Françoise Ruget - Profile on Academia.edu (original) (raw)
Papers by Françoise Ruget
Environmental Modelling and Software
Soil–crop models are increasingly used as predictive tools to assess yield and environmental impa... more Soil–crop models are increasingly used as predictive tools to assess yield and environmental impacts of agriculture in a growing diversity of contexts. They are however seldom evaluated at a given time over a wide domain of use. We tested here the performances of the STICS model (v8.2.2) with its standard set of parameters over a dataset covering 15 crops and a wide range of agropedoclimatic conditions in France. Model results showed a good overall accuracy, with little bias. Relative RMSE was larger for soil nitrate (49%) than for plant biomass (35%) and nitrogen (33%) and smallest for soil water (10%). Trends induced by contrasted environmental conditions and management practices were well reproduced. Finally, limited dependency of model errors on crops or environments indicated a satisfactory robustness. Such performances make STICS a valuable tool for studying the effects of changes in agro-ecosystems over the domain explored.
Simulation of winter wheat yield and its variability in different climates of Europe: A comparison of eight crop growth models
Effect of climate change in herbivorous livestock systems, including arable crops, in the French area
The effects of atmospheric changes on climate are assessed through GCM (General circulation model... more The effects of atmospheric changes on climate are assessed through GCM (General circulation model). We have used the results of one of these models, the ARPEGE model, developed by the CNRM (Météo-France) concerning two scenarios of economic, technical and socio-economic development. There are the A2 scenario, with little attention to GHG emissions leading to a high CO2 concentration in the atmosphere at the end of the century (800 ppm) and the B1 scenario, a moderate scenario where the CO2 concentration would be better controlled, allowing to reach only 550 ppm at the end of the century. Our study contains studies at 2 periods in the future, the near (2020-2049) and the distant (2070-2099) future, using a mean effect for each period, without any representation of the evolution inside each period. We have done three types of analyses using the present and future climate data : first, we analyzed the climatic data, with means, maps and multiple factor analysis second, we used a crop m...
Using remote sensing information and simulation models to estimate pastures production at the national scale
Pastures constitute an important terrestrial ecosystem. In France, pastures occupy 21% of the tot... more Pastures constitute an important terrestrial ecosystem. In France, pastures occupy 21% of the total area. There is a big effort to develop a real time systematic approach to estimate biomass production at the national level, focusing on spatial and seasonal variability in relation to drought. The non-existence of indirect methods of low cost that can be applied to large areas contributes to this situation. The advances registered in crop modeling and remote sensing offer new methodological and operative possibilities to solve this problem. In this work, thirteen Forage Regions (FR) of France were selected for their different geomorphologic, climatic and soil conditions with regard to pastoral productions. Images from the VEGETATION sensor on board SPOT4 satellite (1 km spatial resolution) were used to forecast some productive variables estimated by STICS Prairie simulation model. There was a general good agreement between the satellite and productive data. Particularly, the relation...
Application of a crop model forced with remote sensing data at high spatio-temporal resolution to estimate evaporation and yields of irrigated grasslands in the South Eastern France
This study focused on the feasibility of using remote sensing data acquired at high spatial and t... more This study focused on the feasibility of using remote sensing data acquired at high spatial and temporal resolution (FORMOSAT-2 images(http://www.spotimage.fr/web/en/977--formosat-2-images.php) for crop monitoring at regional scale. The monitoring of agricultural practices such as grassland mowing and irrigation is essential to simulate accurately all processes related to crop system. This information is needed for example in crop simulation models to estimate production, water and fertilizer consumption and can thus serve to better understand the interactions between agriculture and climate. The analysis of these interactions is especially important in Mediterranean region where the effects of climate changes and crop management modifications are increasingly marked. In this context, an experiment was conducted in 2006 in Crau region in the South-Eastern France. In this area, permanent grassland represents 67 % of the usable agricultural area, and it is often used with irrigation (...
