La multiplication du fraisier à l'île de la Réunion. Première partie : Acclimatation de jeunes plants de fraisiers issus de micropropagation

Un des principaux objectifs du programme de recherche sur fraisier, engagé à l'île de la Réunion par l'IRFA en 1985, est la production locale de plants. L'IRFA a adapté aux conditions locales, la méthode appliquée en métropole pour acclimater les jeunes plants de fraisier issus de culture in vitro. A cette première partie, traitant de l'acclimatation de jeunes plants, en succèdera une seconde sur la multiplication en pépinière. (Résumé d'auteur

La multiplication du fraisier à l'île de la Réunion. Deuxième partie : la multiplication de plants en pépinière

La station IRFA de l'île de la Réunion a débuté en 1985 un programmme de recherche dont l'objectif essentiel était la production locale de plants de fraisier. L'IRFA est aujourd'hui à même de proposer un intinéraire technique fiable, adapté aux conditions climatiques de l'île, permettant de produire du plant de fraisier de bonne qualité et en quantité suffisante. (Résumé d'auteur

Coût de production de la fraise à l'île de la Réunion

L'inventaire de tous les postes de dépenses a été établi, en s'appuyant sur les techniques culturales préconisées par l'IRFA, et chacun d'entre eux évalué. Le coût de production en 1990 d'un kilogramme de fraises à la Réunion passe de 18,68 à 11,14 F pour des rendements bruts allant de 500 à 900 g/plant, dont environ 70 p. 100 commercialisables, et des vitesses de récolte, variant entre 6 et 10 kg/heure par cueilleur. Ce document a pour objectif d'aider le fraisiculteur à définir le prix de revient de sa production et à mieux prévoir les besoins en trésorerie de son exploitation. Le calcul des coûts est réalisé à partir de données chiffrées et de techniques culturales datant de 1990. (Résumé d'auteur

Contribution of formal modelling and field experiment to leverage knowledge and expertise for designing crop protection guidelines

International audiencePesticide use is still much too often systematic on many crops. However, there is scientific consensus that many farmers could change their crop protection practices without putting their revenue in jeopardy. There is need for crop protection management systems that yield significantly lower pesticide consumption. For many crops such management systems are not available, although knowledge about the pathosystems exists. We present here two crop protection formal guidelines (Decision Workflow Systems, DeWS) which were elicited and formalised using the Statechart (Grape-MilDeWS) and the coloured Petri nets (POD BLé) modelling languages. Elicitation and formal model-ling helped the pathologists to ameliorate their design and provided a convenient computer ready format. Moreover, the main purpose of DeWS models is to provide an exhaustive specification, which can then be transferred. This permits large experimental networks to be created. Such networks are necessary to collect data about the behaviour of the pathosystem under low input management and to assess the DeWS robustness and efficiency. Finally DeWS are learning tools for the growers, development workers and for its original designers as well

Towards a global characterization of winter wheat cultivars behavior in response to stressful environments during grain-filling

International audienceStarting from grain yield, quality and resistance against multiple diseases, the characterization of the cultivar’s behavior increased in recent decades. Needs in quantitative assessments of a larger range of criteria has greatly evolved towards yield stability in a large range of fluctuating environments. Using a large dataset crossing cultivars and environments, we thus explored the relationships between yield and Healthy Area Duration (HAD), as affected by genotype, environment and septoria caused by Zygmoseptoria tritici. A set of indexes was then proposed to properly profile cultivar’s behavior. A curvilinear relationship relating HAD to potential yield was first parameterized. It allows quantifying HAD efficiency. Susceptibility (HAD loss) was differentiated from total tolerance (the ratio between yield loss and HAD loss). Finally the specific tolerance, i.e. not due to HAD level, was quantified. Correlations between indexes pointed out that no trade-off was shown between total tolerance and actual or potential yield as well as disease susceptibility. These correlations partially depended on the nitrogen status of crops, underlining other G×E interactions indexes may trap. Finally, as HAD efficiency appeared more highly linked to actual yield than potential yield we proposed an alternative set on indexes based on Healthy Area Absorption (HAA) that accounted for meteorological variability. Interestingly, these last indexes were insensitive to nitrogen nutrition as well as to cultivar susceptibility to Z. tritici. The developed indexes allowed profiling the cultivars’ behavior under a common range of environments. HAA-based indexes open the way to a useful global characterization of cultivars by breeders. Moreover, HAA can be assessed using high-throughput phenotyping tools. A thorough evaluation of this last point needs to be done

Effets comparés d'un régime enrichi en yoghourt vivant ou thermisé sur le système immunitaire de la souris

International audienc