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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Relative susceptibilities of five fodder radish varieties (Raphanus sativus var. Oleiformis) to Meloidogyne chitwoodi
    Teklu, M.G. ; Schomaker, C.H. ; Been, T.H. - \ 2014
    Nematology 16 (2014)5. - ISSN 1388-5545 - p. 577 - 590.
    root-knot nematode - host status - globodera-pallida - population-density - potato cultivars - resistance - growth - crops - clones - spp.
    The fodder radish varieties Anaconda, Contra, Defender, Doublet and Terranova, known to have some partial resistance, were compared to the standard variety, Radical, to estimate their relative susceptibility (RS) for both population dynamic parameters of Meloidogyne chitwoodi and to evaluate Pi dependency. This approach must eventually lead to new screening methods for partial resistance tests. Plants were grown under controlled glasshouse conditions. Twelve densities of nematodes in five replications were used. Five plants per 7 l pot were allowed to grow for a period of 11 weeks until their early flowering stage. Few seedlings of all the varieties at Pi=32 and 64 J2 (g dry soil)-1, and all seedlings exposed to the highest density, Pi=128 J2 (g dry soil)-1, died within a week after germination. Replanted seedlings developed into normal plants. Total yield, expressed as total fresh weight, was not affected by M. chitwoodi. A lower percentage of plants with galls was observed on partially resistant varieties as compared with Radical. For Radical, a maximum multiplication rate (a) of 0.38 and a maximum population density (M) of 6.43 J2 (g dry soil)-1 were estimated. Radical proved to be a bad host for M. chitwoodi with all final populations lower than the Pi. The parameter estimates of (M) for Anaconda, Contra, Defender, Doublet and Terranova were 0.011, 0.006, 0.027, 0.020 and 0.009 J2 (g dry soil)-1, respectively. With Radical taken to be 100% susceptible, this resulted in RSM values of 0.17, 0.10, 0.42, 0.32 and 0.14% of these varieties, respectively, reducing high population levels of M. chitwoodi by more than 98%. There was no correlation between the rMgalls and the RSM values, indicating that scoring the number of galled plants will not provide a suitable measure for partial resistance.
    Rearing history affects behaviour and performance of two virulent Nasonovia ribisnigri populations on two lettuce cultivars
    Broeke, C.J.M. ten; Dicke, M. ; Loon, J.J.A. van - \ 2014
    Entomologia Experimentalis et Applicata 151 (2014)2. - ISSN 0013-8703 - p. 97 - 105.
    nematode meloidogyne-incognita - myzus-persicae hemiptera - host-plant resistance - feeding-behavior - tissue localization - aphid resistance - clones - gene - homoptera - biotypes
    Many aphid species have become virulent to host-plant resistance, which limits the sustainability of insect resistance breeding. However, when this adaptation to resistant plants is associated with fitness costs for the aphids, virulence can be lost in the absence of resistant plants. For two populations of the lettuce aphid, Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae), we evaluated whether virulence to Nr-gene-based resistance was lost on a susceptible lettuce, Lactuca sativa L. (Asteraceae), and assessed possible costs of virulence. The feeding behaviour and performance of these aphids, reared and tested on susceptible and resistant lettuce, were investigated. The rearing plant affected feeding behaviour and performance of the aphids. Temporary reduction and long-term loss of virulence were found. The total duration of phloem intake was shorter after being reared on susceptible lettuce and tested on resistant lettuce. In addition, one population had a lower survival on resistant lettuce after being reared on susceptible lettuce. There were also indications of fitness costs of the virulence in both populations.
    Multilocus Sequence Typing for Characterization of Staphylococcus pseudintermedius
    Solyman, S.M. ; Black, C.C. ; Duim, B. ; Perreten, V. ; Duijkeren, E. van; Wagenaar, J.A. ; Eberlein, L.C. ; Sadeghi, L.N. ; Videla, R. ; Bemis, D.A. ; Kania, S.A. - \ 2013
    Journal of Clinical Microbiology 51 (2013)1. - ISSN 0095-1137 - p. 306 - 310.
    methicillin-resistant - antibiotic-resistance - north-america - dogs - intermedius - meca - clones - aureus - susceptibility - emergence
    Staphylococcus pseudintermedius is an opportunistic pathogen in dogs. Four housekeeping genes with allelic polymorphisms were identified and used to develop an expanded multilocus sequence typing (MLST) scheme. The new seven-locus technique shows S. pseudintermedius to have greater genetic diversity than previous methods and discriminates more isolates based upon host origin.
