Recent Submissions

  • Journal Article

    Soil biota in vineyards are more influenced by plants and soil quality than by tillage intensity or the surrounding landscape 

    Buchholz, Jacob; Querner, Pascal; Paredes, Daniel; Bauer, Thomas; Strauss, Peter; Guernion, Muriel; Scimia, Jennifer; Cluzeau, Daniel; Burel, Françoise; Kratschmer, Sophie; et al.
    Winter, SilviaPotthoff, MartinZaller, Johann G.
    Scientific Reports 2017; 7(1)
    Tillage is known for its adverse effects on soil biota, at least in arable agroecosystems. However, in vineyards effects might differ as tillage is often performed during dry periods or only in every other inter-row allowing species to re-colonise disturbed areas. We examined the response of earthworms (lumbricids), springtails (collembola) and litter decomposition to periodically mechanically disturbed (PMD) and permanently green covered (PGC) vineyard inter-rows and assessed whether site effects are altered by the surrounding landscape. In commercial vineyards in Austria we sampled earthworms by handsorting, springtails by soil coring and pitfall trapping and installed litter decomposition bags. Earthworm species diversity increased with plant biomass under PMD but not under PGC; earthworm density was unaffected by tillage but increased with plant biomass mainly at high soil quality (soil fertility index). Springtail species diversity was unaffected by tillage; springtail densities (mainly larger species) were reduced under PGC. Litter decomposition was little affected by investigated parameters. Landscape heterogeneity affected the functional diversity of surface springtails, but did not influence soil-dwelling springtails, earthworms or litter decomposition. We conclude that effects on soil biota of periodical tillage in vineyards need not necessarily be detrimental and will be modified by plant biomass and soil quality.
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  • Journal Article

    Effects of forest‐use intensity on vascular epiphyte diversity along an elevational gradient 

    Guzmán‐Jacob, Valeria; Zotz, Gerhard; Craven, Dylan; Taylor, Amanda; Krömer, Thorsten; Monge‐González, María Leticia; Kreft, Holger
    Diversity and Distributions
    Aim: Understanding patterns of tropical plant diversity and their vulnerability to anthropogenic disturbance at different spatial scales remains a great challenge in ecology and conservation. Here, we study how the effects of forest‐use intensity on vascular epiphyte diversity vary along a tropical elevational gradient. Location: 3,500‐m elevational gradient along the eastern slopes of Cofre de Perote, Mexico. Methods: We studied the effects of forest‐use intensity on alpha, beta and gamma diversity of vascular epiphyte assemblages in old‐growth, degraded and secondary forests at eight study sites at 500‐m intervals along the elevational gradient. At each elevation and in each of the three forest‐use intensity levels, we established five 400‐m2 plots yielding a total of 120 plots. Results: Interactive effects of elevation and forest‐use intensity strongly impacted local‐scale patterns of vascular epiphyte diversity. Species diversity peaked at 500 as well as 1,500 m above sea level, which deviates from the previously reported humpshaped pattern. In most cases, alpha diversity did not differ significantly among forest‐ use intensity levels. However, gamma diversity was always lower in secondary forests compared to old‐growth forests across the entire elevational gradient. Within each elevational belt, beta diversity was dominated by species turnover along the forest‐use intensity gradient in the lowlands and declined with increasing elevation, where community composition became increasingly nested. Along the elevational gradient, the spatial turnover of vascular epiphyte community composition was similar among forest‐use intensity levels. Main conclusions: Our results reveal a strong interaction between forest‐use intensity and elevation, making it difficult to extrapolate findings from one elevational belt to another. Our findings highlight the value of old‐growth forest for epiphyte diversity, but also show that degraded and secondary forests—depending on the elevational belt—may maintain a high species diversity and thus play an important role in conservation planning.
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  • Journal Article

    The NLRX R package: A next‐generation framework for reproducible NetLogo model analyses 

