François Piraux - Academia.edu (original) (raw)
Papers by François Piraux
HAL (Le Centre pour la Communication Scientifique Directe), Oct 18, 2017
HAL (Le Centre pour la Communication Scientifique Directe), 2018
From Experimental Network to Meta-analysis, 2019
When planning a network of experiments, it is generally important to know how many experiments sh... more When planning a network of experiments, it is generally important to know how many experiments should be performed. However, it is often forgotten that it is just as important to know how to choose the environments in which the experiments will be performed.
Un vaste réseau d'expérimentations au champ a été conduit pendant plusieurs années à travers la F... more Un vaste réseau d'expérimentations au champ a été conduit pendant plusieurs années à travers la France pour identifier les combinaisons de variétés cultivées de blé d'hiver et d'itinéraires techniques en vue d'atteindre le double objectif de durabilité écologique et de viabilité économique. Cet objectif implique notamment un processus d'extensification chimique, au travers duquel les intrants chimiques, dont les fongicides, sont réduits pour optimiser les performances, notamment économiques, de la production végétale. Peu d'informations sont disponibles pour documenter, dans ce réseau, la variation des niveaux de maladie multiples. Le contrôle des niveaux de maladies constitue pourtant une étape nécessaire à un processus d'extensification chimique. Cet article fournit une description des intensités des maladies du blé dans un ensemble de 101 expérimentations totalisant 3525 parcelles individuelles de blé, pendant huit années successives (2003-2010). Les maladies considérées sont la rouille brune (BR, Puccinia triticina), la rouille jaune (YR, Puccinia striiformis), la fusariose des épis (FHB, Fusarium graminearum, F. culmorum, et F. avenaceum), l'oïdium (PM, Blumeria graminis), et la septoriose (STB, Zymoseptoria tritici). Les intensités de maladies ont été représentées par des variables binaires (épidémie ou non-épidémie). Trois syndromes de maladies ont été identifiés, qui correspondent à des profils de niveau de maladie distincts. Trois groupes de variétés ont également été identifiés, qui se distinguent par leurs réponses aux maladies. Les résultats indiquent que les années climatiques, les variétés de blé et les itinéraires techniques, dans cet ordre décroissant, définissent le risque d'épidémie dans le pathosystème multiple des maladies du blé en France. Des variables synthétiques prenant en compte le climat au printemps et au début de l'été ont été construites. Les associations entre variables climatiques et risques d'épidémies identifiées sont en accord avec les connaissances sur les effets du climat sur les composants de ce pathosystème multiple. Cet article met en avant la valeur de jeux de données à grande échelle pour l'évaluation de la santé végétale et l'utilité d'une démarche analytique permettant d'identifier les facteurs de risques pour les décisions tactiques et stratégiques, pour la gestion de la santé végétale.
From Experimental Network to Meta-analysis, 2019
This chapter presents in detail the principal methods for analyzing networks of experiments with ... more This chapter presents in detail the principal methods for analyzing networks of experiments with a randomized complete block design including one factor (Dagnelie 1981). In networks of this type, each experiment has a randomized complete block design, within which the various experimental units are grouped together in homogeneous blocks. Each block contains as many experimental units as there are study treatments, and each treatment is tested in each block. Thus, in any given experiment, each treatment is present only once in each block. Treatments are distributed at random between the various experimental units, independently in each block. In a randomized complete block design, the uncertainty on the difference between the means of two treatments stems solely from the variability between experimental units within blocks, and the precision of the experiment can be increased by setting up the most homogeneous blocks possible (Cochran and Cox 1957). In agronomic experiments, two neig...
