A role of trehalose on physical states of water in cut bulbous flowers was determined by¹H-NMR spectroscopy and the isopiestic psychrometer. Treatments with 100 and 50 mM trehalose markedly prolonged vase-life in gladiolus and tulip cut flowers, respectively. Trehalose maintained a higher degree of the water content accompanying with suppressing protein degradation and membrane integrity than the control tissues. The long fraction of spin-lattice relaxation time (T¹) of the intracellular water in both tissues indicated that trehalose functioned to protect vacuolar water. Furthermore, trehalose affected to enhance water uptake into tepal tissues though not to promote cell elongation and not to cause osmotic adjustment with maintaining a high level of turgor. On the other hand, the short fraction of spinspin relaxation time (T²) estimated as bound water suggested that cytoplasmic water was also maintained. From these results, it suggests that trehalose does not act as an energy source nor directly participate in osmotic adjustment and these characteristics distinguish it from other sugars such as sucrose. In cut gladiolus and tulip flowers trehalose played an important role to prevent loss of water determined byT¹, T²and turgor measurements.

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Influence of inoculation with arbuscular mycorrhizal (AM) fungi [Gigaspora margarita (GM), Glomus fasciculatum (GF), Glomussp. R10 (GR) ] for the production of tomato (Licopercicon esculentumMill., cv. Momotaro-T93) as plug seedlings was investigated. Twenty eight days after inoculation, in GM plots, dry weights of shoots and roots were heaviest among the plots irrespective of the 3 phosphorus levels (5, 25 and 50 ppm KH₂PO₄in liquid fertilizer), and became maximum in 25 ppm P. As for root ball formation, the percentage of complete root ball formation reached 100% in all the P levels only in GM plots. AM fungal infection level in a root system showed highest values in GM plots among the fungi, irrespective of the P levels. GM plots gave greater P concentration in shoots and roots than did noninoculated ones except 50 ppm P ; in GF and GR, no increase in P concentration occurred among almost of the treatments. Tomato seedlings raised in 25 ppm P, infected with GM, continued to grow rapidly after being transplanted to a new bed soil. These results suggest that AM fungus inoculation is essential for obtaining vigorous tomato seedlings and for enhancing the initial growth of transplants in a plug seedling system, though the effects differed with fungal species.

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Regulatory properties of Fru-2, 6-P₂on pyrophosphate : D-fructose-6-phosphate 1-phosphotransferase (PFP ; EC 2.7.1.90), its molecular weight and subunit structure in illuminated and darkened pineapple (Ananas comosus (L.) Merr. cv. Smooth-cayenne N67-10) leaf were investigated. Polyacrylamide gel electrophoresis and immunoblot revealed two subunits, α (66 kDa) and β (64.1 kDa) in desalted leaf extract. Diurnal PFP activity of pineapple showed the dependency on a day/night regulation. Glycolytic activity of PFP was dependent on pH, the degree of activation by Fru-2, 6-P₂at pH 6.4 was 4.16 and 11.13 fold increases during the day and nighttime, respectively. But gluconeogenic reaction was only weakly affected by Fru-2, 6-P₂at various pH. Activity of PFP was also strongly depended on temperature. In 10-40°C temperature regimes, glycolytic reaction of PFP activity showed about 2 fold activation by Fru-2, 6-P₂in both day and night, but gluconeogenic reaction was weakly affected. In both reactions PFP activity of darkened leaf was always lower than that of day form. This suggested that nocturnal acidification of CAM in pineapple had significant influence on PFP. Results obtained in our experiment suggested that only a part of regulation of pineapple PFP was associated with Fru-2, 6-P₂but some other factors were also responsible for PFP regulation.

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An automatic ebb-and-flow watering system with an analog evapotranspiration meter for transplant production was developed and used for cucumber plug seedlings. The plug sheets consist of plug seedlings, soil mix, and a tray that were placed on a bench with an ebb-and-flow system. The evapotranspiration of a plug sheet located in the center of the bench was measured with an analog evapotranspiration meter using a spring balance equipped with movable pointers for the maximum weight and the weight to start the watering. The evapotranspiration of the plug sheet was estimated with the difference between the pointers for the maximum weight and the current weight. When the pointer for the current weight reached the pointer for the weight to start watering, then a switch to start watering was turned on and all the plug sheets were watered from below, and the weight of the plug sheet increased. When the maximum weight of the plug sheet increased with the seedling growth after watering, the pointers for the maximum weight and the weight to start watering moved simultaneously due to the current weight pointer. Although some sort of mechanical improvement was required to reduce operating errors of the pointers, the watering system controlled the soil-mix moisture in the plug tray in an almost proper range for growth of the plug seedlings during the culture period.

