Henri Darmency

French National Institute for Agricultural Research, Lutetia Parisorum, Île-de-France, France

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Publications (105)252.11 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The introduction of genetically-modified (GM) crops is often accompanied by other changes in cultural practices. The objective of the present study was to evaluate these changes with the simulation model FlorSys which quantifies the effects of cropping systems and pedoclimate on weed dynamics as well as indicators of weed-related biodiversity (species richness and equitability, trophic resources for birds, insects and pollinators) and crop production loss (yield loss, harvest contamination, harvesting problems, field infestation). The study focused on two GM maize variety types, i.e. expressing Bacillus thuringiensis toxins against insects (Bt) and tolerating the non-selective herbicide glyphosate (HT). Two contrasting maize-growing sites were studied: Aquitaine, a region in South-Western France, and Catalonia in North-Eastern Spain. Typical regional cropping systems containing maize were identified for each site from expert knowledge and the Biovigilance database recording French agricultural practices. GM scenarios were based on expert knowledge, literature and current Spanish practices. A total of 11 most probable scenarios (1 conventional, 3 Bt and 8 HT) were simulated over 28 years for each region, and repeated with 10 different regional random weather series. An additional series of 5–7 scenarios per region was run to decorrelate factors, and make it easier to identify the cultural practices responsible for changes in weed flora, biodiversity and production. The simulations showed that the changes accompanying the introduction of GM maize varieties affected weed flora as well as weed-related biodiversity and crop production loss, but that the consequences depended on local conditions. Most of these consequences were caused by simplifications in the cropping systems made possible by the GM varieties, rather than by the glyphosate associated to GM varieties. Simplified tillage or no-till increased weed harmfulness, particularly in Aquitaine where the weed flora was poorer and dominated by larger and more persistent species. Conversely, no-till cancelled part or all of the nefarious effects on biodiversity of simplified rotations (maize/wheat and maize monoculture), particularly by improving trophic resources offered by weeds to birds, insects and pollinators. Overall, biodiversity was less affected by simplified rotations in Catalonia where the initial weed flora was richer and more equitable. Delayed maize sowing reduced weed harmfulness and biodiversity, except food offer for insects and pollinators whose pertinent feeding period covered spring and summer (vs. winter for birds). Based on the two most affected weed-based biodiversity indicators, ex post monitoring after GM introduction should focus on birds in Aquitaine and on pollinators in Catalonia.
    Agricultural Systems 07/2015; 137. DOI:10.1016/j.agsy.2015.03.009 · 2.91 Impact Factor
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    ABSTRACT: The evolutionary trajectory of isolated or small populations of self-incompatible species depends on genetic variation in the capacity to transition to self-compatibility and the impact of inbreeding on plant fitness. Centaurea cyanus is an example of a self-incompatible, arable field-dependent weed species that is in regression in western Europe due to agricultural intensification. However, some cases of self-fertilization have been observed. Here, we investigated how inbreeding depression impacts the plants by studying two generations of self-fertilized families. As early as at the stage of the first selfing generation, we observed reduction in the number of florets per capitulum. By the second selfing generation, we observed reductions in germination rate, plant height, above-ground plant biomass, seed set and the final number and mass of seeds per plant. In particular, dramatically lower germination rate and reduced seed set contributed to a low cumulative fitness index of the generations that resulted from selfing. Nevertheless, although high average inbreeding depression was observed, large variation in cumulative fitness among families would allow some of these selfed families to persist and trigger evolution of selfing in small, isolated populations.
