The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Francois Tardieu - One of the best experts on this subject based on the ideXlab platform.
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Changes in the vertical distribution of leaf area enhanced Light Interception efficiency in maize over generations of selection
Plant Cell and Environment, 2019Co-Authors: Raphael Perez, Christophe Pradal, Christian Fournier, Nicolas Brichet, Claude Welcker, Llorenç Cabrera-bosquet, Simon Artzet, Tsu-wei Chen, Romain Chapuis, Francois TardieuAbstract:Breeders select for yield, thereby indirectly selecting for traits that contribute to it. We tested if breeding has affected a range of traits involved in plant architecture and Light Interception, via the analysis of a panel of 60 maize hybrids released from 1950 to 2015. This was based on novel traits calculated from reconstructions derived from a phenotyping platform. The contribution of these traits to Light Interception was assessed in virtual field canopies composed of 3D plant reconstructions, with a model tested in a real field. Two categories of traits had different contributions to genetic progress. (a) The vertical distribution of leaf area had a high heritability and showed a marked trend over generations of selection. Leaf area tended to be located at lower positions in the canopy, thereby improving Light penetration and distribution in the canopy. This potentially increased the carbon availability to ears, via the amount of Light absorbed by the intermediate canopy layer. (b) Neither the horizontal distribution of leaves in the relation to plant rows nor the response of Light Interception to plant density showed appreciable trends with generations. Hence, among many architectural traits, the vertical distribution of leaf area was the main indirect target of selection.
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high throughput estimation of incident Light Light Interception and radiation use efficiency of thousands of plants in a phenotyping platform
New Phytologist, 2016Co-Authors: Llorenc Cabrerabosquet, Christian Fournier, Nicolas Brichet, Claude Welcker, Benoit Suard, Francois TardieuAbstract:Light Interception and radiation-use efficiency (RUE) are essential components of plant performance. Their genetic dissections require novel high-throughput phenotyping methods. We have developed a suite of methods to evaluate the spatial distribution of incident Light, as experienced by hundreds of plants in a glasshouse, by simulating sunbeam trajectories through glasshouse structures every day of the year; the amount of Light intercepted by maize (Zea mays) plants via a functional-structural model using three-dimensional (3D) reconstructions of each plant placed in a virtual scene reproducing the canopy in the glasshouse; and RUE, as the ratio of plant biomass to intercepted Light. The spatial variation of direct and diffuse incident Light in the glasshouse (up to 24%) was correctly predicted at the single-plant scale. Light Interception largely varied between maize lines that differed in leaf angles (nearly stable between experiments) and area (highly variable between experiments). Estimated RUEs varied between maize lines, but were similar in two experiments with contrasting incident Light. They closely correlated with measured gas exchanges. The methods proposed here identified reproducible traits that might be used in further field studies, thereby opening up the way for large-scale genetic analyses of the components of plant performance.
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high throughput estimation of incident Light Light Interception and radiation use efficiency of thousands of plants in a phenotyping platform
New Phytologist, 2016Co-Authors: Llorenc Cabrerabosquet, Christian Fournier, Nicolas Brichet, Claude Welcker, Benoit Suard, Francois TardieuAbstract:We developed a non-invasive method to measure Light Interception and radiation-use efficiency (RUE) in thousands of maize (Zea mays) plants at the PHENOARCH phenotyping platform. Different models were interfaced to estimate (i) the amount of Light reaching each plant from hemispherical images, (ii) Light intercepted by each plant via a functional-structural plant model, (iii) RUE, as the ratio of plant biomass to intercepted Light. The inputs of these models were leaf area, biomass and architecture estimated from plant images and environmental data collected with a precise spatial and temporal resolution. We have tested this method by comparing two experiments performed in autumn and winter/spring. Biomass and leaf area differed between experiments showing a high G×E interaction. Difference in biomass between experiments was entirely accounted for by the difference in intercepted Light. Hence, the mean RUE was common to both experiments and genotypes ranked similarly. The methods presented here allowed dissecting the differences between experiments into (i) genotypic traits that did not differ between experiments but had a high genetic variability, namely plant architecture and RUE (ii) environmental differences, essentially incident Light, that affected both biomass and leaf area, (iii) plant traits that differed between experiments due to environmental variables, in particular leaf growth.