Hydrology and Earth System Sciences, 2010
The aim of this study is to propose methods to improve crop and water management in Mediterranean... more The aim of this study is to propose methods to improve crop and water management in Mediterranean regions. At landscape scale, there is a spatial variability of agricultural practices, particularly for grasslands irrigated by flooding. These grasslands are harvested three times per year and produce high quality hay, but their productions decreased significantly during the last few years because of the water scarcity. It is therefore important to assess the real water requirement for crops in order to predict productions in the case of agricultural practice modifications. Until now, the spatial variability of agricultural practices was obtained through surveys from farmers, but this method was tedious to describe an entire region. Thus, the specific aim of the study is to develop and assess a new method based on a crop model for estimating water balance and crop yield constrained by products derived from optical remote sensing data with high spatio-temporal resolution.
Modeling Tiller Density, Growth, and Yield of Mediterranean Perennial Grasslands with STICS
Crop Science, 2009
ABSTRACT A generic crop model (STICS) was adapted (STICS-Grassland) to model growth, yield, and e... more ABSTRACT A generic crop model (STICS) was adapted (STICS-Grassland) to model growth, yield, and environmental impacts of grasslands in France. It is a semimechanistic model combining equations of physiological processes and mathematical relationships between processes in a daily time step. The Information et Suivi Objectif des Prairies (ISOP; Grassland Information and Objective Survey) application was developed to estimate and map the real-time status of grass growth and forage production in the 200 forage regions of France, to help decision makers anticipate forage availability in case of severe deficits. Initially, the model could not simulate long, severe droughts typical of Mediterranean regions when plant and tiller densities are significantly reduced. A tiller density module models the dynamics of tiller death during droughts. Since STICS is based on the concept of a mean plant (tiller) covering the whole field, variability was introduced through a law distribution of transpiration deficit by tiller, a threshold value imposing desiccation, and death to tillers reaching this level. Its second part generates incomplete or total recovery of tiller density through new tillering in the next wet season. Species and contrasting groups of cultivars within species can be characterized with a limited number of parameters.
Validation of the European corn borer damage model on maize using X rays
Annals of Applied Biology, 1992
ABSTRACT In order to explain and predict yield losses caused by European corn borer larvae, Ostri... more ABSTRACT In order to explain and predict yield losses caused by European corn borer larvae, Ostrinia nubilalis Hbn. (Lepidoptera: Pyralidae), a mechanistic model was proposed to describe cavity appearance, their lengthwise extension, and their within-plant distribution. It integrates main dynamical processes of larvae: mortality, development and within-plant distribution. After its estimation and test under field conditions in 1988 and 1989, its validation, based upon X-ray photographs, is presented. This method allows cavity appearance and lengthwise extension to be followed without damaging the plants. This study confirms the relevance of the damage model and the rate of cavity lengthwise extension estimated with it.
… and Ecological Statistics, 2001
The air temperature is one of the main input data in models for water balance monitoring or crop ... more The air temperature is one of the main input data in models for water balance monitoring or crop models for yield prediction. The different phenological stages of plant growth are generally de®ned according to cumulated air temperature from the sowing date. When these crop models are used at the regional scale, the meteorological stations providing input climatic data are not spatially dense enough or in a similar environment to re¯ect the crop local climate. Hence spatial interpolation methods must be used. Climatic data, particularly air temperature, are in¯uenced by local environment. Measurements show that the air above dry surfaces is warmer than above wet areas. We propose a method taking into account the environment of the meteorological stations in order to improve spatial interpolation of air temperature. The aim of this study is to assess the impact of thesè`c orrected climatic data'' in crop models. The proposed method is an external drift kriging where the Kriging system is modi®ed to correct local environment effects. The environment of the meteorological stations was characterized using a land use map summarized in a small number of classes considered as a factor in¯uencing local temperature. This method was applied to a region in south-east France (150 6 250 km) where daily temperatures were measured on 150 weather stations for two years. Environment classes were extracted from the CORINE Landcover map obtained from remote sensing data. Categorical external drift kriging was compared to ordinary kriging by a cross validation study. The gain in precision was assessed for different environment classes and for summer days. We then performed a sensitivity study of air temperature with the crop model STICS. The in¯uence of interpolation corrections on the main outputs as yield or harvest date is discussed. We showed that the method works well for air temperature in summer and can lead to signi®cant correction for yield prediction. For example, we observed by cross validation a bias reduction of 0.5 to 1.0 C (exceptionally 2.5 C for some class), which corresponds to differences in yield prediction from 0.6 to 1.5 t/ha.
