Résumé

Aphanomyces euteiches Drechs is a pathogenic soil-borne oomycete that causes root rot of legumes, one of the most serious diseases affecting legume production worldwide. There is currently no registered pesticide and no available resistant pea cultivar. Avoidance of infested fields based on disease risk assessment prior to pea sowing remains the main method available to manage the disease, but time-consuming bioassays are required to assess disease severity on susceptible plants grown in field soil samples. Direct quantification of A. euteiches inoculum in the soil by targeting multicopy genomic sequences of the internal transcribed spacer 1 with a qPCR-based method has been proposed as a rapid alternative for disease prediction. However, the method lacks sensitivity to accurately quantify low inoculum levels from naturally infested fields. We developed a suitable methodology based on droplet digital PCR (ddPCR) to quantify low A. euteiches inoculum levels in naturally infested soils. The methodology was validated on 200 soil samples taken from four naturally infested fields in the main pea cropping area in the north of France. The comparative analysis of inoculum density and disease severity of the 50 samples within each of the four fields revealed a non-homogeneous distribution of the A. euteiches population; this explains why the disease is visible in the form of foci. A significant relationship between pea root rot disease severity determined by bioassays and A. euteiches inoculum density was highlighted, and a linear mixed model is proposed to predict disease severity from inoculum density.

Auteurs, date et publication :

Auteurs Simon Gibert , Véronique Edel-Hermann , Rayanti Moussa Mcolo , Elodie Gautheron , Joël Michel , Eric Bernaud , Nadine Gautheron , Jean-Marie Sol , Gery Capelle , Rachel Galland , Arnaud Bardon-Debats , Claudine Lambert , Christian Steinberg

Publication : European Journal of Plant Pathology

Date : 2021

Volume : 161

Issue : 3

Pages : 503-528

Catégorie(s)

#Genosol #INRAE

Résumé

The short time-scale dynamics of three families of Bdellovibrio and like organisms (i.e. Bdellovibrionaceae, Peredibacteraceae, and Bacteriovoracaceae) were studied on the surface waters of Lake Geneva in summer. Using mesocosms deployed nearshore in July 2019, we simulated an extreme climatic event (an input of carbon from the watershed in response to runoff from the catchment, light reduction, and mixing in response to stormy conditions) and aimed to study the impact of both abiotic and biotic factors on their dynamics. The three families of Bdellovibrio and like organisms (BALOs) showed different dynamics during the experiment. Peredibacteraceae was the most abundant group, whereas Bacteriovoracaceae was the least abundant. Compared with the other two families, the abundance of Bdellovibrionaceae did not fluctuate, remaining relatively stable over time. Environmental variables only partially explained the dynamics of these families; in particular, temperature, pH, and chloride concentrations were positively correlated with Bacteriovoracaceae, Bdellovibrionaceae, and Peredibacteraceae abundance, respectively. Prokaryote-like particles (PLPs), such as those with high DNA content (HDNA), were strongly and positively correlated with Peredibacteraceae and Bacteriovoracaceae. In contrast, no relationships were found between Bdellovibrionaceae and PLP abundance, nor between the virus-like particles (VLPs) and the different BALOs. Overall, the experiment revealed that predation was stable in the face of the simulated climatic events. In addition, we observed that Peredibacteraceae and Bacteriovoracaceae share common traits, while Bdellovibrionaceae seems to constitute a distinct category.

Auteurs, date et publication :

Auteurs J. A. Ezzedine , A. Janicot , S. Rasconi , I. Domaizon , S. Jacquet

Publication : Microbial Ecology

Date : 2021

Catégorie(s)

#INRAE #OLA

Résumé

Anaerobic digestion is increasingly used in Europe to treat organic substrates and produce biogas as a renewable energy source. The residual matter (digestate) is used in agriculture as an organic fertilizer. The study aims at assessing the impact of digestate application in the field on earthworms from the short term (few hours) to the long term (two years), and at investigating under laboratory conditions the role of ammonia and earthworm behavior on digestate toxicity in the short term. First, we studied earthworm communities in fields fertilized with digestates, cattle effluents, or chemical fertilizers for two years. Earthworm abundance was assessed before and after the fertilization event of the third year. Earthworm mortality at the soil surface was also assessed immediately after fertilization. Next, the toxicity of digestate or ammonia solutions on Aporrectodea caliginosa and Lumbricus terrestris was measured in microcosms (110 cm3) to better understand the short-term toxicity (two weeks). Finally, we spread digestate (40–80 t ha−1) on soil columns (5300 cm3) and used X-ray tomography after two weeks to assess the burrowing behavior of earthworms in the cores. Earthworm abundance was 150% higher in the fields treated for two years with digestates or cattle effluents compared to the field treated with chemical fertilizers. 0.5 to 2% of adult earthworms died at the soil surface a few hours after liquid digestate and cattle slurry spreading (18 to 24 t ha−1). The digestate (10% to 20% (fresh digestate/dry soil)) and ammonia were also lethal to earthworms in the microcosms within two weeks. In contrast, no mortality occurred inside soil columns two weeks after digestate spreading; A. caliginosa avoided the soil surface with high digestate inputs. This case study highlighted the potential short-term toxicity of digestate (a few hours), which evolved towards a neutral to positive impact in the field in the longer term (from two weeks to two years). Further research is needed to understand the impact of diverse solid and liquid digestates on soil macrofauna in different soils.