Herve Sinoquet - One of the best experts on this subject based on the ideXlab platform.
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multiscale framework for modeling and analyzing Light Interception by trees
Multiscale Modeling & Simulation, 2008Co-Authors: David Da Silva, Frédéric Boudon, Christophe Godin, Herve SinoquetAbstract:This paper presents a new framework for modeling Light Interception by isolated trees which makes it possible to analyze the influence of structural tree organization on Light capture. The framework is based on a multiscale representation of the plant organization. Tree architecture is decomposed into a collection of components representing clusters of leaves at different scales in the tree crown. The components are represented by porous envelopes automatically generated as convex hulls containing components at a finer scale. The component opacity is defined as the Interception probability of a Light beam going through its envelope. The role of tree organization on Light capture was assessed by running different scenarii where the components at any scale were either randomly distributed or localized to their actual three-dimensional (3D) position. The modeling framework was used with 3D digitized fruit trees, namely peach and mango trees. A sensitivity analysis was carried out to assess the effect of the ...
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Light Interception and partitioning between shoots in apple cultivars influenced by training
Tree Physiology, 2008Co-Authors: Jean Stephan, Herve Sinoquet, Nicolas Dones, Nicolas Haddad, Salma Talhouk, Pierreeric LauriAbstract:The effect of two training systems (Central Leader with branch pruning versus Centrifugal Training with minimal pruning, i.e., removal of fruiting laterals only) on canopy structure and Light Interception was analyzed in three architecturally contrasting apple (Malus domestica Borkh.) cultivars: ‘Scarletspur Delicious’ (Type II); ‘Golden Delicious’ (Type III); and ‘Granny Smith’(Type IV). Trees were 3D-digitized at the shoot scale at the 2004 and 2005 harvests. Shoots were separated according to length (short versus long) and type (fruiting versus vegetative). Leaf area density (LAD) and its relative variance ( ), total leaf area (TLA) and crown volume (V) varied consistently with cultivar. ‘Scarletspur Delicious’ had higherLADand and lowerTLAand V compared with the other cultivars with more open canopies. At the whole-tree scale, training had no effect on structure and Light Interception parameters (silhouette to total area ratio, STAR; projected leaf area, PLA). At the shoot scale, Centrifugal Training increased STAR values compared with Central Leader. In both training systems, vegetative shoots had higher STAR values than fruiting shoots. However, vegetative and fruiting shoots had similar TLA and PLA in Centrifugal Trained trees, whereas vegetative shoots had higher TLA and PLA than fruiting shoots in Central Leader trees. This unbalanced distribution of leaf area and Light Interception between shoot types in Central Leader trees partly resulted from the high proportion of long vegetative shoots that developed from latent buds. These shoots developed in the interior shaded zone of the canopy and therefore had low STAR and PLA. In conclusion, training may greatly affect the development and spatial positioning of shoots, which in turn significantly affects Light Interception by fruiting shoots.
