This experiment was carried out to investigate the effects of CO₂ enrichment on growth, yield and fruit quality of strawberry (Fragaria×ananassa Duch. cv. Ai-Berry) grown with two types of rockwool (RW : slub and granule) . The growth and development of plants were hastened in flowering date, maturing days and harvesting date by CO₂ enrichment in both RW media. Between the RW media, the growth was more vigorous and yield was higher in granule compared to those in slub. CO₂ enrichment increased total yield by 50 and 30% in RW slub and granule, respectively. Soluble solid content and titratable acidity of fruits were also increased by the CO₂ enrichment. Although the leaf area of plants grown with CO₂ enrichment was larger compared to the control, the rate of water absorption was almost equal. The electric conductivity of nutrient solution was also markedly decreased by CO² enrichment. In midwinter, the CO₂ concentration in the control greenhouse was lower than outside especially on fine and cold days, and much lower than those in the usual soil cultured greenhouses. Because in greenhouses for soilless culture where no organic substance is applied, only a small amount of CO₂ can be expected to be supplied from the soil, CO₂ enrichment may be necessary when strawberry plants are grown without soil.

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In the production of plug seedlings, the air current speed around the seedlings is an important environmental factor affecting the rates of net photosynthesis (P) and evapotranspiration (E) . In the present experiment, a plug sheet consisting of tomato plug seedlings and soil mix was placed in a wind tunnel with artificial lights, and the P and E rates of the plug sheet were examined under different air current speeds, at an air temperature of 29-30°C, relative humidity of 60-70%, CO₂ concentration of 340-360 μmol mol^-1 and photosynthetic photon flux density of 270 μmol m^-2s^-1 At the inlet and outlet of the wind tunnel, absolute humidities (y_in and y_out, respectively) and CO₂ concentrations (C_in and C_out, respectively) were determined with a dew point analyzer and an infrared CO₂ analyzer, respectively. The weight of the plug sheet was measured with an electronic balance. The E was estimated based on the change with time in the weight of plug sheet. The air flow rate in the wind tunnel, F, was determined using an equation : E = F (y_out-y_in) /A, where A is the area of plug sheet. The P was determined using the equation : P=F (C_in - C_out) /A. The P and E increased as the air current speed and LA! (leaf area index of the seedlings) increased. However, the increase in P with the increase in LAI was less than the increase in E with the increase in LAI. Eleven days after seeding, when LAI=0.43, the P and E at an air current speed of 0.6 m s^-1 were 1.4 and 1.9 times those at an air current of 0.1 m s^-1, respectively.

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The effects of spraying water with different hydrogen-ion concentration exponents (pHs) and free effective chlorine concentrations (ECCs) on the incidence of powdery mildew (Sphaerotheca fuliginea Pollacci) on leaves of cucumber (Cucumis sativus L. cv. Shapu 7) grown in a plastic house were investigated as a fundamental research for the establishment of a crop disease control system with electrolyzed strong acid water. pH-regulated waters (pH: 2.0, 2.3 or 2.6; ECC : 0 ppm ; oxidation-reduction potential (ORP) : almost constant at 510 mV), ECC-regulated waters (ECC : 30, 40 or 50 ppm ; pH : 2.3 ; ORP : almost constant at 1 170 mV), or well water (pH: 7.8, ECC : 0 ppm, ORP : 460 mV) were sprayed, 4 times in 9 days, onto the leaves once every third day. The incidence of powdery mildew on cucumber leaves showed a tendency to decrease with decreasing pH or with increasing ECC of the sprayed water over the 12 days of observation. Water with a pH of 2.0 suppressed the incidence significantly at the 5% level against water with a pH of 2.6 and well water on day 12, which is 3 days after the last spray. Water with an ECC of 50 ppm suppressed the incidence significantly at the 5% level against water with an ECC of 30 ppm and well water on day 12. These results indicate that pH lower than a certain level can be a factor independently capable of controlling powdery mildew on cucumber leaves in spraying electrolyzed strong acid water, and that ECC higher than a certain level under a low pH can be a primary factor capable of controlling it.

