Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Phenotypic Variation of Cell Wall Composition and Stem Morphology in Hemp (Cannabis sativa L.): Optimization of Methods
Petit, Jordi ; Gulisano, Agata ; Dechesne, Annemarie ; Trindade, Luisa M. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Cannabis sativa - cell wall - fiber quality - genetic diversity - hemp - phenotyping methods - stem morphology

The growing demands for sustainable fibers have stimulated the study of genetic diversity in the quality of hemp fiber (Cannabis sativa L.). Nevertheless, the lack of high-throughput phenotyping methods that are suited for the analysis of hemp fiber, hampers the analysis of many accessions, and consequently the breeding for this complex trait. In the present report, we developed and optimized the throughput of five methods to study the diversity in hemp fiber quality including cell wall extraction, biochemical composition of cell wall polysaccharides, quantification of lignin, quantification of crystalline polysaccharides and morphology of the stems. Six hemp accessions contrasting for cell wall properties were used to assess the throughput and suitability of these methods for genetic studies. The methods presented revealed to be highly repeatable, with low coefficients of variation between technical replicates. With these methods we were able to detect significant phenotypic variation in cell wall composition and stem morphology between the six accessions. In addition, the throughput of the methods has been upgraded to a level that enables their use for phenotyping cell wall traits in breeding programs. The cell wall extraction was optimized to extract enough material for the complete characterization of the cell wall of hemp while reducing the time for the entire analysis. The throughput of the stem morphological analysis was improved by decreasing the timing of fixation, infiltration, and embedding of mature and dry hemp stems. Notwithstanding, our methods already have the potential to phenotype large number of accessions in a relatively short period of time. Our methods will enable exploration of genetic diversity of fiber quality and will contribute to the development of new hemp varieties with advanced quality of fibers.

Multi-host disease management: The why and the how to include wildlife
Portier, Julien ; Ryser-Degiorgis, Marie Pierre ; Hutchings, Mike R. ; Monchâtre-Leroy, Elodie ; Richomme, Céline ; Larrat, Sylvain ; Poel, Wim H.M. Van Der; Dominguez, Morgane ; Linden, Annick ; Santos, Patricia Tavares ; Warns-Petit, Eva ; Chollet, Jean Yves ; Cavalerie, Lisa ; Grandmontagne, Claude ; Boadella, Mariana ; Bonbon, Etienne ; Artois, Marc - \ 2019
BMC Veterinary Research 15 (2019)1. - ISSN 1746-6148
Coordination - Decision-making framework - Emerging infectious diseases - Europe - Integrated management - Policy making - Proportionate management - Risk assessment - Wildlife - Zoonosis

In recent years, outbreaks caused by multi-host pathogens (MHP) have posed a serious challenge to public and animal health authorities. The frequent implication of wildlife in such disease systems and a lack of guidelines for mitigating these diseases within wild animal populations partially explain why the outbreaks are particularly challenging. To face these challenges, the French Ministry of Agriculture launched a multi-disciplinary group of experts that set out to discuss the main wildlife specific concepts in the management of MHP disease outbreaks and how to integrate wildlife in the disease management process. This position paper structures the primary specific concepts of wildlife disease management, as identified by the working group. It is designed to lay out these concepts for a wide audience of public and/or animal health officers who are not necessarily familiar with wildlife diseases. The group's discussions generated a possible roadmap for the management of MHP diseases. This roadmap is presented as a cycle for which the main successive step are: step 1-descriptive studies and monitoring; step 2-risk assessment; step 3-management goals; step 4-management actions and step 5-assessment of the management plan. In order to help choose the most adapted management actions for all involved epidemiological units, we integrated a decision-making framework (presented as a spreadsheet). This tool and the corresponding guidelines for disease management are designed to be used by public and health authorities when facing MHP disease outbreaks. These proposals are meant as an initial step towards a harmonized transboundary outbreak response framework that integrates current scientific understanding adapted to practical intervention.

Evidence of trained immunity in a fish: Conserved features in cArp macrophages
Petit, Jules ; Embregts, Carmen W.E. ; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2019
The Journal of Immunology 203 (2019)1. - ISSN 0022-1767 - p. 216 - 224.