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Contributions of foliage distribution and leaf functions to Light Interception, transpiration and photosynthetic capacities in two apple cultivars at branch and tree scales
Tree Physiology, 2008Co-Authors: Catherine Massonnet, Evelyne Costes, Pierreeric Lauri, Jean-luc Regnard, Herve SinoquetAbstract:Both the spatial distribution of leaves and leaf functions affect the Light Interception, transpiration and photosynthetic capacities of trees, but their relative contributions have rarely been investigated. We assessed these contributions at the branch and tree scales in two apple cultivars (Malus x domestica Borkh. 'Fuji' and 'Braeburn') with contrasting architectures, by estimating their branch and tree capacities and comparing them with outputs from a radiation absorption, transpiration and photosynthesis (RATP) functional-structural plant model (FSPM). The structures of three 8-year-old trees of each cultivar were digitized to obtain 3-D representations of foliage geometry. Within-tree foliage distribution was compared with shoot demography, number of leaves per shoot and mean individual leaf area. We estimated branch and tree Light Interception from silhouette to total leaf area ratios (STAR), transpiration from sap flux measurements and net photosynthetic rates by the branch bag method. Based on a set of parameters we previously established for both cultivars, the outputs of the RATP model were tested against STAR values, sap fluxes and photosynthetic measurements. The RATP model was then used to virtually switch foliage distribution or leaf functions (stomatal and photosynthetic properties), or both, between cultivars and to evaluate the effects on branch and tree Light Interception, transpiration and photosynthetic capacities in each cultivar. 'Fuji' trees had a higher proportion of leaf area borne on long shoots, fewer leaves per unit shoot length and a larger individual leaf area than 'Braeburn' trees. This resulted in a lower leaf area density and, consequently, a higher STAR in 'Fuji' than in 'Braeburn' at both branch and tree scales. Transpiration and photosynthetic rates were significantly higher in 'Fuji' than in 'Braeburn'. Branch heterogeneity was greater in 'Braeburn' than in 'Fuji'. An analysis of the virtual switches of foliage distribution or leaf function showed that differences in leaf spatial distribution and functions had additive effects that accounted for the lower transpiration and photosynthetic rates of branches and trees of 'Braeburn' compared with 'Fuji'. Leaf distribution had a more important role at the branch scale than at the tree scale, but the leaf function effect exceeded the leaf distribution effect at both scales. Our study demonstrated the potential of FSPM to disentangle physiological differences between cultivars through in silico scenarios.
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Simple equations to estimate Light Interception by isolated trees from canopy structure features: assessment with three-dimensional digitized apple trees
New Phytologist, 2007Co-Authors: Herve Sinoquet, Pierreeric Lauri, Jean Stephan, Gabriel Sonohat, Philippe MonneyAbstract:Simple models of Light Interception are useful to identify the key structural parameters involved in Light capture. We developed such models for isolated trees and tested them with virtual experiments. Light Interception was decomposed into the projection of the crown envelope and the crown porosity. The latter was related to tree structure parameters. Virtual experiments were conducted with three-dimensional (3-D) digitized apple trees grown in Lebanon and Switzerland, with different cultivars and training. The digitized trees allowed actual values of canopy structure (total leaf area, crown volume, foliage inclination angle, variance of leaf area density) and Light Interception properties (projected leaf area, silhouette to total area ratio, porosity, dispersion parameters) to be computed, and relationships between structure and Interception variables to be derived. The projected envelope area was related to crown volume with a power function of exponent 2/3. Crown porosity was a negative exponential function of mean optical density, that is, the ratio between total leaf area and the projected envelope area. The leaf dispersion parameter was a negative linear function of the relative variance of leaf area density in the crown volume. The resulting models were expressed as two single equations. After calibration, model outputs were very close to values computed from the 3-D digitized databases.
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Does shade improve Light Interception efficiency? A comparison among seedling from shade-tolerant and -intolerant temperate deciduous tree species
New Phytologist, 2006Co-Authors: Sylvain Delagrange, Christian Messier, Pierre Montpied, Erwin Dreyer, Herve SinoquetAbstract:Here, we tested two hypotheses: shading increases Light Interception efficiency (LIE) of broadleaved tree seedlings, and shade-tolerant species exhibit larger LIEs than do shade-intolerant ones. The impact of seedling size was taken into account to detect potential size-independent effects on LIE. LIE was defined as the ratio of mean Light intercepted by leaves to Light intercepted by a horizontal surface of equal area. Seedlings from five species differing in shade tolerance (Acer saccharum, Betula alleghaniensis, A. pseudoplatanus, B. pendula, Fagus sylvatica) were grown under neutral shading nets providing 36, 16 and 4% of external irradiance. Seedlings (1- and 2-year-old) were three-dimensionally digitized, allowing calculation of LIE. Shading induced dramatic reduction in total leaf area, which was lowest in shadetolerant species in all irradiance regimes. Irradiance reduced LIE through increasing leaf overlap with increasing leaf area. There was very little evidence of significant size-independent plasticity of LIE. No relationship was found between the known shade tolerance of species and LIE at equivalent size and irradiance.
