En verger biologique, pour lequel le recours à la lutte directe contre les ravageurs est limité, les possibilités de manipulation de l'habitat des ravageurs et des auxiliaires (l'arbre fruitier et l'environnement végétal du verger) ont été explorées à partir d'expérimentations pluriannuelles en verger de pommiers biologiques et de poiriers. La conduite architecturale du pommier a un impact sur le développement de ses principaux ravageurs. Une étude comparant deux systèmes de conduite a montré un effet globalement freinant (pucerons, acariens) ou parfois (carpocapse) d'un système de conduite nouvellement mis au point et validé pour son intérêt agronomique, la conduite centrifuge, par rapport à la conduite classique en Solaxe. L'étude d'une formation arbustive expérimentale (haie de bordure) conçue pour optimiser la protection du verger de poiriers a par ailleurs permis de valider les principes de base d'une introduction raisonnée de diversité végétale dans l'environnement du verger : existence d'une succession de ressources pour les auxiliaires actifs sur le(s) ravageur(s)-clé(s) de la culture, innocuité pour les cultures (absence de ravageurs ou maladies communs avec les cultures). Ces travaux et d'autres études suggèrent que la manipulation de l'environnement végétal du verger modifie l'entomocénose. En revanche, le bénéfice potentiel en verger se limite au contrôle des ravageurs tolérés à des niveaux de pollution élevés. | The control of pests in organic orchards cannot solely rely on the use of direct control methods. The effects of manipulating the habitat of orchard pests and natural enemies through the architecture and the increase of plant diversity has been investigated in an experimental organic apple orchard and in a pear orchard, in order to provide information about the potential benefits of these cultural practices. Tree training affected the development of the most detrimental pests of apple trees, and the centrifugal training system globally provided better aphid (Dysaphis plantaginea) and mite (Panonychus ulmi) control than the more classical Solaxe system, whereas codling moth (Cydia pomonella) was favoured compared to Solaxe. The study of an experimental hedgerow designed to optimise protection of the pear orchard allowed us to validate the basic principles of designing plant assemblages to increase plant diversity in the orchard surroundings, namely the introduction of a succession of resources favouring the natural enemies of the key orchard pests, and to avoid detrimental effects (pests or diseases shared with the crops). This experiment and other studies suggest that manipulating the plant diversity adjacent to the orchard has an effect on entomocenosis. However, the potential benefits for the orchard only concern the control of pests that can be tolerated at high infestation rates.

En verger biologique, pour lequel le recours à la lutte directe contre les ravageurs est limité, les possibilités de manipulation de l'habitat des ravageurs et des auxiliaires (l'arbre fruitier et l'environnement végétal du verger) ont été explorées à partir d'expérimentations pluriannuelles en verger de pommiers biologiques et de poiriers. La conduite architecturale du pommier a un impact sur le développement de ses principaux ravageurs. Une étude comparant deux systèmes de conduite a montré un effet globalement freinant (pucerons, acariens) ou parfois (carpocapse) d'un système de conduite nouvellement mis au point et validé pour son intérêt agronomique, la conduite centrifuge, par rapport à la conduite classique en Solaxe. L'étude d'une formation arbustive expérimentale (haie de bordure) conçue pour optimiser la protection du verger de poiriers a par ailleurs permis de valider les principes de base d'une introduction raisonnée de diversité végétale dans l'environnement du verger : existence d'une succession de ressources pour les auxiliaires actifs sur le(s) ravageur(s)-clé(s) de la culture, innocuité pour les cultures (absence de ravageurs ou maladies communs avec les cultures). Ces travaux et d'autres études suggèrent que la manipulation de l'environnement végétal du verger modifie l'entomocénose. En revanche, le bénéfice potentiel en verger se limite au contrôle des ravageurs tolérés à des niveaux de pollution élevés. | The control of pests in organic orchards cannot solely rely on the use of direct control methods. The effects of manipulating the habitat of orchard pests and natural enemies through the architecture and the increase of plant diversity has been investigated in an experimental organic apple orchard and in a pear orchard, in order to provide information about the potential benefits of these cultural practices. Tree training affected the development of the most detrimental pests of apple trees, and the centrifugal training system globally provided better aphid (Dysaphis plantaginea) and mite (Panonychus ulmi) control than the more classical Solaxe system, whereas codling moth (Cydia pomonella) was favoured compared to Solaxe. The study of an experimental hedgerow designed to optimise protection of the pear orchard allowed us to validate the basic principles of designing plant assemblages to increase plant diversity in the orchard surroundings, namely the introduction of a succession of resources favouring the natural enemies of the key orchard pests, and to avoid detrimental effects (pests or diseases shared with the crops). This experiment and other studies suggest that manipulating the plant diversity adjacent to the orchard has an effect on entomocenosis. However, the potential benefits for the orchard only concern the control of pests that can be tolerated at high infestation rates.