Trained immunity is a form of innate immune memory best described in mice and humans. Clear evidence of the evolutionary conservation of trained immunity in teleost fish is lacking. Given the evolutionary position of teleosts as early vertebrates with a fully developed immune system, we hypothesize that teleost myeloid cells show features of trained immunity common to those observed in mammalian macrophages. These would at least include the ability of fish macrophages to mount heightened responses to a secondary stimulus in a nonspecific manner. We established an in vitro model to study trained immunity in fish by adapting a well-described culture system of head kidney-derived macrophages of common carp. A soluble NOD-specific ligand and a soluble b-glucan were used to train carp macrophages, after which cells were rested for 6 d prior to exposure to a secondary stimulus. Unstimulated trained macrophages displayed evidence of metabolic reprogramming as well as heightened phagocytosis and increased expression of the inflammatory cytokines il6 and tnf-a. Stimulated trained macrophages showed heightened production of reactive oxygen and nitrogen species as compared with the corresponding stimulated but untrained cells. We discuss the value of our findings for future studies on trained immunity in teleost fish.

The complex interactions between flowering behavior and fiber quality in hemp
Salentijn, Elma M.J. ; Petit, Jordi ; Trindade, Luisa M. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Cannabis sativa - Fiber development - Flowering-time - Hemp - Phenology - Sex determination - Short-day plant

Hemp, Cannabis sativa L., is a sustainable multipurpose fiber crop with high nutrient and water use efficiency and with biomass of excellent quality for textile fibers and construction materials. The yield and quality of hemp biomass are largely determined by the genetic background of the hemp cultivar but are also strongly affected by environmental factors, such as temperature and photoperiod. Hemp is a facultative short-day plant, characterized by a strong adaptation to photoperiod and a great influence of environmental factors on important agronomic traits such as “flowering-time” and “sex determination.” This sensitivity of hemp can cause a considerable degree of heterogeneity, leading to unforeseen yield reductions. Fiber quality for instance is influenced by the developmental stage of hemp at harvest. Also, male and female plants differ in stature and produce fibers with different properties and quality. Next to these causes, there is evidence for specific genotypic variation in fiber quality among hemp accessions. Before improved hemp cultivars can be developed, with specific flowering-times and fiber qualities, and adapted to different geographical regions, a better understanding of the molecular mechanisms controlling important phenological traits such as “flowering-time” and “sex determination” in relation to fiber quality in hemp is required. It is well known that genetic factors play a major role in the outcome of both phenological traits, but the major molecular factors involved in this mechanism are not characterized in hemp. Genome sequences and transcriptome data are available but their analysis mainly focused on the cannabinoid pathway for medical purposes. Herein, we review the current knowledge of phenotypic and genetic data available for “flowering-time,” “sex determination,” and “fiber quality” in short-day and dioecious crops, respectively, and compare them with the situation in hemp. A picture emerges for several controlling key genes, for which natural genetic variation may lead to desired flowering behavior, including examples of pleiotropic effects on yield quality and on carbon partitioning. Finally, we discuss the prospects for using this knowledge for the molecular breeding of this sustainable crop via a candidate gene approach.

Modulation of innate immunity in carp : Diverse approaches to ß-glucanmediated responses
Petit, Jules - \ 2019
Wageningen University. Promotor(en): G.F. Wiegertjes; M. Forlenza. - Wageningen : Wageningen University - ISBN 9789463439466 - 202
An early β-glucan bath during embryo development increases larval size of Nile tilapia
Jesus, Raphael B. de; Petit, Jules ; Pilarski, Fabiana ; Wiegertjes, Geert F. ; Koch, João Fernando A. ; Oliveira, Carlos A.F. de; Zanuzzo, Fábio S. - \ 2019
Aquaculture Research 50 (2019)7. - ISSN 1355-557X - p. 2012 - 2014.
fish larvae - growth performance - hatching - immunostimulant - prebiotics
Studies Into β-Glucan Recognition in Fish Suggests a Key Role for the C-Type Lectin Pathway
Petit, Jules ; Bailey, Erin C. ; Wheeler, Robert T. ; Oliveira, Carlos A.F. de; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2019
Frontiers in Immunology 10 (2019). - ISSN 1664-3224 - 1 p.
C-type lectin-like domain - CTLD - Cyprinidae - primary macrophage - RNAseq analysis - teleost - transcriptome analysis - β-glucan