    Flora - Morphology Distribution Functional Ecology of Plants 02/2015; 212. DOI:10.1016/j.flora.2015.02.003 · 1.47 Impact Factor
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    ABSTRACT: This article investigates the possible existence of mechanisms counterbalancing the negative pleiotropic effects on development and reproduction that are conferred by alleles responsible for herbicide resistance in the weed Alopecurus myosuroides. We considered three herbicide-resistant, mutant acetyl-coenzyme A carboxylase (ACCase) alleles, Leu1781, Asn2041, and Gly2078, found in eight resistant populations.Of these, Gly2078 is the only allele with a known fitness cost. We compared plants homozygous for wild-type ACCase alleles that were siblings of plants carrying a given mutant resistant ACCase allele with plants from three populations where resistance did not evolve. In each of two series of experiments, we measured germination dynamics, seedling vigor, plant height, vegetative biomass, and seed production. The wild-type siblings of plants carrying Gly2078 performed better in the field, on average, than wild-type plants that were sibling of plants carrying other mutant ACCase alleles, and particularly those carrying Leu1781. We propose that rapid evolution of the genetic background of plants from the populations where the Gly2078 allele originally arose could partially counterbalance Gly2078 fitness cost, enhancing the spread of the resistant genotypes.
    Evolution 01/2015; 69:271-278. DOI:10.1111/evo.12531 · 4.61 Impact Factor
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    ABSTRACT: Agricultural intensification has resulted in drastic regression of several arable land–dependent weeds. This decrease, along with reduced pollinator abundance, could lead to population-level extinction of self-incompatible species. Alternatively, it could drive adaptation to self-compatibility through selection on standing genetic variation. We investigated whether pseudo-self-compatible (PSC) or self-compatible (SC) plants are present in populations of the rarified weed Centaurea cyanus in the species’ extreme western distribution limits in Europe.We compared seed production of isolated plants and of pairs of plants in cages with or without pollinators. We showed that pollinators are necessary for self-fertilization. The majority of plants were self-incompatible (SI), but about 12% were PSC, and one was SC. Reproductive traits of PSC plants were not different from those of other plants. There was no difference between plants from two regions that differed in C. cyanus abundance. We conclude that the genetic variation necessary to transition to selfing is present in C. cyanus; this could help to maintain endangered populations, but the transition to selfing does not appear to have happened in nature yet.
    Flora - Morphology Distribution Functional Ecology of Plants 07/2014; 209(7). DOI:10.1016/j.flora.2014.04.002 · 1.47 Impact Factor
  • V Le Corre · S Bellanger · J‐P Guillemin · H Darmency
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    ABSTRACT: Agricultural intensification has recently resulted in the decrease in frequency and abundance of arable weed species. This includes the previously widespread Centaurea cyanus, whose populations are now fragmented and infrequent in western Europe. The consequences of habitat modification and fragmentation in terms of genetic diversity of the remaining populations have not yet been addressed. We used ten microsatellite markers to assess the genetic diversity and genetic structure of populations contained in an agricultural landscape in north-eastern France. The ten microsatellites were all highly polymorphic. Centaurea cyanus appears to be a genetically variable species, with high levels of genetic diversity within each cultivated field. Genetic structure was investigated using a Bayesian method. The partitioning of the genetic variation into three clusters was not associated with sampling locations, and most individuals were admixed. These results suggest that the cornflower populations investigated may have multiple origins in the past and that genetic variation has been reshuffled by human transportation of seeds. Thus, anthropogenic dispersal associated with farming activities is probably a major factor driving the structure of genetic diversity in arable land plants. Despite low levels of genetic differentiation between populations, fine-scale spatial genetic structure was observed within populations, suggesting limited local dispersal. We conclude that in areas where C. cyanus has become rare, the recent fragmentation of populations may in the future cause a loss of genetic diversity and even extinction.
