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See detailShort-term effects of tillage practices and crop residue exportation on earthworm communities and soil physico-chemical properties in silt loam arable soil (Belgium)
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

in Soil & Tillage Research (in press)

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers. They have the ability to influence a wide range of chemical, physical, and biological ... [more ▼]

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers. They have the ability to influence a wide range of chemical, physical, and biological properties of soil environment. In the present study, earthworm and soil samples were collected from wheat cultivated fields in Gembloux, Belgium under four agricultural practices: (1) conventional tillage with crop residues incorporated into the soil (CT/IN); (2) conventional tillage with crop residues exported from the field (CT/OUT); (3) reduced tillage with crop residues incorporated into the soil (RT/IN); and (4) reduced tillage with crop residues exported from the field (RT/OUT). The different agricultural practices were applied on luvisol soil for four consecutive years prior to the initiation of the current study. The purpose of this study was to research the influence of agricultural practices on earthworms with considering species and their interactions with soil properties. Results indicated that agricultural practices affected soil properties and earthworm communities. For each depth, measures of soil physico-chemical properties showed significant differences among treatments. The penetration resistance (PR) measured to a depth of 50 cm increased with increasing soil depth in all treatments. PR was significantly higher in RT compared with CT. Soil moisture was measured before PR determination. Soil samples showed higher P and K concentrations in 0 – 10 cm depth compared with other depths. The main reason for the large K and P accumulation near the soil surface is the incorporation of crop residues. Significant differences were not detected between residue incorporation depth treatments, where results showed mean earthworm abundance was respectively 182 and 180 individuals m-2 in CT and RT. Mean earthworm biomass was similarly not significantly different between CT and RT, where results were respectively 48.5 and 57.3 g.m-2. However, a significant difference was observed between IN and OUT treatments, suggesting the exportation of crop residues will limit earthworm abundance and biomass, and will mask the effect of tillage. The endogeic species Apporectodea caliginosa strongly dominated the earthworm community (64%), whereas epigeic and anecic species remained < 3% and 5% of all earthworms. Findings indicate that endogeic and epi-anecic groups appears to be highly affected by tillage practice and the exportation of crop residues. Consequently, it seems that the effect of residue exportation was stronger than tillage effect. In compacted soils, L. terrestris, L. castaneus and A. caliginosa species showed an increased abundance. The obtained results were attributable to earthworm activity and crop residues, suggesting earthworms contributed to nutrient dynamics and soil structure, particularly at increased soil depths. Overall, the results emphasise the influence of crop residues exportation on earthworm community and also, the important influence of earthworm activity on soil physico-chemical properties change, processes which are closely linked. [less ▲]

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See detailDaily intake and bacteriological quality of meat consumed in the households of Kigali, Rwanda
Niyonzima, Eugene ULg; Ongol, Martin Patrick; Brostaux, Yves ULg et al

in Food Control (2016), 69

Meat is consumed worldwide as a source of animal proteins, but it is recognized as one of the most important vehicles for food borne infections in humans. This study was conducted to determine the daily ... [more ▼]

Meat is consumed worldwide as a source of animal proteins, but it is recognized as one of the most important vehicles for food borne infections in humans. This study was conducted to determine the daily intake; the levels of hygiene indicator bacteria, namely the total mesophilic bacteria (TMC) and Escherichia coli counts (ECC); and the prevalence of Salmonella in meat consumed within the households of Kigali (Rwanda). The survey on meat consumption was carried out in 400 households by using a questionnaire, whereas the bacteriological analyses of meat samples were performed by using conventional culture methods. The results from the survey indicated that beef was the type of meat mostly consumed in Kigali city households, and the daily meat intake significantly varied with the social category of the household. No significant difference was observed between daily meat intakes in different age classes of household members. In the samples where microorganisms were detected, the average levels of TMCs and ECCs in raw meat were found to be 5.4 and 1.6 log cfu/g, respectively, whereas in cooked meat they were significantly reduced to 3.1 and 1.1 log cfu/g, respectively. The prevalence of Salmonella was reduced from 21.4% in raw meat to 3.4% in ready-to-eat cooked meat. Salmonella was not detected in cooked meat consumed in high-income households. The results from this study highlight the need for hygiene improvements in meat shops as well as in the households of Kigali, particularly those with low and medium incomes. [less ▲]