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This experiment was carried out to investigate the effects of CO₂ enrichment (700-800 ppm in the day time) on the absorption of water and mineral nutrients in strawberry (Fragaria × ananassa Duch. cv. Nyoho) grown by nutrient film technique. The concentration of major elements in the nutrient solution were NO₃^- : 5, NH₄⁺ : 1, H₂PO₄^- : 1, K⁺ : 3, Ca²⁺ : 1, Mg²⁺: 1 mmol·L^-1. Vigorous growth and high yield were obtained by CO₂ enrichment. In control (ambient CO₂, 200-400 ppm), the uptake concentration (each mineral absorbed per unit volume of water absorbed, n/w) was almost equal to the concentration of the solution, throughout growing period. However, under CO₂ enriched condition, n/w and total uptake amount of minerals increased by 30-60% compared to control, especially, from November to February when the temperature and light intensity were low. The n/w of minerals were also 50-100% higher than the concentration of the nutrient solution. Total-N concentration in leaves was markedly decreased by CO₂ enrichment, while there was little difference in P, K, Ca and Mg. To keep the concentration of nutrients in the solution, the concentration of nutrients should be kept 50-100% higher than those previously reported, when strawberry plants are grown with CO₂ enrichment.

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水稲の周年養液栽培法と生産性の高い栽培技術を確立する目的で, 高圧ナトリウムランプとメタルハライドランプを設置した完全制御室, 太陽光併用高圧ナトリウムランプ室, 混合光室, メタルハライドランプ室および太陽光室を利用し, 1994～1995年に3回, 栽培試験を行った.
PPFDの大きさは補光ランプを点灯した完全制御室>高圧ナトリウム室>混合光室>メタルハライド室の順で, 太陽光室は最も小さかった.PPFDは玄米重との間で有意な正の, 屑米重歩合との間では負の有意な相関がみられた.また, 玄米重を決定する変数増減法により重回帰分析を行った緒果, PPFDは第1ステップで取り込むと寄与率は96%で, 水稲の生育・収量に大きく影響を与えていた.とくに完全制御室と混合光室では, ランプの光合成増進効果により生育・収量は優るとみられた.また, 全平均照度は玄米重の決定に寄与するが, PPFDよりも寄与率は大きく劣るとみられた.このように, 高圧ナトリウムランプおよびこれとメタルハライドランプの混合光およびこれに太陽光を併用した場合は玄米重は増収し, 植物工場における増収技術になると考えられるが, 実用場面ではさらに検討を要する.
本論文を作成するにあたり, 弘前大学農学部卜蔵健治教授から有益なご教示を賜った.また, 青森県農業試験場育種部長中堀登司光氏, 同前栽培部長玉川和長氏には調査にご協力を戴いた.ここに厚く謝意を表する.

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Dynamics of fruit growth and photoassimilate translocation in tomato plants (Lycopersicon esculentum Mill.) as affected by irradiation and day/night air temperature were analyzed in relation to respiration, photosynthesis and transpiration of the fruit and the leaf. Fruit growth was explained by about 80% of sap flux imported into the fruit and was scarcely affected by transpirational water loss from the fruit. Irradiation clearly enhanced fruit growth and photoassimilate translocation, and about 70% of fruit growth and about 80% of photoassimilate translocation were brought during the light period with highly activated leaf photosynthesis and fruit respiration under day/night air temperature of 25/15°C. In particular, when air temperature around fruits rose to 25°C in the light period, remarkable increases in fruit growth and photoassimilate translocation were found with the activated fruit respiration. On the other hand, decreases in fruit growth and photoassimilate translocation were found during the dark period without effects of air temperature. From these results, it was suggested that energy-dependent transport process of sugar in fruits is one of the determinant processes regulating fruit growth and photoassimilate translocation in tomato plants under light.

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核酸の螢光プローブとしてacridine orange (AO) を用い, ニンジン不定胚形成過程における極性の発現を調べた.細胞塊および不定胚をAOで染色し, 発せられる螢光を共焦点レーザー走査型顕微鏡で二つの波長域 (緑および赤) に分け, 観察した.DNAと結合したAOが発する緑色螢光は, どのステージの細胞塊においても, おもに核から発せられていた.また, RNAと結合したAOが発する赤色螢光の強度は不定胚誘導処理後増加した.さらに, 球状胚形成直前の細胞塊内に, 赤色螢光の分布の偏りがみられた.このことは, これらの細胞塊内に生理的に異なる細胞が存在することを示唆するものであり, 不定胚形成過程において, 形態的な変化以前に生理的な極性が生じているという考えを支持するものである.

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In order to know the effect of supplemental UV-A irradiation on the growth of lettuce (Lactuca sativa L. cv. Okayama) and radish (Raphanus sativus L, cv. Comet), these plants were grown under artificial irradiation with 3-band fluorescent lamps and additional UV-A lamps. The UV-A irradiation promoted shoot growth of both plants, and reduced the bitter taste intensity of mature lettuce leaves. However, the UV-A effects varied with stage of vegetative development. Moreover, there was no significant effect of the UV-A on the hypocotyl growth of radish plants.

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