Immune-modulatory effects of β-glucans are generally considered beneficial to fish health. Despite the frequent application of β-glucans in aquaculture practice, the exact receptors and downstream signalling remains to be described for fish. In mammals, Dectin-1 is a member of the C-type lectin receptor (CLR) family and the best-described receptor for β-glucans. In fish genomes, no clear homologue of Dectin-1 could be identified so far. Yet, in previous studies we could activate carp macrophages with curdlan, considered a Dectin-1-specific β-(1,3)-glucan ligand in mammals. It was therefore proposed that immune-modulatory effects of β-glucan in carp macrophages could be triggered by a member of the CLR family activating the classical CLR signalling pathway, different from Dectin-1. In the current study, we used primary macrophages of common carp to examine immune modulation by β-glucans using transcriptome analysis of RNA isolated 6 h after stimulation with two different β-glucan preparations. Pathway analysis of differentially expressed genes (DEGs) showed that both β-glucans regulate a comparable signalling pathway typical of CLR activation. Carp genome analysis identified 239 genes encoding for proteins with at least one C-type Lectin Domains (CTLD). Narrowing the search for candidate β-glucan receptors, based on the presence of a conserved glucan-binding motif, identified 13 genes encoding a WxH sugar-binding motif in their CTLD. These genes, however, were not expressed in macrophages. Instead, among the β-glucan-stimulated DEGs, a total of six CTLD-encoding genes were significantly regulated, all of which were down-regulated in carp macrophages. Several candidates had a protein architecture similar to Dectin-1, therefore potential conservation of synteny of the mammalian Dectin-1 region was investigated by mining the zebrafish genome. Partial conservation of synteny with a region on the zebrafish chromosome 16 highlighted two genes as candidate β-glucan receptor. Altogether, the regulation of a gene expression profile typical of a signalling pathway associated with CLR activation and, the identification of several candidate β-glucan receptors, suggest that immune-modulatory effects of β-glucan in carp macrophages could be a result of signalling mediated by a member of the CLR family.

