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We consider a modified nonlocal FKPP equation to describe the spatial organization of a single-species population in a refuge (high-quality region immersed in a hostile environment). In addition to the spatial-dependence of the growth rate, which is the main distinguishing feature of a refuge, it is realistic to consider that also the mobility can be heterogeneous. We focus on two cases where the diffusivity responds to the population density, either decreasing or increasing with population density. This state dependency can produce a feedback that is missing in homogeneous environments. For comparison, we also address space-dependent diffusivity with different values inside and outside the refuge. The objective is to characterize how the diffusion variability affects the spatial organization of the population inside and outside the refuge. We note that the conditions for pattern formation within the refuge are not strongly affected by the heterogeneity in the diffusivity profile, but this affects the shape and stability of the patterns., 8 pages, 9 figures

Practical courses focused on forage systems must navigate a key challenge: teaching material that is multidisciplinary and complex. To help with this challenge, an educational activity was designed in which a serious game, Rami fourrager, was used to teach future engineers about forage systems. Hem, we studied the activity's utility. Students were separated into groups of 4-5. Half the groups were assigned one type of farm, and the other half were assigned a different type of farm. The farm types had contrasting forage systems. The activity was led by two instructors in the agricultural sciences and animal husbandry. It aimed to teach students about designing optimal forage systems over the crop year (e.g., forage estimates and fluctuation) and over the long term (e.g., anticipating climatic variability). We found that Rami fourrager(C) can help students better understand forage system management and diversity. It teaches multidisciplinary concepts in an entertaining way using the project approach, peer learning, and critical analysis.

To improve fruit color features research has focused on the use of foliar nutrition with zinc. There is a lack of know about apples. The aim of this trial was to evaluate the effects of foliar zinc treatment on the qualitative characteristics of ‘Gala’ apple. Apple trees Cv ‘Gala’ were submitted to a foliar spray application of Zn in the form of aqueous solution of 0.2% and 0.4% zinc sulfate (ZnSO4) for three times. Fruit was harvested at commercial ripening and physicochemical parameters, yield, crop load, yield effi ciency and zinc leaf content were measured. Results revealed that yield, crop load, fruit weight, cover color index and cover color percentage of the observed trees was infl uenced by zinc foliar spray treatment in each harvest date. The foliar fertilization using zinc infl uenced yield and several fruit quality traits. Since the ZN1 and ZN2 treatments do not differ signifi cantly in the effect, the choice may lie in the adoption of the fi rst treatment as it yields more economic and sustainable outcomes.

Les associations végétales, par la complexité du couvert végétal qu’elles créent, sont le siège d’interactions biotiques particulières avec les ravageurs, les prédateurs, les champignons pathogènes, les adventices ou encore les organismes non pathogènes du sol. Cet article traite de la diversité des mécanismes en jeu (modification de paramètres tels que la disponibilité, la compétition et la complémentarité temporelle et spatiale pour les ressources, le microclimat, les stimuli variés, l’allélopathie) permettant de mieux comprendre leurs effets potentiels sur ces interactions pour diverses combinaisons d’espèces. De nombreux exemples mettent en avant l’intérêt des associations végétales pour lutter contre les bioagresseurs. Par ailleurs de nouveaux mécanismes sont aujourd’hui explorés notamment au niveau de la biologie des sols, qui semblent avoir un effet important sur le fonctionnement des associations végétales. Cependant, même si les travaux de recherche se développent sur l’analyse des facteurs biotiques pour une diversité de combinaisons d’espèces, ils restent encore rares en France et doivent se poursuivre tout en s’appuyant sur les observations (réussites et échecs) des agriculteurs et sur plusieurs essais en conditions agricoles avant leur déploiement pour un objectif donné bien identifié., Several particular biotic interactions including pests, predators, pathogens, weeds and non-pathogenic soil organisms occur in intercropping systems due to the diversity of the canopy. This paper deals with the range of mechanisms (modification of different parameters such as availability of resources, competition and temporal and spatial complementarity for resources, microclimate, various stimuli, allelopathy) involved in order to better understand the potential effects in various intercropping systems. Several examples illustrate the positive effects of intercropping on pests, diseases and weeds. Moreover new mechanisms including soil organisms have also been recently investigated and may have major effects on the functioning of intercrops. There is an increase in published papers recently concerning biotic factors for a wide range of intercropping systems. However studies remain scarce in France and should be further developed while involving farmers (observations of success and failures) and testing new practices in agricultural conditions before their implementation for a well-defined objective.

