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Dive into the research topics where Laetitia Bernard is active.

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Featured researches published by Laetitia Bernard.


Plant Physiology | 2011

P for Two, Sharing a Scarce Resource: Soil Phosphorus Acquisition in the Rhizosphere of Intercropped Species

Philippe Hinsinger; Elodie Betencourt; Laetitia Bernard; Alain Brauman; Claude Plassard; Jianbo Shen; Xiaoyan Tang; Fusuo Zhang

Phosphorus (P) scarcity and the need for ecologically sound intensification of agroecosystems are major challenges we face. To improve nutrient efficiency in agriculture, especially for P, multispecies crop stands may outperform their monospecific counterparts, especially under low input conditions. There is increasing evidence that biomass, grain yield and nutrient acquisition are improved in cereal/legume intercropping systems, relative to cereal or legume grown alone. Hereafter, we consider these observations, outline the underlying mechanisms, and examine recent work that advances our knowledge of how cereal/legume intercropping systems acquire P in their rhizospheres, through various types of positive belowground-interactions. First, we discuss how complementarity may operate when cereals are intercropped with legumes by addressing cases of complementary use of soil P resources in space and time, and showing how functionally diverse intercropped species can use different pools of soil P. Then we address examples of facilitation, i.e. positive interactions between two intercropped species, in which the legume (or cereal) may increase P availability for the benefit of the intercropped cereal (or legume). Finally, the relevance of a range of root-induced or microbially-mediated rhizosphere processes driving P acquisition are discussed.


The ISME Journal | 2012

Endogeic earthworms shape bacterial functional communities and affect organic matter mineralization in a tropical soil

Laetitia Bernard; Lydie Chapuis-Lardy; Tantely Razafimbelo; Malalatiana Razafindrakoto; Anne-Laure Pablo; Elvire Legname; Julie Poulain; Thomas Brüls; Michael O'Donohue; Alain Brauman; Jean-Luc Chotte; Eric Blanchart

Priming effect (PE) is defined as a stimulation of the mineralization of soil organic matter (SOM) following a supply of fresh organic matter. This process can have important consequences on the fate of SOM and on the management of residues in agricultural soils, especially in tropical regions where soil fertility is essentially based on the management of organic matter. Earthworms are ecosystem engineers known to affect the dynamics of SOM. Endogeic earthworms ingest large amounts of soil and assimilate a part of organic matter it contains. During gut transit, microorganisms are transported to new substrates and their activity is stimulated by (i) the production of readily assimilable organic matter (mucus) and (ii) the possible presence of fresh organic residues in the ingested soil. The objective of our study was to see (i) whether earthworms impact the PE intensity when a fresh residue is added to a tropical soil and (ii) whether this impact is linked to a stimulation/inhibition of bacterial taxa, and which taxa are affected. A tropical soil from Madagascar was incubated in the laboratory, with a 13C wheat straw residue, in the presence or absence of a peregrine endogeic tropical earthworm, Pontoscolex corethrurus. Emissions of 12CO2 and 13CO2 were followed during 16 days. The coupling between DNA-SIP (stable isotope probing) and pyrosequencing showed that stimulation of both the mineralization of wheat residues and the PE can be linked to the stimulation of several groups especially belonging to the Bacteroidetes phylum.


Plant and Soil | 2016

Phosphorus availability and microbial community in the rhizosphere of intercropped cereal and legume along a P-fertilizer gradient

Xiaoyan Tang; Sarah Placella; Florent Daydé; Laetitia Bernard; Agnès Robin; Etienne-Pascal Journet; Eric Justes; Philippe Hinsinger

Background and aimsPositive below-ground interactions (facilitation) should be more pronounced when resources limit crop growth, according to the stress-gradient hypothesis. Our aim was to test this hypothesis for intercropped durum wheat and faba bean along a P-fertilizer gradient.MethodsA field experiment was conducted in a long-term P-fertilizer trial with three rates of P-fertilization (No, Low and High P). Microbial biomass was assessed by chloroform fumigation-extraction. Quantitative PCR was applied to evaluate the abundance of relevant microbial groups.ResultsPhosphorus availability and microbial biomass systematically increased in the rhizosphere compared to bulk soil. P-fertilization resulted in higher abundance of targeted bacterial phyla, whole bacterial and fungal communities, and depressed mycorrhizal colonization of durum wheat, but not faba bean. Microbial biomass carbon significantly increased in the rhizosphere only in P-fertilized treatments, pointing to P limitation of microbial communities. Intercropping yielded a significant effect on rhizosphere microbial properties only at High P. Microbial biomass P increased in the rhizosphere of intercropped faba bean only at No P level, and was thus the sole finding supporting the stress-gradient hypothesis.ConclusionsP-fertilization was the main driver of microbial communities in this field trial, and P-fertilizer application modulated the species-specific effect in the intercrop. Plant performance did not validate the stress-gradient hypothesis as positive plant-plant interactions occurred regardless of the level of P-fertilization.


