| Co-Investigator(Kenkyū-buntansha) |
KIWATA Takahiro Kanazawa University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40225107)
KIMURA Sigeo Kanazawa University, Faculty of Engineering, Professor, 工学部, 教授 (70272953)
OKAJIMA Atsushi Kanazawa University, Faculty of Engineering, Professor, 工学部, 教授 (80013689)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
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
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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. Less
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