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Berghuijs HNC, Yin X, Ho QT, Driever SM, Retta MA, Nicolaï BM, Struik PC. Mesophyll conductance and reaction-diffusion models for CO 2 transport in C 3 leaves; needs, opportunities and challenges. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 252:62-75. [PMID: 27717479 DOI: 10.1016/j.plantsci.2016.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/19/2016] [Accepted: 05/21/2016] [Indexed: 05/24/2023]
Abstract
One way to increase potential crop yield could be increasing mesophyll conductance gm. This variable determines the difference between the CO2 partial pressure in the intercellular air spaces (Ci) and that near Rubisco (Cc). Various methods can determine gm from gas exchange measurements, often combined with measurements of chlorophyll fluorescence or carbon isotope discrimination. gm lumps all biochemical and physical factors that cause the difference between Cc and Ci. gm appears to vary with Ci. This variability indicates that gm does not satisfy the physical definition of a conductance according to Fick's first law and is thus an apparent parameter. Uncertainty about the mechanisms that determine gm can be limited to some extent by using analytical models that partition gm into separate conductances. Such models are still only capable of describing the CO2 diffusion pathway to a limited extent, as they make implicit assumptions about the position of mitochondria in the cells, which affect the re-assimilation of (photo)respired CO2. Alternatively, reaction-diffusion models may be used. Rather than quantifying gm, these models explicitly account for factors that affect the efficiency of CO2 transport in the mesophyll. These models provide a better mechanistic description of the CO2 diffusion pathways than mesophyll conductance models. Therefore, we argue that reaction-diffusion models should be used as an alternative to mesophyll conductance models, in case the aim of such a study is to identify traits that can be improved to increase gm.
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Affiliation(s)
- Herman N C Berghuijs
- Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
| | - Xinyou Yin
- Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Q Tri Ho
- Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Steven M Driever
- Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Moges A Retta
- Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Bart M Nicolaï
- Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Paul C Struik
- Centre for Crop Systems Analysis, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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Xu G, Singh SK, Reddy VR, Barnaby JY, Sicher RC, Li T. Soybean grown under elevated CO 2 benefits more under low temperature than high temperature stress: Varying response of photosynthetic limitations, leaf metabolites, growth, and seed yield. JOURNAL OF PLANT PHYSIOLOGY 2016; 205:20-32. [PMID: 27589223 DOI: 10.1016/j.jplph.2016.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 08/15/2016] [Accepted: 08/15/2016] [Indexed: 05/20/2023]
Abstract
To evaluate the combined effect of temperature and CO2 on photosynthetic processes, leaf metabolites and growth, soybean was grown under a controlled environment at low (22/18°C, LT), optimum (28/24°C, OT) and high (36/32°C HT) temperatures under ambient (400μmolmol-1; aCO2) or elevated (800μmolmol-1; eCO2) CO2 concentrations during the reproductive stage. In general, the rate of photosynthesis (A), stomatal (gs) and mesophyll (gm) conductance, quantum yield of photosystem II, rates of maximum carboxylation (VCmax), and electron transport (J) increased with temperature across CO2 levels. However, compared with OT, the percentage increases in these parameters at HT were lower than the observed decline at LT. The photosynthetic limitation at LT and OT was primarily caused by photo-biochemical processes (49-58%, Lb) followed by stomatal (27-32%, Ls) and mesophyll (15-19%, Lm) limitations. However, at HT, it was primarily caused by Ls (41%) followed by Lb (33%) and Lm (26%). The dominance of Lb at LT and OT was associated with the accumulation of non-structural carbohydrates (e.g., starch) and several organic acids, whereas this accumulation did not occur at HT, indicating increased metabolic activities. Compared with OT, biomass and seed yield declined more at HT than at LT. The eCO2 treatment compensated for the temperature-stress effects on biomass but only partially compensated for the effects on seed yield, especially at HT. Photosynthetic downregulation at eCO2 was possibly due to the accumulation of non-structural carbohydrates and the decrease in gs and Astd (standard A measured at 400μmolmol-1 sub-stomatal CO2 concentration), as well as the lack of CO2 effect on gm, VCmax, and J, and photosynthetic limitation. Thus, the photosynthetic limitation was temperature-dependent and was primarily influenced by the alteration in photo-biochemical processes and metabolic activities. Despite the inconsistent response of photosynthesis (or biomass accumulation) and seed yield, eCO2 tended to fully or partially compensate for the adverse effect of the respective LT and HT stresses under well-watered and sufficient nutrient conditions.