Dans le contexte actuel de diversification des systèmes agricoles, l’Agriculture Biologique (AB) est souvent réduite à une voie de diversification parmi d’autres, ou à un prototype innovant d’agriculture. Or, des observations, enquêtes et expérimentations menées dans le cadre de recherches participatives, fondent la nécessité de considérer l’AB comme plurielle. Inspirés des travaux de Sylvander et al. (2006), cette pluralité peut être illustrée à travers 4 modèles d’agriculture, définis selon un axe socioéconomique opposant les logiques individuelles à une gouvernance collective, et un axe agroécologique distinguant approches analytiques et systémiques. La considération de cette pluralité modifie-t-elle la manière d’envisager les innovations variétales, l’amélioration des plantes et de penser la construction des marchés ? Interrogés, des chercheurs en génétique, agronomie, biométrie,s ociologie et anthropologie répondent par l’affirmative en différenciant les 4 modèles d’agriculture par (i)la relation au marché (de l’adaptation à la co-construction) (ii) les variétés recherchées : de la ressource patrimoniale jusqu’à la variété multi-fonctionnelle démontrant un progrès technique, éthique et social, (iii)les objectifs : simple progrès génétique ou renforcement du rôle des agriculteurs, (iv) les acteurs de la sélection : de l’agriculteur aux grandes firmes semencières, (v) la perception de l’environnement : du simple milieu biophysique à l’intégration de composantes socio-économiques | Diversity of organic farming systems: Challenges for the construction of markets, varieties and plant breeding techniques New societal values call for the diversification of agriculture to fit contrasted environments. This process can be depicted by four models defined by two axes, a socio-economic axis (individual logic vs. collective governance), and an agro-ecological axis (analytical vs. systemic approaches). These models differ in: (i) their objectives (from improvement in yield to the empowerment of farmers), (ii) their specific expectations with respect to genotypes (from inherited genetic resources to varieties that represent genetic, ethical and social progress), and (iii) their representations of the environment (from a simple interaction between the bio-physical environment and crop management, to a complex interaction including the skills of stakeholders, outlets, regulations and society). Taking this diversity into account changes the way plant improvement is envisioned. Depending on the model, the five classic stages of plant improvement (setting objectives, creating variability, selecting, evaluating and disseminating) may be called into question. Between the existing analytical model (model I) and a holistic model (model IV) that remains to be developed, lies the challenge of ensuring the sustainability, efficiency and acceptability of plant breeding and resulting innovations