Field Crops Research, 2019
Nitrogen (N) is an essential compound for the production and grain quality of bread wheat, which ... more Nitrogen (N) is an essential compound for the production and grain quality of bread wheat, which must respect market requirements. Improving nitrogen use efficiency (NUE) is a priority to better manage nitrogen for the benefit of farm economy and the environment. Among all the available levers to do this, the choice of the right cultivar is crucial. To this end, an accurate NUE cultivar characterization is needed both for breeding programmes and for agronomic extension services dedicated to advise farmers. These two fields of expertise (genetic and agronomy) do not share exactly the same protocols and indicators to assess the impact of cultivar on wheat NUE. Moreover, although some recent NUE genetic studies have been conducted on cultivars currently available in France, no recent NUE agronomic studies have been made on current French wheat cultivars. Moreover, the latest agronomic studies to date on cultivar effect on wheat N requirement (coefficient "b" used in France) were conducted without considering the need to reach a grain protein concentration of 11.5% (French bread wheat market requirement) in addition to the objective of achieving the yield potential. By using a classical agronomic protocol (network of 12 field trials over 3 years testing bread-wheat cultivars along a complete nitrogen response curve), the presented study aimed to address three specific NUE related topics by characterizing recent French cultivars with a large range of NUE indicators used by geneticists and/or agronomists. Firstly, we demonstrated that N rate and recent French cultivars had a significant effect on NUE and its components (nitrogen uptake efficiency-NupE and nitrogen utilization efficiency-NutE), as well as on apparent fertilizer recovery (AFR). Secondly, we showed that NupE and AFR were strongly correlated, allowing us to compare genetic studies (mainly using NupE) and agronomic studies (mainly using AFR) without any difficulty. Thirdly, we designed a set of new N requirement indicators (coefficients "bc" and "bq") helping the farmer to grow each bread wheat cultivar with a dual objective of optimum yield and grain protein content in line with the market requirements. This could be achieved without significant impact on nitrogen post-harvest losses. The presented study provides a large set of results, usable for breeding and agronomic research programs.
From Experimental Network to Meta-analysis, 2019
Meta-analysis is one of the methods used for synthetic analyses of knowledge. It combines two app... more Meta-analysis is one of the methods used for synthetic analyses of knowledge. It combines two approaches:
Soil Biology and Biochemistry, 2017
The models based on soil properties and cropping history could be further implemented in multidis... more The models based on soil properties and cropping history could be further implemented in multidisciplinary soil-crop models and decision support systems in order to enhance the prediction of N dynamics in soils and improve fertilizer recommendations.
European Journal of Plant Pathology, 2016
A large network of field experiments has been conducted over several years across France to ident... more A large network of field experiments has been conducted over several years across France to identify combinations of winter wheat cultivars and management practices in which partial resistances under limited chemical protection would achieve adequate disease management, while leading to satisfactory yield performance, and so achieve the double objective of ecological sustainability and economic viability. Little information is available to document the variation in multiple disease levels, a necessary step towards a chemical extensification process, in wheat networked experiments. This article provides a description of disease intensities in a set of 101 experiments totalling 3525 individual wheat plots over eight successive years (2003–2010). The diseases considered are brown rust (BR, Puccinia triticina), yellow rust (YR, Puccinia striiformis), fusarium head blight (FHB, Fusarium graminearum, F. culmorum, and F. avenaceum), powdery mildew (PM, Blumeria graminis), and septoria tritici blotch (STB, Zymoseptoria tritici). Hierarchical cluster analysis led to the identification of three variety groups associated with (1) moderate-low disease levels in general, except for YR (moderate levels) – 16 varieties; (2) moderate-low BR, YR, and FHB levels, and moderate PM and STB levels – 12 varieties; (3) comparatively higher BR, YR, FHB, and STB levels, and moderate PM levels – 17 varieties. The association of disease levels represented as binary categories (i.e., epidemics vs. non-epidemics) with climatic years corresponded to chi-square values (χ2 = 87.0–1402) that were one to two orders of magnitude larger than the values corresponding to the associations of diseases with variety groups (χ2 = 6.41–321) or with levels of crop management (χ2 = 21.2–82.1). Multivariate non parametric analyses indicated the existence of three disease syndromes, two of which being dominated by BR or STB, and a third associated with diverse diseases and frequent FHB. This suggests that STB and BR might each be considered as key-stone species dominating specific wheat disease syndromes. Multiple correspondence analysis highlighted the linkages between multiple epidemic occurrence and the three characterized variety groups. Risk factors analyses conducted through logistic regressions provided quantitative estimates of the contribution of climatic years, variety groups, and crop management, to the likelihood of epidemic occurrence for each of the five diseases considered. The results indicate that climatic years, wheat varieties, and crop management, in this decreasing order, define disease epidemic risk in the multiple wheat-diseases pathosystem.
