A condensation type porometer for field use.
A double cup transpiration porometer is described which simultaneously measures the resistance to water vapor diffusion from the upper and lower epidermises of a leaf. In use the cups are dried, the porometer is clamped on the leaf, and the transit time required for water vapor to condense on a cold (0 C) reflective surface in each cup is recorded. Since the sensing element remains at constant temperature, only transit time and leaf temperature are required to calculate leaf resistance.
Moreshet
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Missouri Botanical Garden, St. Louis, Missouri 63110.
Yocum
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CS