Data from: Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe
González Muñoz, N. ; Sterck, F.J. ; Torres-Ruiz, J.M. ; Petit, Giai ; Cochard, Hervé ; Arx, G. von; Lintunen, Anna ; Caldeira, Maria C. ; Capdeville, G. ; Copini, P. ; Gebauer, Roman ; Grönlund, Leila ; Hölttä, Teemu ; Lobo-do-Vale, Raquel L. ; Peltoniemi, M. ; Stritih, A. ; Urban, Josef ; Delzon, S. - \ 2018
hydraulic safety - hydraulic efficiency - phenotypic variability - drought - species distribution
Transcriptome analysis reveals several b-glucan recognition pathways in carp macrophages
Petit, J. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Studying metabolic pathways in macrophages of carp
Wentzel, A.S. ; Petit, J. ; Boer, V.C.J. de; Forlenza, M. ; Wiegertjes, G. - \ 2018
The role of fibers in poultry and swine nutrition’
Vries, Sonja de - \ 2018
Training the immune system to become as healthy as a fish
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Training carp macrophages: establishment of an in vitro screening model for trained immunity in teleost fish
Petit, J. ; Embregts, C.W.E. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; Declerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; O’Rourke, Megan E. ; Rusch, Adrien ; Poveda, Katja ; Jonsson, Mattias ; Rosenheim, Jay A. ; Schellhorn, Nancy A. ; Tscharntke, Teja ; Wratten, Stephen D. ; Zhang, Wei ; Iverson, Aaron L. ; Adler, Lynn S. ; Albrecht, Matthias ; Alignier, Audrey ; Angelella, Gina M. ; Zubair Anjum, Muhammad ; Avelino, Jacques ; Batáry, Péter ; Baveco, Johannes M. ; Bianchi, Felix J.J.A. ; Birkhofer, Klaus ; Bohnenblust, Eric W. ; Bommarco, Riccardo ; Brewer, Michael J. ; Caballero-López, Berta ; Carrière, Yves ; Carvalheiro, Luísa G. ; Cayuela, Luis ; Centrella, Mary ; Ćetković, Aleksandar ; Henri, Dominic Charles ; Chabert, Ariane ; Costamagna, Alejandro C. ; La Mora, Aldo De; Kraker, Joop De; Desneux, Nicolas ; Diehl, Eva ; Diekötter, Tim ; Dormann, Carsten F. ; Eckberg, James O. ; Entling, Martin H. ; Fiedler, Daniela ; Franck, Pierre ; Veen, F.J.F. van; Frank, Thomas ; Gagic, Vesna ; Garratt, Michael P.D. ; Getachew, Awraris ; Gonthier, David J. ; Goodell, Peter B. ; Graziosi, Ignazio ; Groves, Russell L. ; Gurr, Geoff M. ; Hajian-Forooshani, Zachary ; Heimpel, George E. ; Herrmann, John D. ; Huseth, Anders S. ; Inclán, Diego J. ; Ingrao, Adam J. ; Iv, Phirun ; Jacot, Katja ; Johnson, Gregg A. ; Jones, Laura ; Kaiser, Marina ; Kaser, Joe M. ; Keasar, Tamar ; Kim, Tania N. ; Kishinevsky, Miriam ; Landis, Douglas A. ; Lavandero, Blas ; Lavigne, Claire ; Ralec, Anne Le; Lemessa, Debissa ; Letourneau, Deborah K. ; Liere, Heidi ; Lu, Yanhui ; Lubin, Yael ; Luttermoser, Tim ; Maas, Bea ; Mace, Kevi ; Madeira, Filipe ; Mader, Viktoria ; Cortesero, Anne Marie ; Marini, Lorenzo ; Martinez, Eliana ; Martinson, Holly M. ; Menozzi, Philippe ; Mitchell, Matthew G.E. ; Miyashita, Tadashi ; Molina, Gonzalo A.R. ; Molina-Montenegro, Marco A. ; O’Neal, Matthew E. ; Opatovsky, Itai ; Ortiz-Martinez, Sebaastian ; Nash, Michael ; Östman, Örjan ; Ouin, Annie ; Pak, Damie ; Paredes, Daniel ; Parsa, Soroush ; Parry, Hazel ; Perez-Alvarez, Ricardo ; Perović, David J. ; Peterson, Julie A. ; Petit, Sandrine ; Philpott, Stacy M. ; Plantegenest, Manuel ; Plećaš, Milan ; Pluess, Therese ; Pons, Xavier ; Potts, Simon G. ; Pywell, Richard F. ; Ragsdale, David W. ; Rand, Tatyana A. ; Raymond, Lucie ; Ricci, Benoît ; Sargent, Chris ; Sarthou, Jean-Pierre ; Saulais, Julia ; Schäckermann, Jessica ; Schmidt, Nick P. ; Schneider, Gudrun ; Schüepp, Christof ; Sivakoff, Frances S. ; Smith, Henrik G. ; Stack Whitney, Kaitlin ; Stutz, Sonja ; Szendrei, Zsofia ; Takada, Mayura B. ; Taki, Hisatomo ; Tamburini, Giovanni ; Thomson, Linda J. ; Tricault, Yann ; Tsafack, Noelline ; Tschumi, Matthias ; Valantin-Morison, Muriel ; Trinh, Mai Van; Werf, Wopke Van Der; Vierling, Kerri T. ; Werling, Ben P. ; Wickens, Jennifer B. ; Wickens, Victoria J. ; Woodcock, Ben A. ; Wyckhuys, Kris ; Xiao, Haijun ; Yasuda, Mika ; Yoshioka, Akira - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)33. - ISSN 0027-8424 - p. E7863 - E7870.
IPM
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe
González-Muñoz, N. ; Sterck, F. ; Torres-Ruiz, J.M. ; Petit, G. ; Cochard, H. ; Arx, G. von; Lintunen, A. ; Caldeira, M.C. ; Capdeville, G. ; Copini, P. ; Gebauer, R. ; Grönlund, L. ; Hölttä, T. ; Lobo-do-Vale, R. ; Peltoniemi, M. ; Stritih, A. ; Urban, J. ; Delzon, S. - \ 2018
PLoS ONE 13 (2018)5. - ISSN 1932-6203
Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in four tree species, two angiosperms (Betula pendula, Populus tremula) and two conifers (Picea abies, Pinus sylvestris), across their latitudinal distribution in Europe. Growth and hydraulic efficiency varied widely within species and between populations. The variability of embolism resistance was in general weaker than that of growth and hydraulic efficiency, and very low for all species but Populus tremula. In addition, no and weak support for a safety vs. efficiency trade-off was observed for the angiosperm and conifer species, respectively. The limited variability of embolism resistance observed here for all species except Populus tremula, suggests that forest populations will unlikely be able to adapt hydraulically to drier conditions through the evolution of embolism resistance.
Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe
Petit, Giai ; Arx, Georg von; Kiorapostolou, Natasa ; Lechthaler, Silvia ; Prendin, Angela Luisa ; Anfodillo, Tommaso ; Caldeira, Maria C. ; Cochard, Hervé ; Copini, Paul ; Crivellaro, Alan ; Delzon, Sylvain ; Gebauer, Roman ; Gričar, Jožica ; Grönholm, Leila ; Hölttä, Teemu ; Jyske, Tuula ; Lavrič, Martina ; Lintunen, Anna ; Lobo-do-Vale, Raquel ; Peltoniemi, Mikko ; Peters, Richard L. ; Robert, Elisabeth M.R. ; Roig Juan, Sílvia ; Senfeldr, Martin ; Steppe, Kathy ; Urban, Josef ; Camp, Janne Van; Sterck, Frank - \ 2018
New Phytologist 218 (2018)4. - ISSN 0028-646X - p. 1383 - 1392.
Allocation - Climate change - Functional balance - Leaf area - Plant architecture - Sapwood - Structural balance - Xylem
Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL: AX balance in response to climate conditions, but whether trees of different species acclimate in AL: AX in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of AL vs AX in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, AL and AX change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of AL vs AX with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance.
Increased oxygen radicals and phagocytosis, and altered immune response dynamics in trained carp macrophages
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2017
Increased immune activities in "trained" common carp macrophages
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2017
- 1 p.
Intramuscular DNA vaccination of juvenile carp against spring viremia of carp virus induces full protection and Establishes a Virus-Specific B and T Cell Response
Embregts, Carmen W.E. ; Rigaudeau, Dimitri ; Veselỳ, Tomáš ; Pokorová, Dagmar ; Lorenzen, Niels ; Petit, Jules ; Houel, Armel ; Dauber, Malte ; Schütze, Heike ; Boudinot, Pierre ; Wiegertjes, Geert F. ; Forlenza, Maria - \ 2017
Frontiers in Immunology 8 (2017). - ISSN 1664-3224 - 16 p.
B cells - DNA vaccination - Rhabdovirus - Spring viremia of carp virus - T cells

