Jean Dauzat

Jean Dauzat
Cirad - La recherche agronomique pour le développement | CIRAD · Unité Mixte de Recherche Botanique et Bio-Informatique de l’Architecture des Plantes (AMAP)

About

84
Publications
22,517
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2,229
Citations
Citations since 2017
14 Research Items
934 Citations
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2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150

Publications

Publications (84)
Article
Full-text available
Functional-structural plant modelling approaches (FSPM) explore the relationships between the 3D structure and the physiological functioning of plants in relation to environmental conditions. In this study, we present a methodological approach that integrated architectural responses to planting design in an oil palm FSPM, and test the impact of pla...
Article
Full-text available
Eight years of studying coffee ecophysiology and monitoring ecosystem services (ES) in a large coffee farm in Costa Rica revealed several practical recommendations for farmers and policy makers. The cropping system studied within our collaborative observatory (Coffee-Flux) corresponds to a coffee-based agroforestry system (AFS) under the shade of l...
Poster
Full-text available
Introduction Light modelling at the scale of organs is essential to account accurately for the complex interactions between biophysical processes such as photosynthesis, stomatal conductance and energy balance. Yet, the calculation of radiative exchanges at fine scales is computationally-intensive and it remains a hindrance to a widespread use of F...
Conference Paper
Full-text available
El déficit hídrico tiene un impacto negativo en el crecimiento y desarrollo de las plantas a través de alteraciones morfo-fisiológicas. Esta investigación se centró en la dinámica de los rasgos ecofisiológicos y arquitectura de dosel en dos cultivares de café, RUBI-MG1192 (Rubi) y IAPAR59 (I59), sensible y tolerante a la sequía, respectivamente. Lo...
Chapter
Full-text available
Eight years of studying coffee ecophysiology and monitoring ecosystem services (ES) in a large coffee farm in Costa Rica revealed several practical recommendations for farmers and policy makers. The cropping system studied within our collaborative observatory (Coffee-Flux) corresponds to a coffee-based agroforestry system (AFS) under the shade of l...
Chapter
Full-text available
Huit ans de travaux de recherche sur les services écosystémiques dans une grande ferme caféière du Costa Rica (observatoire collaboratif Coffee-Flux, en système agro-forestier à base de caféiers sous de grands arbres d'Erythrina poeppigiana, surface projetée de couronne de l'ordre de 16 %) ont suggéré plusieurs applications pour les agriculteurs et...
Article
Full-text available
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...
Article
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 f...
Article
Leaf area index estimates in dense evergreen tropical moist forest almost exclusively rest on indirect methods most of which being of limited accuracy or spatial resolution. In this study we examine the potential of full waveform Aerial Laser Scanning (ALS) to derive accurate spatially explicit estimates of Plant Area Index (PAI).
Conference Paper
Full-text available
Eight years of monitoring ecophysiology and ecosystem services (ES) in a large coffee farm of Costa Rica yields a range of practical applications for the farmer and stakeholders, thanks to numerous scientific actors and disciplines contributing to our collaborative observatory (Coffee-Flux). • A lot of ecosystem services depend on the soil properti...
Article
Full-text available
Key messageWe combined aerial LiDAR and ground sensors to map the spatial variation in micro-environmental variables of the tropical forest understory. We show that these metrics depend on forest type and proximity to canopy gaps. Our study has implications for the study of natural forest regeneration. ContextLight impacts seedling dynamics and ani...
Article
Full-text available
The development of new breeding strategies to find more sustainable and productive systems is a major challenge to cope with ceaseless increasing demands for palm oil. Optimizing plant architecture to increase radiation interception efficiency could be an option for enhancing potential crop production. Most oil palms grown in the world are Deli dur...
Article
Full-text available
Three-dimensional (3D) reconstruction of plants is time-consuming and involves considerable levels of data acquisition. This is possibly one reason why the integration of genetic variability into 3D architectural models has so far been largely overlooked. In this study, an allometry-based approach was developed to account for architectural variabil...
Article
Full-text available
Background and aims: Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The ai...
Poster
Full-text available
Description of the 3D-reconstruction model of oil palm and its application to estimate light interception among progenies.
Conference Paper
Full-text available
The development of new breeding strategies to find more sustainable and productive systems is a major challenge to cope with ceaseless increasing demands for palm oil. Optimizing plant architecture to increase radiation interception efficiency could be an option for enhancing potential crop production. Most oil palms grown in the world are Deli dur...
Conference Paper
This study aimed to analyze the berry location and maturing within the plant architecture for two planting densities combined with two planting patterns in a first production year. Non destructive measurements of coffee plant architecture (cv. IAPAR 59) were performed on plants grown in two plant densities (6,000 and 10,000 plants ha-1) and plantin...
Conference Paper
Full-text available
This paper gives an overview of French studies realized in the frame of the CNES (French Space Agency) working group on spaceborne lidar missions. These studies include (1) the development of forest scenery and radiative transfer models for the simulation of lidar waveforms under forest cover, (2) preliminary instrumental studies to ensure the feas...
Article