    Onderzoek naar verschillen in aantasting door Chalara fraxinea ('essentaksterfte') in Nederlandse essenselecties : verslag van de waarnemingen en bevindingen over 2012 = Differences in susceptibility to Chalara fraxinea (twig dieback of ash) of selections of Common ash (Fraxinus excelsior) in the Netherlands : report of the observations and results of 2012
    Kopinga, J. ; Vries, S.M.G. de - \ 2013
    Wageningen : Centrum voor Genetische Bronnen Nederland (CGN rapport 26) - 32
    fraxinus excelsior - schimmelziekten - plantenziekteverwekkende schimmels - chalara fraxinea - klonen - resistentie van variëteiten - gevoeligheid van variëteiten - ziekteresistentie - nederland - fraxinus excelsior - fungal diseases - plant pathogenic fungi - chalara fraxinea - clones - varietal resistance - varietal susceptibility - disease resistance - netherlands
    In 2012 zijn opnames uitgevoerd in essenproefvelden van het CGN en zaadgaarden van het Staatsbosbeheer naar de mate waarin de daar aanwezige essen inmiddels zijn aangetast door essentaksterfte, veroorzaakt door de schimmel Chalara fraxinea. Doel van dit onderzoek was om een indruk te krijgen van genetisch bepaalde verschillen in mogelijke resistentie / tolerantie voor deze ziekte. Een aantal handelsklonen profileerden zich in 2012 reeds als bovengemiddeld qua resistentie. Geknotte of sterk gesnoeide bomen zijn significant gevoleiger voor bladaantasting en twijgsterfte dan niet gesnoeide bomen.
    De Es mag niet weg! Onderzoek essenresistentie: nu sector en gebruiker aan zet
    Raats, S. ; Kuik, A.J. van; Hiemstra, J.A. - \ 2013
    Boom in business 2013 (2013)7. - ISSN 2211-9884 - p. 22 - 24.
    fraxinus - straatbomen - genetische bronnen van plantensoorten - rassen (planten) - cultivars - klonen - plantenvermeerdering - boomkwekerijen - resistentie van variëteiten - plantenziekten - chalara fraxinea - fraxinus - street trees - plant genetic resources - varieties - cultivars - clones - propagation - forest nurseries - varietal resistance - plant diseases - chalara fraxinea
    Op de Nederlandse Boominfodag 2012 maakte Jitze Kopinga bekend dat het WUR-CGN (Het Centrum voor Genetische Bronnen Nederland) een aantal redelijk resistente essenklonen bezit en dat de Wageningen Universiteit deze klonen vrijgeeft voor vermeerdering door kwekers. In november bezocht Kopinga in Vilnius een Europese projectbijeenkomst op het gebied van onderzoek naar essentaksterfte. Alle belangrijke onderzoekers in Europa waren daar aanwezig. Als het aan Kopinga ligt, overleeft de es met verve.'Maar dan moeten de sector en de gebruikers wel inzetten op vertrouwen', aldus de onderzoeker.
    Practicalities of using non-local or non-recent multilocus sequence typing data for source attribution in space and time of human campylobacteriosis
    Smid, J.H. ; Gras, L.M. ; Boer, A.G. de; French, N.P. ; Havelaar, A.H. ; Wagenaar, J.A. ; Pelt, W. van - \ 2013
    PLoS ONE 8 (2013)2. - ISSN 1932-6203
    host association - new-zealand - jejuni - genotypes - recombination - switzerland - population - infections - resistance - clones
    In this study, 1208 Campylobacter jejuni and C. coli isolates from humans and 400 isolates from chicken, collected in two separate periods over 12 years in The Netherlands, were typed using multilocus sequence typing (MLST). Statistical evidence was found for a shift of ST frequencies in human isolates over time. The human MLST data were also compared to published data from other countries to determine geographical variation. Because only MLST typed data from chicken, taken from the same time point and spatial location, were available in addition to the human data, MLST datasets for other Campylobacter reservoirs from selected countries were used. The selection was based on the degree of similarity of the human isolates between countries. The main aim of this study was to better understand the consequences of using non-local or non-recent MLST data for attributing domestically acquired human Campylobacter infections to specific sources of origin when applying the asymmetric island model for source attribution. In addition, a power-analysis was done to find the minimum number of source isolates needed to perform source attribution using an asymmetric island model. This study showed that using source data from other countries can have a significant biasing effect on the attribution results so it is important to carefully select data if the available local data lack in quality and/or quantity. Methods aimed at reducing this bias were proposed.
