Associer des itinéraires techniques de niveau d'intrants variés à des variétés rustiques de blé tendre : évaluation économique, environnementale et énergétique

International audienceL’impact de l’utilisation des engrais azotés et des pesticides (Aubertot et al., 2005) sur l’environnement ainsi que l’instabilité des prix de vente des céréales ont suscité un certain nombre de réflexions sur de nouvelles manières de produire du blé tendre d’hiver, en prenant notamment appui sur le progrès variétal. Ainsi, à partir de 1999, l’INRA, l’ITCF (puis ARVALIS-Institut du végétal), les sélectionneurs du GIE Club des Cinq et les chambres d’agriculture d’Indre-et-Loire et du Morbihan ont engagé une collaboration afin d’évaluer l’intérêt des variétés rustiques conduites avec des itinéraires techniques à niveaux d’intrants réduits. Ces variétés ont été choisies parmi celles présentant des caractères de multirésistance aux maladies et à la verse, tout en s’assurant d’un niveau de rendement comparable aux autres cultivars du catalogue. Le réseau expérimental multilocal mis en place de 2000 à 2002 a révélé des performances économiques satisfaisantes de ces itinéraires techniques au regard des recommandations locales, et ce pour le prix de vente moyen de cette période, à savoir 100 € par tonne (Loyce et al., 2001 ; Félix et al., 2002 ; Rolland et al., 2003 ; Loyce et al., accepté)

Gagner de l'efficacité en adaptant la variété à l'environnement de production

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Quantifying uncertainties in N(2)O emission due to N fertilizer application in cultivated areas.

Nitrous oxide (N(2)O) is a greenhouse gas with a global warming potential approximately 298 times greater than that of CO(2). In 2006, the Intergovernmental Panel on Climate Change (IPCC) estimated N(2)O emission due to synthetic and organic nitrogen (N) fertilization at 1% of applied N. We investigated the uncertainty on this estimated value, by fitting 13 different models to a published dataset including 985 N(2)O measurements. These models were characterized by (i) the presence or absence of the explanatory variable "applied N", (ii) the function relating N(2)O emission to applied N (exponential or linear function), (iii) fixed or random background (i.e. in the absence of N application) N(2)O emission and (iv) fixed or random applied N effect. We calculated ranges of uncertainty on N(2)O emissions from a subset of these models, and compared them with the uncertainty ranges currently used in the IPCC-Tier 1 method. The exponential models outperformed the linear models, and models including one or two random effects outperformed those including fixed effects only. The use of an exponential function rather than a linear function has an important practical consequence: the emission factor is not constant and increases as a function of applied N. Emission factors estimated using the exponential function were lower than 1% when the amount of N applied was below 160 kg N ha(-1). Our uncertainty analysis shows that the uncertainty range currently used by the IPCC-Tier 1 method could be reduced

Design workshop with farmers as a promising tool to support the introduction of diversifying crops within a territory: the case of camelina in northern France to supply a local biorefinery

The development of local diversification value-chains requires the design and implementation of cropping systems adapted to a diversity of farms and the management of crops for which very little knowledge is available. In this article, using the example of camelina in northern France to supply a local oilseed biorefinery, we illustrate how (i) the realisation of a design workshop based on the formalization and sharing of local knowledge produced by a multi-stakeholder participatory approach, and (ii) the analysis, formalization and sharing of the outputs of this design workshop, are useful for supporting the introduction of a new species in a territory. In total, each of the nine farmers attending the workshop designed one (or two) proposal(s) to include and manage camelina adapted to their own situation. The precise description of these proposals and the explanation of the technical choices, the identification of the factors explaining the diversity of the proposals designed, as well as the inventory of the functions expected of the crop by the farmers, which are presented in this paper, constitute a set of elements that could also be used to support other farmers in the area who would like to introduce this new species into their cropping system

Mettre en récits la recherche finalisée dans l’action collective: Résultats et enseignements tirés du projet ACOLADE

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Mettre en récits les pratiques de recherche dans l’action collective : un cadre méthodologique

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Characterization of multiple disease systems and cultivar susceptibilities for the analysis of yield losses in winter wheat