In agroforestry systems (AFS), quantifying the competition for light is a prerequisite toward understanding the impact of shade trees on the productivity of the under-crop. Models for homogeneous canopies and shade/full-sun approaches do not address the intra-plot heterogeneity, typical of AFS. For the first time, MAESTRA, a 3D light absorption mod...
Article
Full-text available
Context Understanding the effects of exogenous factors on tree development is of major importance in the current context of global change. Assessing the structure development of trees is difficult given that they are large and complex organisms with lifespan of several decades. Aims We used a retrospective analysis to derive the ontogenetic trends...
Conference Paper
Full-text available
Very high spatial resolution (VHSR) satellite images provide interesting information for parameterizing tree-scale forest process-based models, and in particular their light absorption submodels, which is at the basis of photosynthesis calculation. Such tree-scale models require a large amount of field measurements to describe the forest ecosystems...
Conference Paper
Full-text available
Dans les années 1970, à une époque où les statistiques appliquées aux sciences agronomiques se cantonnaient à travailler sur des productions à l'hectare et des blocs de traitement statistiques des essais génétiques et de fumure, alors même que les études biologiques et génétiques se penchaient plus sur l'intimité de la cellule, un chercheur s'est i...
Article
Full-text available
Research on coffee agroforestry systems in Central America has identified various environmental factors, management strategies and plant characteristics that affect growth, yield and the impact of the systems on the environment. Much of this literature is not quantitative, and it remains difficult to optimise growing area selection, shade tree use...
Article
Full-text available
Coffee is widely grown across Central America at altitudes between 600 and 2500m, mostly in association with trees that provide shade and other services. Research on coffee agroforestry systems has identified many environmental factors, management strategies and plant characteristics that affect growth, yield and environmental impact of the system....
Article
Full-text available
In agroforestry systems, the distribution of light transmitted under tree canopies can be a limiting factor for the development of intercrops. The light available for intercrops depends on the quantity of light intercepted by tree canopies and, consequently, on the architecture of the tree species present. The influence of tree architecture on ligh...
Article
Full-text available
Net primary productivity (NPP) is a key driver of ecosystem C balance. Scaling NPP up to larger areas requires indirect methods: (a) for examble epsilon models based on light use efficiency (LUE = NPP/APAR, where APAR is the absorbed photosynthetically active radiation by green elements of canopy, or else models based on water-use-efficiency (WUE =...
Article
Full-text available
We monitored seasonal variations in net primary production (NPP), estimated by allometric equations from organ dimensions, gross primary production (GPP), estimated by the eddy covariance method, autotrophic respiration (R(a)), estimated by a model, and fruit production in a coconut (Cocos nucifera L.) plantation located in the sub-tropical South P...
Article
Background and Aims: A 3D modelling approach simulating canopy structure was used in combination with a radiative transfer model to simulate light interception, distribution and microclimate in the fruiting zone. Methods and Results: This model was parameterised for four training systems (two vertical shoot-positioned systems with one or two pairs...
Article
Full-text available
Light interception is a major factor influencing plant development and biomass production. Several methods have been proposed to determine this variable, but its calculation remains difficult in artificial environments with heterogeneous light. We propose a method that uses 3D virtual plant modelling and directional light characterisation to estima...
Article
Full-text available
Carbon allocation within a plant depends on complex rules linking source organs (mainly shoots) and sink organs (mainly roots and fruits). The complexity of these rules comes from both regulations and interactions between various plant processes involving carbon. This paper presents these regulations and interactions, and analyses how agricultural...
Article
Full-text available
Cotton shows a marked plasticity vs. density in terms of branch development and geometry, internode elongation and leaf expansion. This paper proposes interpretations for observed plasticity in terms of light quantity and quality. 3-D virtual plants were reconstructed from field observations and 3-D digitization and were used to simulate the light...
Article
Full-text available
Light interception is a critical factor in the production of biomass. The study presented here describes a method used to take account of architectural changes over time in sunflower and to estimate absorbed light at the organ level. The amount of photosynthetically active radiation absorbed by a plant is estimated on a daily or hourly basis throug...
Article
Sun-shade models proved to be simple, fast and reliable tools for estimating the fraction of absorbed PAR (fAPAR) and the photosynthesis of low and simple canopies (e.g. wheat). Applications on tall canopies, or non-ideal canopies (e.g. row-planting, azimuthal heterogeneity, clumping, non-spherical leaf angle distribution, large proportion of non-g...
Article
Full-text available
This article reviews scientific information in order to prepare application of coconut plantations to the Clean Development Mechanism CDM of the Kyoto protocol. It sums up some theory for describing the C cycle within a given plantation, separating the coconut trees, the under-storey and the soil. It synthesizes recent reports about the C cycle (st...
Article
Full-text available
Using 3D architectural models to assess light availability and root bulkiness in agroforestry systems. In many parts of the humid tropics, coconut trees are frequently intercropped with food crops, or tree crops such as cocoa. The performance of such systems depends on planting patterns, but also on growing conditions for crops below the coconut ca...
Article
Full-text available