    Estimation of partial resistance in potato genotypes against Meloidogyne chitwoodi
    Norshie, P.M. ; Been, T.H. ; Schomaker, C.H. - \ 2011
    Nematology 13 (2011)4. - ISSN 1388-5545 - p. 477 - 489.
    root-knot nematode - plant parasitic nematodes - globodera-pallida - population-density - increase - clones
    Three new potato genotypes, designated AR 04-4107, AR 04-4096 and AR 04-4098, with resistance towards Meloidogyne chitwoodi, and the susceptible cv. Désirée were grown at a range of population densities of M. chitwoodi in a climate-controlled glasshouse in order to establish the presence and degree of partial resistance. Tuber parts of about 12 g were planted at densities (Pi) of 0, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 and 256 second-stage juveniles (J2) (g dry soil)-1. The plants were allowed to grow for a period of 105 days. Tomato cv. Moneymaker was included and inoculated at Pi = 2 J2 (g soil)-1 to verify the quality of the inoculum by measuring the multiplication rate. Plant height was measured weekly over 11 weeks. At harvest, fresh shoot, root and tuber weights, and number of tubers were measured to express yield. Final population densities (Pf) were calculated as the total number of nematodes found in soil and roots. Tubers were scored for visible symptoms and a root-knot index was calculated. The relation between pre-plant population densities (Pi) and nematode densities at harvest (Pf) was fitted using R. The multiplication rate a of M. chitwoodi on AR 04-4107, AR 04-4096, AR 04-4098 and cv. Désirée was 0.55, 0.27, 0.91 and 32, respectively. Partial resistance rsa of AR 04-4107, AR 04-4096 and AR 04-4098 was 1.7%, 0.8% and 2.8%, respectively. Partial resistance expressed as rsM was 0.2%, 0.2% and 0.1%, respectively. It can be concluded that AR 04-4107, AR 04-4096 and AR 04-4098 are strongly partially resistant to M. chitwoodi. Also, the population dynamics curves run almost parallel between both the tested genotypes and the reference cultivar, indicating that a simple and cheap partial resistance test is feasible. When tuber yields were fitted to the Seinhorst model for yield reduction, cv. Désirée showed a minimum yield (m) of 0.86, while all three resistant genotypes suffered no yields losses at all (m = 1), which indicates that the observed resistance was associated with tolerance. As a result of the remarkably high partial resistance, quality damage was low compared with cv. Désirée. The root-knot index, which takes into account internal quality damage of the potato tuber, was below 10 for all genotypes with partial resistance, the lower damage threshold used for industrial processing of consumption potatoes. Visible symptoms on the tuber skin were absent up to densities of 32 J2 (g soil)-1 for genotypes AR 04-4098 and AR 04-4096 and 2 J2 (g soil)-1 for AR 04-4107, and significantly reduced at higher densities when compared with the susceptible cv. Désirée. However, when tuber peels were investigated, egg masses were detected in tubers at almost all initial population densities.
    In vitro screening and QTL analysis for drought tolerance in diploid potato
    Anithakumari, A.M. ; Dolstra, O. ; Vosman, B. ; Visser, R.G.F. ; Linden, C.G. van der - \ 2011
    Euphytica 181 (2011)3. - ISSN 0014-2336 - p. 357 - 369.
    water-stress - solanum-tuberosum - polyethylene glycols - gene-expression - tissue-culture - grown plants - rflp maps - deficit - traits - clones
    Drought stress is a major abiotic constraint limiting crop production worldwide. Screening for drought tolerance and the traits that enhance drought tolerance is not straightforward in large mapping populations. In this study, we investigated the possibility of screening a mapping population in vitro for PEG-induced water deficit stress and recovery potential. We have measured several shoot and root growth parameters or traits in the C × E diploid potato mapping population. Significant variation was observed for genotype-specific responses to water deficit and recovery potential. Genetic variation and heritability estimates were high to very high for the measured traits depending on growth conditions. In order to identify potato QTLs for drought tolerance and recovery potential an SNP marker-rich integrated linkage map was used. A total of 23 QTLs were detected under control, stress and recovery treatments explaining 10.3–22.4% of the variance for each phenotypic trait. Among these, 10 QTLs were located on chromosome 2. Three QTLs involved in the important trait root to shoot ratio were identified on linkage groups 2, 3 and 8. These loci explained together 41.1% of the variance for this trait, and may be breeding targets for stress tolerance and yield in the field as well. The SNP markers derived from EST sequences underlying these QTLs led to the identification of putative candidate genes for further study in potato. This study constitutes the first knowledge of in vitro screening of a mapping population for drought tolerance in potato.
