Françoise Ruget | Institut National de la Recherche Agronomique (original) (raw)

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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.

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...

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...

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

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.

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

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, 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

Field Crops Research, 2012

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.

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...

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...

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

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.

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

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, 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

Field Crops Research, 2012