Because of the difficulty and time involved in making exhaustive measurements of the geometric parameters of large tree crowns, simplifying hypotheses are often used in 3D virtual plant modelling, but the effects on the radiation balance of each approximation are rarely assessed. Three hybrid walnut trees aged 7–9years were digitized to analyse the...
Conference Paper
Full-text available
Light interception is a major contributor to biomass accumulation of crops. Beer's law has been extensively used to estimate the amount of light intercepted by a plant at canopy level. This method, based on the use of the leaf area index (LAI), is designed for well-developed crops where the canopy is assumed to be a turbid medium (Jones, 1992). How...
Conference Paper
Most classic ecophysiological models rely on crude representations of canopies as stacks of vegetation layers. Therefore, their use in complex canopies implies complicated adaptations as well as simplifying assumptions that are difficult to validate. Alternatively, the ARCHIMED simulation platform uses 3D virtual stands as a support for numerical s...
Conference Paper
The purpose of this investigation was to develop a method for building simplified geometrical representations (GM) of cotton plants that could be used to simulate plant light interception at low planting densities. Individual plants were observed infield trials throughout their growing period and their 3D architecture (AM) was reproduced at all gro...
Article
For open canopies, the partitioning of energy and water fluxes between the upper canopy and the under-storey is key to understand the competition mechanisms between layers. We monitored stand evapo-transpiration by eddy-covariance (E), tree transpiration (T) by heat-dissipative sapflow, soil (G) and stand (J) heat storage during 3 years in a typica...
Article
Full-text available
Source–sink relationships of field-grown plants of Coffea arabica L. cultivar ‘Caturra’ were manipulated to analyze the contribution of soluble sugars to sink feedback down-regulation of maximal leaf net CO2 assimilation rate (Amax). Total soluble sugar concentration (SSCm) and Amax were measured in the morning and afternoon on mature leaves of gir...
Article
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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...
Article
Full-text available
Increasing fruit load (from no berries present to 25, 50 and 100% of the initial fruit load) significantly decreased branch growth on 5-year-old coffee (Coffea arabica L.) trees of the dwarf cultivar 'Costa Rica 95', during their third production cycle. Ring-barking the branches further reduced their growth. Berry dry mass at harvest was significan...
Article
In countries facing water scarcity, governmental water agencies try to transfer this constraint to farmers, e.g. by encouraging them to shift from traditional to localized irrigation methods to save water. However, water shortage is often much less a problem for farmers than soil limitations, their objective being mostly to maximize their income pe...
Article
ARCHIMED software has been used to estimate the radiative environment of plant stands constituted by 3D virtual plants. The 3D virtual trees used for computation of radiative characteristics were built using the plant generator AMAPsim. Modelling of the functioning of meristems is based upon stochastic processes. The architecture of plants was desc...
Conference Paper
Full-text available
or without plant and leaves shading were studied. Radiative balance was estimated with MIR-MUSC-RADBAL software on 3D numerical plants constructed by the AMAPsim2 software. This approach enables analysing the effect of absorbed radiation on plant development, plant architecture and leaves expansion. Stable relationships related to the amount of abs...
Article
Full-text available
Multidirectional remotely sensed optical and thermal images acquired within a row cotton crop in Montpellier (France) were used to test the opportunities and limitations of an existing water stress index, the Water Deficit Index (WDI, based on the trapezoid approach). The WDI was applied with multidirectional crop surface temperatures (Ts) and refl...
Conference Paper
Full-text available
and various light treatments between 2.5 and 17.5 mol m-2 d-1. Columbia and its mutant serrate are presented here as a sample of the studied genotypes. Radiative balance was calculated on these 3D representations, and allowed accurate estimations of the amount of absorbed radiation by the plants. Robust positive relationships related to the amount...
Article
Existing experimental methods based on the measurement of crop temperature to estimate water stress have been applied for 20 years. However, the application of such techniques is limited because they are not able to totally overcome either soil interference on the measured signal or directional effects involved in temperature measurements according...
Article
Full-text available
A pertinent interpretation of thermal infrared (TIR) information to characterize crop water status requires at least to consider the fraction of crop cover. Even if the crop cover is known, such an interpretation remains difficult and the current issues to be overcome in the field of TIR remote sensing applications stands on bare soil effects. An e...
Article
Preliminary results of coffee berry growth modeling at the branch level are presented. The model, RAMCAF, is based on an existing model developed for peach. Parameters such as light extinction within the coffee tree canopy and potential fruit and shoot growth rates were derived from an experiment conducted over a period of two years on dwarf arabic...
Article
Full-text available
Software modules have been developed to predict the radiative environment of plant stands consisting of computer 'mock-ups' of plants. The architecture of plants used for the computation of radiative characteristics was described at the level of individual organs and simulated according to botanical rules. Three-dimensional stochastic numeric mock-...
Article
Computer representations of plants (virtual plants) are used as the basis for a model simulating leaf transpiration and sap flow. The virtual plants provide a detailed description of plant geometry and topology and, once positioned in a scene, enable a highly realistic reconstruction of a portion of the canopy.Stomatal conductance as well as energy...