Future development of apricot blossom blight under climate change in Southern France

International audienceClimate change will have several consequences for agro-systems, one of which will concern changes to the development of pathogens. Because of the losses it causes, particularly in organic farming, Monilinia laxa is an important pathogen affecting apricot crops. This study focuses on the consequences of climate change regarding blossom and twig blight (Monilinia laxa) of apricot. To achieve this, a Climatic Index of cumulated Blight risk (CIB) was built, to obtain the weighted sum of blossom blight incidence throughout the blooming period. An epidemiological model to calculate the incidence of blossom blight during every potentially infectious episode and based on biological parameters, was calibrated using a trap pot experiment where trees were placed in orchards and subject to various meteorological conditions. The CIB derived from this model was evaluated on field data, and was shown to be a robust and useful tool to predict the effects of climate change on the development of apricot blight. Then, using the CIB with a phenological model to predict blooming periods in the future, we estimated the risks of apricot blight until 2100 on four contrasted apricot cultivars and in three geographical zones under climate change scenarios RCP 4.5 and 8.5. This study revealed different effects of climate change depending on the cultivar and altitude. Apricot trees would bloom earlier (up to a difference of 50 days between 1950 and 2100) under climate change. Under the combined effects of these shifts of blooming period and changing climatic conditions, late cultivars such as Bergarouge might see a reduction in the risk of blossom blight (down to 31%) because of warmer but dryer blooming periods. Other varieties (e.g.: Bergeron) could experience an increase in this risk by up to 27% with a shift of the blooming period towards rainier conditions at the highest altitudes. The results of this study could be used to anticipate future changes as well as be used at present as a decision-support tool for farmers

Building up, management and evaluation of orchard systems: a four-year experience in apple production

National audienceThree apple orchard systems were planted in 2005 to assess agronomic and environmental effects of different pest management regimes: organic farming (OG), conventional supervised (SV) and low-input (LI) systems. Three apple cultivars presenting different susceptibility to scab were planted in each system: Ariane (Vf-resistant), Melrose (low-susceptibility) and Smoothee 2832T® (susceptible), creating nine « system x cultivar » situations. Decision rules were defined within the framework of each system, and their possible interactions were integrated. Starting from planting, the survey included pest and disease assessments, and agronomic and environmental parameters. The OG system was the slowest to produce commercial yield, whereas the SV one showed the highest performances. Although globally low, pest and disease fruit damage at harvest was the highest in the OG system. The treatment frequency index (TFI) was the highest in the SV system, and in Smoothee plots within each system. Two-fold more treatments were applied in any SV plot and in Smoothee OG compared to Melrose LI. The LI system presented the lowest TFI and the lowest environmental impact of pesticides calculated by the I-phyARBO fuzzy expert system. Apart from Smoothee, I-phyARBO in the OG system scored between LI and SV. From the first four years of the experiment, the importance of the cultivar in the management of the orchard diseases (and to some extent pests) is outlined whatever the system, with a high functional tool permitting the conception of decision rule patterns, and also to assess the agronomic, environmental and economical performances of the systems

Innovation variétale en Prunus, 1960-2013 : les enseignements d’une analyse socio-historique co-construite avec les acteurs

International audienceL’arboriculture fruitière se trouve dans un contexte notoirement difficile : elle est exposée non seulement à une crise que l’on qualifie désormais de structurelle, mais aussi à des attentes et contraintes à la fois contradictoires et interdépendantes, portant notamment sur la qualité environnementale, les performances agronomiques, la qualité gustative et l’aptitude à une mise en marché de plus en plus contraignante – d’autant plus qu’en cultures pérennes, les pas de temps contraignent fortement les possibilités d’évolution, par rapport aux cultures annuelles. Dans ce contexte, explorer les évolutions passées et possibles de l’arboriculture, en particulier dans une perspective de réduction des intrants et d’écologisation des pratiques, suppose de traiter des interdépendances entre les stratégies et contraintes des divers acteurs du secteur. Cet article analyse les évolutions, depuis les années 1960 jusqu’à aujourd’hui, de la sélection génétique et de l’offre variétale en pêche et abricot, dans leur interaction avec les autres éléments du système socio-technique : évolution du marché, organisation des acteurs de la filière, politiques publiques, stratégies et pratiques des exploitations agricoles

Innovation variétale en Prunus, 1960-2013 : les enseignements d’une analyse socio-historique co-construite avec les acteurs

