The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach o... more The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach of functional-structural plant modelling (FSPM). During the past decade, models have focussed on morphological aspects of plant development. They now provide crop scientists with general guidelines for building new cereal models. We present some of them here, considering the different aspects of cereal architectural modelling: plant development, pattern formation and plant geometry. We also review some significant examples that illustrate the different types of uses of these models for agronomic research. We conclude that the next generation of cereal models should be based on a less empirical modelling of the processes that control morphogenesis.
Plants react to their environment and to management interventions by adjusting physiological func... more Plants react to their environment and to management interventions by adjusting physiological functions and structure. Functional-structural plant models (FSPM), combine the representation of three-dimensional (3D) plant structure with selected physiological functions. An FSPM consists of an architectural part (plant structure) and a process part (plant functioning). The first deals with (i) the types of organs that are initiated and the way these are connected (topology), (ii) co-ordination in organ expansion dynamics, and (iii) geometrical variables (e.g. leaf angles, leaf curvature). The process part may include any physiological or physical process that affects plant growth and development (e.g. photosynthesis, carbon allocation). This paper addresses the following questions: (i) how are FSPM constructed, and (ii) for what purposes are they useful? Static, architectural models are distinguished from dynamic models. Static models are useful in order to study the significance of plant structure, such as light distribution in the canopy, gas exchange, remote sensing, pesticide spraying studies, and interactions between plants and biotic agents. Dynamic models serve quantitatively to integrate knowledge on plant functions and morphology as modulated by environment. Applications are in the domain of plant sciences, for example the study of plant plasticity as related to changes in the red:far red ratio of light in the canopy. With increasing availability of genetic information, FSPM will play a role in the assessment of the significance towards plant performance of variation in genetic traits across environments. In many crops, growers actively manipulate plant structure. FSPM is a promising tool to explore divergent management strategies.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2009
Hence, we developed a model that enables simulation of stem diameter variations driven by the wat... more Hence, we developed a model that enables simulation of stem diameter variations driven by the water and the carbohydrate flow. Stem diameter variations are calculated as volume changes of both the xylem and the phloem tissue. These volume changes depend on: (i) the water transport according to the cohesion-tension theory, (ii) the transport of carbohydrates according to the Münch hypothesis, (iii) loading and unloading of carbohydrates and (iv) irreversible turgor-driven growth. The model tree is subdivided in three compartments: crown, stem and roots. To validate the model, we conducted double girdling experiments on young oak (Quercus robur L.) trees in growth rooms. During these experiments, data was collected of stem diameter variations, photosynthesis and xylem sap flow for both manipulated and non-manipulated trees. In addition to these plant variables, the micro-climate was also monitored. A good agreement was found between simulated and measured data. Hence, the model is a realistic representation of the processes observed in reality.
Estimating alfalfa low leaf area indices from red (660 nm) and far-red (730 nm) hemispheric refle... more Estimating alfalfa low leaf area indices from red (660 nm) and far-red (730 nm) hemispheric reflectance measurements. The leaf area index of a crop is the main driver of dry matter production. We propose to use the differences between leaf and soil reflectance in the red and far-red wavebands, in order to estimate the leaf area index. Reflectance measurements are made with low-cost sensors measuring hemispheric fluxes around 660 and 730 nm. The reflectance normalized difference, empirically related to the leaf area index of an alfalfa canopy, allows to estimate low (< 2) leaf area indices; the relationship, however, is dependant on soil optical properties, and experimental precautions must be envisaged. The low cost of the sensors enables to propose to use them for crop permanent monitoring. alfalfa / leaf area index / vegetation index / normalized difference / red / far-red
Rose bush architecture, among other factors, such as plant health, determines plant visual qualit... more Rose bush architecture, among other factors, such as plant health, determines plant visual quality. The commercial product is the individual plant and interplant variability may be high within a crop. Thus, both mean plant architecture and interplant variability should be studied. Expansion is an important feature of architecture, but it has been little studied at the level of individual organs in rose bushes. We investigated the expansion kinetics of primary shoot organs, to develop a model reproducing the organ expansion of real crops from non-destructive input variables. We took interplant variability in expansion kinetics and the model's ability to simulate this variability into account. Changes in leaflet and internode dimensions over thermal time were recorded for primary shoot expansion, on 83 plants from three crops grown in different climatic conditions and densities. An empirical model was developed, to reproduce organ expansion kinetics for individual plants of a real...
Les modes de représentation du peuplement végétal cultivé sont nombreux ct peuvent être classés p... more Les modes de représentation du peuplement végétal cultivé sont nombreux ct peuvent être classés par leur degré d'explicitation des mécanismes impliqués ct par le point de vue théorique de l'observateur. Il peut s'agir d'une représentation ''énergétique», oli le peuplement végét a l est as si m ilé ù une surface d'échange thermodynamique avec le milieu qui l'entoure. Cette vision, qualifiée par les Anglo Saxons de représentation « hig leaf » et propre ù prédire la croissance en biomasse, 1. Mégapascal.
