References of "Du Jardin, Patrick"
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See detailEnvironmental controls of biogenic volatile organic compound emissions from a grazed grassland in Dorinne, Belgium
Michel, Colin ULiege; Heinesch, Bernard ULiege; Bachy, Aurélie ULiege et al

Poster (2017, June 15)

Despite the growing interest for oxygenated volatile organic compounds (OVOC) over the last 15 years due to their role in the atmospheric chemistry, current knowledge about OVOC exchanges by grassland and ... [more ▼]

Despite the growing interest for oxygenated volatile organic compounds (OVOC) over the last 15 years due to their role in the atmospheric chemistry, current knowledge about OVOC exchanges by grassland and the environmental factors driving them still entails gaps. However, those ecosystems represent an important part of the total earth surface (13.37%). This study conducted on a grazed grassland therefore aims to quantify OVOC exchanges over full grazing seasons in order to understand the mechanisms behind these OVOC exchanges. The Eddy Covariance method was used for flux quantification, with a PTR-MS for the measurements of OVOCs mixing ratios. It took place within the activities of the CROSTVOC project (CROp Stress VOC) and therefore gives an important attention to the stress induced fluxes. BVOC flux measurements were also performed on a smaller scale by using all-teflon automated dynamic chambers covering a surface of 0.1 m² each. [less ▲]

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See detailGrazing-induced BVOC fluxes from a managed grassland
Mozaffar, Ahsan ULiege; Schoon, N.; Bachy, Aurélie ULiege et al

Poster (2017, April 28)

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See detailAux armes, professeurs de sciences !
du Jardin, Patrick ULiege

Article for general public (2017)

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See detailMethanol emissions from maize: Ontogenetic dependence to varying light conditions and guttation as an additional factor constraining the flux
Mozaffar, Ahsan ULiege; Schoon, N.; Digrado, Anthony ULiege et al

in Atmospheric Environment (2017), 152

Because of its high abundance and long lifetime compared to other volatile organic compounds in the atmosphere, methanol (CH3OH) plays an important role in atmospheric chemistry. Even though agricultural ... [more ▼]

Because of its high abundance and long lifetime compared to other volatile organic compounds in the atmosphere, methanol (CH3OH) plays an important role in atmospheric chemistry. Even though agricultural crops are believed to be a large source of methanol, emission inventories from those crop ecosystems are still scarce and little information is available concerning the driving mechanisms for methanol production and emission at different developmental stages of the plants/leaves. This study focuses on methanol emissions from Zea mays L. (maize), which is vastly cultivated throughout the world. Flux measurements have been performed on young plants, almost fully grown leaves and fully grown leaves, enclosed in dynamic flow-through enclosures in a temperature and light-controlled environmental chamber. Strong differences in the response of methanol emissions to variations in PPFD (Photosynthetic Photon Flux Density) were noticed between the young plants, almost fully grown and fully grown leaves. Moreover, young maize plants showed strong emission peaks following light/dark transitions, for which guttation can be put forward as a hypothetical pathway. Young plants’ average daily methanol fluxes exceeded by a factor of 17 those of almost fully grown and fully grown leaves when expressed per leaf area. Absolute flux values were found to be smaller than those reported in the literature, but in fair agreement with recent ecosystem scale flux measurements above a maize field of the same variety as used in this study. [less ▲]

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See detailPhotosynthetic apparatus response of the Lolium perenne L. to environmental stresses
Digrado, Anthony ULiege; Bachy, Aurélie ULiege; Mozaffar, Ahsan ULiege et al

Scientific conference (2016, June 09)

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See detailDisentangling soil from plant methanol exchanges in a maize field: a first step
Bachy, Aurélie ULiege; Mozaffar, Ahsan ULiege; Aubinet, Marc ULiege et al

Poster (2016, June)

This poster presents the current research done in order to disentangle soil from plant methanol exchanges in a maize field. Methanol exchanges were calculated at ecosystem-scale (therefore including both ... [more ▼]