Variations du nombre de grains chez différents génotypes de maïs
Agronomie, 1985
Use of SPOT4-VEGETATION satellite data to improve pasture production simulated by STICS included in the ISOP French system
Agronomie, 2004
In France, pastures represent a significant land-cover type, which mainly sustains husbandry prod... more In France, pastures represent a significant land-cover type, which mainly sustains husbandry production. For this reason, it is of great benefit to develop real-time monitoring of pasture biomass production, taking into account its spatial and temporal variability. The absence of low-cost methods applicable to large regions has oriented French stakeholders to the use of growth simulation models adequately informed through
Agronomie, 1996
— A simplified method for estimating the leaf area growth of field-grown maize from a reduc... more — A simplified method for estimating the leaf area growth of field-grown maize from a reduced number of measurements A simplified method for leaf area estimation in corn is described. It is shown that during the first half of leaf growth period, growing leaves form the major part of total leaf area. The method uses the number of growing leaves as well as the number and size of full grown leaves. Estimated leaf area and intercepted light are compared with actual leaf measurements (table I) and derived intercepted light estimations (tables I and II). The method produces adequate estimations at flowering but overestimates intercepted light during the first half of leaf growth. leaf area / maize / growing leaves Résumé — Cet article présente une méthode d'estimation de la surface foliaire d'une plante de maïs pendant la mise en place des feuilles. Il montre que, pendant la première moitié de cette période, les feuilles en croissance forment la majeure partie de la surface foliaire totale. La méthode d'estimation de surface proposée ne nécessite, en plus de la mesure de leur taille finale, que des comptages de feuilles pendant leur mise en place. La comparaison à des mesures de référence montre que cette méthode donne des résultats satisfaisants en matière d'estimation de surface et surtout de rayonnement capté à la floraison, mais elle surestime légèrement le rayonnement capté pendant la première moitié de la mise en place des feuilles.
Agronomie, 1998
Drought treatments were applied to seven sets of dwarf bean plants in pots. Each was subjected to... more Drought treatments were applied to seven sets of dwarf bean plants in pots. Each was subjected to water stress during one of the seven phenological phases, ranging from bud stage to grain filling. Treatments consisted of withholding irrigation until 80 % of the available water capacity was used. Evidence of differential effects of water stress according to the phase of application was obtained by tagging all the floral organs (buds or pods) present during the phase. Fallen tags indicated how many organs had aborted before physiological maturity. Periods of flowering (pl: bud, p2: flower opening, p3: fruiting set) were more sensitive than pod elongation (p4 and p5) and grain filling (p6 and p7) phases. Bud abortion rate was 50 % in non-stressed plants and 70 % in stressed ones. The final pod number was 53 % lower in plants stressed during the p1 period (the most sensitive period) than in controls. Pod number was generally much more sensitive to drought than the seed number per pod, which was only 13 % lower than in controls for plants stressed during the p1 period. (© Inra/Elsevier, Paris.) Phaseolus vulgaris / yield component / water stress / phenological phase Résumé -Effet d'un stress hydrique appliqué à différentes phases phénologiques sur les composantes du rendement du haricot nain (Phaseolus vulgaris L.). Nos essais ont pour but d'étudier l'effet d'un stress hydrique de même intensité appliqué à différentes phases phénologiques de la période de reproduction, sur les composantes du rendement exprimées en nombre, du haricot nain (Phaseolus vulgaris L, variété Coco de Prague). Afin d'éviter le phénomène de chevauchement des différents organes fructifères, la période de reproduction est divisée en sept phases phénologiques, de la phase bouton floral à la phase de fin remplissage des gousses. Chaque phase subit une seule fois le stress durant tout le cycle végétatif. Ce stress correspond à un déficit de consommation en eau égal à un taux de tarissement en eau du sol en fin de stress de 80 % de la réserve utile (RU). Le marquage systématique de la période à laquelle les organes
Agronomie, 1998
