Portail Hal-l'Institut Agro Rennes-Angers
Not a member yet
9270 research outputs found
Sort by
Peat shrinkage during drying according to particle size
No full textInternational audienceAn expanded description of particle morphology and the analysis of its relationships with physical properties may help to optimize the selection of raw materials and particle size fractions used as growing media constituents. Previous works have described the outlines of these relations based mostly on sieving procedures to characterize particle size distribution. They have shown limited and sometimes contradictory results due to the different methods used, size fractions selected, and physical properties measured. Also, sieve analysis, which separates particles based on their width, is less accurate for non‐spherical particles, which is the case for most growing media constituents. Recent works have promoted the use of dynamic image analysis (DIA) to precisely analyze both particle length and width. Five raw materials were chosen (white and black peats, coir, pine bark, and wood fiber) and sieved to obtain various particle size fractions. For each particle size fraction and the raw materials, the mean weight diameter (MWD), derived from sieving, was calculated, whereas mean particle length and width were determined using a DIA tool, the QicPic device. Also, physical properties were assessed from water retention curves established using Hyprop systems. The statement that the larger the particle size, the higher the air‐filled porosity (AFP), the lower the water holding capacity (WHC) was more precisely redefined. Large variations in WHC and AFP mainly occurred for finest particle size fractions, whereas changes were conversely very small or non‐existent for larger particle sizes. From data obtained for each particle size fractions, regression models were established to relate mean particle length and width (both determined using DIA) and MWD (determined from sieving) with WHC and AFP. Mean particle length was identified as the most relevant parameter for predicting WHC and AFP of the raw materials tested
Dynamic in vitro gastric digestion of skimmed milk using the NERDT, an advanced human biomimetic digestion system
No full textInternational audienceThe main objective of this study was to assess the ability of the NEar Real Digestive Tract (NERDT), a computer controlled biomimetic in vitro digestion system that considers the biomechanics of the stomach, to reproduce physiologically relevant features of skimmed milk gastric digestion. A second objective was to evaluate the influence of pepsin on the gastric coagulation and emptying of milk proteins from experiments performed with and without pepsin. A mass balance model over the stomach, assuming a perfectly stirred reactor behaviour, has been developed. The results show that the NERDT can adequately reproduce the targeted kinetics of gastric acidification and emptying, with a sieving effect that naturally leads to a delayed emptying of caseins. Milk coagulated earlier and more chyme was emptied towards the end of the experiments in the presence of pepsin than without, hence illustrating the key influence of pepsin on the gastric coagulation of caseins and subsequent hydrolysis and emptying of dairy particles. Overall, this study shows that the NERDT can be adequately controlled to achieve desired gastric digestion conditions, and appears to be a very useful tool to further improve the knowledge of the gastric digestion behaviour of complex foods such as milk.
Positive influence of apple trees on soil chemical and biological activities in agroecological garden orchard system
No full textInternational audienceThe aim of this study was to assess the impact of 20-year-old apple trees on the soil quality in an agroforestry system consisting of 2 rows of apple trees with 5 rows of vegetable beds in between. Measurements were carried out for 2 years, from 2019 to 2021, in apple tree rows (R) and in vegetable beds at 1.5 m (B1), 3 m (B2) and 5 m (C) from the apple tree row. Litter quantities and soil organic matter (SOM) content were measured as well as the decomposition rates of apple tree leaf litter. Soil microbial activity was characterized by measuring (1) in-situ soil respiration and (2) basal (BR) and substrate induced respiration (SIR) under controlled conditions. The results showed that proximity to apple trees was linked to higher SOM content. The litter decomposition rate was up to 1.7 times greater under the tree rows than in vegetable beds. The amplitude of in-situ soil CO2 flux variation and the maximum flux were lower under the tree rows than in vegetable beds, mainly due to lower temperature. Under controlled laboratory conditions, we showed that BR was significantly higher in R, B1 and B2 than in C (5, 5, 4.7 and 3.5 mu gC-CO2.h-1.g-1 soil DW, respectively). In addition, the soil in the apple tree rows was more sensitive to the addition of glucose (SIR) than the soil in the vegetable beds. Our results suggest that soil microbial activity was more intensive up to 3 m from the apple trees
Evolution of benthodemersal fish communities in a changing European estuary at fine and broad temporal scales
No full textInternational audienceAs locations where two distinct bodies of water naturally mix, estuaries are characterized by a variable environment with numerous abiotic gradients at multiple temporal scales (McLusky, 1993). The preponderant salinity gradient is invariably found across estuarine ecosystems worldwide; salinity typically increases from catchment fresh water to oceanic salt water but can fluctuate significantly depending on river discharge and tides (Telesh and Khlebovich, 2010). The suspended-matter gradient peaks in a zone of maximum turbidity that is enriched in organic matter (Mitchell, 2013; McLusky and Elliott, 2004), in which heat-catalyzed biochemical processes involving bacterial mineralization deplete concentrations of dissolved oxygen (DO) in water and induce hypoxic conditions (Riemann et al., 2016). Estuarine organisms—from microalgae to fish predators—are distributed according to their tolerance along these abiotic gradients, with each species occurring in the range of environmental conditions it can withstand (Kinne, 1964). Within these ranges, species have evolved physiological adaptations, such as mucus exudation, or behavioral adaptations through, e.g., a risk avoidance strategy (Ordóñez-Grande et al., 2021; Eby and Crowder, 2002). The need for such adaptations naturally restrains the quantity of taxa present within the estuarine range compared to neighboring ocean and river ecosystems (Whitfield et al., 2012)