    Salecker, Jan; Sciaini, Marco; Meyer, Katrin M.; Wiegand, Kerstin
    Methods in Ecology and Evolution
    1. Agent‐based models find wide application in all fields of science where large‐scale patterns emerge from properties of individuals. Due to increasing capacities of computing resources it was possible to improve the level of detail and structural realism of nextgeneration models in recent years. However, this is at the expense of increased model complexity, which requires more efficient tools for model exploration, analysis and documentation that enable reproducibility, repeatability and parallelization. NetLogo is a widely used environment for agent‐based model development, but it does not provide sufficient built‐in tools for extensive model exploration, such as sensitivity analyses. One tool for controlling NetLogo externally is the r‐package RNetLogo. However, this package is not suited for efficient, reproducible research as it has stability and resource allocation issues, is not straightforward to be setup and used on high performance computing clusters and does not provide utilities, such as storing and exchanging metadata, in an easy way. 2. We present the r‐package nlrx, which overcomes stability and resource allocation issues by running NetLogo simulations via dynamically created XML experiment files. Class objects make setting up experiments more convenient and helper functions provide many parameter exploration approaches, such as Latin Hypercube designs, Sobol sensitivity analyses or optimization approaches. Output is automatically collected in user‐friendly formats and can be post‐processed with provided utility functions. nlrx enables reproducibility by storing all relevant information and simulation output of experiments in one r object which can conveniently be archived and shared. 3. We provide a detailed description of the nlrx package functions and the overall workflow. We also present a use case scenario using a NetLogo model, for which we performed a sensitivity analysis and a genetic algorithm optimization. 4. The nlrx package is the first framework for documentation and application of reproducible NetLogo simulation model analysis.
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  • Journal Article

    EFForTS-LGraf: A landscape generator for creating smallholder-driven land-use mosaics 

    Salecker, Jan; Dislich, Claudia; Wiegand, Kerstin; Meyer, Katrin M.; Pe´er, Guy
    PLOS ONE 2019; 14(9): Art. e0222949
    Spatially-explicit simulation models are commonly used to study complex ecological and socio-economic research questions. Often these models depend on detailed input data, such as initial land-cover maps to set up model simulations. Here we present the landscape generator EFFortS-LGraf that provides artificially-generated land-use maps of agricultural landscapes shaped by small-scale farms. EFForTS-LGraf is a process-based landscape generator that explicitly incorporates the human dimension of land-use change. The model generates roads and villages that consist of smallholder farming households. These smallholders use different establishment strategies to create fields in their close vicinity. Crop types are distributed to these fields based on crop fractions and specialization levels. EFForTS-LGraf model parameters such as household area or field size frequency distributions can be derived from household surveys or geospatial data. This can be an advantage over the abstract parameters of neutral landscape generators. We tested the model using oil palm and rubber farming in Indonesia as a case study and validated the artificially-generated maps against classified satellite images. Our results show that EFForTS-LGraf is able to generate realistic land-cover maps with properties that lie within the boundaries of landscapes from classified satellite images. An applied simulation experiment on landscape-level effects of increasing household area and crop specialization revealed that larger households with higher specialization levels led to spatially more homogeneous and less scattered crop type distributions and reduced edge area proportion. Thus, EFForTS-LGraf can be applied both to generate maps as inputs for simulation modelling and as a stand-alone tool for specific landscape-scale analyses in the context of ecological-economic studies of smallholder farming systems.
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  • Journal Article

    Mortality of Different Populus Genotypes in Recently Established Mixed Short Rotation Coppice with Robinia pseudoacacia L. 

    Rebola-Lichtenberg, Jessica; Schall, Peter; Annighöfer, Peter; Ammer, Christian; Leinemann, Ludger; Polle, Andrea; Euring, Dejuan
    Forests 2019; 10(5): Art. 410
    Short rotation coppices play an increasing role in providing wooden biomass for energy. Mixing fast-growing tree species in short rotation coppices may result in complementary e ects and increased yield. The aim of this study was to analyze the e ect on mortality of eight di erent poplar genotypes (Populus sp.) in mixed short rotation coppices with three di erent provenances of the N-fixing tree species black locust (Robinia pseudoacacia L.). Pure and mixed stands were established at two sites of contrasting fertility. Survival of poplar was assessed for each tree two times a year, for a period of three years. In the first two years, high variation in mortality was observed between the genotypes, but no significant di erences between pure and mixed stands were identified. However, three years after planting, higher mortality rates were observed in the mixtures across all poplar genotypes in comparison to pure stands. The expected advantage on growth of combining an N-fixing tree with an N-demanding tree species, such as poplar, was overshadowed by the Robinia’s dominance and competitiveness.
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  • Journal Article