STICS (Simulateur mulTJdiscplinaire pour les Cultures Standard) is a crop model constructed as a ... more STICS (Simulateur mulTJdiscplinaire pour les Cultures Standard) is a crop model constructed as a simulation tool capable of working under agricultural conditions. Outputs comprise the production (amount and quality) and the environment. Inputs take into account the climate, the soi1 and the cropping system. STICS is presented as a model exhibiting the following qualities: robustness, an easy access to inputs and an uncomplicated f~~t u r e evolution thanks to a modular (easy adaptation to various types of plant) nature and generic. However, STICS is not an entirely new model since most parts use classic formalisms or stem from existing models. The main simulated processes are the growth, the development of the crop and the water and nitrogenous balance of the soil-crop system. The seven modules of STICSdevelopment, shoot growth, yield components, root growth, water balance, thermal environment and nitrogen balanceare presented in tum with a discussion about the theoretical choices in comparison to other models. These choices should render the model capable of exhibiting the announced qualities in classic environmental contexts. However, because some processes (e.g. ammoniac volatilization, clrought resistance, etc.) are not taken into account, the use of STICS is presently limited to several cropping systems. (O InraIElsevier, Paris.) crop modelling / wheat / corn / water balance / nitrogen balance Communicated by G6rard Guyot (Avignon, France) Résumé -STICS : un modhle générique pour simuler les cultures et leurs bilans hydrique et azoté. 1. Théorie et paramétrage appliqués au blé et au maïs.
Présentation d'une méthode simple d'estimation de la contribution des réserves pour le remplissage des grains chez le maïs
Agronomie, 1991
ABSTRACT L'intervention de réserves dans le remplissage des grains, quoique connue, est g... more ABSTRACT L'intervention de réserves dans le remplissage des grains, quoique connue, est généralement mise en évidence à partir de méthodes lourdes, qui conduisent à diminuer la fréquence des observations ou le nombre de traitements. Or, la datation et la quantification des interventions de réserves, indispensables pour une bonne modélisation de la gestion des réserves, nécessitent des mesures nombreuses. Le présent travail propose une estimation des réserves utilisées pendant le remplissage des grains, à partir de la différence entre croissance des grains et croissance de la plante entière. Cette dernière est estimée grâce au rayonnement intercepté par la culture. L'exemple traité ici est celui du maïs, mais pourrait s'adapter à toute autre culture où un organe (grains ou tubercules) est rempli de façon régulière, avec appel aux réserves temporaires en cas d'insuffisance des fournitures directes d'assimilats. An easy method to quantify reserve use in corn grain filling. The use of storage carbohydrates for grain filling has been known for a long time. However, its quantification by carbohydrate concentration prevents frequent measurements from being made. Use of reserves is measured from the difference between grain growth and whole plant growth. As respiratory losses are very small compared to dry matter decrease, they are not taken into account. Figure 1 shows the evolution of whole plant and grain dry matter during grain filling. For each observation period, reserve use between 2 measurement dates is negatively correlated with whole plant growth (fig 2). Reserve use increases with time for all genotypes (fig 3). We propose an easy method to estimate reserve use based on the difference between actual grain growth and maximal dry matter production (estimated from crop light interception). The results are in good agreement with the measurements except for points corresponding to early stages of grain filling (fig 4). These points correspond to high conversion efficiency (fig 5) at the beginning of grain filling (as has already been reported in the literature). This method allows the frequent quantification of reserve use from grain growth, leaf area index and global radiation measurements. It can be used for maize or other plants for which the storage organ (grain or tuber) is the only one to grow towards the end of the life cycle.
Agricultural and Forest Meteorology, 2000
During early growth, when the apical meristem of a maize plant is close to the soil surface, its ... more During early growth, when the apical meristem of a maize plant is close to the soil surface, its temperature may be very different from air temperature. A model is proposed to estimate apex temperature from meteorological data, when the leaf area index is less than 0.5. This model is based on the energy balance of the apical meristem, considered as a vertical cylinder close to the soil surface, called 'apex'. Soil surface temperature was calculated from an energy and water balance of the soil. Input data were hourly standard meteorological data and soil texture. Stomatal conductance was calculated from solar radiation and water vapor deficit.