European Journal of Plant Pathology, 2016
Septoria leaf blotch is a widespread disease caused by the fungus Zymoseptoria tritici (formely k... more Septoria leaf blotch is a widespread disease caused by the fungus Zymoseptoria tritici (formely known as Mycosphaerella graminicola). It causes yield losses in winter wheat crops (Triticum aestivum L.) in many European countries. In this study, we aimed to develop statistical models for estimating regional and site-specific incidence of Septoria leaf blotch from inseason field measurements. Four generalised linear models and four generalised linear mixed-effect models were fitted to six years of data collected from a major wheat-producing area of France, using frequentist and Bayesian methods. We compared the abilities of these models to predict S. tritici incidence over different time scales. We found that the best models were those that included site-year effects and disease risk ratings based on sowing dates and cultivar resistance levels. These models can be used to estimate the dynamics of disease incidence from observations collected in regional surveys and, as such, could help regional extension services evaluate current disease incidence at the regional scale. The proposed models could also be adjusted to make use of site-specific in-season field measurements for the estimation of site-specific disease incidence. With the current survey design, site-specific estimates are more accurate than regional estimates after mid-May. Such estimates could be used to help farmers adapt their control strategies locally during the growing season.
Claviceps purpurea is able to infect numerous of cereal species and grasses in Europe and worldwi... more Claviceps purpurea is able to infect numerous of cereal species and grasses in Europe and worldwide. The pathogene forms a sclerotium also named ergot, which overgrows the developing grain. The sclerotium is a mass of mycelium that contains alkaloids. In 2006, European Commission recommended to perform monitoring on the presence of ergot alkaloids, and to determine; whenever possible, simultaneously the sclerotia content in the sample in order to be able to improve the knowledge on the relation between the content of sclerotia and the level of individual ergot alkaloids. Therefore, ARVALIS - Institut du végétal collected over 1 000 field samples* of common wheat, durum wheat, triticale, barley, rye and oat. Those field samples were collected on 2012 and 2013 harvests. 337 samples contained ergot bodies. Therefore, alkaloid contents were analysed on those samples. Ergométrine, ergotamine, ergosine, ergocristine, ergocryptine, ergocornine and their corresponding epimers (-inine forms)...
Ergot is a cereal disease observed in many countries, whose sporadic presence alters grain qualit... more Ergot is a cereal disease observed in many countries, whose sporadic presence alters grain quality. It can be hazardous for human and animal health. Although studied since the eighteenth century, the biology of Claviceps purpurea remains incompletely known. This work aims at characterizing the disease gradient, that is, the decrease in the presence of ergot resulting from primary contamination, as a function of distance from the source of contamination. The female parent of a gametocide-sterilized wheat hybrid was used as a biological trap for catching wind-dispersed ascospores.
World Mycotoxin Journal, 2011
Deoxynivalenol (DON) produced by Fusarium graminearum in durum wheat is a major issue for the Fre... more Deoxynivalenol (DON) produced by Fusarium graminearum in durum wheat is a major issue for the French food chain. Since this cereal is exclusively used for human consumption, each batch of grain marketed for first-stage processing must comply with the DON legal limit of 1,750 µg/kg set by the European Commission. As a response to this regulation, we have started a study to identify factors affected the DON content in durum wheat kernels. This study has been made by exploiting data from a field survey started in 2001 in French durum wheat producing regions. Over 700 field samples were harvested and grains were analysed for their DON content. For each field, agronomic parameters and weather conditions during flowering were recorded. The study of these parameters has led to the development of decision-making tools to help farmers manage the risk of DON contamination in the field. The first stage of the work was to identify critical factors involved in DON content, these being the previo...
Theoretical and Applied Genetics, 2013
between markers and environmental covariates (ECs). However, when genotypic and environmental inf... more between markers and environmental covariates (ECs). However, when genotypic and environmental information is high dimensional, modeling all possible interactions explicitly becomes infeasible. In this article we show how to model interactions between high-dimensional sets of markers and ECs using covariance functions. The model presented here consists of (random) reaction norm where the genetic and environmental gradients are described as linear functions of markers and of ECs, respectively. We assessed the proposed method using data from Arvalis, consisting of 139 wheat lines genotyped with 2,395 SNPs and evaluated for grain yield over 8 years and various locations within northern France. A total of 68 ECs, defined based on five phases of the phenology of the crop, were used in the analysis. Interaction terms accounted for Abstract Key message New methods that incorporate the main and interaction effects of high-dimensional markers and of high-dimensional environmental covariates gave increased prediction accuracy of grain yield in wheat across and within environments.