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Affiliation(s)
- Guangli Xu
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA; College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Shardendu K Singh
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA; Wye Research and Education Center, University of Maryland, MD, USA.
| | - Vangimalla R Reddy
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA
| | - Jinyoung Y Barnaby
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA
| | - Richard C Sicher
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA
| | - Tian Li
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
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53
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Pugh TAM, Müller C, Arneth A, Haverd V, Smith B. Key knowledge and data gaps in modelling the influence of CO 2 concentration on the terrestrial carbon sink. JOURNAL OF PLANT PHYSIOLOGY 2016; 203:3-15. [PMID: 27233774 DOI: 10.1016/j.jplph.2016.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 06/05/2023]
Abstract
Primary productivity of terrestrial vegetation is expected to increase under the influence of increasing atmospheric carbon dioxide concentrations ([CO2]). Depending on the fate of such additionally fixed carbon, this could lead to an increase in terrestrial carbon storage, and thus a net terrestrial sink of atmospheric carbon. Such a mechanism is generally believed to be the primary global driver behind the observed large net uptake of anthropogenic CO2 emissions by the biosphere. Mechanisms driving CO2 uptake in the Terrestrial Biosphere Models (TBMs) used to attribute and project terrestrial carbon sinks, including that from increased [CO2], remain in large parts unchanged since those models were conceived two decades ago. However, there exists a large body of new data and understanding providing an opportunity to update these models, and directing towards important topics for further research. In this review we highlight recent developments in understanding of the effects of elevated [CO2] on photosynthesis, and in particular on the fate of additionally fixed carbon within the plant with its implications for carbon turnover rates, on the regulation of photosynthesis in response to environmental limitations on in-plant carbon sinks, and on emergent ecosystem responses. We recommend possible avenues for model improvement and identify requirements for better data on core processes relevant to the understanding and modelling of the effect of increasing [CO2] on the global terrestrial carbon sink.
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Affiliation(s)
- T A M Pugh
- School of Geography, Earth & Environmental Sciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, United Kingdom; Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany.
| | - C Müller
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
| | - A Arneth
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany
| | - V Haverd
- CSIRO Oceans and Atmosphere, P.O. Box 3023, Canberra ACT 2601, Australia
| | - B Smith
- Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden
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Sharkey TD. What gas exchange data can tell us about photosynthesis. PLANT, CELL & ENVIRONMENT 2016; 39:1161-3. [PMID: 26390237 DOI: 10.1111/pce.12641] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 09/04/2015] [Accepted: 09/10/2015] [Indexed: 05/21/2023]
Affiliation(s)
- Thomas D Sharkey
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48823, USA
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55
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Bellasio C, Beerling DJ, Griffiths H. An Excel tool for deriving key photosynthetic parameters from combined gas exchange and chlorophyll fluorescence: theory and practice. PLANT, CELL & ENVIRONMENT 2016; 39:1180-97. [PMID: 25923517 DOI: 10.1111/pce.12560] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/10/2015] [Accepted: 02/25/2015] [Indexed: 05/23/2023]
Abstract
Combined photosynthetic gas exchange and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-gas exchange experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of gas exchange data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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56
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Mystakidis S, Davin EL, Gruber N, Seneviratne SI. Constraining future terrestrial carbon cycle projections using observation-based water and carbon flux estimates. GLOBAL CHANGE BIOLOGY 2016; 22:2198-215. [PMID: 26732346 DOI: 10.1111/gcb.13217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 10/20/2015] [Accepted: 11/12/2015] [Indexed: 05/15/2023]
Abstract