The purpose of the present work was to investigate the in vivo concentrations of sorbic acid and vanillin as markers of the fate of organic acids (OA) and natural identical flavors (NIF) from a microencapsulated mixture and from the same mixture non-microencapsulated, and the possible consequences on the intestinal microbial fermentation. Fifteen weaned pigs were selected from 3 dietary groups and were slaughtered at 29.5 +/- 0.27 kg of BW. Diets were (1) control; (2) control supplemented with a blend of OA and NIF microencapsulated with hydrogenated vegetable lipids (protected blend, PB); and (3) control supplemented with the same blend of OA and NIF mixed with the same protective matrix in powdered form but without the active ingredient coating (non-protected blend, NPB). Stomach, cranial jejunum, caudal jejunum, ileum, cecum, and colon were sampled to determine the concentrations of sorbic acid and vanillin contained in the blend and used as tracers. Sorbic acid and vanillin were not detectable in pigs fed the control, and their concentrations were not different in the stomach of PB and NPB treatments. Pigs fed PB showed a gradual decrease of the tracer concentrations along the intestinal tract, whereas pigs fed NPB showed a decline of tracer concentration in the cranial jejunum and onwards, compared with the stomach concentrations. Sorbic acid and vanillin concentrations along the intestinal tract were greater (P = 0.02) in pigs fed PB compared with pigs fed NPB. Pigs fed PB had lower (P = 0.03) coliforms in the caudal jejunum and the cecum than pigs fed the control or NPB. Pigs fed the control or PB had a greater (P = 0.03) lactic acid bacteria plate count in the cecum than pigs fed NPB, which showed a reduction (P = 0.02) of lactic acid concentrations and greater (P = 0.02) pH values in the caudal jejunum. The protective lipid matrix used for microencapsulation of the OA and NIF blend allowed slow-release of both active ingredients and prevented the immediate disappearance of such compounds upon exiting the stomach.

How to combine N supply and biological control in low input systems; How to combine N supply and biological control in low input systems

Fumonisins are mycotoxins found primarily in corn and corn products and are produced by Fusarium verticillioides, F. proliferatum and several other Fusarium species. The toxicity of fumonisin B1 (FB) from culture material with and without activated carbon was evaluated using weaned piglets. Fifty-six weanling pigs were assigned to one of four treatments diets based on weight. The treatment diets were: 1) corn-soybean basal diet with < 2 ppm FB (control), 2) control + activated carbon at 1% of the diet (AC), 3) control + culture material supplying 30 ppm FB (FB), and 4) control + activated carbon at 1% of the diet + culture material supplying 30 ppm FB (AC + FB). A total of 4 replicates of 3 pigs/pen for treatments 3, and 4, and 4 piglets/pen for treatments 1, and 2 were utilized. Feed and water was offered ad libitum for the duration of the experiment (42 days). Compared to pigs fed the control diets (control or AC), pigs receiving FB contaminated diets (FB or AC + FB) had a significantly lower feed efficiency (gain/feed), significantly higher serum concentrations of g-glutamyltransferase (GGT) and glutamic oxaloacetic transaminase (GOT), cholesterol, free sphinganine, sphingosine-1-phosphate and sphinganine 1-phosphate. Although animals consuming FB diets showed no signs of respiratory distress all pigs consuming either the FB or the AC + FB diets had marked pulmonary edema. Significant lesions were observed in the lungs, heart and liver of pigs fed the FB or AC + FB diets and treatment associated changes were also seen in pancreas, intestines, spleen and lymph nodes. No lesions were observed in brain. In liver, lung, heart, pancreas, spleen, intestines and lymph nodes, the histopathological effects were more severe in the AC + FB group suggesting that the AC treatment worsened the toxic effects of FB. Additionally, immunological parameters of macrophage function (CD14) were significantly affected by the consumption of the FB diets. The consumption of FB diets containing 30 ppm FB1, from cultured material, significantly affected performance, biochemical parameters, and organ pathology in post-weaned piglets. The addition of activated carbon added at 1% of the diet was not effective in protecting, against the detrimental effects of fumonisin consumption

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Annexes*INRA Unité Agronomie de Toulouse Diffusion du document : INRA Unité Agronomie de Toulouse Diplôme : Dr. Ing.

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