Biotechnol. Agron. Soc. Environ, 2000
L'utilisation de la microscopie-NIR pour la détection et la quantification des farines de vi... more L'utilisation de la microscopie-NIR pour la détection et la quantification des farines de viande et d'os dans les aliments composés est envisagée. Premièrement, on montre qu'il est possible de reconnaître des particules d'origine animale dans un aliment composé sur ...
... Hétérogénéités du sol: comment les déceler. Autores: Caroline Desbourdes, François Piraux, Be... more ... Hétérogénéités du sol: comment les déceler. Autores: Caroline Desbourdes, François Piraux, Benoît de Solan; Localización: Perspectives agricoles, ISSN 0399-8533, Nº 338, 2007 , pág. 18. Fundación Dialnet. Acceso de usuarios registrados. ...
Applied and Environmental Microbiology, 2011
The fungal pathogen Fusarium verticillioides infects maize ears and produces fumonisins, known fo... more The fungal pathogen Fusarium verticillioides infects maize ears and produces fumonisins, known for their adverse effects on human and animal health. Basic questions remain unanswered regarding the kernel stage(s) associated with fumonisin biosynthesis and the kernel components involved in fumonisin regulation during F. verticillioides -maize interaction under field conditions. In this 2-year field study, the time course of F. verticillioides growth and fumonisin accumulation in developing maize kernels, along with the variations in kernel pH and amylopectin content, were monitored using relevant and accurate analytical tools. In all experiments, the most significant increase in fumonisin accumulation or in fumonisin productivity (i.e., fumonisin production per unit of fungus) was shown to occur within a very short period of time, between 22/32 and 42 days after inoculation and corresponding to the dent stage. This stage was also characterized by acidification in the kernel pH and a ...
Agriculture, Ecosystems & Environment, 2014
Although numerous studies have been conducted on the effect of tillage on soil organic carbon (SO... more Although numerous studies have been conducted on the effect of tillage on soil organic carbon (SOC), there is still no consensus on the importance of sequestration which can be expected from reduced tillage. Most studies have used a synchronic approach in fields or long-term experiments which were often poorly characterized with respect to initial conditions. In this paper, we used a diachronic approach to quantify SOC changes in a 41 years experiment comparing no-till (NT), shallow till (ST) and full inversion tillage (FIT) combined with crop managements (residues removal, rotation and catch crops). It included SOC measurements at time 0 and every 4 years, calculations at equivalent soil mass within or below the old ploughed layer. Results show that tillage or crop management had no significant effect on SOC stocks after 41 years both in the old ploughed layer (ca. 0-28 cm) and deeper (ca. 0-58 cm). Tillage had no effect on crop yields and residues. In the reduced tillage treatments (ST and NT), SOC accumulated in the surface layer (0-10 cm), reaching a plateau after 24 years but declined continuously in the lower layer (10-28 cm) at a rate of 0.42-0.44% yr −1. The difference in SOC stocks (ST or NT minus FIT) over the old ploughed layer followed a non-monotonic pattern over time. Reduced tillage caused a rapid SOC sequestration during the first 4 years which remained more or less constant (mean = 2.17 and 1.31 t ha −1 , resp.) during the next 24 years and disappeared after 28 years. The drop was attributed to the higher water balance recorded during years 24-28. In the reduced tillage treatments, the changes in SOC over time were negatively correlated with the water balance, indicating that sequestration rate was positive in dry periods and negative in wet conditions. This study highlights the interest of diachronic approaches to understand the effect of tillage and its interaction with environmental and management factors.