Although spring viremia of carp virus (SVCV) can cause high mortalities in common carp, a commercial vaccine is not available for worldwide use. Here, we report a DNA vaccine based on the expression of the SVCV glycoprotein (G) which, when injected in the muscle even at a single low dose of 0.1 μg DNA/g of fish, confers up to 100% protection against a subsequent bath challenge with SVCV. Importantly, to best validate vaccine efficacy, we also optimized a reliable bath challenge model closely mimicking a natural infection, based on a prolonged exposure of carp to SVCV at 15°C. Using this optimized bath challenge, we showed a strong age-dependent susceptibility of carp to SVCV, with high susceptibility at young age (3 months) and a full resistance at 9 months. We visualized local expression of the G protein and associated early inflammatory response by immunohistochemistry and described changes in the gene expression of pro-inflammatory cytokines, chemokines, and antiviral genes in the muscle of vaccinated fish. Adaptive immune responses were investigated by analyzing neutralizing titers against SVCV in the serum of vaccinated fish and the in vitro proliferation capacity of peripheral SVCV-specific T cells. We show significantly higher serum neutralizing titers and the presence of SVCV-specific T cells in the blood of vaccinated fish, which proliferated upon stimulation with SVCV. Altogether, this is the first study reporting on a protective DNA vaccine against SVCV in carp and the first to provide a detailed characterization of local innate as well as systemic adaptive immune responses elicited upon DNA vaccination that suggest a role not only of B cells but also of T cells in the protection conferred by the SVCV-G DNA vaccine.

Effect of the middle lamella biochemical composition on the non-linear behaviour of technical fibres of hemp under tensile loading using strain mapping
Fuentes, C.A. ; Willekens, P. ; Petit, J. ; Thouminot, C. ; Müssig, J. ; Trindade, L.M. ; Vuure, A.W. Van - \ 2017
Composites Part A: Applied Science and Manufacturing 101 (2017). - ISSN 1359-835X - p. 529 - 542.
A. Biocomposite - A. Natural fibres - B. Fibre deformation - Strain mapping
This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of technical fibres of hemp used for composite applications. First, the strength and apparent Young's modulus distribution of technical fibres of hemp of 96 hemp samples, corresponding to 32 different hemp accessions cultivated in 3 locations, were analysed using Weibull distribution. From these, 2 samples (one with high and one with low fibre strength) were selected for further analysis. Next, full-field strain measurement at the micro-scale during tensile loading via digital image correlation analysis was used for evaluating both, the stress-strain behaviour at a global scale and the local mechanical behaviour heterogeneity at a micro-scale, along a technical fibre of hemp. The analysis reveals 2 typical types of tensile stress-strain curves, and a complex and very irregular pattern of strain concentrations, which are associated to the technical fibre strength. The non-linear behaviour of the stress-strain curve is explained by the development of shear strain at the elementary fibre (botanically defined as the individual cell) interphases. Micro tomography and biochemical analysis of the technical fibre microstructure showed that alterations in cell wall composition, in particular substitution of pectin, leads to changes in the non-linear behaviour of technical fibres of hemp under tensile loading.
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