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Roses are widely cultivated in greenhouses. In rose cultivation, the basal shoots emerging in the early stage of growth are artificially bent down as assimilation shoots to effectively catch sunlight, and then the shoots that emerge successively are cut and used for rose products. This "shoot-bending" (or "arching") cultivation technique leads to a higher yield and high quality of the flowering shoot. This study investigated : I) the growth of photosynthetic organs in assimilation shoots, and II) development and senescence of photosynthetic capacity in assimilation shoots. To form assimilation shoots having higher photosynthetic capacity, low temperature (LT) is better than high temperature (HT). The optimum temperature for photosynthesis was approximately 20℃ for LT grown leaf, and approximately 30℃ for HT grown leaf. Decrease in photosynthetic rate with senescence of leaves was closely related with Rubisco content and nitrogen content, but less related with chlorophyll content. After leaf expansion, leaf nitrogen content greatly decreased in HT, and it was suggested that the photosynthetic rate greatly decreases if the temperature of bent assimilation shoots is high. The number of days necessary for flowering and the quality of cut rose depended on the temperature during growth. However, it is shown that fewer days are necessary for flowering and the quality of cut rose is better for assimilation shoots grown in LT than in HT.

本研究の一部は第6回国際藻類学会で発表した（1997年8月、オランダ・ライデン大学）

平成12年度～平成13年度科学研究費補助金(基盤研究(C))研究成果報告書, 研究概要：平成12年度は,根から吸収されたKが葉の光合成速度を低下させるプロセスとして,葉のK成分が直接影響を及ぼすのではなく,拮抗的に吸収が抑制されるMgを介して維管束鞘細胞のNADP-MEとRubiscoの活性を低下させ,最終的に光合成速度を低下させていると予想し,その実体を究明した. その結果,根系にKを処理して葉のK含量に差異を生じさせたところ,Kが増大すると光合成速度,気孔伝導度,水ポテンシャルが低下し,また,NADP- ME, Rubiscoも低下した.葉のMg含量を調べたところ,Kの増大に伴い減少した.そこで,酵素活性測定時にMgの濃度を変えてみたところ,高濃度のK条件下で栽培されたサトウキビの葉の両酵素活性は,低濃度で栽培されたものに比較して全体的に低かった.従って,NADP-MEとRubiscoに対するKの影響は,不可逆的であり,葉の成長の初期段階で決定されていると推察された. 平成13年度は,サトウキビの絞りかすであるバガスを炭化して得られるバガス炭が糖度,収量に与える影響を調査し,沖縄におけるK成分に着目した循環型農業の可能性を検討した.バガス炭にはK成分が多量に含まれるが,その混入量の違いがサトウキビの成長および品質に与える影響を調べた.土壌1kgに対しバガス炭を10,30,50gとなるように施用した.施肥は,改良型ホークランド水耕液を週1回,1ポット当たり500ml与え,潅水は適宜行った.植付け5ヵ月後のサトウキビの茎長,茎重,搾汁液元素成分および糖度を測定した. その結果,バガス炭に含まれるKは,サトウキビに吸収されることが確認された.また,バガス炭処理におけるKの吸収量の変化がキビの生育,品質に影響を与えないことから,バガス炭は,K肥料の代替になるのではと考えられた.従って,バガス炭による土壌物理性の改善とともに,サトウキビの肥料の削減が期待できることを明らかにした., 研究概要：In this study, the factor that the root of sugarcane absorbed the superfluous potassium which accumulates in the soil and that the decreased photosynthetic rate of leaf due to the higher potassium content was clarified. As the process, it was clarified that the photosynthetic rate was decreased with the lowering of NADP-ME and Rubisco activities of bundle sheath cell through the lowering of magnesium of which the absorption was suppressed for rivalry like. In addition to the above-mentioned result, the effect of the bagasse charcoal on sugar content and yield of sugarcane was investigated, and the possibility of sustainable agriculture in concerned with the potassium was also examined. The potassium was abundantly included for the bagasse charcoal, and the effect of the difference of the input on growth and quality of the sugarcane was examined. The bagasse charcoal was used in order to become 10, 30, 50 g per 1 Kg soil. The fertilization gave modified Hoagland Solution culture medium once a week (500 ml per pot), and the sprinkling was properly carried out. Fifth month after planting, the stem length, stem weight, elemental component in juice extraction and sugar content of cane were measured. As the result, it was confirmed mat the potassium which is included for the bagasse charcoal was absorbed to the sugarcane. The bagasse charcoal was regarded as becoming the substitution of the potassium fertilizer, because the change of potassium uptake quantity by the bagasse charcoal treatment did not give growth and effect in the quality of the sugarcane. Therefore, it was clarified that the reduction of the fertilizer of sugarcane could be expected with the improvement on the soil physical property through the bagasse charcoal., 未公開：P.11以降(別刷論文のため)