Dans le contexte actuel de diversification des systèmes agricoles, l’Agriculture Biologique (AB) est souvent réduite à une voie de diversification parmi d’autres, ou à un prototype innovant d’agriculture. Or, des observations, enquêtes et expérimentations menées dans le cadre de recherches participatives, fondent la nécessité de considérer l’AB comme plurielle. Inspirés des travaux de Sylvander et al. (2006), cette pluralité peut être illustrée à travers 4 modèles d’agriculture, définis selon un axe socioéconomique opposant les logiques individuelles à une gouvernance collective, et un axe agroécologique distinguant approches analytiques et systémiques. La considération de cette pluralité modifie-t-elle la manière d’envisager les innovations variétales, l’amélioration des plantes et de penser la construction des marchés ? Interrogés, des chercheurs en génétique, agronomie, biométrie,s ociologie et anthropologie répondent par l’affirmative en différenciant les 4 modèles d’agriculture par (i)la relation au marché (de l’adaptation à la co-construction) (ii) les variétés recherchées : de la ressource patrimoniale jusqu’à la variété multi-fonctionnelle démontrant un progrès technique, éthique et social, (iii)les objectifs : simple progrès génétique ou renforcement du rôle des agriculteurs, (iv) les acteurs de la sélection : de l’agriculteur aux grandes firmes semencières, (v) la perception de l’environnement : du simple milieu biophysique à l’intégration de composantes socio-économiques | Diversity of organic farming systems: Challenges for the construction of markets, varieties and plant breeding techniques New societal values call for the diversification of agriculture to fit contrasted environments. This process can be depicted by four models defined by two axes, a socio-economic axis (individual logic vs. collective governance), and an agro-ecological axis (analytical vs. systemic approaches). These models differ in: (i) their objectives (from improvement in yield to the empowerment of farmers), (ii) their specific expectations with respect to genotypes (from inherited genetic resources to varieties that represent genetic, ethical and social progress), and (iii) their representations of the environment (from a simple interaction between the bio-physical environment and crop management, to a complex interaction including the skills of stakeholders, outlets, regulations and society). Taking this diversity into account changes the way plant improvement is envisioned. Depending on the model, the five classic stages of plant improvement (setting objectives, creating variability, selecting, evaluating and disseminating) may be called into question. Between the existing analytical model (model I) and a holistic model (model IV) that remains to be developed, lies the challenge of ensuring the sustainability, efficiency and acceptability of plant breeding and resulting innovations

Nitrogen (N) is an essential plant nutrient at the centre of plant metabolism being present in numerous vital organic compounds including amino acids, proteins, nucleic acids and phytohormones. In highly fertile arable soils supplied with N fertilisers, NO3 - and NH4 + ions are usually considered to be the main N forms in soil solution taken up by crop plants, the ratio of NO3-N to NH4-N often being in the order of 10-20:1. Soluble organic N is receiving increasing attention. The form of N uptake modifies rhizosphere pH which affects uptake of other soil nutrients. Acquisition of the various N forms is regulated not only by their chemical and spatial availability in the soil, but also by transport systems in the plasma membrane of root cells, root system architecture and mechanisms that regulate the activity of N transport systems and root growth, depending on plant requirements. In most fertile soils well supplied with mineral nutrients, neither N transport from the bulk soil to crop roots nor the efficient processes of NO3 - and NH4 + ion uptake by roots limit N acquisition. Uptake of N is regulated by N demand in which shoot-root interactions play an important role. Nitrate acts as a signal for metabolism and plant development which is associated with cytokinin transport. The biochemistry of N assimilation is well understood but control at molecular level much less so. Nitrogen status of plants can be characterised by the concept of critical N concentration (Nc) in relation to the long-term fall in N concentration in the dry matter as plants age. Nc represents the optimum for growth for a given crop and can be related to actual crop N concentration. Fertilisation is needed when [N] / [Nc], i.e. NNI (nitrogen nutritional index) < 1. By determining N status during crop growth, fertilisation can be carried out more efficiently as exemplified in melon cultivation. Examples are presented to demonstrate practical effects of different N forms including NO3-, NH4- and urea-N. These examples include the value of placed stabilised NH4- N in depressing rhizosphere pH on high-pH soils to increase the availability and uptake of sparingly soluble phosphate and micronutrients iron, manganese, copper, zinc and boron. These latter nutrients play a vital role, protecting plants against both biotic and abiotic stresses. The acidifying effect in the rhizosphere of symbiotically grown legumes can be of similar benefit on high pH soils. The use of NH4-N fertilisers to depress rhizosphere pH which is also associated with increased Si and Mn uptake is regularly practiced to control some plant diseases such as mildew and take-all in wheat. Water use efficiency (WUE) also relates to the form of N supply. Foliar application of urea is discussed. Signaling effects of stabilised N forms can be used to influence tiller number and yield components in wheat and barley crops. The use of NH4-N in restricting lateral shoot development in tomato production is discussed

