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.

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    Effect of adjuvant and spray volume on mancozeb residue on potato and onion leaves and on Phythophthora infestans in potato and Peronospora destructor in onion
    Putter, H. de; Schepers, H.T.A.M. ; Topper, C.G. ; Evenhuis, A. - \ 2016
    Wageningen : Wageningen UR (vegIMPACT Report 21) - 21
    arable farming - vegetable growing - outdoor cropping - potatoes - onions - laboratory tests - solanum tuberosum - allium cepa - plant protection - pesticides - akkerbouw - groenteteelt - vollegrondsteelt - aardappelen - uien - laboratoriumproeven - solanum tuberosum - allium cepa - gewasbescherming - pesticiden
    As part of the vegIMPACT project a laboratory test in the Netherlands was done with potato (Solanum tuberosum) var. Bintje and onion (Allium cepa) var. Sturon. In both crops mancozeb was sprayed with and without the adjuvants Bond and Indostick. In both crops these three treatments were applied with high and low spray volumes. After spraying, rain was simulated (0.5, 3 or 6 hours after spraying and a control without rain) to test the sticker properties. After five days, plant leaves were analysed on mancozeb residue. Five days after spraying the potato plants were inoculated with Phytophthora infestans and onions with Peronospora destructor. Subsequently, disease symptoms were observed and visually rated as percentage of infected leaves. In potato lower mancozeb residue levels were measured at high spray volumes. Under dry conditions the effect of adjuvant on mancozeb residue in potato was limited. In onion the spreader characteristics of the adjuvants resulted in higher mancozeb residue concentrations than without adjuvant. The impact of rain simulation was much bigger than the impact of adjuvant on mancozeb residue and late blight incidence. Therefore, it is not recommended to spray when rain is expected within the same day as spraying. With rain simulation in both onion and potato more mancozeb residue was present when using the adjuvant Bond than when spraying mancozeb without an adjuvant. However, also with Bond after rain simulation high amounts of mancozeb were washed off. Mancozeb with Bond in potato resulted in less late blight incidence than with spraying mancozeb without adjuvants. Overall the adjuvant Bond performed better than Indostick in terms of mancozeb retention on both potato and onion leaves . Indostick had good spreading properties that under dry conditions resulted in higher mancozeb residue levels in onion. Under rainy conditions the effect of Indostick on mancozeb residues was not or only slightly better than mancozeb without adjuvant.
    Towards an improved variety assortment for the Dutch organic sector : case studies on onion and spring wheat
    Osman, A.M. - \ 2014
    Wageningen University. Promotor(en): Edith Lammerts van Bueren; Paul Struik, co-promotor(en): Conny Almekinders. - Wageningen : Wageningen University - ISBN 9789462570689 - 212
    allium cepa - uien - triticum aestivum - zomertarwe - biologische landbouw - rassen (planten) - cultivars - rassenproeven - rasreacties - classificatie van rassen - plantenveredeling - allium cepa - onions - triticum aestivum - spring wheat - organic farming - varieties - cultivars - variety trials - varietal reactions - variety classification - plant breeding

    Key words:

    organic farming; principles of organic agriculture; food production chain;

    plant breeding; genetic correlation; plant traits; farmers’ preferences;

    variety testing; Value for Cultivation and Use; EU seed legislation;

    onion; Allium cepa; spring wheat; Triticum aestivum; baking quality

    Variety choice is an important component of organic crop management. The organic sector pursues to produce healthy, nutritious food without using synthetic inputs and excessive amounts of natural resources. Access to varieties that are able to cope with weeds, diseases and pests, and thrive well under an organic fertility management regime, allows actors in the organic food production chain to achieve these aspirations. In this thesis I analyse how the current breeding, variety assessment and registration process should be changed to provide varieties that fulfil the needs of organic farmers, traders and processors. The research is based on the cases of two crops, onion (Allium cepa) and spring wheat (Triticum aestivum), that differ in key issues that influence the options for change: breeding and variety registration aspects; organic seed and crop production issues; destination of the harvest; and composition of and relations between actors in the production chain.

    Variety trials, in which we evaluated onion and spring wheat varieties for traits prioritized by organic stakeholders, revealed that the variety assortment displayed important weaknesses when grown and processed organically. In the case of onion, farmers needed varieties with improvements for resistances against main diseases, root system, storability and erect plant types in combination with high yield. For spring wheat, weed suppressiveness and baking quality were the key traits that required improvements.