Auteurs, date et publication :

Auteurs Victor Moinard , Clément Redondi , Véronique Etiévant , Antoine Savoie , David Duchene , Céline Pelosi , Sabine Houot , Yvan Capowiez

Publication : Applied Soil Ecology

Date : 2021

Volume : 168

Pages : 104149

Catégorie(s)

#INRAE #PRO

Auteurs, date et publication :

Auteurs Fanny Guillet

Date : 2025

Catégorie(s)

#INRAE #PRO #PRO EFELE

Résumé

The increasing disturbances in monocultures around the world are testimony to their instability under global change. Many studies have claimed that temporal stability of productivity increases with species richness, although the ecological fundamentals have mainly been investigated through diversity experiments. To adequately manage forest ecosystems, it is necessary to have a comprehensive understanding of the effect of mixing species on the temporal stability of productivity and the way in which it is influenced by climate conditions across large geographical areas. Here, we used a unique dataset of 261 stands combining pure and two-species mixtures of four relevant tree species over a wide range of climate conditions in Europe to examine the effect of species mixing on the level and temporal stability of productivity. Structural equation modelling was employed to further explore the direct and indirect influence of climate, overyielding, species asynchrony and additive effect (i.e. temporal stability expected from the species growth in monospecific stands) on temporal stability in mixed forests. We showed that by adding only one tree species to monocultures, the level (overyielding: +6%) and stability (temporal stability: +12%) of stand growth increased significantly. We identified the key effect of temperature on destabilizing stand growth, which may be mitigated by mixing species. We further confirmed asynchrony as the main driver of temporal stability in mixed stands, through both the additive effect and species interactions, which modify between-species asynchrony in mixtures in comparison to monocultures. Synthesis and applications. This study highlights the emergent properties associated with mixing two species, which result in resource efficient and temporally stable production systems. We reveal the negative impact of mean temperature on temporal stability of forest productivity and how the stabilizing effect of mixing two species can counterbalance this impact. The overyielding and temporal stability of growth addressed in this paper are essential for ecosystem services closely linked with the level and rhythm of forest growth. Our results underline that mixing two species can be a realistic and effective nature-based climate solution, which could contribute towards meeting EU climate target policies.

Auteurs, date et publication :

Auteurs Miren del Río , Hans Pretzsch , Ricardo Ruiz-Peinado , Hervé Jactel , Lluís Coll , Magnus Löf , Jorge Aldea , Christian Ammer , Admir Avdagić , Ignacio Barbeito , Kamil Bielak , Felipe Bravo , Gediminas Brazaitis , Jakub Cerný , Catherine Collet , Sonia Condés , Lars Drössler , Marek Fabrika , Michael Heym , Stig-Olof Holm

Publication : Journal of Applied Ecology

Date : 2025

Volume : 59

Issue : 11

Pages : 2730-2741

Catégorie(s)

#FORET OPTMix #INRAE

Résumé

Background: Intensive silvicultural practices and the planting of monospecific forests of coniferous, that are more productive compared to hardwoods may threaten over the mid to long-term the sustainability of soil chemical fertility of forest ecosystems, and are a major concern for forest managers and policy.
Methods: We investigated the tree species effect (Quercus sessiliflora Smith, Fagus sylvatica L., Picea abies Karst., Pseudotsuga menziesii Mirb. Franco., Abies nordmanniana Spach. and Pinus nigra Arn. ssp. laricio Poiret var. corsicana) on the change over time of soil chemical properties and nutrient pool sizes in the mineral and organic layers of the soil during the 45 years after the plantation of the Breuil-Chenue common garden experiment (Burgundy, France). The organic and mineral soil layers down to 70-cm depth were sampled in the different monospecific plots in 1974, 2001 and 2019.
Results: Exchangeable Ca and Mg pools and soil pH increased on average over time in the 0–70 cm soil profile in most stands. However, in the topsoil layers (0–15 cm), the decrease of pH, the increase of exchangeable acidity over time under the coniferous stands and the decrease of exchangeable K pools in most stands highlighted that soil acidification is still on-going at Breuil-Chenue site but the intensity of this process depends on the tree species. Indeed, three groups of species could be distinguished: i) Nordmann fir (Abies nordmanniana Spach.)/Norway spruce (Picea abies Karst.) where acidolysis and chelation occurred, resulting in the most pronounced pH decrease in the topsoil, ii) Douglas fir (Pseudotsuga menziesii Mirb. Franco.)/Laricio pine (Pinus nigra Arn. ssp. laricio Poiret var. corsicana) where acidification caused by elevated nitrification rates is probably currently compensated by larger weathering and/or atmospheric depositions fluxes, and iii) oak (Quercus sessiliflora Smith)/beech (Fagus sylvatica L.) where soil acidification was less intense. Counterintuitively, soil acidification at Breuil-Chenue site resulted in an increase in soil CEC which limited the loss of nutrient cations. This change in soil CEC was most likely explained by the precipitation/dissolution dynamics of aluminium (Al) (hydr)oxides in the interfoliar space of phyllosilicates and/or the increase in soil carbon (C) content in the topsoil layers.
Conclusion: After 45 years, tree species continue to exert influence on the chemical fertility of the soil and the pedogenetic processes which in turn may impact forest ecosystem functions and services.

