| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
I improved a portable device for the outdoor measurement of microenvironments and ventilation of aquatic plants. Specific convective efficiency, which is defined as convective gas flow rate per unit surface area per potential pressure difference, was evaluated for leaf thin sections with stomata of 12 floating-leaved and two free-floating plants. Convective air flow due to pressurization was observed for leaf thin sections of Nymphaea odorata, N.alba, N.capensis, two tropical Nymphaea species, Victoria amazonica, Hydrocleis nymphoides, Nymphoides peltata, N.indica, Hydrocharis dubia, and Eichhornia crassipes, while was not in leaves of Brasenia schreberi, Trapa japonica, and Potamogeton distinctus. Species whose leaf thin sections were pressurizing also had gas flow when measured at their cut petioles except for tow free-floating plants, H.dubia and E.crassipes.
Gas emission rates from the submerged soil surface in Zizania latifolia-planted pots were higher than those from unvegetated pots and increased with increasing biomass. In contrast to the results for Z.latifolia, gas emission rates from soil in Phragmites australis-planted pots were lower than those from unvegetated pots. Gas generated in soils could be carried to the atmosphere through the ventilation pathway in the plant body rather than through the soil by diffusion and via the overlying water as air bubbles.
I proposed and improved the method for measuring convective gas through flow with the least damages of plants : first static pressure at a shoot was monitored. At the end of the experiment the shoot was cut to measure a relationship between pressure exercised and air flow rate, from which the convective gas throughflow rate at the static pressure measured actually was determined. The estimate in the present study coincided well with that obtained by a destructive method.
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