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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トマト (Licopercicon esculentumMill., cv. Momotaro-T93) のセル成型苗生長および活着・初期生育に及ぼすarbuscular菌根菌3種 [Gigaspora margarita (GM) , Glomus fasciculatum, Glomussp.R10] の共生の影響について調査した.植物体乾物重は液肥中リン濃度 (5, 25, 50ppmKH₂PO₄) に関わらず, GM区が他の処理区を上回り, 25ppm-P区で最大となった.また, GM区では根鉢形成が促進され, 1個体の根系における感染率も最高となり, 植物体リン含有率は50ppm-P区以外で無接種区より増大した.一方, GMが共生した25ppm-P区の成型苗を移植した場合, 活着後も無接種苗より旺盛な初期生育を示した.以上のことから, トマトセル成型苗生産システムにおいて, AM菌接種の利用により, 活着力の高い健苗育成, 移植後の初期生育促進が図れ, それらの効果には菌種間差が存在することが明らかになった.

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CAMのphase1とphase4にパインアップル葉から抽出したホスホフルクトキナーゼ (PFP; EC2.7.1.90) について, フルクトース2, 6ニリン酸 (Fru-2, 6-P₂) による制御特性と電気泳動特性を調査した.サブユニット構成はα (66kDa) およびβ (64kDa) の2種類よりなることが確認された.解糖方向でのPFP活性はpHにより明らかに影響を受け, pH6.4でのFru-2, 6-P₂による活性化の程度は, phase4で4.2倍, phase1で11.1倍と夜間で高かった.解糖方向でのPFP活性は温度によっても影響を受けた.解糖および糖新生, いずれの方向でのPFP活性も夜間に較べ, 昼間に低かった.この一因はCAMにおける夜間の酸性化の影響と考えられる.本実験の結果は, パインアップル葉身のPFP活性の昼夜変化には, Fru-2, 6-P₂以外の要因も関与していることを示唆している.

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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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ロゼット性が弱いトルコギキョウ品種で苗が低温処理前や処理期間中に抽だいしてしまうのを防ぐため, ロゼット性の弱い‘キャンディーホワイト’と‘キャンディーマリン’を供試し, ウニコナゾールとジベレリンが抽だい・開花に及ぼす影響を調べた.
1) ウニコナゾール処理は苗をロゼット状態に維持したが, ジベレリン散布により苗は2週間のうちに一斉に抽だいした.
2) 低温処理によって抽だいは促進されたが, ウニコナゾール処理でロゼット化した苗では低温処理の効果はなく, ジベレリン処理が効果的であった.
3) ウニコナゾール処理でロゼット化した苗でも小さい花が咲いたことから, ジベレリンはトルコギキョウの花芽分化には関与していないが花芽の発達に必要であることが示された.
以上のように, ロゼット性が弱い易抽だい性品種では, ウニコナゾール処理によって, ロゼット化させておき, 希望する時期にGA処理すれば, 一斉に抽だいさせることが可能であることが明らかになった.

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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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