    Unexpected Sequence Types in Livestock-associated methicillinresistant Staphylococcus aureus (MRSA): MRSA ST9 and Single Locus Variant of ST9 in pig farmin in China
    Wagenaar, J.A. ; Yue, H. ; Pritchard, J. ; Broekhuizen-Stins, M. ; Huijsdens, X. ; Mevius, D.J. ; Bosch, T. van den; Duijkeren, E. van - \ 2009
    Veterinary Microbiology 139 (2009)3-4. - ISSN 0378-1135 - p. 405 - 409.
    field gel-electrophoresis - strains - population - prevalence - farmers - clones - spread
    In October 2008 nine farrow-to-finish pig farms were visited in Shuangliu County in Sichuan Province, China. One farm was empty for one month but not cleaned after depopulation. Dust samples were collected at each farm and analysed for the presence of methicillin-resistant Staphylococcus aureus (MRSA). Dust samples from four farms were also analysed for the presence of methicillin-susceptible S. aureus (MSSA). On 5/9 farms MRSA was isolated and on 2/4 farms MSSA was isolated. On two farms, including the empty farm, no MRSA or MSSA could be detected. All MRSA isolates (n = 43) belonged to spa type t899. MSSA isolates belonged to spa type t899 (n = 12) and spa type t034 (n = 2). From 4/9 farms the MRSA isolates of spa type t899 were assigned to multilocus sequence type (MLST) ST9 whereas on one farm the MRSA spa type t899 isolates belonged to a single locus variant of MLST ST9 (ST1376). MSSA isolates with spa type t899 belonged to MLST ST9 and the MSSA with spa type t034 belonged to MLST ST398. This is the first report on MRSA in pig farms in China and the first time that MRSA ST9 and a single locus variant of ST9 are detected in pig farms. This study shows that livestock associated MRSA is not restricted to clonal lineage ST398 as found in Europe and Northern America in commercial pigs but that other MRSA lineages are able to spread in livestock as well. The study confirms that livestock may act as a reservoir for MRSA.
    Clonal architecture and patch formation of Potamogeton perfoliatus L. : in response to environmental conditions
    Wolfer, S.R. - \ 2008
    Wageningen University. Promotor(en): Marten Scheffer, co-promotor(en): Egbert van Nes; D. Straile. - [S.l.] : S.n. - ISBN 9789085852117 - 120
    potamogeton perfoliatus - milieufactoren - klonen - voedingsstoffen - modellen - groei - potamogeton perfoliatus - environmental factors - clones - nutrients - models - growth

    submersed macrophyte, P. perfoliatus, clonal architecture, spatial growth, shoot density, rhizome, biomass allocation, growth plasticity, foraging, allometry, sediment, porewater, nutrients, fertilization, clonal integration, individual-based model, Lake Constance

    Clonal growth governs the aboveground growth pattern of submerged clonal macrophytes. The research project provides detailed data on the architectural growth rules of Potamogeton perfoliatus L. (perfoliate pondweed) such as rhizome spacer lengths, biomass allocation, branching frequencies, branching angles, as well as maps of rhizome networks and their seasonal development in Lake Constance.
    Besides architectural reasons, the causes for different sizes and shapes of P. perfoliatus patches are dependent on nutrients, light conditions, and clonal integration. Branching was positively related to both irradiation and nutrient supply. Rhizome spacer lengths were negatively related to nutrient supply and positively related to irradiation. Rhizome allocation tended to increase with irradiation and shoot allocation tended to decrease with irradiation. Root allocation was higher at low nutrient supply. Clonal growth was further complicated because the species showed complex sharing of of resources between older and younger ramets, aiming at optimal resource partitioning.
    We present an individual-based clonal model which is able to simulate seasonal growth of Potamogeton patches. Furthermore, it shows that architectural growth affects patch characteristics: both rhizome spacer lengths and growth of rhizome axes relative to those in the previous year considerably determine patch density and patch expansion rates.
    All results on clonal architecture are discussed in the light of foraging theory and allometric rules.