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See detailContribution à l'optimisation technico-économique des élevages laitiers en Wallonie : l'intervalle vêlage
Dalcq, Anne-Catherine ULg; Beckers, Yves ULg; Dogot, Thomas ULg et al

Conference given outside the academic context (2016)

Au cours des dernières décennies, l’intervalle vêlage des vaches laitières a eu tendance à s’allonger au niveau mondial, européen et belge. Les causes sont multiples : évolution du système de production ... [more ▼]

Au cours des dernières décennies, l’intervalle vêlage des vaches laitières a eu tendance à s’allonger au niveau mondial, européen et belge. Les causes sont multiples : évolution du système de production laitière, augmentation du niveau de production,… Les conséquences sont nombreuses également mais se traduisent-elles par un impact économique pour l’éleveur laitier ? La recherche présentée aujourd’hui se base sur près de 1800 bilans comptables de 400 exploitations laitières, fournis par le service technico-économique de l’Association Wallonne de l’Elevage, entre 2007 et 2014, pour déterminer l’impact économique de la durée de l’intervalle vêlage et définir l’optimum technico-économique de ce paramètre de management. Faut-il garder en tête « le veau par vache et par an » ou est-il intéressant économiquement d’allonger la période entre deux vêlages pour une même vache ? L’étude révèle qu’il y a bien une relation entre l’intervalle vêlage et les résultats économiques d’une exploitation. De plus, il n’y aurait pas un seul optimum d’intervalle vêlage mais plusieurs, dépendant du type d’exploitation et plus particulièrement du mode d’alimentation. L’optimum de l’intervalle vêlage a tendance à être plus court pour les exploitations à alimentation plutôt intensive et plus long pour les exploitations à alimentation plutôt extensive. Cependant il ne s’agit que de tendances observées, un travail plus approfondi doit encore être réalisé pour confirmer ces tendances et définir des objectifs plus précis à poursuivre pour maximiser la rentabilité de son exploitation. [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 ULg; Ormeño - Lafuente, Elena; Nguyen, Minh ULg 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 ULg; Baudson, Caroline ULg; Brostaux, Yves ULg 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 detailFlow cytometry community fingerprinting and amplicon sequencing for the assessment of landfill leachate cellulolytic bioaugmentation
Kinet, Romain ULg; Dzaomuho, Phidias; Baert, Jonathan ULg et al

in Bioresource Technology (2016)

Flow cytometry (FCM) is a high throughput single cell technology that is actually becoming widely used for studying phenotypic and genotypic diversity among microbial communities. This technology is ... [more ▼]

Flow cytometry (FCM) is a high throughput single cell technology that is actually becoming widely used for studying phenotypic and genotypic diversity among microbial communities. This technology is considered in this work for the assessment of a bioaugmentation treatment in order to enhance cellulolytic potential of landfill leachate. The experimental results reveal the relevant increase of leachate cellulolytic potential due to bioaugmentation. Cytometric monitoring of microbial dynamics along these assays is then realized. The Flow FP package is used to establish microbial samples fingerprint from initial 2D cytometry histograms. This procedure allows highlighting microbial communities' variation along the assays. Cytometric and 16S rRNA gene sequencing fingerprinting methods are then compared. The two approaches give same evidence about microbial dynamics throughout digestion assay. There are however a lack of significant correlation between cytometric and amplicon sequencing fingerprint at genus or species level. Same phenotypical profiles of microbiota during assays matched to several 16S rRNA gene sequencing ones. Flow cytometry fingerprinting can thus be considered as a promising routine on-site method suitable for the detection of stability/variation/disturbance of complex microbial communities involved in bioprocesses. [less ▲]

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See detailConsumer acceptance of insect-based alternative meat products in Western countries
Caparros Megido, Rudy ULg; Gierts, Chloé; Blecker, Christophe ULg et al

in Food Quality & Preference (2016)

During the past few years, entomophagy has been increasing in significance. As insects are generally high in protein, they are principally considered as meat substitutes. Nevertheless, in Western ... [more ▼]