    Weed Research 05/2014; 54(5). DOI:10.1111/wre.12087 · 1.69 Impact Factor
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    ABSTRACT: Crop-to-wild transgene flow is a critical aspect of the environmental risks associated to the introduction of genetically modified (GM) crops because the integration of an advantageous transgene could make the recipient population of wild species become invasive. This risk relies on three successive steps: (1) the initial GM crop-wild hybridization event, (2) the transmission of the transgene in the successive (backcross) hybrids generations and (3) the spread of the GM hybrid plants via pollen and seed dispersal. Using simulation models is necessary to account for the probabilities associated to all these events in order to make quantitative predictions of the risk of invasion by GM hybrids. We develop a simulation model to predict the fate of an advantageous transgene in a population of a wild relative species, following hybridization with a GM crop. We first present the generic model structure, with its three main components: stage-structure (developmental stages and hybrid classes), spatial realism, and stochasticity (demographic, genetic and dispersal). We show how a preliminary elasticity analysis can be performed to guide the parameterization of an uncertainty analysis by focusing on the most influencing parameters. We then use herbicide tolerant GM oilseed rape and its wild relative wild radish as an application of the simulation model. Despite the large uncertainty on some input parameters, simulations showed that invasion by the transgene was quasi-impossible within decaying wild radish populations whereas it was quasi-certain within viable populations. More generally, the modeling framework developed here provides a generic structure that can be applied to other wild and crop species. Our study underlined that uncertainty analyses are crucial in risk assessment because they permit to translate parameter uncertainty into uncertainty of model predictions.
    Ecological Modelling 03/2014; 276:85–94. DOI:10.1016/j.ecolmodel.2014.01.004 · 2.32 Impact Factor
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    Yongbo Liu · Wei Wei · Keping Ma · Junsheng Li · Yuyong Liang · Henri Darmency
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    ABSTRACT: Numerous studies have focused on the probability of occurrence of gene flow between transgenic crops and their wild relatives and the likelihood of transgene escape, which should be assessed before the commercial release of transgenic crops. This review paper focuses on this issue for oilseed rape, Brassica napus L., a species that produces huge numbers of pollen grains and seeds. We analyze separately the distinct steps of gene flow: (1) pollen and seeds as vectors of gene flow; (2) spontaneous hybridization; (3) hybrid behavior, fitness cost due to hybridization and mechanisms of introgression; (4) and fitness benefit due to transgenes (e.g. herbicide resistance and Bt toxin). Some physical, biological and molecular means of transgene containment are also described. Although hybrids and first generation progeny are difficult to identify in fields and non-crop habitats, the literature shows that transgenes could readily introgress into Brassica rapa, Brassica juncea and Brassica oleracea, while introgression is expected to be rare with Brassica nigra, Hirschfeldia incana and Raphanus raphanistrum. The hybrids grow well but produce less seed than their wild parent. The difference declines with increasing generations. However, there is large uncertainty about the evolution of chromosome numbers and recombination, and many parameters of life history traits of hybrids and progeny are not determined with satisfactory confidence to build generic models capable to really cover the wide diversity of situations. We show that more studies are needed to strengthen and organize biological knowledge, which is a necessary prerequisite for model simulations to assess the practical and evolutionary outputs of introgression, and to provide guidelines for gene flow management.
    Plant Science 10/2013; 211:42-51. DOI:10.1016/j.plantsci.2013.07.002 · 3.61 Impact Factor
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    H. Darmency · C. Sausse · S. Cordeau · J. Gasquez · A. Messean
  • Henri Darmency
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    ABSTRACT: The rapid adoption of genetically engineered herbicide-resistant crop varieties (HRCV) - encompassing 83 % of all GM crops and nearly 8 % of the worldwide arable area - is due to technical efficiency and higher returns. Other herbicide-resistant varieties obtained from genetic resources and mutagenesis have also been successfully released. Although the benefit for weed control is the main criteria for choosing HRCVs, the pleiotropic costs of genes endowing resistance have rarely been investigated in crops. Here the available data of comparisons between isogenic resistant and susceptible varieties are reviewed. Pleiotropic harmful effects on yield are reported in half of the cases, mostly with resistance mechanisms that originate from genetic resources and mutagenesis (atrazine in oilseed rape and millet, trifluralin in millet, imazamox in cotton) rather than genetic engineering (chlorsulfuron and glufosinate in some oilseed rape varieties, glyphosate in soybean). No effect was found for sethoxydim and bromoxynil resistance. Variable minor effects were found for imazamox, chlorsulfuron, glufosinate and glyphosate resistance. The importance of the breeding plan and the genetic background on the emergence of these effects is pointed out. Breeders' efforts to produce better varieties could compensate for the yield loss, which eliminates any possibility of formulating generic conclusions on pleiotropic effects that can be applied to all resistant crops.