International audienceThe relationship between winter wheat (Triticum aestivum L.) cultivar susceptibility to four main fungal diseases, multiple disease systems, and yield loss (YL) levels was studied. Data from 276 wheat cultivar trials carried out in major wheat-growing areas in France over 12 years (1991–2002) were analyzed. Two variables were defined for each disease: actual disease intensity, referring to individual cultivar and potential disease intensity for each trial, calculated from the disease intensities measured on susceptible cultivars. Cultivar was represented by its level of susceptibility to each disease, previously given by GEVES and based on a semi-quantitative scale. YL was estimated for a given cultivar as the difference between the mean yield of fungicide-protected and of untreated plots. Nonparametric multivariate analysis provided a characterization of relationships among variables. Eight cultivar susceptibility profiles (CP), five potential disease profiles (PDP), and six actual disease profiles (ADP) were determined by cluster analysis. Correspondence analyses led to a good description of variation in YL when potential or ADP were considered. General linear models were developed for each of the five PDP, which involved a significant interaction between CP and PDP on YL. These empirical models provided a means of quantifying the effects of CP on YL. These models represent a practical tool to support choices for multiple-disease resistances in a given area, depending on the prevailing disease profile. Results from this study can also be used to improve the disease module of an agronomic model for wheat aimed at designing “cultivar×crop management” combinations for a given environment and cost/price ratio

Understanding and supporting intermediation work to address territorialized public policy issues: The case of a Territorial Food Project in France

International audienceBACKGROUND: Few ergonomics studies have explored the work required to implement territorialized public policies. OBJECTIVE: To identify key challenges for ergonomists who analyse and support intermediation work taking place in the design and implementation of a Territorial Food Project or TFP (a public policy device). METHODS: We adapted a framework developed in the field of political sociology. The analysis focuses on two scales to identify key characteristics of intermediation work: the agri-urban area as delimited and targeted by the TFP; and the farm and its relationships to food systems. To capture how intermediation work articulates prescription and action, we studied first the work carried out by the actors to use a public policy device such as TFP, and second the evolving farming work systems’ connections to food systems and how they are supported by various actors. RESULTS: Intermediation work is spread across a wide diversity of actors. Coordination at governance level aims to allocate resources among institutional actors and to check the progress of the elaborated action plan. Coordination at operational level, which is meant to support farming work systems dynamics or to implement the action plan, focuses on fostering the emergence of initiatives but seems to lack a shared vision and time availability. CONCLUSION: We identify two main challenges: to further develop a framework for analysing the intermediation work occurring in a multi-scale and territorial perspective; and new intervention methods so that ergonomists can take part in and support such intermediation work

Modeling the effect of cultivar resistance on yield losses of winter wheat in natural multiple disease conditions

The use of winter wheat (Triticum aestivum L.) cultivars resistant to diseases may make it possible to reduce yield losses without the need to use fungicides, which are expensive and may damage the environment. The cultivar resistances favored depend on the region considered and the nature of the most widespread diseases in that region. We have constructed a statistical linear model for the estimation of relative yield loss due to diseases, making it possible to assess the effects of winter wheat cultivars in various disease conditions. We considered the interactions “potential disease intensity × winter wheat cultivar” for four main fungal diseases: septoria tritici blotch (Mycosphaerella graminicola), brown rust (Puccinia triticina), yellow rust (Puccinia striiformis) and powdery mildew (Erysiphe graminis). This model can therefore be readily adapted to different regions with diverse combinations of these diseases. The potential intensity of each disease in each trial was calculated based on the symptoms observed on susceptible cultivars not treated with fungicide. The cultivar effect was characterized by the ratings of cultivar susceptibility to each disease and by cultivar earliness. The parameters of the model were estimated from 276 wheat cultivar trials carried out over 12 years (1991–2002) in the major wheat-growing areas of France. This model can help to choose from the cultivars resistant to several diseases (but very rarely resistant to all the diseases), those cultivars best adapted to a given environment, according to the hierarchy of potential disease intensities encountere

Fitted response curves obtained with the four selected nonlinear models (A) and the four selected linear models (B).

<p>Black points correspond to N₂O data (96.04% of available observations are displayed; the other data are too extreme for graphical presentation).</p