The terrestrial biosphere is currently acting as a sink for about a third of the total anthropogenic CO2 emissions. However, the future fate of this sink in the coming decades is very uncertain, as current earth system models (ESMs) simulate diverging responses of the terrestrial carbon cycle to upcoming climate change. Here, we use observation-based constraints of water and carbon fluxes to reduce uncertainties in the projected terrestrial carbon cycle response derived from simulations of ESMs conducted as part of the 5th phase of the Coupled Model Intercomparison Project (CMIP5). We find in the ESMs a clear linear relationship between present-day evapotranspiration (ET) and gross primary productivity (GPP), as well as between these present-day fluxes and projected changes in GPP, thus providing an emergent constraint on projected GPP. Constraining the ESMs based on their ability to simulate present-day ET and GPP leads to a substantial decrease in the projected GPP and to a ca. 50% reduction in the associated model spread in GPP by the end of the century. Given the strong correlation between projected changes in GPP and in NBP in the ESMs, applying the constraints on net biome productivity (NBP) reduces the model spread in the projected land sink by more than 30% by 2100. Moreover, the projected decline in the land sink is at least doubled in the constrained ensembles and the probability that the terrestrial biosphere is turned into a net carbon source by the end of the century is strongly increased. This indicates that the decline in the future land carbon uptake might be stronger than previously thought, which would have important implications for the rate of increase in the atmospheric CO2 concentration and for future climate change.
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Affiliation(s)
- Stefanos Mystakidis
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, Switzerland
- Center for Climate Systems Modeling, ETH Zurich, Universitätstrasse 16, Zurich, 8092, Switzerland
| | - Edouard L Davin
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, Switzerland
| | - Nicolas Gruber
- Center for Climate Systems Modeling, ETH Zurich, Universitätstrasse 16, Zurich, 8092, Switzerland
- Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätstrasse 16, Zurich, 8092, Switzerland
| | - Sonia I Seneviratne
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, Switzerland
- Center for Climate Systems Modeling, ETH Zurich, Universitätstrasse 16, Zurich, 8092, Switzerland
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57
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Singh SK, Reddy VR. Methods of mesophyll conductance estimation: its impact on key biochemical parameters and photosynthetic limitations in phosphorus-stressed soybean across CO2. PHYSIOLOGIA PLANTARUM 2016; 157:234-54. [PMID: 26806194 DOI: 10.1111/ppl.12415] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/26/2015] [Accepted: 11/18/2015] [Indexed: 05/04/2023]
Abstract
Despite the development of various methods, the rapid estimation of mesophyll conductance (gm ) for a large number of samples is still a daunting challenge. Although the accurate estimation of gm is critical to partition photosynthetic limitations by stomatal (Ls ) and mesophyll (Lm ) conductance and by photo-biochemical (Lb ) processes, the impact of various gm estimation methods on this is ambiguous. As phosphorus (P) starvation and elevated CO2 (eCO2 ) strongly affect photosynthetic processes, their combined effect on the proportional changes in these limitations are not well understood. To investigate this, while also evaluating distinct recent methods of gm estimation sharing few common theories and assumptions, soybean was grown under a range of P nutrition at ambient and eCO2 . Methods significantly affected gm and carboxylation efficiency (VCmax ) but not other photosynthetic parameters. In all the methods, all photosynthetic parameters responded similarly to treatments. However, the percentage difference between VCmax assuming finite and infinite gm was highly inconsistent among methods. The primary mechanism responsible for P limitation to soybean photosynthesis was not CO2 diffusion limitations but Lb comprised of reduced chlorophyll, photochemistry and biochemical processes. The eCO2 decreased Lb but increased Lm without affecting Ls across leaf P concentration. Although each method explored advances of our understanding about gm variability, they all require assumptions of varying degrees, which lead to the discrepancy in the gm values. Among the methods, the oxygen sensitivity-based gm estimation appeared to be suitable for the quick assessment of a large number of samples or genotypes. Digital tools are provided for the easy estimation of gm for some methods.
