Record Display for the EPA National Library Catalog

RECORD NUMBER: 44 OF 117

OLS Field Name OLS Field Data
Main Title Gas Exchange in 'Quercus rubra' (Northern Red Oak) during a Drought: Analysis of Relations among Photosynthesis Transpiration, and Leaf Conductance.
Author Weber, J. A. ; Gates, D. M. ;
CORP Author Michigan Univ., Ann Arbor.;Corvallis Environmental Research Lab., OR.
Publisher c1990
Year Published 1990
Report Number EPA/600/J-90/472;
Stock Number PB91-182188
Additional Subjects Photosynthesis ; Transpiration ; Droughts ; Trees ; Plant physiology ; Carbon dioxide ; Leaves(Botany) ; Humidity ; Reprints ; Gas exchange ; Quercus rubra
Holdings
Library Call Number Additional Info Location Last
Modified
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Status
NTIS  PB91-182188 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 09/04/1991
Collation 11p
Abstract
Development of water stress in leaves of mature Quercus rubra L. caused a marked midday depression in photosynthesis (A) and transpiration (E). At external CO2 partial pressures of 100-110 Pa, a constant temperature of 30 C and a constant photosynthetic photon flux density of about 1000 micromol/sq m/s, A was 8 micromol/sq m at low leaf water potentials (-1.5 to -2.0 MPa), whereas it was 20 micromol/sq m/s in non-stressed leaves (-1.0 ,Pa). At lower external CO2 partial pressures, the effect of low leaf water potential on A was less. The midday depression in gas exchange was relieved by an overnight rain of 2.5 cm. No difference in carboxylation efficiency or CO2 compensation point was found between leaves before and after rain. The relationship between A and E was linear for a given external CO2 partial pressure, but the slope varied with CO2 concentration. Modification of the model of stomatal response proposed by Ball et al. (1987) produced a linear relationship between leaf conductance and a factor incorporating A, relative humidity, and CO2. (Copyright (c) 1990 Heron Publishing - Victoria, Canada.)