This poster presents the current research done in order to disentangle soil from plant methanol exchanges in a maize field. Methanol exchanges were calculated at ecosystem-scale (therefore including both components). It bases on the following observation: methanol exchanges on bare soil (measured when maize was at germination stage) were as important as when plants were fast growing (and thereby, when the highest methanol plant methanol emissions were expected), and this under similar weather conditions. The goal of this poster is thus to understand why emissions were similar at these two periods. First, it addresses the question of the actual contribution of maize plants in methanol exchanges, by comparing up-scaled methanol exchanges measured on maize at leaf-scale (Mozaffar A.) to those measured at ecosystem-scale. Then, it investigates methanol exchanges mechanisms in order to evaluate how did soil methanol emissions evolve along the maize growing season. At the end of this poster, the hypothesis of decreasing soil methanol emissions along the maize growing season is proposed. [less ▲]

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See detailHow do Rhizobacterial Volatiles Influence Root System Architecture, Biomass Production and Allocation of the Model Grass Brachypodium distachyon?
Delaplace, Pierre ULiege; Ormeño - Lafuente, Elena; Nguyen, Minh ULiege et al

Conference (2016, January 12)

Plant growth-promoting rhizobacteria are increasingly considered as a complement of conventional inputs in agricultural systems. Their effects on their host plants are diverse and include volatile ... [more ▼]

Plant growth-promoting rhizobacteria are increasingly considered as a complement of conventional inputs in agricultural systems. Their effects on their host plants are diverse and include volatile-mediated growth enhancement. The present study aims at assessing the effects of bacterial volatile production on the biomass production and the root system architecture of Brachypodium distachyon (L.) Beauv. (line Bd-21). An in vitro experimental set-up allowing plant-bacteria interaction through the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth promotion ability over a 10-day cocultivation period. Using principal component analysis followed by hierarchical clustering and two-way analysis of variance, five groups of bacteria were defined and characterized based on their combined influence on biomass production and root system architecture. The observed effects range from unchanged to highly increased biomass production coupled with increased root length and branching. Primary root length was only increased by the volatile compounds emitted by Enterobacter cloacae JM22 and Bacillus pumilus T4. Overall, the most significant results were obtained with Bacillus subtilis GB03 which induced a 81% increase in total biomass and enhanced total root length, total secondary root length and total adventitious root length by 88, 196 and 473% respectively. The analysis of the emission kinetics of bacterial volatile organic compounds is underway and should lead to the identification of volatile compounds candidates responsible for the observed growth promotion effects. Taking into account the inherent characteristics of our in vitro system, the next experimental steps are identified and discussed from a fundamental and applied viewpoint. [less ▲]

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See detailarchiDART: an R package for the automated computation of plant root architectural traits
Delory, Benjamin ULiege; Baudson, Caroline ULiege; Brostaux, Yves ULiege et al

in Plant and Soil (2016), 398(1), 351-365

Background and Aims In order to analyse root system architectures (RSAs) from captured images, a variety of manual (e.g. Data Analysis of Root Tracings, DART), semi-automated and fully automated software ... [more ▼]

Background and Aims In order to analyse root system architectures (RSAs) from captured images, a variety of manual (e.g. Data Analysis of Root Tracings, DART), semi-automated and fully automated software packages have been developed. These tools offer complementary approaches to study RSAs and the use of the Root System Markup Language (RSML) to store RSA data makes the comparison of measurements obtained with different (semi-) automated root imaging platforms easier. The throughput of the data analysis process using exported RSA data, however, should benefit greatly from batch analysis in a generic data analysis environment (R software). Methods We developed an R package (archiDART) with five functions. It computes global RSA traits, root growth rates, root growth directions and trajectories, and lateral root distribution from DART-generated and/or RSML files. It also has specific plotting functions designed to visualise the dynamics of root system growth. Results The results demonstrated the ability of the package’s functions to compute relevant traits for three contrasted RSAs (Brachypodium distachyon [L.] P. Beauv., Hevea brasiliensis Müll. Arg. and Solanum lycopersicum L.). Conclusions This work extends the DART software package and other image analysis tools supporting the RSML format, enabling users to easily calculate a number of RSA traits in a generic data analysis environment. [less ▲]