    Biodiversity data integration—the significance of data resolution and domain 

    König, Christian; Weigelt, Patrick; Schrader, Julian; Taylor, Amanda; Kattge, Jens; Kreft, Holger
    PLOS Biology 2019; 17(3): Art. e3000183
    ecent years have seen an explosion in the availability of biodiversity data describing the distribution, function, and evolutionary history of life on earth. Integrating these heterogeneous data remains a challenge due to large variations in observational scales, collection purposes, and terminologies. Here, we conceptualize widely used biodiversity data types according to their domain (what aspect of biodiversity is described?) and informational resolution (how specific is the description?). Applying this framework to major data providers in biodiversity research reveals a strong focus on the disaggregated end of the data spectrum, whereas aggregated data types remain largely underutilized. We discuss the implications of this imbalance for the scope and representativeness of current macroecological research and highlight the synergies arising from a tighter integration of biodiversity data across domains and resolutions. We lay out effective strategies for data collection, mobilization, imputation, and sharing and summarize existing frameworks for scalable and integrative biodiversity research. Finally, we use two case studies to demonstrate how the explicit consideration of data domain and resolution helps to identify biases and gaps in global data sets and achieve unprecedented taxonomic and geographical data coverage in macroecological analyses.
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  • Journal Article

    Collembola interact with mycorrhizal fungi in modifying oak morphology, C and N incorporation and transcriptomics 

    Graf, Marcel; Bönn, Markus; Feldhahn, Lasse; Kurth, Florence; Grams, Thorsten E. E.; Herrmann, Sylvie; Tarkka, Mika; Buscot, Francois; Scheu, Stefan
    Royal Society Open Science 2019; 6(3): Art. 181869
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  • Journal Article

    A new instrument for stable isotope measurements of C-13 and O-18 in CO2 - instrument performance and ecological application of the Delta Ray IRIS analyzer 

    Braden-Behrens, Jelka; Yan, Yuan; Knohl, Alexander
    Atmospheric Measurement Techniques 2017; 10(11) p.4537-4560
    We used the recently developed commercially available Delta Ray isotope ratio infrared spectrometer (IRIS) to continuously measure the CO2 concentration c and its isotopic composition δ13C and δ18O in a managed beech forest in central Germany. Our objectives are (a) to characterize the Delta Ray IRIS and evaluate its internal calibration procedure and (b) to quantify the seasonal variability of c, δ13C, δ18O and the isotopic composition of nighttime net ecosystem CO2 exchange (respiration) Reco13C and Reco18O derived from Keeling plot intercepts. The analyzer's minimal Allan deviation (as a measure of precision) was below 0.01 ppm for the CO2 concentration and below 0.03 ‰ for both δ values. The potential accuracy (defined as the 1σ deviation from the respective linear regression that was used for calibration) was approximately 0.45 ppm for c, 0.24 ‰ for 13C and 0.3 ‰ for 18O. For repeated measurements of a target gas in the field, the long-term standard deviation from the mean was 0.3 ppm for c and below 0.3 ‰ for both δ values. We used measurements of nine different inlet heights to evaluate the isotopic compositions of nighttime net ecosystem CO2 exchange Reco13C and Reco18O in a 3-month measurement campaign in a beech forest in autumn 2015. During this period, an early snow and frost event occurred, coinciding with a change in the observed characteristics of both Reco13C and Reco18O. Before the first snow, Reco13C correlated significantly (p  <  10−4) with time-lagged net radiation Rn, a driver of photosynthesis and photosynthetic discrimination against 13C. This correlation became insignificant (p  >  0.1) for the period after the first snow, indicating a decoupling of δ13C of respiration from recent assimilates. For 18O, we measured a decrease of 30 ‰ within 10 days in Reco18O after the snow event, potentially reflecting the influence of 18O depleted snow on soil moisture. This decrease was 10 times larger than the corresponding decrease in δ18O in ambient CO2 (below 3 ‰) and took 3 times longer to recover (3 weeks vs. 1 week). In summary, we conclude that (1) the new Delta Ray IRIS with its internal calibration procedure provides an opportunity to precisely and accurately measure c, δ13C and δ18O at field sites and (2) even short snow or frost events might have strong effects on the isotopic composition (in particular 18O) of CO2 exchange on an ecosystem scale.
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  • Journal Article

    Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia 

    Sabajo, Clifton R.; le Maire, Guerric; June, Tania; Meijide, Ana; Roupsard, Olivier; Knohl, Alexander
    Biogeosciences 2017; 14(20) p.4619-4635
    Indonesia is currently one of the regions with the highest transformation rate of land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. Land cover changes, which modify land surface properties, have a direct effect on the land surface temperature (LST), a key driver for many ecological functions. Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on the LST in Indonesia. We analyze LST from the thermal band of a Landsat image and produce a highresolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which suffered large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, normalized differenced vegetation index (NDVI) and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear-cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 2.6 C (mean SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets the albedo warming effect. Our analysis of the LST trend of the past 16 years based on MODIS data shows that the average daytime surface temperature in the Jambi province increased by 1.05 C, which followed the trend of observed land cover changes and exceeded the effects of climate warming. This study provides evidence that the expansion of oil palm plantations and other cash crops leads to changes in biophysical variables, warming the land surface and thus enhancing the increase of the air temperature because of climate change.
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  • Journal Article

    Land-use choices follow profitability at the expense of ecological functions in Indonesian smallholder landscapes 

    Clough, Yann; Krishna, Vijesh V.; Corre, Marife D.; Darras, Kevin; Denmead, Lisa H.; Meijide, Ana; Moser, Stefan; Musshoff, Oliver; Steinebach, Stefanie; Veldkamp, Edzo; et al.
    Allen, KaraBarnes, Andrew D.Breidenbach, NatalieBrose, UlrichBuchori, DamayantiDaniel, RolfFinkeldey, ReinerHarahap, IdhamHertel, DietrichHoltkamp, A. MareikeHörandl, ElviraIrawan, BambangJaya, I. Nengah SuratiJochum, MalteKlarner, BernhardKnohl, AlexanderKotowska, Martyna M.Krashevska, ValentynaKreft, HolgerKurniawan, SyahrulLeuschner, ChristophMaraun, MarkMelati, Dian NurainiOpfermann, NicolePérez-Cruzado, CésarPrabowo, Walesa EdhoRembold, KatjaRizali, AkhmadRubiana, RatnaSchneider, DominikTjitrosoedirdjo, Sri SudarmiyatiTjoa, AiyenTscharntke, TejaScheu, Stefan
    Nature Communications 2016; 7
    Smallholder-dominated agricultural mosaic landscapes are highlighted as model production systems that deliver both economic and ecological goods in tropical agricultural landscapes, but trade-offs underlying current land-use dynamics are poorly known. Here, using the most comprehensive quantification of land-use change and associated bundles of ecosystem functions, services and economic benefits to date, we show that Indonesian smallholders predominantly choose farm portfolios with high economic productivity but low ecological value. The more profitable oil palm and rubber monocultures replace forests and agroforests critical for maintaining above- and below-ground ecological functions and the diversity of most taxa. Between the monocultures, the higher economic performance of oil palm over rubber comes with the reliance on fertilizer inputs and with increased nutrient leaching losses. Strategies to achieve an ecological-economic balance and a sustainable management of tropical smallholder landscapes must be prioritized to avoid further environmental degradation.
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  • Journal Article

    Economic and ecological trade-offs of agricultural specialization at different spatial scales 