Plant and Soil | 2014

Endogeic earthworms modify soil phosphorus, plant growth and interactions in a legume–cereal intercrop

Mathieu Coulis; Laetitia Bernard; Frédéric Gérard; Philippe Hinsinger; Claude Plassard; Manon Villeneuve; Eric Blanchart

Background and aimsIntercropping of legumes and cereals appears as an alternative agricultural practice to decrease the use of chemical fertilizers while maintaining high yields. A better understanding of the biotic and abiotic factors determining interactions between plants in such associations is required. Our study aimed to analyse the effect of earthworms on the legume–cereal interactions with a focus on the modifications induced by earthworms on the forms of soil phosphorus (P).MethodsIn a glasshouse experiment we investigated the effect of an endogeic earthworm (Allolobophora chlorotica) on the plant biomass and on N and P acquisition by durum wheat (Triticum turgidum durum L.) and chickpea (Cicer arietinum L.) either grown alone or intercropped. The modifications of the different organic and inorganic P forms in the bulk soil were measured.ResultsThere was no overyielding of the intercrop in the absence of earthworms. Earthworms had a strong influence on biomass and resource allocation between roots and shoots whereas no modification was observed in terms of total biomass production and P acquisition. Earthworms changed the interaction between the intercropped species mainly by reducing the competition for nutrients. Facilitation (positive plant–plant interactions) was only observed for the root biomass and P acquisition in the presence of earthworms. Earthworms decreased the amount of organic P extracted with NaOH (Po NaOH), while they increased the water soluble inorganic P (Pi H2O) content.ConclusionsIn this experiment, earthworms could be seen as “troubleshooter” in plant–plant interaction as they reduced the competition between the intercropped species. Our study brings new insights into how earthworms affect plant growth and the P cycle.


MethodsX | 2015

Modification of a commercial DNA extraction kit for safe and rapid recovery of DNA and RNA simultaneously from soil, without the use of harmful solvents

Estelle Tournier; Laurie Amenc; Anne-Laure Pablo; Elvire Legname; Eric Blanchart; Claude Plassard; Agnès Robin; Laetitia Bernard

Graphical abstract


Agronomy for Sustainable Development | 2015

Fourteen years of evidence for positive effects of conservation agriculture and organic farming on soil life

Ludovic Henneron; Laetitia Bernard; Mickaël Hedde; Céline Pelosi; Cécile Villenave; Claire Chenu; Michel Bertrand; Cyril Girardin; Eric Blanchart


Applied Soil Ecology | 2010

Effect of the endogeic earthworm Pontoscolex corethrurus on the microbial structure and activity related to CO2 and N2O fluxes from a tropical soil (Madagascar)

L. Chapuis-Lardy; A. Brauman; Laetitia Bernard; A.L. Pablo; J. Toucet; M.J. Mano; L. Weber; D. Brunet; Tantely Razafimbelo; Jean-Luc Chotte; Eric Blanchart


Soil Biology & Biochemistry | 2014

Increase in microbial biomass and phosphorus availability in the rhizosphere of intercropped cereal and legumes under field conditions

Xiaoyang Tang; Laetitia Bernard; Alain Brauman; Tanguy Daufresne; Philippe Deleporte; Dominique Desclaux; Gérard Souche; Sarah Placella; Philippe Hinsinger


Journal of Nematology | 2015

Plant Roots Increase Bacterivorous Nematode Dispersion through Nonuniform Glass-bead Media

Jean Trap; Laetitia Bernard; Alain Brauman; Anne-Laure Pablo; Claude Plassard; Mahafaka Patricia Ranoarisoa; Eric Blanchart


Soil Biology & Biochemistry | 2018

Effects of a bacterivorous nematode on rice 32 P uptake and root architecture in a high P-sorbing ferrallitic soil

Mahafaka Patricia Ranoarisoa; Christian Morel; Andry Andriamananjara; Christophe Jourdan; Laetitia Bernard; Thierry Becquer; Lilia Rabeharisoa; Koloina Rahajaharilaza; Claude Plassard; Eric Blanchart; Jean Trap

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Eric Blanchart

Institut de recherche pour le développement

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Alain Brauman

Institut national de la recherche agronomique

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Philippe Hinsinger

Institut national de la recherche agronomique

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Tantely Razafimbelo

Institut de recherche pour le développement

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Claire Chenu

Université Paris-Saclay

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Elvire Legname

Institut national de la recherche agronomique

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Eric Blanchart

Institut de recherche pour le développement

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