To establish an efficient cultivation system for producing high-quality cucumbers (Cucumissativus L. cv. Kema), a comparison of cucumbers grown in soil culture and hydroponic solution culture with different nutrient levels was carried out. The hydroponically grown cucumbers were bitter compared with the cucumbers grown in soil. The maximum and minimum fruit productions were obtained at high and low nutrient levels, respectively. However, most of the cucumbers were bitter when they were grown at high nutrient level. The cucumbers had the lowest concentration of nitrate ion in the hydroponic culture solution with low nutrient level, and vice versa. Nitrate ions may cause bitterness in cucumbers by promoting nitrogen metabolism, which in turn favors the enzymatic synthesis of cucurbitacin C. From these results, we conclude that the yield of bitter cucumbers can be reduced by growing them in soil culture rather than in rockwool culture and in hydroponic solution with low nutrient level.

　To establish an efficient cultivation system for producing high-quality cucumbers (Cucumis sativus L. cv. Kema), a comparison of cucumbers grown in hydroponic solution culture with different fertilizers applied and nutrient media used were investigated. In the hydroponic solution culture, the cucumber s grown the application of chemical fertilizer were more bitter than the cucumbers grown with the application of organic fertilizer. The cucumbers grown in the chemical hydroponic solution by the deep-flow technique were bitter compared with the cucumbers grown in the hybrid hydroponic solutions (with chemical and organic fertilizers) with a solid substrate. The greatest number of harvested cucumbers was obtained in the chemical hydroponic solutions with a solid substrate, and the least number of harvested cucumbers was obtained in the hydroponic solution with organic fertilizer with a solid substrate. In hydroponics by the deep-flow technique, the cucumbers grown with the application of organic fertilizer had the lowest total phenol concentration, whereas the cucumbers grown with the application of chemical fertilizer had the highest total phenol concentration. The cucumbers grown using organic hydroponics by the deep-flow technique had the lowest nitrate ion concentration, whereas the cucumbers grown using chemical hydroponics by the deep-flow technique had the highest nitrate ion concentration. From these results, we conclude that the yield of bitter cucumbers can be reduced by the application of organic fertilizer in hydroponics rather than by the application of chemical fertilizer, and by the use of hydroponics with a solid substrate rather than by the deep-flow technique.

　1-methylcyclopropene（1-MCP）水溶液への浸漬処理のバナナ果実の追熟に及ぼす影響が調べられた。エチレン処理開始後2日に，緑熟バナナは，コントロールとして水，または0.1，1，10，50，100，1,000 μg L^－1の1-MCP水溶液に10分間浸漬処理され，その後20℃暗所下で貯蔵された。50，100，および1,000 μg L^－1の1-MCP水溶液で処理された果実では，カラースコアの増加が抑制され，褐色斑点の表面積に占める割合の増加はわずかであり，エチレン処理開始後12日まで低いままであった。浸漬時間が追熟に及ぼす影響を調べるために，エチレン処理開始後2日に，果実は100 μg L－1の1-MCP水溶液に0.5，1，3，6，10または15分間浸漬処理され，20℃暗所下で貯蔵された。なお，コントロールは浸漬処理をおこなわないもののとした。10分間および15分間処理した果実では，カラースコアと褐色斑点の表面積に占める割合の増加が抑制された。追熟の抑制に効果的かつ効率的であった，100 μg L^－1の1-MCP水溶液に10分間浸漬処理を行った果実の内部品質はコントロールと差異は認められず，また果実の可食期間は2倍以上に延長された。これらの結果から，1-MCP水溶液によるバナナ果実への処理は，その有用性から極めて実用的な収穫後の処理であることが示唆された。