Field Crops Research, 2012
and sharing with colleagues.
Environmental Modelling and Software
Soil–crop models are increasingly used as predictive tools to assess yield and environmental impa... more Soil–crop models are increasingly used as predictive tools to assess yield and environmental impacts of agriculture in a growing diversity of contexts. They are however seldom evaluated at a given time over a wide domain of use. We tested here the performances of the STICS model (v8.2.2) with its standard set of parameters over a dataset covering 15 crops and a wide range of agropedoclimatic conditions in France. Model results showed a good overall accuracy, with little bias. Relative RMSE was larger for soil nitrate (49%) than for plant biomass (35%) and nitrogen (33%) and smallest for soil water (10%). Trends induced by contrasted environmental conditions and management practices were well reproduced. Finally, limited dependency of model errors on crops or environments indicated a satisfactory robustness. Such performances make STICS a valuable tool for studying the effects of changes in agro-ecosystems over the domain explored.
Simulation of winter wheat yield and its variability in different climates of Europe: A comparison of eight crop growth models
Effect of climate change in herbivorous livestock systems, including arable crops, in the French area
The effects of atmospheric changes on climate are assessed through GCM (General circulation model... more The effects of atmospheric changes on climate are assessed through GCM (General circulation model). We have used the results of one of these models, the ARPEGE model, developed by the CNRM (Météo-France) concerning two scenarios of economic, technical and socio-economic development. There are the A2 scenario, with little attention to GHG emissions leading to a high CO2 concentration in the atmosphere at the end of the century (800 ppm) and the B1 scenario, a moderate scenario where the CO2 concentration would be better controlled, allowing to reach only 550 ppm at the end of the century. Our study contains studies at 2 periods in the future, the near (2020-2049) and the distant (2070-2099) future, using a mean effect for each period, without any representation of the evolution inside each period. We have done three types of analyses using the present and future climate data : first, we analyzed the climatic data, with means, maps and multiple factor analysis second, we used a crop m...
Using remote sensing information and simulation models to estimate pastures production at the national scale
Pastures constitute an important terrestrial ecosystem. In France, pastures occupy 21% of the tot... more Pastures constitute an important terrestrial ecosystem. In France, pastures occupy 21% of the total area. There is a big effort to develop a real time systematic approach to estimate biomass production at the national level, focusing on spatial and seasonal variability in relation to drought. The non-existence of indirect methods of low cost that can be applied to large areas contributes to this situation. The advances registered in crop modeling and remote sensing offer new methodological and operative possibilities to solve this problem. In this work, thirteen Forage Regions (FR) of France were selected for their different geomorphologic, climatic and soil conditions with regard to pastoral productions. Images from the VEGETATION sensor on board SPOT4 satellite (1 km spatial resolution) were used to forecast some productive variables estimated by STICS Prairie simulation model. There was a general good agreement between the satellite and productive data. Particularly, the relation...
Application of a crop model forced with remote sensing data at high spatio-temporal resolution to estimate evaporation and yields of irrigated grasslands in the South Eastern France
This study focused on the feasibility of using remote sensing data acquired at high spatial and t... more This study focused on the feasibility of using remote sensing data acquired at high spatial and temporal resolution (FORMOSAT-2 images(http://www.spotimage.fr/web/en/977--formosat-2-images.php) for crop monitoring at regional scale. The monitoring of agricultural practices such as grassland mowing and irrigation is essential to simulate accurately all processes related to crop system. This information is needed for example in crop simulation models to estimate production, water and fertilizer consumption and can thus serve to better understand the interactions between agriculture and climate. The analysis of these interactions is especially important in Mediterranean region where the effects of climate changes and crop management modifications are increasingly marked. In this context, an experiment was conducted in 2006 in Crau region in the South-Eastern France. In this area, permanent grassland represents 67 % of the usable agricultural area, and it is often used with irrigation (...