Evelyne Costes - One of the best experts on this subject based on the ideXlab platform.
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designing oil palm architectural ideotypes for optimal Light Interception and carbon assimilation through a sensitivity analysis of leaf traits
Annals of Botany, 2018Co-Authors: Raphael P A Perez, Jean Dauzat, Julien Lamour, Benoît Pallas, Evelyne Costes, Philippe Verley, Jean-pierre Caliman, Robert FaivreAbstract:Background and Aims: Enhancement of Light harvesting in annual crops has successfully led to yield increases since the green revolution. Such an improvement has mainly been achieved by selecting plants with optimal canopy architecture for specific agronomic practices. For perennials such as oil palm, breeding programmes were focused more on fruit yield, but now aim at exploring more complex traits. The aim of the present study is to investigate potential improvements in Light Interception and carbon assimilation in the study case of oil palm, by manipulating leaf traits and proposing architectural ideotypes. Methods: Sensitivity analyses (Morris method and metamodel) were performed on a functional-structural plant model recently developed for oil palm which takes into account genetic variability, in order to virtually assess the impact of plant architecture on Light Interception efficiency and potential carbon acquisition. Key Results: The most sensitive parameters found over plant development were those related to leaf area (rachis length, number of leaflets, leaflet morphology), although fine attributes related to leaf geometry showed increasing influence when the canopy became closed. In adult stands, optimized carbon assimilation was estimated on plants with a leaf area index between 3.2 and 5.5 m2 m-2 (corresponding to usual agronomic conditions), with erect leaves, short rachis and petiole, and high number of leaflets on the rachis. Four architectural ideotypes for carbon assimilation are proposed based on specific combinations of organ dimensions and arrangement that limit mutual shading and optimize Light distribution within the plant crown. Conclusions: A rapid set-up of leaf area is critical at young age to optimize Light Interception and subsequently carbon acquisition. At the adult stage, optimization of carbon assimilation could be achieved through specific combinations of architectural traits. The proposition of multiple morphotypes with comparable level of carbon assimilation opens the way to further investigate ideotypes carrying an optimal trade-off between carbon assimilation, plant transpiration and biomass partitioning.
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3d plant model assessed by terrestrial lidar and hemispherical photographs a useful tool for comparing Light Interception among oil palm progenies
Agricultural and Forest Meteorology, 2018Co-Authors: Raphael Perez, Evelyne Costes, Jean-pierre Caliman, Frederic Theveny, Sebastien Griffon, Jean DauzatAbstract:The paradigm of functional-structural models (FSPM) assumes that studying the detailed organisation of plant structure allows a better understanding of functional processes; in particular the way plants capture Light for performing photosynthesis. However, much attention must be paid toward the consistency between virtual plants and plants in the field in terms of size and geometry to accurately evaluate Light Interception. This paper thus aimed at i) assessing the capacity of a 3D architectural model based on oil palms (Elaeis guineensis) to accurately represent plants structural characteristics at both the scale of the individual plant and the cultivated plot and ii) employing the validated 3D mock-ups to investigate how Light Interception efficiency varies among progenies that exhibit different architectures. Innovative indicators related to plant geometry and topology were derived from terrestrial LiDAR scanners (TLS) and hemispherical photographs (HP) in order to assess a 3D plant model. Indicators such as plant height, width and volume, gap fractions and solid angle projections were established from field measurements and were compared to equivalent indicators that had been extracted from virtual TLS (VTLS) and virtual HP (VHP) simulated on 3D mock-ups. Indicators were then evaluated for their significance in terms of Light Interception. Progeny effect on Light Interception efficiency was finally evaluated for five progenies. The structural indicators estimated from VTLS and VHP were significantly correlated with equivalent indicators estimated from TLS and HP, respectively, and with simulated outputs related to Light Interception. Light Interception efficiencies estimated from validated 3D mock-ups differed significantly among the five progenies under study, most notably along plant development. Our results highLight the relevance of combining TLS- and HP-derived indicators to evaluate the reliability of virtual 3D reconstruction of plants in relation to Light capture, at both the plant and plot scales. The study paves the way for further investigations aiming at unravelling the relationships between oil palm architecture and the physiological processes driving its production.(Resume d'auteur)