    Pest Management Science 08/2013; 69(8). DOI:10.1002/ps.3522 · 2.69 Impact Factor
  • Biofutur 02/2013; · 0.05 Impact Factor
  • Yongbo Liu · Wei Wei · Keping Ma · Henri Darmency
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    ABSTRACT: Introgression between transgenic, insect-resistant crops and their wild relatives could lead to a progressive increase of the frequency of resistant plants in wild populations. However, few studies help predict the impact on the population dynamics. To simulate the performance of introgressed insect-resistant plants of wild Brassica juncea, independently from the interspecific hybridization cost, healthy plants were cultivated in pure and mixed stands with damaged plants through cutting leaves in field experiments over two field seasons. As expected, resistant (healthy) plants held a competitive advantage when in competition with susceptible (damaged) plants. Individual biomass and seed production of both types of plants decreased as the percentage of resistant plants increased, so that the relative advantage of resistant plants increased. The combined effects of defoliation and competition on the individual performance of B. juncea were additive. Replacement series experiments confirmed this trend but did not show different seed output in pure stand of susceptible versus resistant plots. The total vegetative and reproductive production of mixed populations was not significantly different of that of pure populations. These results suggest that if a transgene for insect-resistance were to colonize wild populations, high herbivory of susceptible plant and low resource availability would facilitate the spread of resistant individuals. However, at the population level, the shift from an insect-susceptible to a predominantly resistant population would not result in exacerbated habitat colonization.
    Transgenic Research 12/2012; 22(4). DOI:10.1007/s11248-012-9679-y · 2.32 Impact Factor
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    ABSTRACT: Bellanger S, Guillemin J-P, Bretagnolle V & Darmency H (2012). Centaurea cyanus as a biological indicator of segetal species richness in arable fields. Weed Research52, 551–563. Agricultural intensification has resulted in a loss of biological diversity within European agroecosystems. Biological indicator species are important tools for monitoring species diversity. The aim of this study was to determine whether cornflower, Centaurea cyanus, an arable land specialist segetal species that is easily identified in the countryside, is an appropriate indicator of weed species diversity in the Poitou-Charentes region of western France. The study zones selected were those in which C. cyanus was present in agricultural fields when monitoring was conducted in both 2006 and 2007. All plant species in sample fields sown with winter crops (cereals and oilseed rape) within the study zones were then inventoried in two consecutive years: 2008 and 2009. For these winter crops, C. cyanus presence was not a good indicator of overall species richness within the fields. However, C. cyanus presence did correlate with the presence of other arable land specialists, herein called segetal species. Reciprocally, the presence of most other segetal species found at low frequencies in the study zones also correlated with higher segetal richness. We discuss the conditions for using C. cyanus as an indicator of segetal diversity with regards to conservation and ecosystem services.
    Weed Research 12/2012; 52(6). DOI:10.1111/j.1365-3180.2012.00946.x · 1.69 Impact Factor
  • H. Darmency
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    ABSTRACT: This chapter explores basic biological, agronomic, and economical issues relevant to sugar beet agriculture, as well as the different possible sources of admixture between GM and non-GM sugar beet roots. Admixture occurs primarily within sown seed lots, due to gene flow and seed handling in the nursery, and through root collection procedures that occur between the time of harvest and product arrival at the sugar refinery. Other coexistence issues must be addressed because sugar beets exhibit a low rate of bolting, which results in accidental pollen flow to the surrounding area. In addition, roots left unharvested in the field can survive through the winter and flower the following year. I present analyses of the consequences of gene flow from GM beets to: sea beets (posing a threat to genetic resources), vegetable and garden beets (posing a threat to private propagation), and weed beets (posing a threat to farming systems, especially in the case of herbicide-resistant GM beets).