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See detailRoot-emitted volatile organic compounds: can they mediate belowground plant-plant interactions?
Delory, Benjamin ULiege; Delaplace, Pierre ULiege; Fauconnier, Marie-Laure ULiege et al

in Plant and Soil (2016), 402

Background Aboveground, plants release volatile organic compounds (VOCs) that act as chemical signals between neighbouring plants. It is now well documented that VOCs emitted by the roots in the plant ... [more ▼]

Background Aboveground, plants release volatile organic compounds (VOCs) that act as chemical signals between neighbouring plants. It is now well documented that VOCs emitted by the roots in the plant rhizosphere also play important ecological roles in the soil ecosystem, notably in plant defence because they are involved in interactions between plants, phytophagous pests and organisms of the third trophic level. The roles played by root-emitted VOCs in between- and within-plant signalling, however, are still poorly documented in the scientific literature. Scope Given that (1) plants release volatile cues mediating plant-plant interactions aboveground, (2) roots can detect the chemical signals originating from their neighbours, and (3) roots release VOCs involved in biotic interactions belowground, the aim of this paper is to discuss the roles of VOCs in between- and within-plant signalling belowground. We also highlight the technical challenges associated with the analysis of root-emitted VOCs and the design of experiments targeting volatile-mediated root-root interactions. Conclusions We conclude that root-root interactions mediated by volatile cues deserve more research attention and that both the analytical tools and methods developed to study the ecological roles played by VOCs in interplant signalling aboveground can be adapted to focus on the roles played by root-emitted VOCs in between- and within-plant signalling. [less ▲]

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See detailReview: Implementing biostimulants and biocontrol strategies in the agroecological management of cultivated ecosystems
Le Mire, Géraldine ULiege; Nguyen, Minh ULiege; Fassotte, Bérénice ULiege et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2016)

This review describes the current methods for exploiting and applying plant growth-promoting rhizbacteria (PGPR), elicitors and semiochemical products in contemporary agricultural systems. The future of ... [more ▼]

This review describes the current methods for exploiting and applying plant growth-promoting rhizbacteria (PGPR), elicitors and semiochemical products in contemporary agricultural systems. The future of these biostimulant and biocontrol tools for the sustainable management of agricultural practices is also discussed. Special attention is given to the formulation of these products and the network of interactions taking place in cultivated ecosystems [less ▲]

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See detailEvaluation of the allelopathic potential of water-soluble compounds of barley (Hordeum vulgare L. subsp. vulgare) and great brome (Bromus diandrus Roth.) using a modified bioassay
Bouhaouel, Imen ULiege; Gfeller, Aurélie; Fauconnier, Marie-Laure ULiege et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016), 20(4), 482-494

Description of the subject. The present study focuses on the description of the allelopathic interactions between wild and crop species that may occur in a given ecosystem. Objectives. The objective is ... [more ▼]

Description of the subject. The present study focuses on the description of the allelopathic interactions between wild and crop species that may occur in a given ecosystem. Objectives. The objective is the evaluation of the allo- and autoinhibition activity of root exudates of barley (Hordeum vulgare L. subsp. vulgare) and great brome (Bromus diandrus Roth.) seedlings by water-soluble allelochemicals. Method. The allelopathic activities of five Tunisian barley genotypes (modern varieties and landraces), one Saudi Arabian barley landrace and great brome were assessed using a modified laboratory bioassay named “seedling-after-seedling agar method”. Results. The barley or the great brome reduced, to a greater extent, the root growth compared to the shoot growth of receiver species. The response of the root system architecture of the great brome towards barley root exudates was studied in detail. All the measured root traits were highly sensitive to the presence of barley. In our conditions, the allelopathic activity of barley root exudates had no apparent relationship with the size of the root and a prominent action of genetic determinants in the allelopathic potential between genotypes is proposed. The alloinhibitory activity of barley or great brome root exudates deferred between the receiver species but was always higher than the autoinhibition potential. The autoinhibition in barley proved to depend on whether the genotypes used as donor and receiver are identical or different, suggesting a specific interaction of allelochemicals with the receiver plant. These molecules seem to be the main actors in the allelopathic barley potential as external factors such variations of pH have no evident relevance in the inhibition process. Conclusions. Barley and great brome exude molecules in their surroundings. This affects the growth of the receiver plants, suggesting that these compounds might contribute to the plant community dynamics. [less ▲]

