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Pierre Cellier - One of the best experts on this subject based on the ideXlab platform.
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Model of stomatal ammonia Compensation Point (STAMP) in relation to the plant nitrogen and carbon metabolisms and environmental conditions
Ecological Modelling, 2010Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Alain Perrier, Pierre CellierAbstract:Agricultural crops can be either a source or a sink of ammonia (NH3). Most NH3 exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed Compensation Points. We present here a leaf-scale simplified NH3 stomatal Compensation Point model related to the plants N and carbon (C) metabolisms, for C3 plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH4+), NH3 and nitrate (NO3-) between the different compartments, NH4+ production through photorespiration and NO3- reduction, NH4+ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH3. The simulated Compensation Point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH4+ flux to the leaf. Atmospheric NH3 concentration seem to have very little effect on the Compensation Point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH3 Compensation Point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH4+ may be required.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:Abstract The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 μg m−3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3−]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:1st NitroEurope Open Science Conference on Reactive Nitrogen and the European Greenhouse Gas Balance, Ghent (Belgique), 20-02-2008/21-02-2008The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 ?g m-3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3-]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental pollution (Barking Essex : 1987), 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:Abstract The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83–110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental Pollution, 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83e110), which represents the exchanges between the plant’s nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
Raia Silvia Massad - One of the best experts on this subject based on the ideXlab platform.
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Model of stomatal ammonia Compensation Point (STAMP) in relation to the plant nitrogen and carbon metabolisms and environmental conditions
Ecological Modelling, 2010Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Alain Perrier, Pierre CellierAbstract:Agricultural crops can be either a source or a sink of ammonia (NH3). Most NH3 exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed Compensation Points. We present here a leaf-scale simplified NH3 stomatal Compensation Point model related to the plants N and carbon (C) metabolisms, for C3 plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH4+), NH3 and nitrate (NO3-) between the different compartments, NH4+ production through photorespiration and NO3- reduction, NH4+ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH3. The simulated Compensation Point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH4+ flux to the leaf. Atmospheric NH3 concentration seem to have very little effect on the Compensation Point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH3 Compensation Point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH4+ may be required.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:Abstract The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 μg m−3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3−]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:1st NitroEurope Open Science Conference on Reactive Nitrogen and the European Greenhouse Gas Balance, Ghent (Belgique), 20-02-2008/21-02-2008The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 ?g m-3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3-]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental pollution (Barking Essex : 1987), 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:Abstract The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83–110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental Pollution, 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83e110), which represents the exchanges between the plant’s nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
T. Kaneyoshi - One of the best experts on this subject based on the ideXlab platform.
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A graphene-like Ising nanoparticle decorated with Ising trimer: High critical temperature, Compensation Point and characteristic magnetization curves
Solid State Communications, 2021Co-Authors: T. KaneyoshiAbstract:Abstract The decorated nanoparticle which is consisted of two paramagnetic (hexagonal and trimer) nanoparticles and tied by an exchange interaction is examined by the effective-field theory with correlations. It is discussed whether it can exhibit a critical temperature larger than that of a bulk system. The phase diagram and the thermal variations of magnetizations are investigated. When some appropriate conditions are satisfied for exchange interactions, a Compensation Point and characteristic thermal variations can be found in the total magnetization.
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Compensation Point Phenomena in a Transverse Ising Antiferromagnet: Unconventional Effects of an Applied Magnetic Field
Journal of Superconductivity and Novel Magnetism, 2016Co-Authors: T. KaneyoshiAbstract:The thermal variations of magnetizations in a transverse Ising antiferromagnet consisting of two magnetic (A and B) layers are examined by the use of the effective-field theory with correlations, applying a magnetic field p. Particular attentions are paid to the systems with a Compensation Point in the zero applied field (p = 0.0), when crystallographically equivalent conditions between the A and B layers are broken. We find some characteristic phenomena, such as the possibility of more than one Compensation Point induced by a finite applied magnetic field and the thermally induced first-order transition.
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the possibility of a Compensation Point induced by a transverse field in transverse ising nanoparticles with a negative core shell coupling
Solid State Communications, 2012Co-Authors: T. KaneyoshiAbstract:Abstract The phase diagram and magnetizations of two 2D nanoparticles with a negative core–shell interaction, described by the transverse Ising model, are investigated by the use of the effective field theory with correlations. The behaviors of a Compensation Point in these nanosystems are examined by changing an applied transverse field. It is proved that a Compensation Point can be induced in the two nanosystems by applying a transverse field.
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The possibility of a Compensation Point induced by a transverse field in transverse Ising nanoparticles with a negative core–shell coupling
Solid State Communications, 2012Co-Authors: T. KaneyoshiAbstract:Abstract The phase diagram and magnetizations of two 2D nanoparticles with a negative core–shell interaction, described by the transverse Ising model, are investigated by the use of the effective field theory with correlations. The behaviors of a Compensation Point in these nanosystems are examined by changing an applied transverse field. It is proved that a Compensation Point can be induced in the two nanosystems by applying a transverse field.