    MRSA transmission between cows and humans
    Juhasz-Kaszanyitzky, E. ; Janosi, S. ; Somogyi, P. ; Dan, A. ; Graaf-van Bloois, L. van der; Dulijkeren, E. van; Wagenaar, J.A. - \ 2007
    Emerging Infectious Diseases 13 (2007)4. - ISSN 1080-6040 - p. 630 - 632.
    resistant staphylococcus-aureus - methicillin-resistant - strains - animals - clones - pcr
    We isolated methicillin-resistant Staphylococcus aureus (MRSA) from cows with subclinical mastitis and from a person who worked with these animals. The bovine and human strains were indistinguishable by phenotyping and genotyping methods and were of a low frequency spa type. To our knowledge, this finding indicates the first documented case of direct transmission of MRSA between cows and humans.
    Occurence of arbuscular mycorrhiza and extomycorrhiza on Leptospermum scoparium from the Rakaia catchment, Canterbury.
    Weijtmans, K. ; Davis, M. ; Clinton, P. ; Kuyper, T.W. ; Greenfield, L. - \ 2007
    New Zealand Journal of Ecology 31 (2007)2. - ISSN 0110-6465 - p. 255 - 260.
    new-zealand - salix-repens - fungi - colonization - infection - clones - communities - tremuloides - ecosystems - urophylla
    Leptospermum is one of only three New Zealand genera that are colonised by ectomycorrhizal (EM) fungi, and L. scoparium is one of the very few New Zealand species that can be colonised by both arbuscular mycorrhizal (AM) and EM fungi. This study examined AM and EM colonisation on L. scoparium growing within AM grassland ecosystems or adjoining Nothofagus forest in the Rakaia catchment, Canterbury. Very low AM colonisation was found (
    Iepziekteresistentie en gebruiksmogelijkheden van iepenklonen; een onderzoek aan de hand van literatuur en ervaringen uit de provincie Friesland
    Wolf, R.J.A.M. ; Kopinga, J. - \ 2006
    Wageningen : Alterra (Alterra-rapport 1432) - 47
    ulmus - ulmaceae - ophiostoma ulmi - plantenziekten - plantenziekteverwekkende schimmels - ziekteresistentie - klonen - soorten - straatbomen - friesland - ulmus - ulmaceae - ophiostoma ulmi - plant diseases - plant pathogenic fungi - disease resistance - clones - species - street trees - friesland
    In dit rapport worden per iepensoort, -kloon en kweekvorm de iepziekteresistentie en gebruiksmogelijkheden in beeld gebracht van laan- en straatbeplantingen in het stedelijk en landelijk gebied. Het rapport is gebaseerd op literatuur en op praktijkgegevens over aanplant en uitval in Friesland. Mede op grond van de hoeveelheid kennis en ervaring die tot nu toe in Nederland is opgedaan, worden aanbevelingen gegeven over de aanplant van iepen. Ook worden suggesties gedaan voor kennisvergroting via informatieuitwisseling, experimenten, praktijkproeven, monitoring en ander onderzoek. Goede, gerichte communicatie blijkt cruciaal om het negatieve imago af te schudden dat de iep door haar iepziekteverleden ten onrecht heeft. Het huidige iepensortiment biedt veel gebruiksmogelijkheden en heeft een beheersbaar (iep)ziekterisico
    TOPAAS, a tomato and potato assembly assistance system for selection and finishing of bacterial artificial chromosomes 1[W]
    Peters, S.A. ; Haarst, J.C. van; Jesse, T. ; Woltinge, D. ; Jansen, K. ; Hesselink, T. ; Staveren, M.J. van; Abma-Henkens, M.H.C. ; Klein Lankhorst, R.M. - \ 2006
    Plant Physiology 140 (2006). - ISSN 0032-0889 - p. 805 - 817.