Towards pesticide-free agriculture. Research and innovations in a future crop protection paradigm
No full textInternational audienceThe use of chemical pesticides is a major societal concern due to their negative impact on the environment and health. The French Priority Research Programme "Growing and Protecting Crops Differently", led by INRAE, has a structuring role in the evolution of scientific communities and in the emergence of scientific fronts enabling pesticide-free crop protection. The aim of this book is to explain the foundations of this strategy and the principles for action. On a course to pesticide-free agriculture, research is attempting to overcome current obstacles and produce breakthrough innovations in the biotechnical and socio-economic fields.In addition to research, teaching and the agricultural sector, this book also targets actors in innovation, development and advisory services
Botanique Historique : entre sauvage et cultivé ; entre systématique, dénomination et transmission
No full textCe travail présente les travaux que j’ai menés, seul ou en collaboration, depuis plus de 20 ans de participation à la recherche, ainsi que les projets qui en découlent. Ces travaux, menés et projetés, se focalisent sur l’histoire et la systématique des végétaux, en particulier des Angiospermes (plantes à fleurs) sauvages ou cultivées, qu’il s’agisse de la reconstruction de cette histoire à l’échelle interspécifique (reconstruction de phylogénie), ou intra-spécifique (histoire de la sélection et généalogie entre individus). Les activités de systématique végétale mises en oeuvre se déclinent selon les trois axes décrire-classer-nommer, qui sont confortés par des activités concernant l’histoire de la construction de ces savoirs, l’histoire des individus ayant produit ces savoirs et la transmission de ces connaissances.Au sein de l’UMR GenHort puis de l’UMR IRHS j’ai développé des activités qui peuvent de répartir selon quatre axes : 1) La description et l’histoire des végétaux ; 2) l’étude du contexte historique de la découverte, de la description et de la classification des végétaux ; 3) l’expertise nomenclaturale et 4) la transmission des savoirs sur les végétaux. Mon projet de recherche vise à poursuivre ces activités et traite, globalement, de la systématique des végétaux cultivés et sélectionnés, au travers de cinq directions complémentaires et de volumes variables. Il s’agit en particulier de proposer des systèmes taxonomiques cohérents pour la diversité sauvage et cultivée, de réviser et donc de proposer des classifications cohérentes pour le genre Rosa, mais aussi et de manière moindre, de participer à la mise en cohérence de référentiels nomenclaturaux et taxonomiques, en particulier en ce qui concerne les noms des taxons cultivés, de participer à la réflexion sur l’identité des plantes autochtones depuis les populations « indigènes », jusqu’à celles qui sont en culture et aux populations qui se naturalisent, et enfin, de transmettre des connaissances sur les végétaux
Whole genome sequencing and epigenotyping for multiple generations of selection using Oxford Nanopore Technology
No full textInternational audienc
Does the chemical composition of organic waste products applied on soil impact the dissolved organic carbon concentration along the soil profile ?
No full textInternational audienceOrganic waste products (OWP) application and cover crops are agronomic levers to improve soil health. OWP can be valorized by anaerobic digestion to produce biogas. The chemical composition of digestate differs from that of its source material. Labile fraction being partly consumed by microorganisms, recalcitrant molecules accumulate in digestate. Studies on transfer of DOM (dissolved organic matter) towards the subsoil in soil receiving digestate are scarce. In a previous lysimeter study over 9 years, higher topsoil-DOC (dissolved organic carbon) concentrations underdigestate were observed every year compared to its original slurry and associated with different winter crops, probably in relation to the root development of the crop. The extra-DOC could come from a higher production of root exudates due to a potential auxin effect of the digestate and/or a solubilization of the recalcitrant organic matter from digestate via the alkalinization of rhizosphere. To check this hypothesis, the evolution of DOM chemical composition after digestate application (i) associated with different winter crops, (ii) during the drainage season and (iii) between the topsoil and the subsoil was studied. Lysimeters at 40 cm (topsoil) and 90 cm (subsoil) depths were monitored in 2018-2019 (wheat) and 2020-2021 (mustard), from November to March under pig slurry (PS) and digestate from PS (PS-DIG). The DOM composition of lysimeters samples and water extracts from PS and PS-DIG (WEOM) were analyzed by thermochemolysis coupled to gas chromatography and massspectrometry (THM-GC–MS). A higher proportion in phenols and dicarboxylic acids was measured in WEOM from PS-DIG compared to PS. Under mustard, the DOM composition of the PS-DIG modality at the beginning of the drainage season was close to the one of WEOM of PS-DIG. Under wheat, the DOM composition of the PS-DIG modality in the middle of the drainage season seemed only partly influenced by the PS-DIG application, with a higher proportion of dicarboxylic acids but no difference in phenols proportion compared to PS. Keywords: digestate, DOM, chemical composition, THM-GC-MS, recalcitranc