    Genetically Modified and Non-Genetically Modified Food Supply Chains: Co-Existence and Traceability, 10/2012: pages 35-48; , ISBN: 9781444337785
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    Mathilde Sester · Henri Darmency · Nathalie Colbach
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    ABSTRACT: Weed beet cannot be controlled by herbicides in sugar beet (except via height-selective applicators) as it is a crop relative, descending from accidentally flowering sugar beet (Beta vulgaris) crop plants either because of vernalization during cold springs, or presence of a dominant bolting allele in sugar beet seed lots due to cross-pollination by annual wild beet (B. vulgaris ssp. maritima) in seed production areas. A second, minor source of weed beet are crop roots lost during harvest. These roots (“groundkeepers”) can reproduce in the year after sugar beet and potentially contribute to weed beet dynamics and gene flow. Bolting, flowering and seed production timing and potential of groundkeepers were measured in field experiments. Bolting and flowering were faster in groundkeepers vs. weed beet; flower and seed production was lower in groundkeepers but the latter were less sensitive to competitive crops. The measured parameters were used to introduce a ground-keeper life-cycle into the GeneSys-Beet model which quantifies the effects of cropping systems on weed beet in landscapes. Simulations over several years showed weed beet dynamics to be more sensitive to groundkeeper parameter values than to root loss at sugar beet harvest. Groundkeepers were identified as a key source of weed beet populations and of gene escape from novel sugar beet varieties (e.g. genetically-modified herbicide-tolerant varieties) in the absence of crop bolters. The control of the latter, either by manual weeding or by genetic improvement of sugar beet varieties, was shown to be essential for controlling weed beet populations and avoid the advent of herbicide-tolerant weed beet.
    Field Crops Research 06/2012; 135:46-57. DOI:10.1016/j.fcr.2012.06.019 · 2.98 Impact Factor
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    Yong-Bo Liu · Zhi-Xi Tang · Henri Darmency · C Neal Stewart · Kun Di · Wei Wei · Ke-ping Ma
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    ABSTRACT: Seed size has significant implications in ecology, because of its effects on plant fitness. The hybrid seeds that result from crosses between crops and their wild relatives are often small, and the consequences of this have been poorly investigated. Here we report on plant performance of hybrid and its parental transgenic oilseed rape (Brassica napus) and wild B. juncea, all grown from seeds sorted into three seed-size categories. Three seed-size categories were sorted by seed diameter for transgenic B. napus, wild B. juncea and their transgenic and non-transgenic hybrids. The seeds were sown in a field at various plant densities. Globally, small-seeded plants had delayed flowering, lower biomass, fewer flowers and seeds, and a lower thousand-seed weight. The seed-size effect varied among plant types but was not affected by plant density. There was no negative effect of seed size in hybrids, but it was correlated with reduced growth for both parents. Our results imply that the risk of further gene flow would probably not be mitigated by the small size of transgenic hybrid seeds. No fitness cost was detected to be associated with the Bt-transgene in this study.
