Hydrogen-isotope composition of leaf water in C3 and C4 plants: its relationship to the hydrogen-isotope composition of dry matter期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

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Hydrogen-isotope composition of leaf water in C3 and C4 plants: its relationship to the hydrogen-isotope composition of dry matter

Authors:	F W Leaney C B Osmond G B Allison H Ziegler

Institution:	(1) Division of Soils, CSIRO, Private Bag 2, 5064 Glen Osmond, S.A., Australia;(2) Department of Environmental Biology, Research School of Biological Sciences, Australian National University, P. O. Box 475, 2601 Canberra City, ACT, Australia;(3) Institut für Botanik und Mikrobiologie der Technischen Universität, Arcisstrasse 21, D-8000 München 2, Federal Republic of Germany

Abstract:	The natural abundance hydrogen-isotope composition of leaf water ( $\delta _{\text{D}}^{{\text{H}}_{\text{2}} {\text{O}}}$ ) and leaf organic matter ( _D ^org ) was measured in leaves of C₃ and C₄ dicotyledons and monocotyledons. The $\delta _{\text{D}}^{{\text{H}}_{\text{2}} {\text{O}}}$ value of leaf water showed a marked diurnal variation, greatest enrichment being observed about midday. However, this variation was greater in the more slowly transpiring C₄ plants than in C₃ plants under comparable environmental conditions. A model based on analogies with a constant feed pan of evaporating water was developed and the difference between C₃ and C₄ plants expressed in terms of either differences in kinetic enrichment or different leaf morphology. Microclimatic and morphological features of the leaves which may be associated with this factor are discussed. There was no daily excursion in the _D ^org value in leaves of either C₃ or C₄ plants. When _D ^org values were referenced to the mean $\delta _{\text{D}}^{{\text{H}}_{\text{2}} {\text{O}}}$ values during the period of active photosynthesis, the discrimination against deuterium during photosynthetic metabolism (D) was greater in C₃ plants (-117 to -121) than in C₄ plants (-86 to -109).These results show that the different water use strategies of C₃ and C₄ plants are responsible for the measured difference in deuterium-isotope composition of leaf water. However, it is unlikely that these physical processes account fully for the differences in hydrogen-isotope composition of the products of C₃ and C₄ photosynthetic metabolism.Symbols $\delta _{\text{D}}^{{\text{H}}_{\text{2}} {\text{O}}}$ Hydrogen-isotope composition of leaf water - _D ^org hydrogen-isotope composition of leaf organic matter

Keywords:	C₃ C₄ plants (H-isotope composition) Deuterium Hydrogen-isotope composition Leaf (H-isotope composition)
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