    resistance gene - genome - sequence - clones - evolution - alignment - markers - contigs - sol
    We have developed the software package Tomato and Potato Assembly Assistance System (TOPAAS), which automates the assembly and scaffolding of contig sequences for low-coverage sequencing projects. The order of contigs predicted by TOPAAS is based on read pair information; alignments between genomic, expressed sequence tags, and bacterial artificial chromosome (BAC) end sequences; and annotated genes. The contig scaffold is used by TOPAAS for automated design of nonredundant sequence gap-flanking PCR primers. We show that TOPAAS builds reliable scaffolds for tomato (Solanum lycopersicum) and potato (Solanum tuberosum) BAC contigs that were assembled from shotgun sequences covering the target at 6- to 8-fold coverage. More than 90% of the gaps are closed by sequence PCR, based on the predicted ordering information. TOPAAS also assists the selection of large genomic insert clones from BAC libraries for walking. For this, tomato BACs are screened by automated BLAST analysis and in parallel, high-density nonselective amplified fragment length polymorphism fingerprinting is used for constructing a high-resolution BAC physical map. BLAST and amplified fragment length polymorphism analysis are then used together to determine the precise overlap. Assembly onto the seed BAC consensus confirms the BACs are properly selected for having an extremely short overlap and largest extending insert. This method will be particularly applicable where related or syntenic genomes are sequenced, as shown here for the Solanaceae, and potentially useful for the monocots Brassicaceae and Leguminosea
    Effect of cytokinins on shoot regeneration from cotyledon and leaf segment of stem mustard (Brassica juncea var. tsatsai)
    Guo, D.P. ; Zhu, Z.J. ; Hu, X.X. ; Zheng Sijun, S.J. - \ 2005
    Plant Cell, Tissue and Organ Culture: an international journal on in vitro culture of higher plants 83 (2005)1. - ISSN 0167-6857 - p. 123 - 127.
    agrobacterium-tumefaciens - mediated transformation - expression - explants - italica - clones - czern - coss
    Cotyledon and leaf segments of stem mustard (Brassica juncea var. tsatsai) were cultured on Murashige and Skoog medium supplemented with various concentrations of different cytokinins [6-benzyladenine (BA), N-(2-chloro-4-pyridyl)-n-phenylurea (CPPU), 6-furfurylaminopurine (KT) and thidiazuron (TDZ)] in combinations with different levels of ¿-naphthalene acetic acid (NAA). The shoot regeneration frequency of cotyledon and leaf segment was dependent on the kinds and concentrations of cytokinins used in the medium, while in most cases cotyledon gave high regeneration frequency than leaf segment. TDZ proved to be the best cytokinin to induce shoot from both cotyledon and leaf segments compared to BA, KT and CPPU. The highest frequency of shoot regeneration was 61.3¿67.9 % in cotyledon and 40.7¿52.4% in leaf segment respectively when 2.27 or 4.54 ¿M TDZ was combined with 5.37 ¿M NAA. Next to TDZ, CPPU was also very suitable to induce shoot formation both in cotyledon and leaf segment. When 1.61 ¿M CPPU was combined with 2.69 ¿M NAA, shoot regeneration frequency was 45.0% in cotyledon and 36.4% in leaf segment, respectively. It was also shown that KT and BA affected shoot regeneration from cotyledon and leaf segment, the shoot regeneration was greatly increased when NAA was added together with cytokinins. The efficient and reliable shoot regeneration system was developed in both cotyledon and leaf segments. This regeneration protocol may be applicable to the improvement of this crop by genetic engineering in the future
    Clusters of Quercus robur and Q. petraea at the Veluwe (the Netherlands)
    Copini, P. ; Buiteveld, J. ; Ouden, J. den; Sass, U.G.W. - \ 2005
    Wageningen : CGN (Report / Centre for Genetic Resources 1) - 45
    quercus petraea - quercus robur - centra van herkomst - genetica - klonen - genetische bronnen - morfologie - struiken - historische ecologie - veluwe - quercus petraea - quercus robur - centres of origin - genetics - clones - genetic resources - morphology - shrubs - historical ecology - veluwe
    In this report three main questions were studied: (1) are oak clusters genetically identical, (2) can leaf morphology be used to identify clonal structures of oak and (3) what is the origin of oak clusters. The study sites were situated in a drift sand area (Maanschoten) as well as in an area with pre-glacial material (Wilde Kamp).
    Diversity in fertility potential and organo-sulphur compounds among garlics from Central Asia
    Kamenetsky, R. ; Shafir, I.L. ; Khassanov, F. ; Kik, C. ; Heusden, A.W. van; Vrielink-van Ginkel, M. ; Burger-Meijer, K. ; Auger, J. ; Arnault, I. ; Rabinowitch, H.D. - \ 2005
    Biodiversity and Conservation 14 (2005)2. - ISSN 0960-3115 - p. 281 - 295.
