scholarly journals Internal Conductance to CO2 Diffusion and C18OO Discrimination in C3 Leaves

2000 ◽  
Vol 123 (1) ◽  
pp. 201-214 ◽  
Author(s):  
Jim S. Gillon ◽  
Dan Yakir
Keyword(s):  
Co2 Diffusion ◽  
Internal Conductance

Is a Low Internal Conductance to CO2 Diffusion a Consequence of Succulence in Plants with Crassulacean Acid Metabolism?

1997 ◽  
Vol 24 (6) ◽  
pp. 777 ◽  
Author(s):  
Kate Maxwell ◽  
Susanne von Caemmerer ◽  
John R. Evans
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Ambient Air ◽  
Co2 Assimilation ◽  
Co2 Partial Pressure ◽  
Co2 Diffusion ◽  
Internal Conductance ◽  
C3 Species ◽  
Cam Species ◽  
Transient Phases

Leaf internal conductance to CO2 (gi) from substomatal cavity to the carboxylation sites of Rubisco was measured in the leaf succulent CAM species, Kalanchoe daigremontiana Hamet et Perr. Measurements were made during Rubisco-mediated atmospheric C3 carboxylation in phase IV photosynthesis. Using simultaneous gas exchange and chlorophyll fluorescence techniques, internal conductance was calculated to be 0.05 mol m-2 s-1 bar-1 , when measured at both saturating and limiting light. This is one of the lowest recorded values for gi as compared to a range of C3 species with comparable Rubisco content and indicates a large diffusion limitation to atmospheric CO2 fixation through the C3 pathway in K. daigremontiana. In ambient air, CO2 partial pressure at the carboxylation sites of Rubisco was 109 µbar. Internal diffusion is limited by a thick leaf consisting of densely packed, succulent mesophyll with a small portion of airspace. We speculate that a low internal conductance to CO2 diffusion results from the compromise between a succulent mesophyll required for C4 acid storage and access for CO2 diffusion to both PEPC in the cytoplasm and Rubisco in the chloroplasts. Restricted diffusion of CO2 within the leaf makes CO2 assimilation less efficient during the transient phases of crassulacean acid metabolism.

Deactivation of aquaporins decreases internal conductance to CO2 diffusion in tobacco leaves grown under long-term drought

2008 ◽  
Vol 35 (7) ◽  
pp. 553 ◽  
Author(s):  
Shin-Ichi Miyazawa ◽  
Satomi Yoshimura ◽  
Yuki Shinzaki ◽  
Masayoshi Maeshima ◽  
Chikahiro Miyake
Keyword(s):  
Water Permeability ◽  
Abaxial Epidermis ◽  
Tobacco Leaves ◽  
Surface Areas ◽  
Co2 Diffusion ◽  
Internal Conductance ◽  
Air Space ◽  
Leaf Tissues ◽  
Intercellular Air Space

We compared the diffusion conductance to CO2 from the intercellular air space to the chloroplasts (internal conductance (g i)) between tobacco leaves acclimated to long-term drought (drought-acclimated (DA)) and those grown under sufficient irrigation (well-watered (WW)), and analysed the changes in g i in relation to the leaf anatomical characteristics and a possible CO2 transporter, aquaporin. The g i, which was estimated by combined analyses of CO2 gas exchange with chlorophyll fluorescence, in the DA plants was approximately half of that in the WW plants. The mesophyll and chloroplast surface areas exposing the intercellular air space, which potentially affect g i, were not significantly different between the WW and DA plants. The amounts of plasma membrane aquaporins (PIP), immunochemically determined using radish PIP antibodies, were unrelated to g i. After treatment with HgCl2, an aquaporin inhibitor, the water permeability of the leaf tissues (measured as the weight loss of fully-turgid leaf disks without the abaxial epidermis in 1 m sorbitol) in WW plants decreased with an increase in HgCl2 concentration. The g i in the WW plants decreased to similar levels to the DA plants when the detached leaflets were fed with 0.5 mm HgCl2. In contrast, both water permeability and g i were insensitive to HgCl2 treatments in DA plants. These results suggest that deactivation of aquaporins is responsible for the significant reduction in g i observed in plants growing under long-term drought.

scholarly journals Mesophyll conductance in cotton bracts: anatomically determined internal CO2 diffusion constraints on photosynthesis

2018 ◽  
Author(s):  
Jimei Han ◽  
Zhangying Lei ◽  
Jaume Flexas ◽  
Yujie Zhang ◽  
Marc Carriquí ◽  
...  
Keyword(s):  
Mesophyll Conductance ◽  
Co2 Diffusion ◽  
Internal Co2 ◽  
Cotton Bracts

Frequency-response studies of CO2 diffusion in commercial 5A powders and pellets

1996 ◽  
Vol 5 (5) ◽  
pp. 279-288 ◽  
Author(s):  
György Onyestyák ◽  
Dongmin Shen ◽  
Lovat V.C. Rees
Keyword(s):  
Frequency Response ◽  
Co2 Diffusion

scholarly journals A new model of the global biogeochemical cycle of carbonyl sulfide – Part 2: Use of ocs to constrain gross primary productivity of current vegetation models

2014 ◽  
Vol 14 (20) ◽  
pp. 27663-27729 ◽  
Author(s):  
T. Launois ◽  
P. Peylin ◽  
S. Belviso ◽  
B. Poulter
Keyword(s):  
Northern Hemisphere ◽  
Seasonal Variations ◽  
Gross Primary Production ◽  
Experimental Studies ◽  
Carbonyl Sulfide ◽  
Surface Fluxes ◽  
Atmospheric Measurements ◽  
Mixing Ratios ◽  
Co2 Diffusion ◽  
Vegetation Models

Abstract. Clear analogies between carbonyl sulfide (OCS) and carbon dioxide (CO2) diffusion pathways through leaves have been revealed by experimental studies with plant uptake playing an important role for the atmospheric budget of both species. Here we use atmospheric OCS to evaluate the gross primary production (GPP) of three dynamic global vegetation models (LPJ, NCAR-CLM4 and ORCHIDEE). Vegetation uptake of OCS is modeled as a linear function of GPP and LRU, the ratio of OCS to CO2 deposition velocities to plants. New parameterizations for the non-photosynthetic sinks (oxic soils, atmospheric oxidation) and biogenic sources (oceans and anoxic soils) of OCS are also provided. Despite new large oceanic emissions, global OCS budgets created with each vegetation model show exceeding sinks by several hundreds of Gg S yr−1. An inversion of the surface fluxes (optimization of a global scalar which accounts for flux uncertainties) led to balanced OCS global budgets, as atmospheric measurements suggest, mainly by drastic reduction (−30%) of soil and vegetation uptakes. The amplitude of variations in atmospheric OCS mixing ratios is mainly dictated by the vegetation sink over the Northern Hemisphere. This allows for bias recognition in the GPP representations of the three selected models. Main bias patterns are (i) the terrestrial GPP of ORCHIDEE at high Northern latitudes is currently over-estimated, (ii) the seasonal variations of the GPP are out of phase in the NCAR-CLM4 model, showing a maximum carbon uptake too early in spring in the northernmost ecosystems, (iii) the overall amplitude of the seasonal variations of GPP in NCAR-CLM4 is too small, and (iv) for the LPJ model, the GPP is slightly out of phase for northernmost ecosystems and the respiration fluxes might be too large in summer in the Northern Hemisphere.

Sign in / Sign up

Export Citation Format

Share Document