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See detailEléments pour une nouvelle ingénierie de l'agriculture
du Jardin, Patrick ULiege

in Dubois J.F. Michel, Sauvée Loïc (Ed.) Evolution aérotechnique contemporaine - Les transformations de la culture technique agricole (2016)

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See detailBarley (Hordeum distichon L.) roots synthesise volatile aldehydes with a strong age-dependent pattern and release (E)- non-2-enal and (E,Z)-nona-2,6-dienal after mechanical injury
Delory, Benjamin M.; Delaplace, Pierre ULiege; du Jardin, Patrick ULiege et al

in Plant Physiology and Biochemistry (2016), 104

In the context of chemical ecology, the analysis of the temporal production pattern of volatile organic compounds (VOCs) in root tissues and the emission rate measurement of root-emitted VOCs are of major ... [more ▼]

In the context of chemical ecology, the analysis of the temporal production pattern of volatile organic compounds (VOCs) in root tissues and the emission rate measurement of root-emitted VOCs are of major importance for setting up experiments to study the implication of these compounds in biotic interactions. Such analyses, however, remain challenging because of the belowground location of plant root systems. In this context, this study describes the evolution of the root VOC production pattern of barley (Hordeum distichon L.) at five developmental stages from germination to the end of tillering and evaluates the emission of the identified VOCs in an artificial soil. VOCs produced by crushed root tissues and released by unexcavated root systems were analysed using dynamic sampling devices coupled to a gas chromatography-mass spectrometry methodology (synchronous SCAN/SIM). The results showed that, at each analysed developmental stage, crushed barley roots produced mainly four volatile aldehydes: hexanal; (E)-hex-2-enal; (E)-non-2-enal; and (E,Z)-nona-2,6-dienal. Higher total and individual VOC concentrations were measured in 3-day-old seminal roots compared with older phenological stages. For each developmental stage, the lipoxygenase (LOX) activity was greater for linoleic acid than α-linolenic acid and the greatest LOX activities using linoleic and α- linolenic acids as substrates were measured in 7- and 3-day-old roots, respectively. The analysis of VOCs released by barley roots into the soil showed that (E)-non-2- enal and (E,Z)-nona-2,6-dienal were the only VOCs emitted in quantifiable amounts by mechanically injured roots. [less ▲]

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See detailarchiDART: Plant Root System Architecture Analysis Using DART and RSML Files
Delory, Benjamin ULiege; Baudson, Caroline ULiege; Brostaux, Yves ULiege et al

Computer development (2015)

Analysis of complex plant root system architectures (RSA) using the output files created by Data Analysis of Root Tracings (DART), an open-access software dedicated to the study of plant root architecture ... [more ▼]

Analysis of complex plant root system architectures (RSA) using the output files created by Data Analysis of Root Tracings (DART), an open-access software dedicated to the study of plant root architecture and development across time series (Le Bot et al (2010) DART: a software to analyse root system architecture and development from captured images, Plant and Soil, DOI: 10.1007/s11104-009-0005-2), and RSA data encoded with the Root System Markup Language (RSML) (Lobet et al (2015) Root System Markup Language: toward a unified root architecture description language, Plant Physiology, DOI: 10.1104/pp.114.253625). More information can be found in Delory et al (2015) archiDART: an R package for the automated computation of plant root architectural traits, Plant and Soil, DOI: 10.1007/s11104-015-2673-4. [less ▲]