    allium-sativum-l - markers - growth - clones
    Extending the collection of garlic (Allium sativum L.) accessions is an important means that is available for broadening the genetic variability of this cultivated plant, with regard to yield, quality, and tolerance to biotic and abiotic traits; it is also an important means for restoring fertility and flowering. In the framework of the EU project Garlic and Health, 120 garlic accessions were collected in Central Asia - the main centre of garlic diversity. Plants were documented and thereafter maintained in field collections in both Israel and The Netherlands. The collection was evaluated for biological and economic traits. Garlic clones vary in most vegetative characteristics (leaf number, bulb size and structure), as well as in floral scape elongation and inflorescence development. A clear distinction was made between incomplete bolting and bolting populations; most of the accessions in the latter populations produced flowers with fertile pollen and receptive stigma. Wide variations were recorded with regard to differentiation of topsets, their size, number and rapidity of development. Furthermore, significant variation in organo-sulphur compounds (alliin, isoalliin, allicin and related dipeptides) was found within garlic collections and between plants grown under differing environmental conditions. Genetic fingerprinting by means of AFLP markers revealed three distinct groups within this collection, differing also in flowering ability and organo-S content.
    Host plant preference and performance of the vine weevil Otiorhynchus sulcatus
    Tol, R.W.H.M. van; Dijk, N. van; Sabelis, M.W. - \ 2004
    Agricultural and Forest Entomology 6 (2004)4. - ISSN 1461-9555 - p. 267 - 278.
    curculionidae - coleoptera - strawberry - oviposition - resistance - responses - clones
    1. The relationship between reproductive performance and preference for potential host plants of the vine weevil is investigated, as shown in tests on contact (or feeding) preference, presented herein, and tests on olfactory preference, published elsewhere. 2. Assessment of reproductive performance shows that the host-plant range of the adult vine weevil Otiorhynchus sulcatus in Europe is limited to one gymnosperm genus (Taxus sp.) and a broad range of angiosperm plants in two subclasses of the Dicotyledonae, namely Dilleniidae and Rosidae. The successful reproduction on very distantly related plant taxa suggests that the original weevil- and plant-habitat has mediated the current host-plant range of the vine weevil. 3. Contact-preference tests with equally suitable hosts, such as Aronia, Fragaria, Euonymus and Taxus, and one less suitable host, Humulus, indicate a mismatch between contact preference and performance and, as far as olfactory preferences are known, these match neither the contact preferences nor the performance. This mismatch may arise because (i) host plant species offered do not occur in weevil habitat in Europe (e.g. Aronia and the cultivated Fragaria come from North America) and (ii) predation (or disease) risks differ among host plants, thereby altering effective reproductive performance. 4. With respect to performance on novel hosts (Thuja, Prunus) and bad hosts (Rhododendron), some between-individual variation is found within a single population, suggesting that local populations harbour (possibly genetic) variation for adaptation to new hosts. How this variation is maintained in the face of strong selection pressures on local populations of flightless and thelytokous weevils, is an important question for understanding the broad host plant range in the vine weevil
    Klimop: de struikvormen onder de loep.
    Hop, M.E.C.M. - \ 2002
    Tuin en Landschap 24 (2002)22. - ISSN 0165-3350 - p. 12 - 15.
    hedera - houtachtige planten als sierplanten - struiken - groeifasen, rijp - rijpheid - plantenontwikkeling - plantenmorfologie - habitus - cultivars - rassen (planten) - klonen - rassenproeven - prestatie-onderzoek - inspectie - gebruikswaarde - nomenclatuur - biologische naamgeving - taxonomie - classificatie van rassen - ornamentele waarde - hedera - ornamental woody plants - shrubs - maturity stage - maturity - plant development - plant morphology - habit - cultivars - varieties - clones - variety trials - performance testing - inspection - use value - nomenclature - biological nomenclature - taxonomy - variety classification - ornamental value
    Beschrijving en illustraties, oude en nieuwe naamgeving, keuringsresultaten en gebruiksmogelijkheden van de volwassen cultivars van Hedera (Arborescent Group) en de niet-klimmende jeugdvormen (Oddity Group). Zowel gestekte als geënte exemplaren werden door PPO sector Bomen getest op proefvelden in Boskoop en Horst in de jaren 1999-2002
    On indigenous production, genetic diversity and crop ecology of enset (Ensete ventricosum (Welw.) Cheesman)
    Tsegaye, A. - \ 2002
    Wageningen University. Promotor(en): P.C. Struik. - S.l. : S.n. - ISBN 9789058086280 - 198
