solution. 2, 4-dichlorobenzoic acid exhibited the strongest inhibitory activity ; others were very weak. 4. 2, 4-dichlorobenzoic acid at 2 μmol·liter^-1 in nutrient solution had no effect on plant growth but it lowered fruit yield and shortened fruit harvesting period, compared with the control. Any inhibition was eliminated by adding activated charcoal to the nutrient solution. 5. Thus, 2, 4-dichlorobenzoic acid, the most effective inhibitor in the nutrient solution nourishing growing cucumber plants can be eliminated by adding activated charcoal.

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Inflorescences of Gypsophila paniculata L. 'Bristol Fairy', harvested with 30% of their buds open, were held in deionized water and kept at 20, 23, 26, or 29°C. Petals of flowers held at 20°C became translucent and desiccated, although the floret shape remained unchanged. When the inflorescences were kept at 23 °C or higher, the petals of open florets turned brown, wilted and inrolled into calyxes ; commercially the phenomenon is called "flower browning". Following a pulse of 0.2 mM silver thiosulfate (STS), a continuous supply of 4% sucrose and 0.26 mM 8-hydroxyquinoline sulfate (8-HQS) to bud-cut inflorescences not only enhanced bud opening but also inhibited the occurrence of "flower browning" even under an inductive stress of 25°C. Days between bud-cutting, when the terminal floret had just open, to the marketable stage with 30% of open buds, were 5 and 3 at 20 and 25°C, respectively. Light intensity of 15.0 W·m^-2 during the forcing period for bud opening after harvest was desirable for getting marketable inflorescences with good quality and long vase life. The rate of respiration by cut inflorescences increased exponentially with increasing temperature ; the respiration rate at 20°C was c. 210 μmol CO₂·hr^-1·100gfw^-1 (Q₁₀=1.5). At 25°C, a severe decrease in sugar content of florets occurred on cut inflorescences. On days 2 and 4, glucose and fructose contents per floret at 25 °C were one-half to one-third of those at 20°C ; whereas sucrose content was almost one-fourth. Application of sucrose helped maintain a high soluble sugar level in florets which may contribute to prevent petals from wilting and browning even under inductive temperature conditions. Bud-cut inflorescences treated with STS could be stored with their stem base in a solution containing sucrose and 8-HQS at 1°C for 4 weeks without lowering cut-flower quality and longevity.

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Freshly harvested 'Bridal Pink' roses (Rosa hybrida Hort.) were held in deionized water and placed in a room at 20°C under continuous dark, light, or a 12-hr photoperiod. Cut flower weight, water uptake, transpiration, petal water potential, and bud opening stage were measured at 4-hr intervals. Under continuous dark conditions, water uptake and transpiration rates were slow, ranging around 1 g·100 gfw^-1·hr^-1. Because transpiration did not exceed the water uptake throughout the three-day experimental period, a steady increase in fresh weight resulted. Petal water potential ranged around -0.2 MPa, decreased slightly (becoming more negative) after 7 : 00. Under continuous light, water uptake and transpiration rates changed cyclically with increases between 7 : 00 and 19 : 00. Transpiration rate began to exceed the water uptake at 7 : 00&acd;11 : 00 on Day 3 ; concurrently, fresh weight, which had been increasing began to decrease. Petal water potential decreased between 7 : 00 and 19 : 00 and increased from 19 : 00. But the tendency for water potential was to gradually decline with time. Although bud opening stage was advanced early in the morning under both dark and light conditions, it proceeded faster under latter. Diurnal periodicity was detected in some parameters obtained under the light conditions by using Fourier analysis. Fluctuations in the water uptake and transpiration rates closely corresponded to diurnal periodicity under a 12-hr photoperiod, being elevated in the light and depressed in the dark. These diurnal changes in water uptake and transpiration were greatest during the third and fourth light periods. Transpiration exceeded water uptake in the fourth light period and thereafter. Thus, fresh weight initially increased but decreased in the light and increased again in the dark. But the tendency for fresh weight was to gradually decline with time. Petal water potential decreased in the light and increased in the dark, but the recovery in the dark became insufficient so that the petals finally wilted completely. Bud opening stage advanced immediately after the beginning of light periods except for Day 1 and 2 during which it lagged.

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Samples of dorsal leaf surfaces taken from 16 species of the subgenus Rhododendron section Tsutsusi were examined to establish distinctive characters indicative of the presence of Ryukyu azalea genes in Kurume azalea hybrids family. The Suzuki Universal Micro-Printing method was used to prepare microscope slides for examination with a light microscope, equipped with differential interference contrast optics. Specific characteristics of the epidermal cells, cuticular topography, and stomata and the existence of trichomes were studied. Recording specific morphological characteristics is an accepted technique for taxonomically differentiating species within section Tsutsusi. Eight groups of the 16 species could be characterized by dorsal leaf features alone. Because the frequencies and sizes of stomata overlapped among species, they were useless as identifying taxonomic characters. Based on our data, R. macrosepalum and R. mucronatum var. ripense which are original species of Ryukyu azalea, are clearly distinguishable from R. kaempferi, R. kiusianum and R. kiusianum var. staense, which are generally considered to be the original species of Kurume azalea hybrids family.