During the past few years, entomophagy has been increasing in significance. As insects are generally high in protein, they are principally considered as meat substitutes. Nevertheless, in Western countries, meat substitute consumption is actually very low, principally due to food neophobia and poor sensory qualities in comparison with meat. In insect particular case, food neophobia is clearly high. To reduce insect food neophobia, previous studies suggest to insert invisible insect in food preparation and/or to associate them with known flavors. In this study, a survey on entomophagy perception and hedonic tests were realized to assess the level of sensory-liking of hybrid insect-based burgers (beef, lentils, mealworms and beef, mealworms and lentils). Participants’ overall liking of the four burgers differed between genders and was influenced by burger appearance and taste. Women clearly preferred beef burger appearance, whereas men preferred the appearance of beef and insect-based burgers. Concerning insect-based burger taste, participants (men and women) rated it intermediately, between that of the beef and lentil burger, with a preference for the mealworm and beef burger. Results also showed that people with previous entomophagy experience was limited but that they gave globally higher ratings to all preparations. In conclusion, insect tasting sessions are important to decrease food neophobia, as they encourage people to “take the first step” and become acquainted with entomophagy. Nevertheless, insect integration into Western food culture will involve a transitional phase with minced or powdered insects incorporated into ready-to-eat preparations, as people are not ready to add insects to their diets in “whole form.” [less ▲]

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See detailImpact of climatic factors on the release of E-β-caryophyllene from alginate beads
Daems, Frédéric ULg; Bera, François ULg; Lorge, Stéphanie ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2016), 20(2),

Description of the subject. Alginate beads that release semiochemical compounds are interesting biological control devices used to attract the natural enemies of aphids in infested crops. Little ... [more ▼]

Description of the subject. Alginate beads that release semiochemical compounds are interesting biological control devices used to attract the natural enemies of aphids in infested crops. Little information, however, is available about the impact of climatic factors on the release of semiochemicals from this diffusive system. Objectives. The objective of this scoping study was to investigate the impact of temperature, relative humidity and wind speed, on the release of E-β-caryophyllene from alginate beads. Method. The impact of the three climatic factors on the release of E-β-caryophyllene from alginate beads was evaluated using a Box-Behnken experimental design and a laboratory scale volatile collection system. The influence of relative humidity on bead water content and size, with and without this semiochemical, was also investigated using a gravimetric method and an easy-to-use photographic device, respectively. Results. The results showed that an increase in temperature caused a significant increase in the E-β¬-caryophyllene release rate. Neither relative humidity nor airflow, however, had a significant effect on the release of this semiochemical when relative humidity and wind speed ranged from 33% to 75% and from 6.61 x10-4 m.s-1 to 2.05 x10-2 m.s-1, respectively. The isotherm curves obtained were characteristic of food products and biopolymer materials. The isotherm shapes were not modified by the incorporation of the semiochemical into alginate beads, and showed an important increase in water content when relative humidity values exceeded 85%. Fortunately, this water content increase did not affect bead size, which facilitates the calculation of E-β-caryophyllene release. Conclusion. The present study shows for the first time the impact of the three main climatic factors on the release of E-β-caryophyllene from alginate beads. It allows learning more about how these biological control devices operate in order to optimize future field trials. [less ▲]

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See detailImproving Farmers’ Profitability, Soil and Water Conservation through an Adapted Tillage Technique: Experiences from the Cultivation of Potatoes in Bamiléké’s Hills, Cameroon
Djoukeng, Henri Grisseur ULg; Brostaux, Yves ULg; Tankou, Christopher Mubeteneh et al

in International Journal of Agriculture Innovations and Research (2016), 4(4), 708-716

On farms situated on slopes, such as those in the Western Highlands of Cameroon, the implementation of soil and water conservation techniques remains a major concern. The land preparation methods commonly ... [more ▼]