L’arboriculture fruitière se trouve dans un contexte notoirement difficile : elle est exposée non seulement à une crise que l’on qualifie désormais de structurelle, mais aussi à des attentes et contraintes à la fois contradictoires et interdépendantes, portant notamment sur la qualité environnementale, les performances agronomiques, la qualité gustative et l’aptitude à une mise en marché de plus en plus contraignante – d’autant plus qu’en cultures pérennes, les pas de temps contraignent fortement les possibilités d’évolution, par rapport aux cultures annuelles. Dans ce contexte, explorer les évolutions passées et possibles de l’arboriculture, en particulier dans une perspective de réduction des intrants et d’écologisation des pratiques, suppose de traiter des interdépendances entre les stratégies et contraintes des divers acteurs du secteur. Cet article analyse les évolutions, depuis les années 1960 jusqu’à aujourd’hui, de la sélection génétique et de l’offre variétale en pêche et abricot, dans leur interaction avec les autres éléments du système socio-technique : évolution du marché, organisation des acteurs de la filière, politiques publiques, stratégies et pratiques des exploitations agricoles

La Normandie : coopérer ou s'affirmer ? Douze géographes des Universités de Caen, du Havre et de Rouen prennent position dans le débat sur la Normandie

Brennetot Arnaud, Brocard Madeleine, Buléon Pascal, Bussi Michel, Ruffray Sophie de, Fixot Anne-Marie, Frémont Armand, Gay François-Jean, Guermond Yves, Herin Robert, Lecoquierre Bruno, Lévêque Laurent. La Normandie : coopérer ou s'affirmer ? Douze géographes des Universités de Caen, du Havre et de Rouen prennent position dans le débat sur la Normandie. In: Études Normandes, 60e année, n°2, 2011. 911-2011 Happy Birthday, Normandie ? pp. 73-74

Nature of the periplastidial pathway of starch synthesis in the cryptophyte Guillardia theta.

The nature of the periplastidial pathway of starch biosynthesis was investigated with the model cryptophyte Guillardia theta. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of starch from green algae and land plants. Most starch granules displayed a shape consistent with biosynthesis occurring around the pyrenoid through the rhodoplast membranes. A protein with significant similarity to the amylose-synthesizing granule-bound starch synthase 1 from green plants was found as the major polypeptide bound to the polysaccharide matrix. N-terminal sequencing of the mature protein proved that the precursor protein carries a nonfunctional transit peptide in its bipartite topogenic signal sequence which is cleaved without yielding transport of the enzyme across the two inner plastid membranes. The enzyme was shown to display similar affinities for ADP and UDP-glucose, while the V(max) measured with UDP-glucose was twofold higher. The granule-bound starch synthase from Guillardia theta was demonstrated to be responsible for the synthesis of long glucan chains and therefore to be the functional equivalent of the amylose-synthesizing enzyme of green plants. Preliminary characterization of the starch pathway suggests that Guillardia theta utilizes a UDP-glucose-based pathway to synthesize starch

BioREco, Méthodologie et expérimentation système pour la réduction de l'utilisation des pesticides en vergers de pommier

Ce numéro est constitué d’articles de synthèse des projets DEPHY EXPE publiés à l’occasion du colloque national DEPHY, qui s’est déroulé les 13 et 14 novembre 2018 à la Cité des Sciences et de l'Industrie (Paris). Nous vous invitons à découvrir le bilan et les enseignements des 21 projets conduits sur la période 2012-2017.To reduce pesticide use is challenging but crucial to improve fruit production sustainability. The ‘BioREco’ system experiment permitted to assess the possibilities to decrease pesticide use in apple orchards. Compared to the regional reference, pesticide use at full production (2009-2015) was on average decreased by 38-45% in systems combining low-susceptibility cultivars, alternative methods to chemicals and an accurate evaluation of the risk of damage. In those systems, yield was either similar (low-input systems) or lower (organic farming) than the reference. The multicriteria evaluation that Simon S. et al 74 Innovations Agronomiques 70 (2018), 73-86considered agronomic, environmental, technico-economical and feasability aspects displayed the benefits and the limits of the experimented systems. This work also enabled interactions among stakeholders in the food system about the experimental approach, the orchards, the multicriteria evaluation, the results and knowledge necessary to design the orchards of tomorrow. Keywords: Malus x floribunda, Cropping system, Multicriteria evaluation, Pest and disease management, Pesticide.La réduction de l’utilisation des pesticides est un enjeu majeur en arboriculture. Le dispositif BioREco a permis d’explorer dans la durée le potentiel de réduction de l’utilisation des pesticides en verger de pommiers. Par rapport à la référence régionale, pour la période de pleine production (2009-2015), il a en moyenne été possible de réduire l’utilisation des pesticides de 38 à 45 % en combinant des variétés peu sensibles ou résistantes aux maladies, un ensemble de pratiques alternatives aux pesticides et une évaluation fine du risque de dégâts. Cette réduction a été atteinte pour des niveaux de rendement équivalents (systèmes bas-intrants) ou moindres (systèmes en Agriculture Biologique). L’évaluation multicritère réalisée (agronomique, environnementale, technico-économique et faisabilité) a permis d’identifier les points forts et les points d’amélioration des systèmes expérimentés. Ce dispositif a également permis de créer une dynamique au sein de la filière, autour de l’approche expérimentale, des vergers, de leur évaluation multicritère, des résultats et des connaissances nécessaires pour repenser les vergers de demain