Hydrology and Earth System Sciences, 2010
The aim of this study is to propose methods to improve crop and water management in Mediterranean... more The aim of this study is to propose methods to improve crop and water management in Mediterranean regions. At landscape scale, there is a spatial variability of agricultural practices, particularly for grasslands irrigated by flooding. These grasslands are harvested three times per year and produce high quality hay, but their productions decreased significantly during the last few years because of the water scarcity. It is therefore important to assess the real water requirement for crops in order to predict productions in the case of agricultural practice modifications. Until now, the spatial variability of agricultural practices was obtained through surveys from farmers, but this method was tedious to describe an entire region. Thus, the specific aim of the study is to develop and assess a new method based on a crop model for estimating water balance and crop yield constrained by products derived from optical remote sensing data with high spatio-temporal resolution.
Modeling Tiller Density, Growth, and Yield of Mediterranean Perennial Grasslands with STICS
Crop Science, 2009
ABSTRACT A generic crop model (STICS) was adapted (STICS-Grassland) to model growth, yield, and e... more ABSTRACT A generic crop model (STICS) was adapted (STICS-Grassland) to model growth, yield, and environmental impacts of grasslands in France. It is a semimechanistic model combining equations of physiological processes and mathematical relationships between processes in a daily time step. The Information et Suivi Objectif des Prairies (ISOP; Grassland Information and Objective Survey) application was developed to estimate and map the real-time status of grass growth and forage production in the 200 forage regions of France, to help decision makers anticipate forage availability in case of severe deficits. Initially, the model could not simulate long, severe droughts typical of Mediterranean regions when plant and tiller densities are significantly reduced. A tiller density module models the dynamics of tiller death during droughts. Since STICS is based on the concept of a mean plant (tiller) covering the whole field, variability was introduced through a law distribution of transpiration deficit by tiller, a threshold value imposing desiccation, and death to tillers reaching this level. Its second part generates incomplete or total recovery of tiller density through new tillering in the next wet season. Species and contrasting groups of cultivars within species can be characterized with a limited number of parameters.
Validation of the European corn borer damage model on maize using X rays
Annals of Applied Biology, 1992
ABSTRACT In order to explain and predict yield losses caused by European corn borer larvae, Ostri... more ABSTRACT In order to explain and predict yield losses caused by European corn borer larvae, Ostrinia nubilalis Hbn. (Lepidoptera: Pyralidae), a mechanistic model was proposed to describe cavity appearance, their lengthwise extension, and their within-plant distribution. It integrates main dynamical processes of larvae: mortality, development and within-plant distribution. After its estimation and test under field conditions in 1988 and 1989, its validation, based upon X-ray photographs, is presented. This method allows cavity appearance and lengthwise extension to be followed without damaging the plants. This study confirms the relevance of the damage model and the rate of cavity lengthwise extension estimated with it.
… and Ecological Statistics, 2001
The air temperature is one of the main input data in models for water balance monitoring or crop ... more The air temperature is one of the main input data in models for water balance monitoring or crop models for yield prediction. The different phenological stages of plant growth are generally de®ned according to cumulated air temperature from the sowing date. When these crop models are used at the regional scale, the meteorological stations providing input climatic data are not spatially dense enough or in a similar environment to re¯ect the crop local climate. Hence spatial interpolation methods must be used. Climatic data, particularly air temperature, are in¯uenced by local environment. Measurements show that the air above dry surfaces is warmer than above wet areas. We propose a method taking into account the environment of the meteorological stations in order to improve spatial interpolation of air temperature. The aim of this study is to assess the impact of thesè`c orrected climatic data'' in crop models. The proposed method is an external drift kriging where the Kriging system is modi®ed to correct local environment effects. The environment of the meteorological stations was characterized using a land use map summarized in a small number of classes considered as a factor in¯uencing local temperature. This method was applied to a region in south-east France (150 6 250 km) where daily temperatures were measured on 150 weather stations for two years. Environment classes were extracted from the CORINE Landcover map obtained from remote sensing data. Categorical external drift kriging was compared to ordinary kriging by a cross validation study. The gain in precision was assessed for different environment classes and for summer days. We then performed a sensitivity study of air temperature with the crop model STICS. The in¯uence of interpolation corrections on the main outputs as yield or harvest date is discussed. We showed that the method works well for air temperature in summer and can lead to signi®cant correction for yield prediction. For example, we observed by cross validation a bias reduction of 0.5 to 1.0 C (exceptionally 2.5 C for some class), which corresponds to differences in yield prediction from 0.6 to 1.5 t/ha.