On farms situated on slopes, such as those in the Western Highlands of Cameroon, the implementation of soil and water conservation techniques remains a major concern. The land preparation methods commonly practiced in the Western Highlands agro-ecological zone of Cameroon are ridging along the steepest slopes (RASS) and the flatbed (FB). Field observations showed FB and RASS promote erosion by runoff, thereby compromising some agriculture functions (environmental function, production function and even social function). In order to ensure soil stability and maintain good water quality for rivers, a new land preparation method, tied ridging (TR), was tested. Erosion by runoff tests were conducted with four blocks of three plots on each of the most commonly exploited slopes, namely 11% and 29% gradient. With the main crop in the area (potato, Solanum tuberosum L.), the performance of RASS, FB, and TR were compared during crop years 2013 and 2014. The water runoff and sediments were collected per plot and per block after every rainfall. The results showed a significant difference between the FB or RASS and TR in terms of soil loss (Fmin(2, 2) = 322.7, p = 0.003), yields (F(2, 2) = 287.7, p = 0.003), and runoff water (Fmin(2, 12) = 2.4x106, p < 0.001). The TR technique generated a 7% increase in seedlings density, a 41% increase in the workforce, and an 81% and 100% increase in yields compared to FB in 11% and 29% slopes, respectively. The TR increased farmer’s profitability by 686 US$.ha-1 and 1420 US$.ha-1 over RASS in 11% and 29% slopes, respectively. The TR showed undeniable advantages: for the producer, the stress of additional work was offset by the gain in yields while creating additional job opportunities and improving the conservation of soil and water. Although the technique has several advantages, the provision of financial means for its implementation could be a negative point. Twelve farmers were involved in the experiment. The test results convinced the participants and other curious farmers who adopted the technology during the second experiment. [less ▲]

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See detailarchiDART: Plant Root System Architecture Analysis Using DART and RSML Files
Delory, Benjamin ULg; Baudson, Caroline ULg; Brostaux, Yves ULg 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 detailEarthworms Eisenia fetida affect the uptake of heavy metals by plants Vicia faba and Zea mays in metal-contaminated soils
Lemtiri, Aboulkacem ULg; Liénard, Amandine ULg; Alabi, Taofic ULg et al

in Applied Soil Ecology (2015)

Earthworms increase the availability of heavy metals in some situations and aid in maintaining the structure and quality of soil. The introduction of earthworms into metal-contaminated soils has been ... [more ▼]

Earthworms increase the availability of heavy metals in some situations and aid in maintaining the structure and quality of soil. The introduction of earthworms into metal-contaminated soils has been suggested as an aid for phytoremediation processes. In Wallonia, Belgium, a century of industrial metallurgic activities has led to the substantial pollution of soils by heavy metals, including copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), due to atmospheric dusts. Two plant species, Vicia faba and Zea mays, and earthworms (Eisenia fetida) (Savigny, 1826) were exposed to different concentrations of long-term-contaminated soils for 42 days. The soil samples, which were collected from the land surrounding a former Zn-Pb ore-treatment plant, exhibited different levels of heavy metals. Our aim was to evaluate the role of earthworms E. fetida on the availability of metals in soils and their effects on metal uptake by V. faba and Z. mays plants at different soil concentrations. The results suggest that earthworms and plants modified the availability of metals in contaminated soils after 42 days of exposure. Earthworm life-cycle parameters were affected by metal contamination and/or the addition of plants; cocoon production and weight were more responsive to adverse conditions than earthworm survival or weight change. The concentrations of Pb and Cd in earthworm tissues decreased in the presence of plants. Results showed that metal accumulation in plants depended on the metal element considered and the presence of earthworms. However, the presence of earthworms did not change the concentrations of metals in plants, except for Cd. In the presence or absence of earthworms, V. faba accumulated higher concentrations of Cu and Zn compared with Z. mays, which accumulated higher concentrations of Cd. These findings have revealed that earthworm activities can modify the availability of heavy metals for uptake by plants in contaminated soils. Moreover, the study results show that the ecological context of phytoremediation should be broadened by considering earthworm-plant-soil interaction, which influence both the health of the plant and the uptake of heavy metals by plants. [less ▲]

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See detailDe l'application des mathématiques en biologie : acquis et perspectives
Brostaux, Yves ULg

Conference (2015, October 03)

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See detailInfluence of rhizobacterial volatiles on the root system architecture and the production and allocation of biomass in the model grass Brachypodium distachyon (L.) P. Beauv.
Delaplace, Pierre ULg; Delory, Benjamin ULg; Baudson, Caroline ULg et al

in BMC Plant Biology (2015), 15(195),

Background Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include ... [more ▼]