From Experimental Network to Meta-analysis, 2019
In analyses of experimental networks, it is always advisable to begin by analyzing the various in... more In analyses of experimental networks, it is always advisable to begin by analyzing the various individual experiments separately. In an experimental network, different experimental designs may be used in different experiments. In such cases, the model for the analysis of individual experiments should take into account the specific experimental design for each experiment.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 18, 2017
HAL (Le Centre pour la Communication Scientifique Directe), 2018
From Experimental Network to Meta-analysis, 2019
When planning a network of experiments, it is generally important to know how many experiments sh... more When planning a network of experiments, it is generally important to know how many experiments should be performed. However, it is often forgotten that it is just as important to know how to choose the environments in which the experiments will be performed.
Un vaste réseau d'expérimentations au champ a été conduit pendant plusieurs années à travers la F... more Un vaste réseau d'expérimentations au champ a été conduit pendant plusieurs années à travers la France pour identifier les combinaisons de variétés cultivées de blé d'hiver et d'itinéraires techniques en vue d'atteindre le double objectif de durabilité écologique et de viabilité économique. Cet objectif implique notamment un processus d'extensification chimique, au travers duquel les intrants chimiques, dont les fongicides, sont réduits pour optimiser les performances, notamment économiques, de la production végétale. Peu d'informations sont disponibles pour documenter, dans ce réseau, la variation des niveaux de maladie multiples. Le contrôle des niveaux de maladies constitue pourtant une étape nécessaire à un processus d'extensification chimique. Cet article fournit une description des intensités des maladies du blé dans un ensemble de 101 expérimentations totalisant 3525 parcelles individuelles de blé, pendant huit années successives (2003-2010). Les maladies considérées sont la rouille brune (BR, Puccinia triticina), la rouille jaune (YR, Puccinia striiformis), la fusariose des épis (FHB, Fusarium graminearum, F. culmorum, et F. avenaceum), l'oïdium (PM, Blumeria graminis), et la septoriose (STB, Zymoseptoria tritici). Les intensités de maladies ont été représentées par des variables binaires (épidémie ou non-épidémie). Trois syndromes de maladies ont été identifiés, qui correspondent à des profils de niveau de maladie distincts. Trois groupes de variétés ont également été identifiés, qui se distinguent par leurs réponses aux maladies. Les résultats indiquent que les années climatiques, les variétés de blé et les itinéraires techniques, dans cet ordre décroissant, définissent le risque d'épidémie dans le pathosystème multiple des maladies du blé en France. Des variables synthétiques prenant en compte le climat au printemps et au début de l'été ont été construites. Les associations entre variables climatiques et risques d'épidémies identifiées sont en accord avec les connaissances sur les effets du climat sur les composants de ce pathosystème multiple. Cet article met en avant la valeur de jeux de données à grande échelle pour l'évaluation de la santé végétale et l'utilité d'une démarche analytique permettant d'identifier les facteurs de risques pour les décisions tactiques et stratégiques, pour la gestion de la santé végétale.
From Experimental Network to Meta-analysis, 2019
This chapter presents in detail the principal methods for analyzing networks of experiments with ... more This chapter presents in detail the principal methods for analyzing networks of experiments with a randomized complete block design including one factor (Dagnelie 1981). In networks of this type, each experiment has a randomized complete block design, within which the various experimental units are grouped together in homogeneous blocks. Each block contains as many experimental units as there are study treatments, and each treatment is tested in each block. Thus, in any given experiment, each treatment is present only once in each block. Treatments are distributed at random between the various experimental units, independently in each block. In a randomized complete block design, the uncertainty on the difference between the means of two treatments stems solely from the variability between experimental units within blocks, and the precision of the experiment can be increased by setting up the most homogeneous blocks possible (Cochran and Cox 1957). In agronomic experiments, two neig...