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The maturity of 'Carabao' mango fruits at the time of harvest was determined by specific gravity. Fruits that sank in 1% salt solution (S) were considered fully mature. Fruits that sank in water but floated in the 1% salt solution (Sw) and those that floated in water (Fw) were categorized as relatively immature. All fruits were subjected to a hot water treatment (52-55°C, 10min.) within a day of harvest. Half of the lot was subjected to the vapor heat treatment (VHT) to a pulp temperature of 46°C for 10min. ; the other half served as the untreated control. The fruits were then stored at 25°C. 1. Sw fruits attained peel color index (PCI) 5 on day 3, whereas S and Fw fruits reached PCI 4 on day 4 in control. VHT had no effect on the rate of peel color progression ; internal breakdown, anthracnose, and stem end rot did not occur in any treatments during the experimental period. 2. Starch content decreased in all fruits during storage ; VHT fruits had lower starch content than the control immediately after treatment. 3. Among the sugars in the fruit, sucrose had the highest concentration. Total sugar and sucrose contents in VHT-fruits were higher than were those of the control. 4. Citric acid concentration was highest among three organic acids ; it decreased during ripening. VHT effectively reduced citric acid in S or Sw fruits on day 1. 5. Respiration rate of fruits was unaffected by VHT.

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To elucidate the mechanism of ethylene-enhanced degreening in satsuma mandarin (Citrus unshiu Marc. c.v. Nichinan No. 1) fruits, a water-soluble chlorophyllase (chlorophyll-chlorophyllide-hydrolase, E.C. 3.1.1.14) was prepared from the peel of ethylene-treated fruits. The maximum catabolic rate of chlorophyll a (Chl a) to chlorophyllide a occurred in the presence of 30&acd;40% concentration of acetone at 30°C. Optimum concentrations of substrate and protein for the reaction were 12.4 μM and 2.6 mg/4.5ml, respectively. The optimum pH value was 7.6 with a phosphate buffer, 7.86 with a borate buffer, and 7.5 with an acetate buffer. At pH 7.6 (phosphate buffer) and 25°C in the presence of 33% acetone, the tentative Km value for Chl a hydrolysis activity was approximately 6.5 μM. Moreover, when the reaction mechanism of Chl a degradation was investigated using the 3-dimensional fluorescence spectral measurements, fluorescent Chl catabolites (FCC, Ex/Em : 440/670 nm) were detected but the fluorescent Chl-ring cleavage catabolites (Ex/Em : around 320&acd;360/440&acd;460 nm) were not. The FCC formation was inhibited by p-chloromercuribenzoate (PCMB), an inhibitor of chlorophyllase, but the inhibition was reversible by the addition of reduced glutathione. These results suggest that Chl a degradation occurred through chlorophyllide a formation catalyzed by a water-soluble chlorophyllase from ethylene-treated Citrus unshiu fruits. A possible participation of the enzyme in ethylene-enhanced degreening of the fruit peel is briefly discussed.

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Immature and mature Japanese persimmon 'Tonewase' fruit were treated with 1) 100% CO₂ for 24 hr (control) or 2) 100% CO₂ for 17 hr and gradual reduction to 0% CO₂ for 7 hr (combination treatment) to remove their astringency ; a third group was left untreated. The levels of 1-aminocyclopropane-1-carboxylic acid (ACC) and ACC synthase and ACC oxidase activities in their extracts were analyzed. The effects of adding catechin and bovine serum (BSA) separately to the extraction medium on the enzyme activities were also determined. 1. The ACC content in immature untreated and control fruit rapidly increased during storage at 20°C, whereas that in fruits exposed to the combination treatment remained low during storage. Mature treated fruits responded similarly to the immature treated ones. 2. The ACC synthase activity of immature fruit exposed to the combination treatment remained very low compared to the untreated and control fruit. The ACC synthase activity of immature fruit was significantly inhibited by the combination treatment compared to that of mature fruit. 3. The ACC oxidase activity in both immature and mature fruit was less inhibited by the combination treatment, compared to ACC synthase activity. 4. The ACC synthase activity was inhibited by the addition of catechin in the extraction medium but it was promoted by the addition of BSA. These results indicate that the inhibition of ethylene evolution by Japanese persimmon 'Tonewase' with 100% CO₂ for 24 hr or the combination treatment in which CO₂ is reduced to 0% may be attributed to the blockage of S-adenosylmethionine conversion to ACC.

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Several kinds of vegetables and cultivars of turnip rapes were analyzed for four calcium components. The components were : 1) water soluble calcium, consisting of organic acid salts, inorganic salts, and calcium ion, 2) 1N NaCl soluble calcium pectate and protein binding calcium, 3) 2% acetic acid soluble calcium phosphate, and 4) 5% HCl soluble calcium oxalate. 1. Turnip rape contained the highest content of total calcium and water soluble calcium compared to chrysanthemums, lettuce, spinach, and welsh onions. In turnip rapes, the major calcium component was water soluble calcium. 2. Among four cultivars of turnip rape (Brassica napus L.), 'Miyauchina', 'Shinkirina', 'Keichikuzairai', and 'Gogatsuna', 'Keichikuzairai' had the highest content of water soluble calcium and 2% acetic acid soluble calcium. 3. Among three cultivars of turnip rape (Brassica campestris L.), 'Komatsuna', 'Bitaminna', and 'Haruna', 'Haruna' possessed the highest content of water soluble calcium.

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Interspecific hybrids from 12 cross combinations were obtained, when Nerine alta, N. bowdenii 'Pink Triumph', N. crispa, N. filamentosa, N. humilis, N. pudica and N. sarniensis were crossed with each other in 24 combinations. Intergeneric hybrids from 6 cross combinations resulted, when N. filamentosa, N. humilis or N. sarniensis were hybridized with × Amacrinum, Amaryllis belladonna, × Amaryne, × Hippeaskeria, Lycoris aurea, Sprekelia formosissima or Vallota speciosa in 19 combinations.

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