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Amendements organiques et maraîchage biologique sous abri : résultats de 8 années d’expérimentation

L’agriculture biologique repose sur des apports fréquents de matière organique pour maintenir un bon fonctionnement du sol. Ces apports sont particulièrement importants en cas de reconversion de sol en maraîchage, les sols étant dans ce cas généralement appauvris en matière organique. Avec la raréfaction des ressources en fumier, des composts commerciaux conditionnés en bouchon sont fréquemment utilisés, ainsi que depuis quelques années les composts de déchets verts, économiquement très intéressants mais de composition mal connue. Une expérimentation conduite sur du moyen terme (8 années) à l’INRA d’Alénya a permis de mieux connaître l’évolution des 2 types de compost fréquemment utilisés en système maraîcher sous abri. Ceci permettra d’optimiser les pratiques dans un double objectif : améliorer les sols et tenir compte de la minéralisation azotée pour la fertilisation des cultures, notamment les cultures longues d’été pour lesquelles les engrais organiques usuels ne permettent pas une alimentation tardive correcte

Enjeux de l’évaluation des Maisons des sciences de l’Homme

Les structures fédératives constituent en France un cas très particulier en matière d’évaluation. Le Réseau des Maisons des sciences de l’homme (MSH) est d’autant plus intéressant comme cas de figure qu’il s’agit d’une structure interinstitutionnelle et pluridisciplinaire au niveau national, et que chaque Maison est elle-même une structure de ce type. De par la diversité des disciplines et l’importance des effectifs de chercheurs et d’en..

Multi-species summer cover crop in protected vegetable systems (DiverIMPACTS Practice Abstract)

This cover crop mixture provides biomass which is crushed and incorporated into the soil. Benefits include improved organic matter and soil structure, reduced risk of nitrogen leaching (the C/N ratio of the cover crop ranges from 10 to 40) and improved weed, pest and disease management. Cover crop mixture botanical families should differ from that of the vegetables to increase rotation diversity and contribute to the management of soilborne pathogens

Solar supergranulation revealed by granule tracking

Context: Supergranulation is a pattern of the velocity field at the surface of the Sun, which has been known about for more than fifty years, however, no satisfactory explanation of its origin has been proposed. Aims: New observational constraints are therefore needed to guide theoretical approaches which hesitate between scenarios that either invoke a large-scale instability of the surface turbulent convection or a direct forcing by buoyancy. Method: Using the 14-Mpixel CALAS camera at the Pic-du-Midi observatory, we obtained a 7.5h-long sequence of high resolution images with unprecedented field size. Tracking granules, we have determined the velocity field at the Sun's surface in great detail from a scale of 2.5Mm up to 250Mm. Results: The kinetic energy density spectrum shows that supergranulation peaks at 36Mm and spans on scales ranging between 20Mm and 75Mm. The decrease of supergranular flows in the small scales is close to a $k^{-2}$-power law, steeper than the equipartition Kolmogorov one. The probability distribution function of the divergence field shows the signature of intermittency of the supergranulation and thus its turbulent nature.Comment: 4 pages, accepted in Astronomy and Astrophysics (Letters

A Randomized Controlled Clinical Trial in Healthy Older Adults to Determine Efficacy of Glycine and N-Acetylcysteine Supplementation on Glutathione Redox Status and Oxidative Damage.

Glycine and cysteine are non-essential amino acids that are required to generate glutathione, an intracellular tripeptide that neutralizes reactive oxygen species and prevents tissue damage. During aging glutathione demand is thought to increase, but whether additional dietary intake of glycine and cysteine contributes towards the generation of glutathione in healthy older adults is not well understood. We investigated supplementation with glycine and n-acetylcysteine (GlyNAC) at three different daily doses for 2 weeks (low dose: 2.4 g, medium dose: 4.8 g, or high dose: 7.2 g/day, 1:1 ratio) in a randomized, controlled clinical trial in 114 healthy volunteers. Despite representing a cohort of healthy older adults (age mean = 65 years), we found significantly higher baseline levels of markers of oxidative stress, including that of malondialdehyde (MDA, 0.158 vs. 0.136 µmol/L, p < 0.0001), total cysteine (Cysteine-T, 314.8 vs. 276 µM, p < 0.0001), oxidized glutathione (GSSG, 174.5 vs. 132.3 µmol/L, p < 0.0001), and a lower ratio of reduced to oxidized glutathione (GSH-F:GSSG) (11.78 vs. 15.26, p = 0.0018) compared to a young reference group (age mean = 31.7 years, n = 20). GlyNAC supplementation was safe and well tolerated by the subjects, but did not increase levels of GSH-F:GSSG (end of study, placebo = 12.49 vs. 7.2 g = 12.65, p-value = 0.739) or that of total glutathione (GSH-T) (end of study, placebo = 903.5 vs. 7.2 g = 959.6 mg/L, p-value = 0.278), the primary endpoint of the study. Post-hoc analyses revealed that a subset of subjects characterized by high oxidative stress (above the median for MDA) and low baseline GSH-T status (below the median), who received the medium and high doses of GlyNAC, presented increased glutathione generation (end of study, placebo = 819.7 vs. 4.8g/7.2 g = 905.4 mg/L, p-value = 0.016). In summary GlyNAC supplementation is safe, well tolerated, and may increase glutathione levels in older adults with high glutathione demand. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT05041179, NCT05041179

Avenir de la recherche et Maisons des sciences de l’Homme

Cette réédition, en 2020, de l’ouvrage paru en 2006 et consacré aux Maisons des sciences de l’homme permet de mettre en lumière les fondamentaux scientifiques et institutionnels à l'origine de la création des MSH et de leur réseau, déployé au cours des années 2000 sur le territoire national. Ce livre s’adresse à tous ceux qui s’intéressent aux sciences humaines et sociales et aux évolutions désicives pour les acteurs français. Il est destiné à être complété par un deuxième volume qui couvrira la période 2012-2020. C’est une initiative du Réseau national des MSH soutenue par l’alliance Athéna

Steppes, savannahs, forests and phytodiversity reservoirs during the Pleistocene in the Iberian Peninsula

A palaeobotanical analysis of the Pleistocene floras and vegetation in the Iberian Peninsula shows the existence of patched landscapes with Pinus woodlands, deciduous and mixed forests, parklands (savannah-like), shrublands, steppes and grasslands. Extinctions of Arctotertiary woody taxa are recorded during the Early and Middle Pleistocene, but glacial refugia facilitated the survival of a number of temperate, Mediterranean and Ibero-North African woody angiosperms. The responses of Iberian vegetation to climatic changes during the Pleistocene have been spatially and temporarily complex, including rapid changes of vegetation in parallel to orbital and suborbital variability, and situations of multi-centennial resilience or accommodation to climatic changes. Regional characteristics emerged as soon as for the Middle Pleistocene, if not earlier: Ericaceae in the Atlantic coast indicating wetter climate, thermo-mediterranean elements in the south as currently, and broad-leaf trees in the northeastern. Overall, steppe landscapes and open Pinus woodlands prevailed over many continental regions during the cold spells of the Late Pleistocene. The maintenance of a high phytodiversity during the glacials was linked to several refuge zones in the coastal shelves of the Mediterranean and intramountainous valleys. Northern Iberia, especially on coastal areas, was also patched with populations of tree species, and this is not only documented by palaeobotanical data (pollen, charcoal) but also postulated by phylogeographical models