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Light Interception efficiency of apple trees a multiscale computational study based on mapplet
Ecological Modelling, 2014Co-Authors: David Da Silva, Liqi Han, Evelyne CostesAbstract:The Light Interception efficiency of a fruit tree plays a key role in its transpiration and photosynthesis, and therefore has a strong impact on its growth and yield. Manipulations of tree architecture, either through genetics or by agronomic practices, can help in improving Light Interception efficiency. However, the complexity of fruit tree structure and their long growth period makes it difficult to use real trees for exploring the link between architecture and Light Interception throughout tree development. In order to save time, resource and labor, this study relies a modelling approach to implement in silico experiments.The simulated trees were valid in terms of volume and associated leaf area density. The influence of the within-tree organisation of apple trees on their Light Interception was analyzed at four scales, leaves, shoots, branches and whole tree. The STAR, namely the silhouette to total area ratio, was used to evaluate the level of Interception efficiency. Light Interception estimation on simulated apple trees were compared with bibliographic data and STAR values were interpreted in relation with the spatial organization of components and shoot types within the tree. It was shown that an important part of the foliage clumpi-ness (>70%) was due to the multiscale organization of the tree. Additionally, as trees reached maturity,the short shoots became the predominant vegetative growth unit and among the different scales, the organization of the shoot scale showed the strongest effect on Light interaction efficiency. These results were interpreted as a consequence of tree ontogeny and branching organisation.
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Influence of the variation of geometrical and topological traits on Light Interception efficiency of apple trees: sensitivity analysis and metamodelling for ideotype definition
Annals of Botany, 2014Co-Authors: David Da Silva, Liqi Han, Robert Faivre, Evelyne CostesAbstract:Background and AimsThe impact of a fruit tree's architecture on its performance is still under debate, especially with regard to the definition of varietal ideotypes and the selection of architectural traits in breeding programmes. This study aimed at providing proof that a modelling approach can contribute to this debate, by using in silico exploration of different combinations of traits and their consequences on Light Interception, here considered as one of the key parameters to optimize fruit tree production.MethodsThe variability of organ geometrical traits, previously described in a bi-parental population, was used to simulate 1- to 5-year-old apple trees (Malus × domestica). Branching sequences along trunks observed during the first year of growth of the same hybrid trees were used to initiate the simulations, and hidden semi-Markov chains previously parameterized were used in subsequent years. Tree total leaf area (TLA) and silhouette to total area ratio (STAR) values were estimated, and a sensitivity analysis was performed, based on a metamodelling approach and a generalized additive model (GAM), to analyse the relative impact of organ geometry and lateral shoot types on STAR.Keys ResultsA larger increase over years in TLA mean and variance was generated by varying branching along trunks than by varying organ geometry, whereas the inverse was observed for STAR, where mean values stabilized from year 3 to year 5. The internode length and leaf area had the highest impact on STAR, whereas long sylleptic shoots had a more significant effect than proleptic shoots. Although the GAM did not account for interactions, the additive effects of the geometrical factors explained >90% of STAR variation, but much less in the case of branching factors.ConclusionsThis study demonstrates that the proposed modelling approach could contribute to screening architectural traits and their relative impact on tree performance, here viewed through Light Interception. Even though trait combinations and antagonism will need further investigation, the approach opens up new perspectives for breeding and genetic selection to be assisted by varietal ideotype definition.