Field Crops Research, 2019
Nitrogen (N) is an essential compound for the production and grain quality of bread wheat, which ... more Nitrogen (N) is an essential compound for the production and grain quality of bread wheat, which must respect market requirements. Improving nitrogen use efficiency (NUE) is a priority to better manage nitrogen for the benefit of farm economy and the environment. Among all the available levers to do this, the choice of the right cultivar is crucial. To this end, an accurate NUE cultivar characterization is needed both for breeding programmes and for agronomic extension services dedicated to advise farmers. These two fields of expertise (genetic and agronomy) do not share exactly the same protocols and indicators to assess the impact of cultivar on wheat NUE. Moreover, although some recent NUE genetic studies have been conducted on cultivars currently available in France, no recent NUE agronomic studies have been made on current French wheat cultivars. Moreover, the latest agronomic studies to date on cultivar effect on wheat N requirement (coefficient "b" used in France) were conducted without considering the need to reach a grain protein concentration of 11.5% (French bread wheat market requirement) in addition to the objective of achieving the yield potential. By using a classical agronomic protocol (network of 12 field trials over 3 years testing bread-wheat cultivars along a complete nitrogen response curve), the presented study aimed to address three specific NUE related topics by characterizing recent French cultivars with a large range of NUE indicators used by geneticists and/or agronomists. Firstly, we demonstrated that N rate and recent French cultivars had a significant effect on NUE and its components (nitrogen uptake efficiency-NupE and nitrogen utilization efficiency-NutE), as well as on apparent fertilizer recovery (AFR). Secondly, we showed that NupE and AFR were strongly correlated, allowing us to compare genetic studies (mainly using NupE) and agronomic studies (mainly using AFR) without any difficulty. Thirdly, we designed a set of new N requirement indicators (coefficients "bc" and "bq") helping the farmer to grow each bread wheat cultivar with a dual objective of optimum yield and grain protein content in line with the market requirements. This could be achieved without significant impact on nitrogen post-harvest losses. The presented study provides a large set of results, usable for breeding and agronomic research programs.
From Experimental Network to Meta-analysis, 2019
Meta-analysis is one of the methods used for synthetic analyses of knowledge. It combines two app... more Meta-analysis is one of the methods used for synthetic analyses of knowledge. It combines two approaches:
Soil Biology and Biochemistry, 2017
The models based on soil properties and cropping history could be further implemented in multidis... more The models based on soil properties and cropping history could be further implemented in multidisciplinary soil-crop models and decision support systems in order to enhance the prediction of N dynamics in soils and improve fertilizer recommendations.
European Journal of Plant Pathology, 2016
A large network of field experiments has been conducted over several years across France to ident... more A large network of field experiments has been conducted over several years across France to identify combinations of winter wheat cultivars and management practices in which partial resistances under limited chemical protection would achieve adequate disease management, while leading to satisfactory yield performance, and so achieve the double objective of ecological sustainability and economic viability. Little information is available to document the variation in multiple disease levels, a necessary step towards a chemical extensification process, in wheat networked experiments. This article provides a description of disease intensities in a set of 101 experiments totalling 3525 individual wheat plots over eight successive years (2003–2010). The diseases considered are brown rust (BR, Puccinia triticina), yellow rust (YR, Puccinia striiformis), fusarium head blight (FHB, Fusarium graminearum, F. culmorum, and F. avenaceum), powdery mildew (PM, Blumeria graminis), and septoria tritici blotch (STB, Zymoseptoria tritici). Hierarchical cluster analysis led to the identification of three variety groups associated with (1) moderate-low disease levels in general, except for YR (moderate levels) – 16 varieties; (2) moderate-low BR, YR, and FHB levels, and moderate PM and STB levels – 12 varieties; (3) comparatively higher BR, YR, FHB, and STB levels, and moderate PM levels – 17 varieties. The association of disease levels represented as binary categories (i.e., epidemics vs. non-epidemics) with climatic years corresponded to chi-square values (χ2 = 87.0–1402) that were one to two orders of magnitude larger than the values corresponding to the associations of diseases with variety groups (χ2 = 6.41–321) or with levels of crop management (χ2 = 21.2–82.1). Multivariate non parametric analyses indicated the existence of three disease syndromes, two of which being dominated by BR or STB, and a third associated with diverse diseases and frequent FHB. This suggests that STB and BR might each be considered as key-stone species dominating specific wheat disease syndromes. Multiple correspondence analysis highlighted the linkages between multiple epidemic occurrence and the three characterized variety groups. Risk factors analyses conducted through logistic regressions provided quantitative estimates of the contribution of climatic years, variety groups, and crop management, to the likelihood of epidemic occurrence for each of the five diseases considered. The results indicate that climatic years, wheat varieties, and crop management, in this decreasing order, define disease epidemic risk in the multiple wheat-diseases pathosystem.