    Klasen, Stephan; Meyer, Katrin M.; Dislich, Claudia; Euler, Michael; Faust, Heiko; Gatto, Marcel; Hettig, Elisabeth; Melati, Dian N.; Jaya, I. Nengah Surati; Otten, Fenna; et al.
    Pérez-Cruzado, CésarSteinebach, StefanieTarigan, SuriaWiegand, Kerstin
    Ecological Economics 2016; 122 p.111-120
    Specialization in agricultural systems can lead to trade-offs between economic gains and ecosystem functions. We suggest and explore a conceptual framework in which economic gains can be maximized when production activities are specialized at increasingly broader scales (from the household to the village, region or above), particularly when markets for outputs and inputs function well. Conversely,more specialization likely reduces biodiversity and significantly limits ecosystem functions. When agricultural specialization increases and moves to broader scales as a result of improved infrastructure and markets or other drivers, ecosystem functions can also be endangered at broader spatial scales. Policies to improve agricultural incomes may influence the level of specialization at different scales and thus affect the severity of the trade-offs. This paper takes Jambi province in Indonesia, a current hotspot of rubber and oil palm monoculture, as a case study to illustrate these issues.We empirically show that the level of specialization differs across scales with higher specialization at household and village levels and higher diversification towards the province level. We discuss ways to resolve trade-offs between economic gains and ecological costs, including landscape design, targeted policies, and adoption of longterm perspectives.
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  • Journal Article

    Fast Growing Plantations for Wood Production – Integration of Ecological Effects and Economic Perspectives 

    Bredemeier, Michael; Busch, Gerald; Hartmann, Linda; Jansen, Martin; Richter, Falk; Lamersdorf, Norbert P.
    Frontiers in Bioengineering and Biotechnology 2015; 3 p.1-14: Art. 72
    Biomass crops are perceived as a feasible means to substitute sizeable amounts of fossil fuel in the future. A prospect of CO2 reduction (resp. CO2 neutrality) is credited to biomass fuels, and thus a potential contribution to mitigate climate change. Short rotation coppices (SRCs) with fast growing poplar and willow trees are an option for producing high yields of woody biomass, which is suitable for both energetic and material use. One negative effect that comes along with the establishment of SRC may be a decrease in groundwater recharge, because high rates of transpiration and interception are anticipated. Therefore, it is important to measure, analyze, and model the effects of SRC-planting on landscape water budgets. To analyze the effects on the water budget, a poplar SRC plot was studied by measuring hydrological parameters to be used in the hydrological model WaSim. Results reveal very low or even missing ground water recharge for SRC compared to agricultural land use or grassland, especially succeeding dry years. However, this strong effect on plot level is moderated on the larger spatial scale of catchment level, for which the modeling was also performed. In addition to water, nutrient fluxes and budgets were studied. Nitrogen is still a crucial issue in today’s agriculture. Intensive fertilization or increased applications of manure from concentrated livestock breeding are often leading to high loads of nitrate leaching, or enhanced N2O emissions to the atmosphere on arable crop fields. SRC or agroforestry systems on former crop land may offer an option to decrease such N losses, while simultaneously producing woody biomass. This is mainly due to the generally smaller N requirements of woody vegetation, which usually entail no need for any fertilization. The trees supply deep and permanent rooting systems, which can be regarded as a “safety net” to prevent nutrient leaching. Thus, SRC altogether can help to diminish N eutrophication. It is important to offer viable and attractive economic perspectives to farmers and other land managers besides of the potential ecological benefits of SRCs. For this reason, an integrated tool for scenario analysis was developed within the BEST project (“BEAST – Bio-Energy Allocation and Scenario Tool”). It combines ecological assessments with calculations of economic revenue as a basis for a participative regional dialog on sustainable land use and climate protection goals. Results show a substantial capacity for providing renewable energy from economically competitive arable SRC sites while generating ecological synergies.
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  • Journal Article

    Implementing REDD+ (Reducing Emissions from Deforestation and Degradation): evidence on governance, evaluation and impacts from the REDD-ALERT project 