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Investigating the influence of geometrical traits on Light Interception efficiency of apple trees: A modelling study with MAppleT
2012 IEEE 4th International Symposium on Plant Growth Modeling Simulation Visualization and Applications, 2012Co-Authors: Liqi Han, Frédéric Boudon, Thomas Cokelaer, Evelyne Costes, David Da Silva, Christophe Pradal, Robert FaivreAbstract:MAppleT is a functional-structural plant model that has been built for simulating architectural development of apple trees. It has the capability of representing tree growth within a virtual space where the development of individual organs depends on geometrical traits. The purpose of this research is to investigate the influence of apple trees' architectural variability on their Light Interception efficiency. The STAR, i.e. the silhouette to total area ratio, of leaves, was chosen to evaluate the level of such efficiency. The strategy is to integrate MAppleT with the Light Interception model provided by the Fractalysis module of the VPlants software library. Target values of four major traits (internode length, leaf area, branching angle and top shoot diameter), are varied in range previously observed in a segregating population of apple hybrids. A sensitivity analysis based on polynomial and generalized additive models was performed for highLighting the most influential trait on Light Interception. The contribution of stochastic processes that control tree topology in MAppleT is also investigated in the sensitivity analysis. This study not only provides a time- and resource-saving alternative for data collection, but also sets a methodology for ideotype definition and further genetic improvement of apple trees.
Jean Dauzat - One of the best experts on this subject based on the ideXlab platform.
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designing oil palm architectural ideotypes for optimal Light Interception and carbon assimilation through a sensitivity analysis of leaf traits
Annals of Botany, 2018Co-Authors: Raphael P A Perez, Jean Dauzat, Julien Lamour, Benoît Pallas, Evelyne Costes, Philippe Verley, Jean-pierre Caliman, Robert FaivreAbstract:Background and Aims: Enhancement of Light harvesting in annual crops has successfully led to yield increases since the green revolution. Such an improvement has mainly been achieved by selecting plants with optimal canopy architecture for specific agronomic practices. For perennials such as oil palm, breeding programmes were focused more on fruit yield, but now aim at exploring more complex traits. The aim of the present study is to investigate potential improvements in Light Interception and carbon assimilation in the study case of oil palm, by manipulating leaf traits and proposing architectural ideotypes. Methods: Sensitivity analyses (Morris method and metamodel) were performed on a functional-structural plant model recently developed for oil palm which takes into account genetic variability, in order to virtually assess the impact of plant architecture on Light Interception efficiency and potential carbon acquisition. Key Results: The most sensitive parameters found over plant development were those related to leaf area (rachis length, number of leaflets, leaflet morphology), although fine attributes related to leaf geometry showed increasing influence when the canopy became closed. In adult stands, optimized carbon assimilation was estimated on plants with a leaf area index between 3.2 and 5.5 m2 m-2 (corresponding to usual agronomic conditions), with erect leaves, short rachis and petiole, and high number of leaflets on the rachis. Four architectural ideotypes for carbon assimilation are proposed based on specific combinations of organ dimensions and arrangement that limit mutual shading and optimize Light distribution within the plant crown. Conclusions: A rapid set-up of leaf area is critical at young age to optimize Light Interception and subsequently carbon acquisition. At the adult stage, optimization of carbon assimilation could be achieved through specific combinations of architectural traits. The proposition of multiple morphotypes with comparable level of carbon assimilation opens the way to further investigate ideotypes carrying an optimal trade-off between carbon assimilation, plant transpiration and biomass partitioning.
