Interactions between carbon dioxide and water deficits affecting leaf photosynthesis: Simulation and testing

Journal Article · · Crop Science; (United States)

DOI:https://doi.org/10.2135/cropsci1992.0011183X003200060003x· OSTI ID:6880203

Grant, R F

Atmospheric CO[sub 2] concentration is known to have contrasting effects on photosynthesis, particularly in C[sub 3] plant species. These effects, along with water-deficit effects, may be produced mathematically through the combination of a biochemically based submodel of CO[sub 2] fixation in leaf chloroplasts with a physically based submodel of CO[sub 2] and H[sub 2]O diffusion through leaf surfaces and atmospheric boundary layers. The behavior of a combined model was tested against data recorded under atmospheric CO[sub 2] concentrations of 330 and 660 [mu]mol mol[sup [minus]1] in the Soil-Plant-Atmosphere Research Units at the University of Florida. The model reproduced changes in the quantum requirements of CO[sub 2] fixation and in diurnal CO[sub 2] fluxes of soybean [Glycine max. (L.) Merr.] leaves at these different concentrations. Simulated CO[sub 2] fixation at midday responded more to increased CO[sub 2] concentration at high irradiance than at low. Under water deficits light saturation of CO[sub 2] fixation occurred at lower irradiance, again consistent with experimental findings. Interaction between the water deficit effects in each submodel allowed the combined model to simulate a higher sensitivity of CO[sub 2] fixation at 660 [mu]mol mol[sup [minus]1] than at 330 when [psi][sub 1] was reduced to -1.55n from -0.60 MPa. The theoretical basis for CO[sub 2] effects on photosynthesis is well established, allowing them to be reproduced with confidence in the absence of water deficits. However, the theoretical basis for water deficit effects on photosynthesis is incomplete such that the reproduction of CO[sub 2] effects on photosynthesis in the presence of water deficits must still be regarded as speculative. 41 refs., 4 figs.

• OSTI ID: 6880203
• Journal Information: Crop Science; (United States), Journal Name: Crop Science; (United States) Vol. 32:6; ISSN 0011-183X; ISSN CRPSAY
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON DIOXIDE FIXATION
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DEMAND
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
SIMULATION
SYNTHESIS
TESTING
WATER REQUIREMENTS