European Journal of Plant Pathology, 2016
Septoria leaf blotch is a widespread disease caused by the fungus Zymoseptoria tritici (formely k... more Septoria leaf blotch is a widespread disease caused by the fungus Zymoseptoria tritici (formely known as Mycosphaerella graminicola). It causes yield losses in winter wheat crops (Triticum aestivum L.) in many European countries. In this study, we aimed to develop statistical models for estimating regional and site-specific incidence of Septoria leaf blotch from inseason field measurements. Four generalised linear models and four generalised linear mixed-effect models were fitted to six years of data collected from a major wheat-producing area of France, using frequentist and Bayesian methods. We compared the abilities of these models to predict S. tritici incidence over different time scales. We found that the best models were those that included site-year effects and disease risk ratings based on sowing dates and cultivar resistance levels. These models can be used to estimate the dynamics of disease incidence from observations collected in regional surveys and, as such, could help regional extension services evaluate current disease incidence at the regional scale. The proposed models could also be adjusted to make use of site-specific in-season field measurements for the estimation of site-specific disease incidence. With the current survey design, site-specific estimates are more accurate than regional estimates after mid-May. Such estimates could be used to help farmers adapt their control strategies locally during the growing season.
Claviceps purpurea is able to infect numerous of cereal species and grasses in Europe and worldwi... more Claviceps purpurea is able to infect numerous of cereal species and grasses in Europe and worldwide. The pathogene forms a sclerotium also named ergot, which overgrows the developing grain. The sclerotium is a mass of mycelium that contains alkaloids. In 2006, European Commission recommended to perform monitoring on the presence of ergot alkaloids, and to determine; whenever possible, simultaneously the sclerotia content in the sample in order to be able to improve the knowledge on the relation between the content of sclerotia and the level of individual ergot alkaloids. Therefore, ARVALIS - Institut du végétal collected over 1 000 field samples* of common wheat, durum wheat, triticale, barley, rye and oat. Those field samples were collected on 2012 and 2013 harvests. 337 samples contained ergot bodies. Therefore, alkaloid contents were analysed on those samples. Ergométrine, ergotamine, ergosine, ergocristine, ergocryptine, ergocornine and their corresponding epimers (-inine forms)...
Ergot is a cereal disease observed in many countries, whose sporadic presence alters grain qualit... more Ergot is a cereal disease observed in many countries, whose sporadic presence alters grain quality. It can be hazardous for human and animal health. Although studied since the eighteenth century, the biology of Claviceps purpurea remains incompletely known. This work aims at characterizing the disease gradient, that is, the decrease in the presence of ergot resulting from primary contamination, as a function of distance from the source of contamination. The female parent of a gametocide-sterilized wheat hybrid was used as a biological trap for catching wind-dispersed ascospores.
World Mycotoxin Journal, 2011
Deoxynivalenol (DON) produced by Fusarium graminearum in durum wheat is a major issue for the Fre... more Deoxynivalenol (DON) produced by Fusarium graminearum in durum wheat is a major issue for the French food chain. Since this cereal is exclusively used for human consumption, each batch of grain marketed for first-stage processing must comply with the DON legal limit of 1,750 µg/kg set by the European Commission. As a response to this regulation, we have started a study to identify factors affected the DON content in durum wheat kernels. This study has been made by exploiting data from a field survey started in 2001 in French durum wheat producing regions. Over 700 field samples were harvested and grains were analysed for their DON content. For each field, agronomic parameters and weather conditions during flowering were recorded. The study of these parameters has led to the development of decision-making tools to help farmers manage the risk of DON contamination in the field. The first stage of the work was to identify critical factors involved in DON content, these being the previo...
Theoretical and Applied Genetics, 2013
between markers and environmental covariates (ECs). However, when genotypic and environmental inf... more between markers and environmental covariates (ECs). However, when genotypic and environmental information is high dimensional, modeling all possible interactions explicitly becomes infeasible. In this article we show how to model interactions between high-dimensional sets of markers and ECs using covariance functions. The model presented here consists of (random) reaction norm where the genetic and environmental gradients are described as linear functions of markers and of ECs, respectively. We assessed the proposed method using data from Arvalis, consisting of 139 wheat lines genotyped with 2,395 SNPs and evaluated for grain yield over 8 years and various locations within northern France. A total of 68 ECs, defined based on five phases of the phenology of the crop, were used in the analysis. Interaction terms accounted for Abstract Key message New methods that incorporate the main and interaction effects of high-dimensional markers and of high-dimensional environmental covariates gave increased prediction accuracy of grain yield in wheat across and within environments.