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3d plant model assessed by terrestrial lidar and hemispherical photographs a useful tool for comparing Light Interception among oil palm progenies
Agricultural and Forest Meteorology, 2018Co-Authors: Raphael Perez, Evelyne Costes, Jean-pierre Caliman, Frederic Theveny, Sebastien Griffon, Jean DauzatAbstract:The paradigm of functional-structural models (FSPM) assumes that studying the detailed organisation of plant structure allows a better understanding of functional processes; in particular the way plants capture Light for performing photosynthesis. However, much attention must be paid toward the consistency between virtual plants and plants in the field in terms of size and geometry to accurately evaluate Light Interception. This paper thus aimed at i) assessing the capacity of a 3D architectural model based on oil palms (Elaeis guineensis) to accurately represent plants structural characteristics at both the scale of the individual plant and the cultivated plot and ii) employing the validated 3D mock-ups to investigate how Light Interception efficiency varies among progenies that exhibit different architectures. Innovative indicators related to plant geometry and topology were derived from terrestrial LiDAR scanners (TLS) and hemispherical photographs (HP) in order to assess a 3D plant model. Indicators such as plant height, width and volume, gap fractions and solid angle projections were established from field measurements and were compared to equivalent indicators that had been extracted from virtual TLS (VTLS) and virtual HP (VHP) simulated on 3D mock-ups. Indicators were then evaluated for their significance in terms of Light Interception. Progeny effect on Light Interception efficiency was finally evaluated for five progenies. The structural indicators estimated from VTLS and VHP were significantly correlated with equivalent indicators estimated from TLS and HP, respectively, and with simulated outputs related to Light Interception. Light Interception efficiencies estimated from validated 3D mock-ups differed significantly among the five progenies under study, most notably along plant development. Our results highLight the relevance of combining TLS- and HP-derived indicators to evaluate the reliability of virtual 3D reconstruction of plants in relation to Light capture, at both the plant and plot scales. The study paves the way for further investigations aiming at unravelling the relationships between oil palm architecture and the physiological processes driving its production.(Resume d'auteur)
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Integrated responses of rosette organogenesis, morphogenesis and architecture to reduced incident Light in Arabidopsis thaliana results in higher efficiency of Light Interception
Functional Plant Biology, 2005Co-Authors: Karine Chenu, Jean Dauzat, Nicolas Franck, Jean-françois Barczi, Hervé Rey, Jérémie LecoeurAbstract:Plants have a high phenotypic plasticity in response to Light. We investigated changes in plant architecture in response to decreased incident Light levels in Arabidopsis thaliana (L.) Heynh, focusing on organogenesis and morphogenesis, and on consequences for the efficiency of Light Interception of the rosette. A. thaliana ecotype Columbia plants were grown under various levels of incident photosynthetically active radiation (PAR), with blue Light (BL) intensity proportional to incident PAR intensity and with a high and stable red to far-red Light ratio. We estimated the PAR absorbed by the plant, using data from precise characterisation of the Light environment and 3-dimensional simulations of virtual plants generated with AMAPsim software. Decreases in incident PAR modified rosette architecture; leaf area decreased, leaf blades tended to be more circular and petioles were longer and thinner. However, the efficiency of Light Interception by the rosette was sLightly higher in plants subjected to lower PAR intensities, despite the reduction in leaf area. Decreased incident PAR delayed leaf initiation and slowed down relative leaf expansion rate, but increased the duration of leaf expansion. The leaf initiation rate and the relative expansion rate during the first third of leaf development were related to the amount of PAR absorbed. The duration of leaf expansion was related to PAR intensity. The relationships identified could be used to analyse the phenotypic plasticity of various genotypes of Arabidopsis. Overall, decreases in incident PAR result in an increase in the efficiency of Light Interception.
Kevin S. Gould - One of the best experts on this subject based on the ideXlab platform.
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leaf orientation and Light Interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and Light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of Interception of diffuse and direct Light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced Interception of direct and diffuse PAR when compared to Interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of Interception of diffuse PAR, but had a variable effect on the Interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse Light, regardless of their value as a source of direct Light. By maximising diffuse Light Interception while reducing direct Light Interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse Light Interception for plants growing in partially shaded environments.
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leaf orientation and Light Interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and Light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of Interception of diffuse and direct Light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced Interception of direct and diffuse PAR when compared to Interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of Interception of diffuse PAR, but had a variable effect on the Interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse Light, regardless of their value as a source of direct Light. By maximising diffuse Light Interception while reducing direct Light Interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse Light Interception for plants growing in partially shaded environments.