International audience | Nitrogen (N) is an essential plant nutrient at the centre of plant metabolism being present in numerous vital organic compounds including amino acids, proteins, nucleic acids and phytohormones. In highly fertile arable soils supplied with N fertilisers, NO3 - and NH4 + ions are usually considered to be the main N forms in soil solution taken up by crop plants, the ratio of NO3-N to NH4-N often being in the order of 10-20:1. Soluble organic N is receiving increasing attention. The form of N uptake modifies rhizosphere pH which affects uptake of other soil nutrients. Acquisition of the various N forms is regulated not only by their chemical and spatial availability in the soil, but also by transport systems in the plasma membrane of root cells, root system architecture and mechanisms that regulate the activity of N transport systems and root growth, depending on plant requirements. In most fertile soils well supplied with mineral nutrients, neither N transport from the bulk soil to crop roots nor the efficient processes of NO3 - and NH4 + ion uptake by roots limit N acquisition. Uptake of N is regulated by N demand in which shoot-root interactions play an important role. Nitrate acts as a signal for metabolism and plant development which is associated with cytokinin transport. The biochemistry of N assimilation is well understood but control at molecular level much less so. Nitrogen status of plants can be characterised by the concept of critical N concentration (Nc) in relation to the long-term fall in N concentration in the dry matter as plants age. Nc represents the optimum for growth for a given crop and can be related to actual crop N concentration. Fertilisation is needed when [N] / [Nc], i.e. NNI (nitrogen nutritional index) < 1. By determining N status during crop growth, fertilisation can be carried out more efficiently as exemplified in melon cultivation. Examples are presented to demonstrate practical effects of different N forms including NO3-, NH4- and urea-N. These examples include the value of placed stabilised NH4- N in depressing rhizosphere pH on high-pH soils to increase the availability and uptake of sparingly soluble phosphate and micronutrients iron, manganese, copper, zinc and boron. These latter nutrients play a vital role, protecting plants against both biotic and abiotic stresses. The acidifying effect in the rhizosphere of symbiotically grown legumes can be of similar benefit on high pH soils. The use of NH4-N fertilisers to depress rhizosphere pH which is also associated with increased Si and Mn uptake is regularly practiced to control some plant diseases such as mildew and take-all in wheat. Water use efficiency (WUE) also relates to the form of N supply. Foliar application of urea is discussed. Signaling effects of stabilised N forms can be used to influence tiller number and yield components in wheat and barley crops. The use of NH4-N in restricting lateral shoot development in tomato production is discussed

By combining cultivation, harvesting and conservation practices, the farmers are able to find the best compromise between the amount of herbage harvested and its feeding value. Present environmental requirements however do question a certain number of the practices that had made possible the intensification of the forage production. This paper is the synthesis of the present knowledge acquired by INRA on the feeding value of the forages and of its variation with the cultivation, harvesting and conservation practices. The recently completed INRA Tables supply values for the chemical composition, nutritive value, intake and mineral contents of a great diversity of forages and situations. These reference values make it possible to estimate the value of a forage and this can be made more accurate by the use of forecast tools when a chemical analysis is available. These data are essential for determining the diets of the animals and for analysing the forage systems. In the future, these tables should be complemented by data on the forecast of intake and digestion flows, and by other values characterizing the interest of the forages for the production of high-quality animal products.

By combining cultivation, harvesting and conservation practices, the farmers are able to find the best compromise between the amount of herbage harvested and its feeding value. Present environmental requirements however do question a certain number of the practices that had made possible the intensification of the forage production. This paper is the synthesis of the present knowledge acquired by INRA on the feeding value of the forages and of its variation with the cultivation, harvesting and conservation practices. The recently completed INRA Tables supply values for the chemical composition, nutritive value, intake and mineral contents of a great diversity of forages and situations. These reference values make it possible to estimate the value of a forage and this can be made more accurate by the use of forecast tools when a chemical analysis is available. These data are essential for determining the diets of the animals and for analysing the forage systems. In the future, these tables should be complemented by data on the forecast of intake and digestion flows, and by other values characterizing the interest of the forages for the production of high-quality animal products.