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Surface Magnetizations of a Semi-Infinite Ferrimagnetic System with a Compensation Point in the Bulk
physica status solidi (b), 1992Co-Authors: T. KaneyoshiAbstract:Thermal variations of magnetizations at or near a surface are investigated by using a semi-infinite mixed spin ferrimagnetic system within the framework of the effective-field theory and the three-layer approximation. Depending on the value of single-ion anisotropy in the bulk or at the surface, the system can exhibit the Compensation Point in the bulk magnetization or magnetization near the surface. The effects of Compensation Point in the bulk on magnetizations at or near the surface are in particular examined. A number of interesting phenomena are found, such as a fact that the Compensation temperature in the vicinity of the surface may be different from that in the bulk. Im Rahmen der Effektivfeldtheorie und der Dreischichtnaherung werden die thermischen Anderungen der Magnetisierung an oder in der Nahe einer Oberflache mittels eines halbunendlichen ferrimagnetischen Systems mit gemischtem Spin untersucht. In Abhangigkeit vom Wert der Einionenanisotropie im Volumen oder an der Oberflache kann das System den Kompensationspunkt in der Volumenmagnetisierung oder Oberflachenmagnetisierung zeigen. Die Einflusse des Kompensationspunktes im Volumen auf Magnetisierungen an oder in der Nahe der Oberflache werden besonders untersucht. Eine Anzahl interessanter Phanomene wird gefunden, wie die Tatsache, das die Kompensationstemperatur in der Nahe der Oberflache von der im Volumen verschieden sein kann.
Benjamin Loubet - One of the best experts on this subject based on the ideXlab platform.
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Model of stomatal ammonia Compensation Point (STAMP) in relation to the plant nitrogen and carbon metabolisms and environmental conditions
Ecological Modelling, 2010Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Alain Perrier, Pierre CellierAbstract:Agricultural crops can be either a source or a sink of ammonia (NH3). Most NH3 exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed Compensation Points. We present here a leaf-scale simplified NH3 stomatal Compensation Point model related to the plants N and carbon (C) metabolisms, for C3 plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH4+), NH3 and nitrate (NO3-) between the different compartments, NH4+ production through photorespiration and NO3- reduction, NH4+ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH3. The simulated Compensation Point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH4+ flux to the leaf. Atmospheric NH3 concentration seem to have very little effect on the Compensation Point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH3 Compensation Point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH4+ may be required.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:Abstract The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 μg m−3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3−]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied.
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Temporal variability in bioassays of the stomatal ammonia Compensation Point in relation to plant and soil nitrogen parameters in intensively managed grassland
Biogeosciences, 2009Co-Authors: M. Mattsson, Benjamin Loubet, B. Herrmann, Marie David, M. Riedo, M.r. Theobald, M.a. Sutton, D. Bruhn, A. Neftel, J.k. SchjoerringAbstract:The exchange of ammonia between crop canopies and the atmosphere depends on a range of plant parameters and climatic conditions. However, little is known about effects of management factors. We have here investigated the stomatal ammonia Compensation Point in response to cutting and fertilization of a grass sward dominated by Lolium perenne. Tall grass had a very low NH3 Compensation Point (around 1 nmol mol-1), reflecting the fact that leaf nitrogen (N) concentration was very low. During re-growth after cutting, leaf tissue concentrations of NO3-, NH4+, soluble N and total N increased along with apoplastic NH4+ concentrations. In contrast, apoplastic pH decreased resulting in largely unaltered NH3 Compensation Points. Nitrogen fertilization one week after cutting caused the apoplastic NH4+ concentration of the newly emerging leaves to increase dramatically. The NH3 Compensation Point peaked between 15 and 25 nmol mol-1 the day after the fertiliser was applied and thereafter decreased over the following 10 days until reaching the same level as before fertilisation. Ammonium concentrations in leaf apoplast, bulk tissue and litter were positively correlated (P=0.001) throughout the experimental period. Bulk tissue NH4+ concentrations, total plant N and soil NH4+ concentrations also showed a positive correlation. A very high potential for NH3 emission was shown by the plant litter.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:1st NitroEurope Open Science Conference on Reactive Nitrogen and the European Greenhouse Gas Balance, Ghent (Belgique), 20-02-2008/21-02-2008The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 ?g m-3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3-]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental pollution (Barking Essex : 1987), 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:Abstract The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83–110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
Andree Tuzet - One of the best experts on this subject based on the ideXlab platform.
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Model of stomatal ammonia Compensation Point (STAMP) in relation to the plant nitrogen and carbon metabolisms and environmental conditions
Ecological Modelling, 2010Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Alain Perrier, Pierre CellierAbstract:Agricultural crops can be either a source or a sink of ammonia (NH3). Most NH3 exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed Compensation Points. We present here a leaf-scale simplified NH3 stomatal Compensation Point model related to the plants N and carbon (C) metabolisms, for C3 plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH4+), NH3 and nitrate (NO3-) between the different compartments, NH4+ production through photorespiration and NO3- reduction, NH4+ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH3. The simulated Compensation Point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH4+ flux to the leaf. Atmospheric NH3 concentration seem to have very little effect on the Compensation Point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH3 Compensation Point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH4+ may be required.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:Abstract The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 μg m−3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3−]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied.
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Ammonia stomatal Compensation Point of young oilseed rape leaves during dark/light cycles under various nitrogen nutritions
Agriculture Ecosystems & Environment, 2009Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Hervé Autret, Pierre CellierAbstract:1st NitroEurope Open Science Conference on Reactive Nitrogen and the European Greenhouse Gas Balance, Ghent (Belgique), 20-02-2008/21-02-2008The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal Compensation Point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here. We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal Compensation Point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution. Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation Points were calculated by two different methods and ranged between 0.8 and 12.2 ?g m-3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3-]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply. Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal Compensation Point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental pollution (Barking Essex : 1987), 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:Abstract The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83–110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.
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Relationship between ammonia stomatal Compensation Point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches
Environmental Pollution, 2008Co-Authors: Raia Silvia Massad, Andree Tuzet, Benjamin Loubet, Pierre CellierAbstract:The ammonia stomatal Compensation Point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal Compensation Point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83e110), which represents the exchanges between the plant’s nitrogen pools. The first step to model the ammonia stomatal Compensation Point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal Compensation Point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.