BioREco, Méthodologie et expérimentation système pour la réduction de l'utilisation des pesticides en vergers de pommier

La réduction de l’utilisation des pesticides est un enjeu majeur en arboriculture. Le dispositif BioREco a permis d’explorer dans la durée le potentiel de réduction de l’utilisation des pesticides en verger de pommiers. Par rapport à la référence régionale, pour la période de pleine production (2009-2015), il a en moyenne été possible de réduire l’utilisation des pesticides de 38 à 45 % en combinant des variétés peu sensibles ou résistantes aux maladies, un ensemble de pratiques alternatives aux pesticides et une évaluation fine du risque de dégâts. Cette réduction a été atteinte pour des niveaux de rendement équivalents (systèmes bas-intrants) ou moindres (systèmes en Agriculture Biologique). L’évaluation multicritère réalisée (agronomique, environnementale, technico-économique et faisabilité) a permis d’identifier les points forts et les points d’amélioration des systèmes expérimentés. Ce dispositif a également permis de créer une dynamique au sein de la filière, autour de l’approche expérimentale, des vergers, de leur évaluation multicritère, des résultats et des connaissances nécessaires pour repenser les vergers de demain.To reduce pesticide use is challenging but crucial to improve fruit production sustainability. The ‘BioREco’ system experiment permitted to assess the possibilities to decrease pesticide use in apple orchards. Compared to the regional reference, pesticide use at full production (2009-2015) was on average decreased by 38-45% in systems combining low-susceptibility cultivars, alternative methods to chemicals and an accurate evaluation of the risk of damage. In those systems, yield was either similar (low-input systems) or lower (organic farming) than the reference. The multicriteria evaluation that Simon S. et al 74 Innovations Agronomiques 70 (2018), 73-86 considered agronomic, environmental, technico-economical and feasability aspects displayed the benefits and the limits of the experimented systems. This work also enabled interactions among stakeholders in the food system about the experimental approach, the orchards, the multicriteria evaluation, the results and knowledge necessary to design the orchards of tomorrow. Keywords: Malus x floribunda, Cropping system, Multicriteria evaluation, Pest and disease management, Pesticide

Pathway of Cytosolic Starch Synthesis in the Model Glaucophyte Cyanophora paradoxa▿

The nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model glaucophyte Cyanophora paradoxa. The storage polysaccharide granules are shown to be composed of both amylose and amylopectin fractions, with a chain length distribution and crystalline organization similar to those of green algae and land plant starch. A preliminary characterization of the starch pathway demonstrates that Cyanophora paradoxa contains several UDP-glucose-utilizing soluble starch synthase activities related to those of the Rhodophyceae. In addition, Cyanophora paradoxa synthesizes amylose with a granule-bound starch synthase displaying a preference for UDP-glucose. A debranching enzyme of isoamylase specificity and multiple starch phosphorylases also are evidenced in the model glaucophyte. The picture emerging from our biochemical and molecular characterizations consists of the presence of a UDP-glucose-based pathway similar to that recently proposed for the red algae, the cryptophytes, and the alveolates. The correlative presence of isoamylase and starch among photosynthetic eukaryotes is discussed

The Heterotrophic Dinoflagellate Crypthecodinium cohnii Defines a Model Genetic System To Investigate Cytoplasmic Starch Synthesis▿ †

The nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model heterotrophic dinoflagellate Crypthecodinium cohnii. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of green algae and land plant starch. Preliminary characterization of the starch pathway demonstrated that C. cohnii contains multiple forms of soluble starch synthases and one major 110-kDa granule-bound starch synthase. All purified enzymes displayed a marked substrate preference for UDP-glucose. At variance with most other microorganisms, the accumulation of starch in the dinoflagellate occurs during early and mid-log phase, with little or no synthesis witnessed when approaching stationary phase. In order to establish a genetic system allowing the study of cytoplasmic starch metabolism in eukaryotes, we describe the isolation of marker mutations and the successful selection of random recombinant populations after homothallic crosses