Variations du nombre de grains chez différents génotypes de maïs
Agronomie, 1985
Use of SPOT4-VEGETATION satellite data to improve pasture production simulated by STICS included in the ISOP French system
Agronomie, 2004
In France, pastures represent a significant land-cover type, which mainly sustains husbandry prod... more In France, pastures represent a significant land-cover type, which mainly sustains husbandry production. For this reason, it is of great benefit to develop real-time monitoring of pasture biomass production, taking into account its spatial and temporal variability. The absence of low-cost methods applicable to large regions has oriented French stakeholders to the use of growth simulation models adequately informed through
Agronomie, 1996
— A simplified method for estimating the leaf area growth of field-grown maize from a reduc... more — A simplified method for estimating the leaf area growth of field-grown maize from a reduced number of measurements A simplified method for leaf area estimation in corn is described. It is shown that during the first half of leaf growth period, growing leaves form the major part of total leaf area. The method uses the number of growing leaves as well as the number and size of full grown leaves. Estimated leaf area and intercepted light are compared with actual leaf measurements (table I) and derived intercepted light estimations (tables I and II). The method produces adequate estimations at flowering but overestimates intercepted light during the first half of leaf growth. leaf area / maize / growing leaves Résumé — Cet article présente une méthode d'estimation de la surface foliaire d'une plante de maïs pendant la mise en place des feuilles. Il montre que, pendant la première moitié de cette période, les feuilles en croissance forment la majeure partie de la surface foliaire totale. La méthode d'estimation de surface proposée ne nécessite, en plus de la mesure de leur taille finale, que des comptages de feuilles pendant leur mise en place. La comparaison à des mesures de référence montre que cette méthode donne des résultats satisfaisants en matière d'estimation de surface et surtout de rayonnement capté à la floraison, mais elle surestime légèrement le rayonnement capté pendant la première moitié de la mise en place des feuilles.
Agronomie, 1998
Drought treatments were applied to seven sets of dwarf bean plants in pots. Each was subjected to... more Drought treatments were applied to seven sets of dwarf bean plants in pots. Each was subjected to water stress during one of the seven phenological phases, ranging from bud stage to grain filling. Treatments consisted of withholding irrigation until 80 % of the available water capacity was used. Evidence of differential effects of water stress according to the phase of application was obtained by tagging all the floral organs (buds or pods) present during the phase. Fallen tags indicated how many organs had aborted before physiological maturity. Periods of flowering (pl: bud, p2: flower opening, p3: fruiting set) were more sensitive than pod elongation (p4 and p5) and grain filling (p6 and p7) phases. Bud abortion rate was 50 % in non-stressed plants and 70 % in stressed ones. The final pod number was 53 % lower in plants stressed during the p1 period (the most sensitive period) than in controls. Pod number was generally much more sensitive to drought than the seed number per pod, which was only 13 % lower than in controls for plants stressed during the p1 period. (© Inra/Elsevier, Paris.) Phaseolus vulgaris / yield component / water stress / phenological phase Résumé -Effet d'un stress hydrique appliqué à différentes phases phénologiques sur les composantes du rendement du haricot nain (Phaseolus vulgaris L.). Nos essais ont pour but d'étudier l'effet d'un stress hydrique de même intensité appliqué à différentes phases phénologiques de la période de reproduction, sur les composantes du rendement exprimées en nombre, du haricot nain (Phaseolus vulgaris L, variété Coco de Prague). Afin d'éviter le phénomène de chevauchement des différents organes fructifères, la période de reproduction est divisée en sept phases phénologiques, de la phase bouton floral à la phase de fin remplissage des gousses. Chaque phase subit une seule fois le stress durant tout le cycle végétatif. Ce stress correspond à un déficit de consommation en eau égal à un taux de tarissement en eau du sol en fin de stress de 80 % de la réserve utile (RU). Le marquage systématique de la période à laquelle les organes
Agronomie, 1998