Biotechnol. Agron. Soc. Environ, 2000
L'utilisation de la microscopie-NIR pour la détection et la quantification des farines de vi... more L'utilisation de la microscopie-NIR pour la détection et la quantification des farines de viande et d'os dans les aliments composés est envisagée. Premièrement, on montre qu'il est possible de reconnaître des particules d'origine animale dans un aliment composé sur ...
... Hétérogénéités du sol: comment les déceler. Autores: Caroline Desbourdes, François Piraux, Be... more ... Hétérogénéités du sol: comment les déceler. Autores: Caroline Desbourdes, François Piraux, Benoît de Solan; Localización: Perspectives agricoles, ISSN 0399-8533, Nº 338, 2007 , pág. 18. Fundación Dialnet. Acceso de usuarios registrados. ...
Applied and Environmental Microbiology, 2011
The fungal pathogen Fusarium verticillioides infects maize ears and produces fumonisins, known fo... more The fungal pathogen Fusarium verticillioides infects maize ears and produces fumonisins, known for their adverse effects on human and animal health. Basic questions remain unanswered regarding the kernel stage(s) associated with fumonisin biosynthesis and the kernel components involved in fumonisin regulation during F. verticillioides -maize interaction under field conditions. In this 2-year field study, the time course of F. verticillioides growth and fumonisin accumulation in developing maize kernels, along with the variations in kernel pH and amylopectin content, were monitored using relevant and accurate analytical tools. In all experiments, the most significant increase in fumonisin accumulation or in fumonisin productivity (i.e., fumonisin production per unit of fungus) was shown to occur within a very short period of time, between 22/32 and 42 days after inoculation and corresponding to the dent stage. This stage was also characterized by acidification in the kernel pH and a ...
Agriculture, Ecosystems & Environment, 2014
Although numerous studies have been conducted on the effect of tillage on soil organic carbon (SO... more Although numerous studies have been conducted on the effect of tillage on soil organic carbon (SOC), there is still no consensus on the importance of sequestration which can be expected from reduced tillage. Most studies have used a synchronic approach in fields or long-term experiments which were often poorly characterized with respect to initial conditions. In this paper, we used a diachronic approach to quantify SOC changes in a 41 years experiment comparing no-till (NT), shallow till (ST) and full inversion tillage (FIT) combined with crop managements (residues removal, rotation and catch crops). It included SOC measurements at time 0 and every 4 years, calculations at equivalent soil mass within or below the old ploughed layer. Results show that tillage or crop management had no significant effect on SOC stocks after 41 years both in the old ploughed layer (ca. 0-28 cm) and deeper (ca. 0-58 cm). Tillage had no effect on crop yields and residues. In the reduced tillage treatments (ST and NT), SOC accumulated in the surface layer (0-10 cm), reaching a plateau after 24 years but declined continuously in the lower layer (10-28 cm) at a rate of 0.42-0.44% yr −1. The difference in SOC stocks (ST or NT minus FIT) over the old ploughed layer followed a non-monotonic pattern over time. Reduced tillage caused a rapid SOC sequestration during the first 4 years which remained more or less constant (mean = 2.17 and 1.31 t ha −1 , resp.) during the next 24 years and disappeared after 28 years. The drop was attributed to the higher water balance recorded during years 24-28. In the reduced tillage treatments, the changes in SOC over time were negatively correlated with the water balance, indicating that sequestration rate was positive in dry periods and negative in wet conditions. This study highlights the interest of diachronic approaches to understand the effect of tillage and its interaction with environmental and management factors.
From Experimental Network to Meta-analysis, 2019
In analyses of experimental networks, it is always advisable to begin by analyzing the various in... more In analyses of experimental networks, it is always advisable to begin by analyzing the various individual experiments separately. In an experimental network, different experimental designs may be used in different experiments. In such cases, the model for the analysis of individual experiments should take into account the specific experimental design for each experiment.