EFFECT OF LEAF ANATOMY ON HYPOSTOMATOUS LEAF GAS EXCHANGE : A THEORETICAL STUDY WITH THE 2DLEAF MODEL
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概要
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The two-dimensional model of leaf gas exchange, 2DLEAF, which accounts for leaf intercellular structure, was used to study the effect of leaf anatomy on the photosynthesis and transpiration rates of hypostomatous C_3 plants. The theoretical study was conducted to exclude the interacting effects of all other factors on leaf gas exchange; an exclusion that is very difficult to achieve in experiments with real leaves. Clements (1905) identified four types of leaf anatomy, (1) staurophyll consisting entirely of palisade cells, (2) spongophyll containing only spongy cells, (3) diphotophyll composed of palisade cells adjacent to an adaxial and spongy cells adjacent to an abaxial sides of the leaf, and (4) diplophyll in which there are palisade cells adjacent to each leaf surface and spongy cells between them. These four types of leaf anatomy were studied assuming the same leaf thickness for all types and plus an additional thickness (+50%) for the diphotophyll. Photosynthesis and transpiration rates calculated by 2DLEAF were compared for the same external conditions: 2000μmol m^<-2>s^<-1> (PPFD), 30℃, 60% relative air humidity, and 350 and 700μmol m^<-3> of CO_2 in air, [CO_2]. The biochemical parameters of 2DLEAF were given identical values for all anatomy types and both thicknesses. Stomatal density was assumed to be 300 per mm^<-2> and stomatal apertures were varied from 2 to 20μm with an increment of 2μm. Photosynthesis rate at both values of [CO_2] depended on the internal leaf structure. For leaves of the same thickness, photosynthesis increased with increasing cell area index (CAI), the surface area of photosynthesizing cells per unit leaf surface area. Photosynthesis rate of a thick leaf of the same CAI value was lower than that of a thinner one, but this difference was less in high [CO_2]. Transpiration rates were less sensitive to changes in the internal leaf geometry than photosynthesis rates.
- 九州大学の論文
著者
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Acock B.
Usda Ars Remote Sensing And Modeling Laboratory
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Pachepsky L.
Duke Universtity Department Of Botany:usda Ars Remote Sensing And Modeling Laboratory
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ACOCK B.
USDA, ARS, Remote Sensing and Modeling Laboratory