The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach o... more The Gramineae have been a pioneer group among non-woody plants to be modelled with the approach of functional-structural plant modelling (FSPM). During the past decade, models have focussed on morphological aspects of plant development. They now provide crop scientists with general guidelines for building new cereal models. We present some of them here, considering the different aspects of cereal architectural modelling: plant development, pattern formation and plant geometry. We also review some significant examples that illustrate the different types of uses of these models for agronomic research. We conclude that the next generation of cereal models should be based on a less empirical modelling of the processes that control morphogenesis.
Plants react to their environment and to management interventions by adjusting physiological func... more Plants react to their environment and to management interventions by adjusting physiological functions and structure. Functional-structural plant models (FSPM), combine the representation of three-dimensional (3D) plant structure with selected physiological functions. An FSPM consists of an architectural part (plant structure) and a process part (plant functioning). The first deals with (i) the types of organs that are initiated and the way these are connected (topology), (ii) co-ordination in organ expansion dynamics, and (iii) geometrical variables (e.g. leaf angles, leaf curvature). The process part may include any physiological or physical process that affects plant growth and development (e.g. photosynthesis, carbon allocation). This paper addresses the following questions: (i) how are FSPM constructed, and (ii) for what purposes are they useful? Static, architectural models are distinguished from dynamic models. Static models are useful in order to study the significance of plant structure, such as light distribution in the canopy, gas exchange, remote sensing, pesticide spraying studies, and interactions between plants and biotic agents. Dynamic models serve quantitatively to integrate knowledge on plant functions and morphology as modulated by environment. Applications are in the domain of plant sciences, for example the study of plant plasticity as related to changes in the red:far red ratio of light in the canopy. With increasing availability of genetic information, FSPM will play a role in the assessment of the significance towards plant performance of variation in genetic traits across environments. In many crops, growers actively manipulate plant structure. FSPM is a promising tool to explore divergent management strategies.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2009
Hence, we developed a model that enables simulation of stem diameter variations driven by the wat... more Hence, we developed a model that enables simulation of stem diameter variations driven by the water and the carbohydrate flow. Stem diameter variations are calculated as volume changes of both the xylem and the phloem tissue. These volume changes depend on: (i) the water transport according to the cohesion-tension theory, (ii) the transport of carbohydrates according to the Münch hypothesis, (iii) loading and unloading of carbohydrates and (iv) irreversible turgor-driven growth. The model tree is subdivided in three compartments: crown, stem and roots. To validate the model, we conducted double girdling experiments on young oak (Quercus robur L.) trees in growth rooms. During these experiments, data was collected of stem diameter variations, photosynthesis and xylem sap flow for both manipulated and non-manipulated trees. In addition to these plant variables, the micro-climate was also monitored. A good agreement was found between simulated and measured data. Hence, the model is a realistic representation of the processes observed in reality.
Estimating alfalfa low leaf area indices from red (660 nm) and far-red (730 nm) hemispheric refle... more Estimating alfalfa low leaf area indices from red (660 nm) and far-red (730 nm) hemispheric reflectance measurements. The leaf area index of a crop is the main driver of dry matter production. We propose to use the differences between leaf and soil reflectance in the red and far-red wavebands, in order to estimate the leaf area index. Reflectance measurements are made with low-cost sensors measuring hemispheric fluxes around 660 and 730 nm. The reflectance normalized difference, empirically related to the leaf area index of an alfalfa canopy, allows to estimate low (< 2) leaf area indices; the relationship, however, is dependant on soil optical properties, and experimental precautions must be envisaged. The low cost of the sensors enables to propose to use them for crop permanent monitoring. alfalfa / leaf area index / vegetation index / normalized difference / red / far-red
Rose bush architecture, among other factors, such as plant health, determines plant visual qualit... more Rose bush architecture, among other factors, such as plant health, determines plant visual quality. The commercial product is the individual plant and interplant variability may be high within a crop. Thus, both mean plant architecture and interplant variability should be studied. Expansion is an important feature of architecture, but it has been little studied at the level of individual organs in rose bushes. We investigated the expansion kinetics of primary shoot organs, to develop a model reproducing the organ expansion of real crops from non-destructive input variables. We took interplant variability in expansion kinetics and the model's ability to simulate this variability into account. Changes in leaflet and internode dimensions over thermal time were recorded for primary shoot expansion, on 83 plants from three crops grown in different climatic conditions and densities. An empirical model was developed, to reproduce organ expansion kinetics for individual plants of a real...
Les modes de représentation du peuplement végétal cultivé sont nombreux ct peuvent être classés p... more Les modes de représentation du peuplement végétal cultivé sont nombreux ct peuvent être classés par leur degré d'explicitation des mécanismes impliqués ct par le point de vue théorique de l'observateur. Il peut s'agir d'une représentation ''énergétique», oli le peuplement végét a l est as si m ilé ù une surface d'échange thermodynamique avec le milieu qui l'entoure. Cette vision, qualifiée par les Anglo Saxons de représentation « hig leaf » et propre ù prédire la croissance en biomasse, 1. Mégapascal.
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