Background Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include volatile-mediated growth enhancement. This study sought to assess the effects of bacterial volatiles on the biomass production and root system architecture of the model grass Brachypodium distachyon (L.) Beauv. Results An in vitro experiment allowing plant-bacteria interaction throughout the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth-promotion ability over a 10-day co-cultivation period. Five groups of bacteria were defined and characterised based on their combined influence on biomass production and root system architecture. The observed effects ranged from unchanged to greatly increased biomass production coupled with increased root length and branching. Primary root length was increased only 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 an 81% increase in total biomass, as well as enhancing total root length, total secondary root length and total adventitious root length by 88.5, 201.5 and 474.5%, respectively. Conclusions This study is the first report on bacterial volatile-mediated growth promotion of a grass plant. Contrasting modulations of biomass production coupled with changes in root system architecture were observed. Most of the strains that increased total plant biomass also modulated adventitious root growth. Under our screening conditions, total biomass production was strongly correlated with the length and branching of the root system components, except for primary root length. An analysis of the emission kinetics of the bacterial volatile compounds is being undertaken and should lead to the identification of the compounds responsible for the observed growth-promotion effects. Within the context of the inherent characteristics of our in vitro system, this paper identifies the next critical experimental steps and discusses them from both a fundamental and an applied perspective. [less ▲]

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See detailIs western lowland gorilla a good gardener? Effect of fecal matrix and deposition at nest sites on seedling growth
Haurez, Barbara ULg; Brostaux, Yves ULg; Petre, Charles-Albert ULg et al

Conference (2015, June 25)

The Western lowland gorilla is a key dispersal agent, which disperses viable seeds of various size. In consequence of its nesting behavior, gorilla deposits half of its feces, and therefore about half of ... [more ▼]

The Western lowland gorilla is a key dispersal agent, which disperses viable seeds of various size. In consequence of its nesting behavior, gorilla deposits half of its feces, and therefore about half of dispersed seeds, at nest sites. This study was conducted in a logging concession of southeast Gabon where 78 % of the observed nest sites (n=183) were installed in open canopy terra firma forest. The aim of this research was to assess if seed deposition by gorillas (i) in fecal matrix and (ii) at nest sites is advantageous for seedling growth. To assess the effect of fecal matrix, seeds of Santiria trimera (Burseraceae), Chrysophyllum lacourtianum (Sapotaceae) and Plagiostyles africana (Euphorbiaceae) collected in gorilla feces were sown with and without fecal matrix in a nursery at the study site. The impact of seed deposition at nest sites on seedling growth was evaluated in situ. Seedlings of Santiria trimera and Dacryodes normandii (Burseraceae) were installed at nest sites and at closed canopy terra firma forest sites. For both type of trials, seedling growth was monitored. [less ▲]

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See detailRhizobacterial volatiles influence root system architecture, biomass production and allocation of the model grass Brachypodium distachyon (L.) P. Beauv.
Delaplace, Pierre ULg; Ormeño-Lafuente, Elena; Delory, Benjamin ULg et al

Conference (2015, June 18)

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 detailScreening for interesting elicitors to protect wheat against Zymoseptoria tritici
Le Mire, Géraldine ULg; Siah, Ali; Fauconnier, Marie-Laure ULg et al

Conference (2015, May 19)

Plants face an array of biotic and abiotic stresses in their environment, making it necessary to use various chemical inputs to maintain satisfactory yield. Today, conventional agriculture is evolving ... [more ▼]

Plants face an array of biotic and abiotic stresses in their environment, making it necessary to use various chemical inputs to maintain satisfactory yield. Today, conventional agriculture is evolving towards more sustainable practices, out of respect for human health and the environment. Elicitors are considered as promising biological control tools and draw major interest in IPM strategies. These plant-immunity triggering compounds, also called “stimulators of plant natural defenses”, induce a general and systemic resistance in the plant to various diseases. Although numerous elicitors have already been identified and some of them reached the market since the late 1970s, further investigations are still required to better understand the mode of action of these molecules in the plant and ensure a consistent efficiency under various field conditions. Few elicitors have yet been successfully tested and formulated to protect crop plants such as wheat, which is cultivated over large areas in Europe. This study focuses on the screening of ten potential elicitor products of various origins and structures to protect winter wheat against the fungal pathogen Zymoseptoria tritici. Greenhouse trials were carried out to measure the ability of the different products to reduce disease foliar symptoms (necrosis, chlorosis and pycnidia). In addition, the phytotoxicity and biocide activities of these products were evaluated under greenhouse and laboratory conditions, respectively. The corresponding results will be presented and discussed with the perspective to choose the best elicitor candidates and to undertake investigations on the signaling pathway and the influence of environmental parameters on the elicitation capacity. [less ▲]

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