Designing innovative combinations of techniques to improve the sustainability of cropping systems in poor countries is a major challenge. Here, we developed a prototyping methodology to design, assess and adapt a crop management system for a specific set of constraints. It was applied in Mali with the aim of designing innovative prototypes of cotton management systems to be further tested and adapted by farmers. The prototype aimed at shortening the cotton cycle to overlap the rainy season. The prototype is particularly suited for late sowing and for regions where rainfall is often insufficient. We propose a conceptual model that organizes technical interventions to shorten the cotton cycle. We developed a set of indicators to evaluate the relevance of each modified technical intervention, by comparison with current farmer practices. We evaluated the overall performances of the prototype by taking into account economic, environmental and social factors. The prototype was tested and adjusted in six trials between 2002 and 2004. Our results show that the cotton growth cycle was reduced by 15 days on average, mainly through the shortening of the flowering period. The combination of much higher stand density than currently applied in the region and application of the growth regulator mepiquat chloride produced a much higher number of bolls per hectare of +69%. The prototype produced higher seed-cotton yields, of +44% on average, and much higher gross margin than the standard cotton management system. The method was therefore successful in designing a new cotton management system that helps farmers to adapt to diverse cropping conditions

Designing innovative combinations of techniques to improve the sustainability of cropping systems in poor countries is a major challenge. Here, we developed a prototyping methodology to design, assess and adapt a crop management system for a specific set of constraints. It was applied in Mali with the aim of designing innovative prototypes of cotton management systems to be further tested and adapted by farmers. The prototype aimed at shortening the cotton cycle to overlap the rainy season. The prototype is particularly suited for late sowing and for regions where rainfall is often insufficient. We propose a conceptual model that organizes technical interventions to shorten the cotton cycle. We developed a set of indicators to evaluate the relevance of each modified technical intervention, by comparison with current farmer practices. We evaluated the overall performances of the prototype by taking into account economic, environmental and social factors. The prototype was tested and adjusted in six trials between 2002 and 2004. Our results show that the cotton growth cycle was reduced by 15 days on average, mainly through the shortening of the flowering period. The combination of much higher stand density than currently applied in the region and application of the growth regulator mepiquat chloride produced a much higher number of bolls per hectare of +69%. The prototype produced higher seed-cotton yields, of +44% on average, and much higher gross margin than the standard cotton management system. The method was therefore successful in designing a new cotton management system that helps farmers to adapt to diverse cropping conditions

– The ripening of industrial soft cheeses manufactured using a liquid pre-cheese produced from the ultrafiltration (UF) of milk was observed to be slow in comparison to that of cheese manufactured by a traditional process. Moreover, in the UF-cheeses investigated in this study, which were produced using Penicillium camemberti as the surface flora, several surface defects were observed: the texture was ‘carton’ like and the rind frequently detached from the cheese. To gain a fuller understanding of the development of these surface defects in UF-cheeses, the migration of different minerals and ions, and the study of the rind microstructure by scanning electron microscopy and X-ray mapping were performed. The results suggest that the slower diffusion of lactate, possibly due to the mineral layer at the surface of cheeses, acting as a barrier to its diffusion, may have caused an alteration in the metabolism and growth of the surface mould andmay explain the surface defects of these UF-cheeses.

– The ripening of industrial soft cheeses manufactured using a liquid pre-cheese produced from the ultrafiltration (UF) of milk was observed to be slow in comparison to that of cheese manufactured by a traditional process. Moreover, in the UF-cheeses investigated in this study, which were produced using Penicillium camemberti as the surface flora, several surface defects were observed: the texture was ‘carton’ like and the rind frequently detached from the cheese. To gain a fuller understanding of the development of these surface defects in UF-cheeses, the migration of different minerals and ions, and the study of the rind microstructure by scanning electron microscopy and X-ray mapping were performed. The results suggest that the slower diffusion of lactate, possibly due to the mineral layer at the surface of cheeses, acting as a barrier to its diffusion, may have caused an alteration in the metabolism and growth of the surface mould andmay explain the surface defects of these UF-cheeses.

International audience