@techreport{oai:kanazawa-u.repo.nii.ac.jp:00034858,
 month = {Mar},
 note = {Water transport in green plants is important for maintaining plant life and numerical researches taking account of the anatomy of plants have been presented in the view of agricultural engineering and plant physiology. Recently, in crop science and horticulture the effects of the environment on the transpiration stream have been investigated quantitatively. However, there is not enough of quantitative and reliable data based on simultaneous measurement for the rates of the transpiration and absorption because of the lack of a simple and accurate method of measurement under natural conditions. Water movement must be investigated more thoroughly in the connection between these data and plant physiology. Modeling and measurement of driving forces and resistances to water movement : To investigate a mechanism of transpiration stream, the suction pressures for water absorption and transfer resistances of three organs, i.e., leaves, stem, roots, were measured by the potometer method. Suction p ressures due to the leaves and roots were determined from the conditions of zero-absorption rate, which was attained by the reduction of the hydrostatic pressure head applied on the roots immersed in the water. Three values of the resistances were estimated by the three kinds of experiments. Based on the experimental results, a simple model for water absorption was developed. Some results predicted by the model were well consistent with measured data. Development of a method of simultaneous measurement for transpiration and absorption rate : In the developed method in the case of plants immersed in the water, two electronic balances were used. A balance weighs water in the bath for measuring the absorption loss, and the other balance weighs the only plant, root of which are to be floated in the water bath, for measuring the absorption minus transpiration loss. Transpiration loss of water is obtained by the sum of two balances. In the case of the roots in the soil, a potted plant in the soil is to be floated in the water bath. In this case the effect of buoyant force on absorption must be considered. Using these method, instantaneous and accurate measurements were attainable. Experiments of plant responses to environment : Step responses of water movement to illumination and atmospheric temperature, and to cutting of roots were examined, using the above-mentioned method. Relation between the transpiration and absorption, aspect of pulsation of water movement were investigated by using the plants in the water and those in the soil. It was noted that the transpiration rate showed the large overshoot from the steady value and in phase lag to the absorption rate. On the other hand, those phase relation by cutting the roots was conducted reversely., 本研究では,2台の電子天秤による同時測定により,蒸散および吸水の瞬間流量を計測する簡便な手法を提案し,環境変化に対する蒸散・吸水量の微視的な応答解析に応用した。特に,過渡応答として,光照度のステップ変化に対し吸水量は蒸散量に対し位相が遅れ,蒸散量は定常値をオーバーシュートすること,根を切断した場合や渇水状態において十分な水分を根部に供給するとき吸水量が蒸散量より位相が進むことを明らかにした。定常特性として,植物の成長が盛んなとき吸水量が蒸散量を上回ること,根部が土壌中にある場合は蒸散・吸水流量が脈動しやすいこと,植物のしおれの影響,根部が水中および土壌中にある場合の比較などを実験的に明らかにした。これらの結果は,過渡応答計測や長時間自動計測に有効な吸水・蒸散量の同時計測法の開発によって明確にされたものである。 一方,吸水量をポトメータ法により測定し,根がある植物および根を切断した植物に対し根部の静水圧を減少させ吸水量が零となる静水圧の測定,茎部の流動抵抗の測定,茎部断面の道管直径・道管本数の顕微鏡撮影の結果から,葉部の吸水圧(駆動圧),根部吸水圧および葉・茎・根の各部流動抵抗を実測した。これらのデータは従来,ほとんど公表されていない。以上の計測結果を基に,吸水圧の和が流動抵抗の和と釣り合うとする簡単な吸水モデルを構築した。本実験により,供試植物(ピレア)の葉部:根部の吸水圧比が9:1であり,植物器官の流動抵抗比は葉:茎:根が1:1:1.5であることを示した。また,葉および根による吸水圧は葉の枚数に依存せず一定であり,本モデルにより吸水量は葉の枚数(表面積)に比例するのではないことを明らかにした。さらに,根部の吸水圧が大気圧以上になると,過剰な吸水量となるため根は吸水力源でなく内部抵抗源となることを見いだした。研究成果として,4回の口頭発表を行った。, 研究課題/領域番号:09650181, 研究期間(年度):1997–1999, 平成11(1999)年度 科学研究費補助金 基盤研究(C) 研究成果報告書の一部(概要)を掲載, 出典：「植物内の蒸散流計測用センサーの開発と吸水量制御による水ストレスへの影響」研究成果報告書　課題番号09650181
(KAKEN：科学研究費助成事業データベース（国立情報学研究所）)
　　　本文データは著者版報告書より作成},
 title = {植物内の蒸散流計測用センサーの開発と吸水量制御による水ストレスへの影響},
 year = {2000}
}