Auteurs, date et publication :

Auteurs Margaux Clesse , Arnaud Legout , Jacques Ranger , Bernd Zeller , Gregory van der Heijden

Publication : Forest Ecosystems

Date : 2025

Volume : 9

Pages : 100043

Catégorie(s)

#ANR-Citation #FORET Breuil #INRAE

Résumé

The dreissenids, quagga mussel Dreissena bugensis and zebra mussel D. polymorpha, are invasive freshwater mussels in Europe and North America. These species strongly impact aquatic ecosystems, such as the food web through their high abundance and filtration rate. They spread quickly within and between waterbodies, and have the ability to colonize various substrates and depths. The zebra mussel invaded and established in Swiss lakes in the 1960s, whereas the quagga mussel was not detected until 2014. We collected all available data from cantonal as well as local authorities and other institutions to describe the colonization pattern of quagga mussels in perialpine lakes north of the Alps. We also collected data regarding the distribution of larval stages of the mussels, the so-called veliger larvae. We observed that in lakes colonized by the quagga mussel, veligers are present the whole year round, whereas they are absent in winter in lakes with only zebra mussels. Additionally, we present detailed information about the invasion and colonization pattern of quagga mussels in Lake Constance. Quagga mussels colonized the lakeshore within a few years (~ 2016–2018), outcompeted zebra mussels, and have reached densities > 5000 ind. m-2 in the littoral zone, even at 80 m densities above 1000 ind. m-2 were found at some locations. At the end of the article, we discussed possibilities on how the spread of quagga mussels within and among northern perialpine lakes should be monitored and prevented in the future.

Auteurs, date et publication :

Auteurs Linda Haltiner , Hui Zhang , Orlane Anneville , Lukas De Ventura , Tyrell DeWeber , John Hesselschwerdt , Michael Koss , Serena Rasconi , Karl-Otto Rothhaupt , Roland Schick , Brigitte Schmidt , Piet Spaak , Petra Teiber-Siessegger , Martin Wessels , Markus Zeh , Stuart Dennis

Publication : Aquatic Invasions

Date : 2025

Volume : 17

Issue : 2

Pages : 153-173

Catégorie(s)

#INRAE #OLA

Auteurs, date et publication :

Auteurs AF Didelot , E Jardé , T Morvan , F Gaillard , M. Liotaud , A Jaffrezic

Date : 2025

Catégorie(s)

#INRAE #PRO #PRO EFELE

Auteurs, date et publication :

Auteurs T Morvan , C Fléchard , A M Pourcher , C Ziebal , G Pérès , K Hoeffner , D Cluzeau , Y Bénard , L Carteaux , M Guernion , H Hotte , F Corroler , L Paillat , M Roucaute , F Gaillard , P Germain , B Bourel , F Elsass , V Etievant , S Joimel

Date : 2025

Catégorie(s)

#INRAE #PRO #PRO EFELE

Résumé

Diagnosis and determinants of grassland sustainability. Soil and the sustainability of grasslands: a virtuous circle The physical, chemical and biological properties of the soil will affect plant growth and condition the sustainability of the grasslands. Thus, soil compaction due to grazing or machine traffic will result in a loss of yield, the effects being variable according to texture (more pronounced on more clayey soils) and season. On the other hand, the preservation of soil organisms and associated functions will contribute to increasing yields. On the other hand, grassland management will also impact soil properties. Thus, the int roduction of grassland in the crop rotation will quickly allow, from the second year, to favor soil biodiversity (fauna, microorganisms ) and their activities. More broadly, the introduction of grassland into an annual crop rotation positively influences the maintenance of soil structure and the conservation of biodiversity, without modifying water regulation. The positive effect inherited from grasslands in th e rotation can be observed even three years after recultivation. The sustainability of the grasslands will be conditioned by several factors: the duration of the grassland in the rotation, grazing management (load, period), fertilization and plant diversity. Levers exist to ensure the sustainability of these temporary or permanent grassland systems.

Auteurs, date et publication :

Auteurs G Pérès , K Hoeffner , D Cluzeau , M-L Decau , F Gastal , M Legras , F Vertès

Publication : Fourrages

Date : 2025

Issue : 250

Pages : 39-47

Catégorie(s)

#ACBB #ACBB Laqueuille #ACBB Theix #INRAE