    ensete ventricosum - ensete - teeltsystemen - genetische variatie - genetische merkers - random amplified polymorphic dna - klonen - landrassen - inheemse kennis - genetische bronnen - groei - verplanten - snoeien - gewasopbrengst - verliezen bij het oogsten - verwerking - voedselproductie - ethiopië - agro-ecologie - ensete ventricosum - ensete - cropping systems - genetic variation - genetic markers - random amplified polymorphic dna - clones - landraces - indigenous knowledge - genetic resources - growth - transplanting - pruning - crop yield - harvesting losses - processing - food production - ethiopia - agroecology

    Keywords : Enset, staple, indigenous knowledge, genetic diversity, AFLP, characterisation, conservation, Leaf Appearance Rate, Radiation Use Efficiency, yield potential, transplanting, leaf pruning, fermentation, 'kocho', food security

    The indigenous enset-farming complex of the south and southwestern highlands of Ethiopia has supported a higher population density than any other farming system. Enset ( Ensete ventricosum (Welw.) Cheesman) has been cultivated as (co-)staple food for about 7-10 million people. Since the last three decades, however, because of population pressure, recurrent drought and diseases there has been degradation of natural resources and, thus, the system failed to sustain the population. In the study, described in this thesis, the indigenous enset production methods, farm-based enset biodiversity and the plant characteristics and environmental factors influencing productivity were analysed to identify yield potentials and constraints in Sidama, Wolaita and Hadiya. The ultimate goal was to develop improved agronomic practices and enhance the use of the existing genetic diversity to reduce the gap between the actual yield and yield potential.

    Some indigenous cultivation methods vary among regions: initiation of suckers, frequency of transplanting, leaf pruning and planting patterns. Morphologically diverse enset clones were identified in Sidama (52), Wolaita (55) and Hadiya (59). Among 146 clones, a total of 180 AFLP fragments was scored of which 104 (58%) appeared polymorphic. The AFLP-based dendrogram showed more duplication groups than the farmers' characterisation method suggesting that farmers overestimate the genetic diversity. The correlation between the two methods was only weak. Yet, the comparison between the AFLP-based and farmers-based characterisation methods showed that some aspects such as absence of clear regional clusters and clustering of clones with various prefixes to a single group corresponded well. Duplications in the clones identified by both methods may be safely removed from a conservation programme. Variation in farmers' skill in discriminating between clones may suggest that the areas where the people's culture is closely associated with the crop, should receive high priority for collecting clones or serving as sites for in situ conservation.

    Plant height and LAI of different clones increased faster at Awassa or Areka than at Sidama because of a higher leaf appearance rate associated with temperatures being closer to the optimum. This led to higher early interception of photosynthetically active radiation and higher dry matter production. The mean extinction coefficient was between 0.56-0.91 and radiation use efficiency (RUE) ranged from 1.43-2.67 g MJ -1. Yield potential differences between clones existed, mainly because of differences in RUE. The average ratio actual yield : yield potential (0.24) suggest that much can be done to reduce the yield gap.

    Transplanting suckers directly into permanent field shortens the period until maturity, provides a reasonable yield soon after removing the suckers from the mother corm and reduces the chance of attack by disease or pests. The partitioning of dry matter to the harvestable parts, the harvest indices at different states of processing and the losses caused by scraping or fermentation, however, became more advantageous as a result of repetitive transplanting. At flowering, harvest indices based on fermented enset products of once, twice and three times transplanted suckers were 0.20, 0.35 and 0.25, respectively. Leaf pruning or the interaction between leaf pruning and transplanting did not significantly affect dry matter partitioning, harvest index or processing losses.

    The maximum fresh weights of kocho after fermentation from enset plants transplanted once, twice and thrice were respectively 25.9, 54.1 and 37.1 kg plant -1. In terms of weight and energy, enset is the most productive crop in the country, sweet potato is second, taro is third and Irish potato is fourth. The cultivation of enset in densely populated areas under low-input conditions can sustain the population better than that of any other crop. Moreover, enset produces various by-products and the prolonged presence of a closed canopy has an ecological advantage similar to that of forest.

    This study combines indigenous technical knowledge, agronomic, physiological and molecular studies. It has contributed significantly to the understanding of the production methods and the genetic diversity. It has also investigated some strategies to reduce the gap between the actual yield and yield potential. Furthermore, it has underlined the relevance of physiological studies by generating basic physiological parameters. The information gained in this study also helped to underline future research topics.

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