STICS (Simulateur mulTJdiscplinaire pour les Cultures Standard) is a crop model constructed as a ... more STICS (Simulateur mulTJdiscplinaire pour les Cultures Standard) is a crop model constructed as a simulation tool capable of working under agricultural conditions. Outputs comprise the production (amount and quality) and the environment. Inputs take into account the climate, the soi1 and the cropping system. STICS is presented as a model exhibiting the following qualities: robustness, an easy access to inputs and an uncomplicated f~~t u r e evolution thanks to a modular (easy adaptation to various types of plant) nature and generic. However, STICS is not an entirely new model since most parts use classic formalisms or stem from existing models. The main simulated processes are the growth, the development of the crop and the water and nitrogenous balance of the soil-crop system. The seven modules of STICSdevelopment, shoot growth, yield components, root growth, water balance, thermal environment and nitrogen balanceare presented in tum with a discussion about the theoretical choices in comparison to other models. These choices should render the model capable of exhibiting the announced qualities in classic environmental contexts. However, because some processes (e.g. ammoniac volatilization, clrought resistance, etc.) are not taken into account, the use of STICS is presently limited to several cropping systems. (O InraIElsevier, Paris.) crop modelling / wheat / corn / water balance / nitrogen balance Communicated by G6rard Guyot (Avignon, France) Résumé -STICS : un modhle générique pour simuler les cultures et leurs bilans hydrique et azoté. 1. Théorie et paramétrage appliqués au blé et au maïs.
Présentation d'une méthode simple d'estimation de la contribution des réserves pour le remplissage des grains chez le maïs
Agronomie, 1991
ABSTRACT L'intervention de réserves dans le remplissage des grains, quoique connue, est g... more ABSTRACT L'intervention de réserves dans le remplissage des grains, quoique connue, est généralement mise en évidence à partir de méthodes lourdes, qui conduisent à diminuer la fréquence des observations ou le nombre de traitements. Or, la datation et la quantification des interventions de réserves, indispensables pour une bonne modélisation de la gestion des réserves, nécessitent des mesures nombreuses. Le présent travail propose une estimation des réserves utilisées pendant le remplissage des grains, à partir de la différence entre croissance des grains et croissance de la plante entière. Cette dernière est estimée grâce au rayonnement intercepté par la culture. L'exemple traité ici est celui du maïs, mais pourrait s'adapter à toute autre culture où un organe (grains ou tubercules) est rempli de façon régulière, avec appel aux réserves temporaires en cas d'insuffisance des fournitures directes d'assimilats. An easy method to quantify reserve use in corn grain filling. The use of storage carbohydrates for grain filling has been known for a long time. However, its quantification by carbohydrate concentration prevents frequent measurements from being made. Use of reserves is measured from the difference between grain growth and whole plant growth. As respiratory losses are very small compared to dry matter decrease, they are not taken into account. Figure 1 shows the evolution of whole plant and grain dry matter during grain filling. For each observation period, reserve use between 2 measurement dates is negatively correlated with whole plant growth (fig 2). Reserve use increases with time for all genotypes (fig 3). We propose an easy method to estimate reserve use based on the difference between actual grain growth and maximal dry matter production (estimated from crop light interception). The results are in good agreement with the measurements except for points corresponding to early stages of grain filling (fig 4). These points correspond to high conversion efficiency (fig 5) at the beginning of grain filling (as has already been reported in the literature). This method allows the frequent quantification of reserve use from grain growth, leaf area index and global radiation measurements. It can be used for maize or other plants for which the storage organ (grain or tuber) is the only one to grow towards the end of the life cycle.
Agricultural and Forest Meteorology, 2000
During early growth, when the apical meristem of a maize plant is close to the soil surface, its ... more During early growth, when the apical meristem of a maize plant is close to the soil surface, its temperature may be very different from air temperature. A model is proposed to estimate apex temperature from meteorological data, when the leaf area index is less than 0.5. This model is based on the energy balance of the apical meristem, considered as a vertical cylinder close to the soil surface, called 'apex'. Soil surface temperature was calculated from an energy and water balance of the soil. Input data were hourly standard meteorological data and soil texture. Stomatal conductance was calculated from solar radiation and water vapor deficit.
Field Crops Research, 2012
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