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See detailEffects of Plant Growth-Promoting Rhizobacteria on Wheat Growth under Greenhouse and Field Conditions in combination with different nitrogen fertilizer levels
Nguyen, Minh ULiege; Ongena, Marc ULiege; Colinet, Gilles ULiege et al

Poster (2015, November 23)

Many Plant Growth-Promoting Rhizobacteria (PGPR) are able to enhance root growth, mineral availability, and nutrient use efficiency of crops. The aim of this project is to screen commercially available ... [more ▼]

Many Plant Growth-Promoting Rhizobacteria (PGPR) are able to enhance root growth, mineral availability, and nutrient use efficiency of crops. The aim of this project is to screen commercially available PGPR formulations and lab strains to increase wheat growth and yield in combination with an optimized nitrogen (N) fertilizer application scheme. This could lead to a significant reduction of N fertilizer application without affecting the subsequent grain yields. The screened products collection includes (1) Mix1 (a mix of Azospirillum sp., Azorhizobium sp., and Azoarcus sp.), (2) Mix2 (a mix of Mix1 complemented with two strains of phosphorus-solubilizing Bacillus sp.), (3) Bacillus amyloliquefaciens a, (4) B. subtilis, and (5) B. amyloliquefaciens b. These products were screened under greenhouse and field conditions in 2014 by using spring and winter wheat varieties, respectively. Under greenhouse conditions, there was a significant increase in root dry weight and in root per shoot ratio of plants inoculated with Mix1. Under field conditions, the interaction between PGPR inoculation and different N fertilizer doses was assessed. The grain yield was negatively impacted by low N fertilizer applications. Under such conditions, the inoculation of the wheat rhizosphere with B. subtilis increased the grain yield by 15% relative to the water control. However, in the field trial, the variability between plot replicates was high and lead to non-significant results. Based on these results, modified screening strategies for PGPR selection were set up for the next trials. [less ▲]

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See detailImpacts of Plant Growth-Promoting Rhizobacteria-based Biostimulants on Wheat Growth under Greenhouse and Field Conditions
Nguyen, Minh ULiege; Ongena, Marc ULiege; Colinet, Gilles ULiege et al

Poster (2015, November 16)

Plant Growth-Promoting Rhizobacteria (PGPR) are one of the main biostimulant classes due to their capacity of stimulating root growth and enhancing soil mineral availability, hence increasing nutrient use ... [more ▼]

Plant Growth-Promoting Rhizobacteria (PGPR) are one of the main biostimulant classes due to their capacity of stimulating root growth and enhancing soil mineral availability, hence increasing nutrient use efficiency in crops. The aim of this study is to screen commercially PGPR-containing products to enhance wheat growth and yield in combination with an optimized nitrogen (N) fertilizer application scheme. This could lead to a significant reduction of N fertilizer application without affecting the subsequent grain yields. The screened products collection includes (1) Mix1 (a mix of Azospirillum sp., Azorhizobium sp., and Azoarcus sp.), (2) Mix2 (a mix of Mix1 complemented with two strains of phosphorus-solubilizing Bacillus sp.), (3) Bacillus amyloliquefaciens a, (4) B. subtilis, and (5) B. amyloliquefaciens b. These biostimulants were screened under greenhouse and field conditions in 2014 by using spring and winter wheat varieties respectively. There was a significant increase in root dry weight and in root per shoot ratio of plants inoculated with Mix1. Under field conditions, the interaction between PGPR inoculation and N fertilizer application was assessed. The grain yield was negatively impacted by low N fertilizer applications. Under such conditions, the inoculation of the wheat rhizosphere with Bacillus subtilis increased the grain yield by 15% relative to the water control. However, in the field trial, the variability between plot replicates was high and lead to non-significant results. Based on those results, modified screening strategies for PGPR selection were set up for the 2015 trials to reduce field variability and possibly achieve higher yield increases. [less ▲]

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