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Root temperature effects on tuberous root growth of sweetpotato were examined using a hydroponic system where the temperature conditions of shoot, tuberous root and fibrous roots were controlled independently. Plants were grown under various root temperature conditions of 24/24, 24/28, 28/28, 32/28 and 32/32°C (tuberous root temp./fibrous root temp.), and volume changes in the tuberous root were measured on-line. Growth of fibrous roots was also examined for 16, 20, 24, 28 or 32°C of fibrous root temperature in another experiment. In all the experiments, shoot environment was controlled at 28°C, 70% RH, PPFD 300 μmol m^-2s^-1and a photoperiod of 12 h. In the fibrous roots, rates of elongation and dry matter accumula-tion were enhanced by an increase in the temperature. In the tuberous root, rates of growth and dry matter accumulation were higher in the temperature combinations of 24/24°C and 28/28°C, and extremely lower in 24/28°C and 32/32°C. The inhibition of the tuberous root growth in those temperature conditions was found to be caused by changes in ratio of carbon partitioning between the tuberous root and the fibrous roots in relation to sink strength of fibrous root. Based on our findings, the tuberous root growth of sweetpotato is sensitive to growth activity of fibrous root.

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With autumn production, seedlings of easy-boltingEustomacultivars tend to bolt before or during low temperature treatment. This results in plants that have not reach adequate size length to ensure being high quality cut flower stems. In an attempt to avoid this problem, we treated easy-boltingEustomacv. Candy White and Candy Marine with Uniconazole alone or in combination with gibberellic acid to investigate their influence on the bolting and flowering with the following results. (1) Uniconazole (50 ppm) inhibited bolting and kept seedlings rosetted through the experimental period. (2) Gibberellic acid (GA, 100 ppm) completely reversed uniconazole inhibition and induced rapid bolting within 2 weeks with or without low temperature treatment (10°C, 4 weeks) . (3) Uniconazole-treated seedlings remained rosetted, but produced much smaller flowers than normal ones, which indicated that GA was not involved in flower bud differentiation but involved in flower development ofEustomacultivars. We concluded that premature bolting of easy-boltingEustomacultivars could be avoided by uniconazole treatment and that uniconazole-induced rosetting could also be reversed to bolting by GA at desired time.

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Tomato (Lycopersicon esculentumMill., cv. Momotaro) plug transplants were grown in a closed-type (CTPS) and an open-type (OTPS ; i.e., greenhouse) transplant production systems during summer (11-15 August to 1 September, 2000) . The quality of transplants and water consumption in the CTPS were compared with those in the OTPS. Electric energy consumption per transplant was estimated in the CTPS. The CTPS was a system designed to produce transplants under artificial light in a relatively airtight structure with thermally insulated walls, and to produce high quality transplants using minimal resources. The CTPS employed a sub-irrigation system. Air temperature in the CTPS was maintained at 28°C during a 16 h photoperiod and at 19°C during an 8 h dark period by using an air conditioner. The OTPS employed an overhead irrigation system. Air temperature in the OTPS was partly controlled by using roof and side ventilators, but varied from 23 to 43°C depending on the weather conditions. The quality of transplants was higher in the CTPS than in the OTPS. Electric energy consumption per transplant in the CTPS was 0.7 MJ (0.2 kWh), which corresponded to a cost of 2.9-3.2 Japanese Yen. The amount of water consumed during the transplant production period in the CTPS was 1/12-1/16 of that in the OTPS. These results suggested that value-added transplants could be produced at a lower water consumption of resources in the CTPS than in the OTPS at low electricity consumption.

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The allometric relationship between the sucrose synthase (SS) (EC 2.4.1.13) activity per fruit and fresh weight (FW) of cucumber (Cucumis sativusL. cv. Asomidori No. 5) fruits as affected by 60 mM NaCl salinity was examined. The allometric coefficient was close to 2/3, which is consistent with the localization of the enzyme in the cytosol. SS activity on the basis of FW2/3 was fairly constant during the fruit development until 7 d after anthesis, and it was consistently lower at 60 mM NaCI than control, suggesting the involvement of SS in the salinity response.

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