    Matthews, Robin B.; van Noordwijk, Meine; Lambin, Eric; Meyfroidt, Patrick; Gupta, Joyeeta; Verchot, Louis; Hergoualc’h, Kristell; Veldkamp, Edzo
    Mitigation and Adaptation Strategies for Global Change
    he REDD-ALERT (Reducing Emissions from Deforestation and Degradation from Alternative Land Uses in the Rainforests of the Tropics) project started in 2009 and finished in 2012, and had the aim of evaluating mechanisms that translate international-level agreements into instruments that would help change the behaviour of land users while minimising adverse repercussions on their livelihoods. Findings showed that some developing tropical countries have recently been through a forest transition, thus shifting from declining to expanding forests at a national scale. However, in most of these (e.g. Vietnam), a significant part of the recent increase in national forest cover is associated with an increase in importation of food and timber products from abroad, representing leakage of carbon stocks across international borders. Avoiding deforestation and restoring forests will require a mixture of regulatory approaches, emerging market-based instruments, suasive options, and hybrid management measures. Policy analysis and modelling work showed the high degree of complexity at local levels and highlighted the need to take this heterogeneity into account—it is unlikely that there will be a one size fits all approach to make Reducing Emissions from Deforestation and Degradation (REDD+) work. Significant progress was made in the quantification of carbon and greenhouse gas (GHG) fluxes following land-use change in the tropics, contributing to narrower confidence intervals on peat-based emissions and their reporting standards. There are indications that there is only a short and relatively small window of opportunity of making REDD+ work—these included the fact that forest-related emissions as a fraction of total global GHG emissions have been decreasing over time due to the increase in fossil fuel emissions, and that the cost efficiency of REDD+ may be much less than originally thought due to the need to factor in safeguard costs, transaction costs and monitoring costs. Nevertheless, REDD+ has raised global awareness of the world’s forests and the factors affecting them, and future developments should contribute to the emergence of new landscape-based approaches to protecting a wider range of ecosystem services.
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  • Journal Article

    Identification of markers associated with bacterial blight resistance loci in cowpea [Vigna unguiculata (L.) Walp.] 

    Agbicodo, E. M.; Fatokun, C. A.; Bandyopadhyay, R.; Wydra, K.; Diop, N. N.; Muchero, W.; Ehlers, J. D.; Roberts, P. A.; Close, T. J.; Visser, R. G. F.; et al.
    Linden, C. G.
    Euphytica 2010; 175(2) p.215-226
    Cowpea bacterial blight (CoBB), caused by Xanthomonas axonopodis pv. vignicola (Xav), is a worldwide major disease of cowpea [Vigna unguiculata (L.) Walp.]. Among different strategies to control the disease including cultural practices, intercropping, application of chemicals, and sowing pathogen-free seeds, planting of cowpea genotypes with resistance to the pathogen would be the most attractive option to the resource poor cowpea farmers in sub-Saharan Africa. Breeding resistance cultivars would be facilitated by marker-assisted selection (MAS). In order to identify loci with effects on resistance to this pathogen and map QTLs controlling resistance to CoBB, eleven cowpea genotypes were screened for resistance to bacterial blight using 2 virulent Xav18 and Xav19 strains isolated from Kano (Nigeria). Two cowpea genotypes Danila and Tvu7778 were identified to contrast in their responses to foliar disease expression following leaf infection with pathogen. A set of recombinant inbred lines (RILs) comprising 113 individuals derived from Danila (resistant parent) and Tvu7778 (susceptible parent) were infected with CoBB using leaf inoculation method. The experiments were conducted under greenhouse conditions (2007 and 2008) and disease severity was visually assessed using a scale where 0 = no disease and 4 = maximum susceptibility with leaf drop. A single nucleotide polymorphism (SNP) genetic map with 282 SNP markers constructed from the same RIL population was used to perform QTL analysis. Using Kruskall-Wallis and Multiple-QTL model of MapQTL 5, three QTLs, CoBB-1, CoBB-2 and CoBB-3 were identified on linkage group LG3, LG5 and LG9 respectively showing that potential resistance candidate genes cosegregated with CoBB resistance phenotypes. Two of the QTLs CoBB-1, CoBB-2 were consistently confirmed in the two experiments accounting for up to 22.1 and to 17.4% respectively for the first and second experiments. Whereas CoBB-3 was only discovered for the first experiment (2007) with less phenotypic variation explained of about 10%. Our results represent a resource for molecular marker development that can be used for marker assisted selection of bacterial blight resistance in cowpea.
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