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Affiliation(s)
- Shardendu K Singh
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA
- Wye Research and Education Center, University of Maryland, College Park, MD, USA
| | - Vangimalla R Reddy
- Crop Systems and Global Change Laboratory, USDA-ARS, Beltsville, MD 20705, USA
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58
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Walker BJ, VanLoocke A, Bernacchi CJ, Ort DR. The Costs of Photorespiration to Food Production Now and in the Future. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:107-29. [PMID: 26865340 DOI: 10.1146/annurev-arplant-043015-111709] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Photorespiration is essential for C3 plants but operates at the massive expense of fixed carbon dioxide and energy. Photorespiration is initiated when the initial enzyme of photosynthesis, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), reacts with oxygen instead of carbon dioxide and produces a toxic compound that is then recycled by photorespiration. Photorespiration can be modeled at the canopy and regional scales to determine its cost under current and future atmospheres. A regional-scale model reveals that photorespiration currently decreases US soybean and wheat yields by 36% and 20%, respectively, and a 5% decrease in the losses due to photorespiration would be worth approximately $500 million annually in the United States. Furthermore, photorespiration will continue to impact yield under future climates despite increases in carbon dioxide, with models suggesting a 12-55% improvement in gross photosynthesis in the absence of photorespiration, even under climate change scenarios predicting the largest increases in atmospheric carbon dioxide concentration. Although photorespiration is tied to other important metabolic functions, the benefit of improving its efficiency appears to outweigh any potential secondary disadvantages.
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Affiliation(s)
- Berkley J Walker
- Global Change and Photosynthesis Research Unit, US Department of Agriculture Agricultural Research Service (USDA/ARS), Urbana, Illinois 61801;
- Carl R. Woese Institute for Genomic Biology and
| | - Andy VanLoocke
- Department of Agronomy, Iowa State University, Ames, Iowa 50011
| | - Carl J Bernacchi
- Global Change and Photosynthesis Research Unit, US Department of Agriculture Agricultural Research Service (USDA/ARS), Urbana, Illinois 61801;
- Carl R. Woese Institute for Genomic Biology and
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Donald R Ort
- Global Change and Photosynthesis Research Unit, US Department of Agriculture Agricultural Research Service (USDA/ARS), Urbana, Illinois 61801;
- Carl R. Woese Institute for Genomic Biology and
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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59
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Li X, Zhu Z, Zeng H, Piao S. Estimation of gross primary production in China (1982–2010) with multiple ecosystem models. Ecol Modell 2016. [DOI: 10.1016/j.ecolmodel.2015.12.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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60
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61
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Wohlfahrt G, Gu L. The many meanings of gross photosynthesis and their implication for photosynthesis research from leaf to globe. PLANT, CELL & ENVIRONMENT 2015; 38:2500-7. [PMID: 25988305 PMCID: PMC4681079 DOI: 10.1111/pce.12569] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/13/2015] [Indexed: 05/18/2023]
Abstract
(1) Gross photosynthesis is a key term in plant biology and carbon cycle science, however has been used with different meanings by different communities (2) We review the history of this term and associated concepts to clarify the terminology and make recommendations about a consistent use of terms in accordance with photosynthetic theory. (3) We show that a widely used eddy covariance CO2 flux partitioning approach yields estimates which are quantitatively closer to the definition of true photosynthesis despite aiming at estimating apparent photosynthesis.
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Affiliation(s)
- Georg Wohlfahrt
- Institute of Ecology, University of Innsbruck, 6020, Innsbruck, Austria
- European Academy of Bolzano, 39100, Bolzano, Italy
| | - Lianhong Gu
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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62
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Busch FA. Reducing the gaps in our understanding of the global terrestrial carbon cycle. THE NEW PHYTOLOGIST 2015; 206:886-888. [PMID: 25865164 DOI: 10.1111/nph.13399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Affiliation(s)
- Florian A Busch
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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