    PLoS ONE 06/2012; 7(6):e39705. DOI:10.1371/journal.pone.0039705 · 3.23 Impact Factor
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    ABSTRACT: Dormancy and longevity of soil-buried weed seeds: from examples to generalization
  • Nathalie Colbach · B. CHAUVEL · Henri Darmency · Yann Tricault
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    ABSTRACT: Cropping systems contain a diverse multi-species weed flora including several species that cross-breed with and/or descend from crops, including weed beet (Beta vulgaris ssp. vulgaris). The effects of cropping systems on this weed flora are complex because of their large range of variation and their numerous interactions with climate and soil conditions. In order to study and quantify the long-term effects of cropping system components (crop succession and cultural techniques) on weed population dynamics, a biophysical process-based model called GENESYS-Beet has previously been developed for weed beet. In the present paper, the model was modified to remove the crop–weed connection and employed to identify and rank the weed life-traits as a function of their effect on weed emergence timing and density as well as on weed densities at plant, adult and seed bank stages, using a global sensitivity analysis to model parameters. A similar method has already been used with the complete GENESYS-Beet model (i.e. including the crop–weed connection) based on Monte Carlo simulations with simultaneous randomization of all life-trait parameters and run in three cropping systems differing in their risk of infestation by weed beet. Simulated weed emergence timing and density, as well as surviving plant, adult and seed bank densities, were then analysed with regression models as a function of model parameters to rank life-cycle processes and related life-traits and quantify their effects. The comparison of the present, crop-independent results to those of the previous, crop-dependent study showed that the crop-relative weed beet can be considered as a typical crop-independent spring weed as long as no traits conferring a selective advantage are inherited and in rotations where crops favouring weed emergence and reproduction are frequent. In such rotations, advice for controlling the crop-relative and the crop-independent weed is more or less identical. The rarer these favourable crops, the more important pre-emergence processes become for the crop-independent weed; management advice should thus focus more on seed bank survival and seedling emergence. For the crop-relative, post-emergence processes become dominant because of the increasing necessity for a new population founding event; management advice should mostly concern the avoidance of crop bolters. In both studies, the key parameters were more or less the same, i.e. those determining the timing and success of growth, development, seed maturation and the physiological end of seed production. Timing parameters were usually more important than success parameters, showing for instance that optimal timing of weed management operations is often more important than its exact efficacy. Comparison with previous sensitivity analyses carried out for autumn-emerging weed species showed that some of the present conclusions are probably specific to spring-emerging weed species only. For autumn-emerging species, pre-emergence traits would be more important. In the rotations with frequent favourable crops and insufficient weed control, interactions between traits were small, indicating that diverse populations and species with contrasting traits could prosper, potentially leading to a diverse multi-species weed flora. Conversely, when favourable crops were rare and weed control optimal, traits had little impact individually, indicating that a small number of optimal combinations of traits would be successful, thus limiting both intra- and inter-specific variability.
    The Journal of Agricultural Science 11/2011; 149(06):679 - 700. DOI:10.1017/S0021859611000220 · 0.65 Impact Factor
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    ABSTRACT: Longévité et dormance de semences enfouies dans le sol chez deux espèces adventices
  • H. Darmency · C. Ouin · J. Pernes
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    ABSTRACT: An interspecific cross was carried out between the cultivated foxtail millet, Setaria italica, and its wild relative the green foxtail, S. viridis. Quantitative characters (19 descriptors of morphology and reproduction) were studied using the F1 F2, and F3 generations. Moreover, this F2 was compared with the tetraploid F2 obtained from a colchicine-induced F1. The multivariate analysis of the diploid F2 showed two complex associations of characters: one concerning developmental traits (organs dimensions and flowering) and the other dealing with taxonomical characteristics (tillering, seed shedding, and seed weight). The tetraploidization resulted in a shift in characteristics towards the crop species, especially a twofold increase in seed weight. Nonadditive effects were found for most characters, except for the seed shedding, which was found to be encoded by at least four loci. However, cultivated type plants were easily recovered in both the diploid and the tetraploid F2. This demonstrates the potential of interspecific hybridization and polyploidization to improve the crop properties of the foxtail millet.
    Genome 02/2011; 29(3):453-456. DOI:10.1139/g87-078 · 1.42 Impact Factor

Publication Stats

2k Citations
252.11 Total Impact Points


  • 1985–2014
    • French National Institute for Agricultural Research
      Lutetia Parisorum, Île-de-France, France
  • 2008
    • University of Burgundy
      Dijon, Bourgogne, France
  • 1987
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
    • Université Paris-Sud 11
      Orsay, Île-de-France, France