    Interviews with conventional onion breeders showed that they focussed on yield and post-harvest traits (storability, bulb quality). In addition to these traits, breeding for the organic sector would require breeders to pay more attention to the selection of field traits like partial resistance against leaf diseases and a better root system. To improve key traits for organic growers, selection should take place in a growing environment without the fungicides and herbicides that are typically applied in conventional nurseries.

    Interviewing conventional wheat breeders made clear that selection for the organic market would conflict with achieving the high yield demanded by conventional growers. Breeders have achieved high yields by increasing the harvest index, which goes at the expense of baking quality through a relative decrease in protein content. Based on a literature review, we propose two alternative approaches to improve yield and protein content simultaneously: selection for increased total biomass or/and selection for protein quality. The first approach would deliver taller, leafier varieties that are also more competitive against weeds. Improving protein quality would require selection under low nitrogen input or organic growing conditions as protein composition is strongly influenced by soil nitrogen availability. Analysis of data of our own conventional and organic variety trials, together with datasets from other European countries showed that for other important traits (e.g., yield, disease resistance, plant length) selection for the organic sector could also be conducted in non-organically managed breeding nurseries, which typically refrain from fungicides and growth regulator applications, as genetic correlations for these traits were high (0.8 -1.0).

    Conducting variety trials in organic fields and evaluating these for traits prioritized by the stakeholders make results more relevant for the latter. In the specific case of Value for Cultivation and Use (VCU) testing, that is part of the official variety registration procedure of field crops in the EU, adapting the research protocol proved crucial to provide market access to varieties better adapted to organic production. The organic spring wheat VCU testing resulted in the inclusion of varieties in an organic section of the Dutch Recommended List of Varieties, showing that the statutory variety testing system is flexible to address new needs. However, procedures are costly and not in proportion to market size and in this way prohibit the release of varieties for organic and other small markets.

    Although specifically wheat breeders proved to be open to consider adaptations in their programme, the relatively small market prevents conventional private sector breeders from investing in selecting varieties specifically targeted at the organic sector. Therefore we elaborate options to set up a way of breeding that is in line with organic principles and overcomes this economic barrier.

    Effect van selectie onder biologische en gangbare omstandigheden bij ui
    Nuijten, H.A.C.P. ; Tiemens-Hulscher, M. ; Lammerts Van Bueren, E. - \ 2012
    Driebergen : Louis Bolk Instituut (Publicatie / Louis Bolk Instituut nr. 2012-040 LbP) - 39
    allium cepa - uien - biologische landbouw - akkerbouw - rassen (planten) - selectie - plantenveredeling - biologische plantenveredeling - onions - organic farming - arable farming - varieties - selection - plant breeding - organic plant breeding
    Een belangrijke vraag voor de biologische landbouw is hoe veredeling kan bijdragen aan betere rassen voor biologische teeltomstandigheden. De rassen die biologische telers gebruiken komen voort uit gangbare veredelingsprogramma’s. Deze rassen zijn niet altijd even goed aangepast aan biologische productiemethoden. Uit eerder onderzoek bleek dat er grote verschillen in zaadkwaliteit waren van de gangbare en biologische selecties, waardoor moeilijk te zeggen is in hoeverre verschillen in wortelgroei het gevolg zijn van zaadkwaliteit dan wel selectie.
    Stoombehandelingen eerstejaars plantuien tegen valse meeldauw
    Evenhuis, A. ; Spruijt, J. ; Topper, C.G. - \ 2011
    Lelystad : Praktijkonderzoek Plant & Omgeving, Business Unit AGV - 12
    allium cepa - uien - plantuien - plantenziekteverwekkende schimmels - peronospora destructor - plantenziektebestrijding - stomen - nederland - akkerbouw - onions - onion sets - plant pathogenic fungi - plant disease control - steaming - netherlands - arable farming
    In de winter van 2010-2011 zijn in opdracht van het Productschap Akkerbouw verschillende stoombehandelingsvarianten bij Ruvoma uitgevoerd. Namelijk bij 40, 42.5 en 45 ∘C, bij 85 en 95 % RV en gedurende één en twee dagen. De uitjes zijn vervolgens in een biotoets in de kas getoetst op kieming en systemische aantasting.
    Appearance of Neotoxoptera formosana (Homoptera: Aphididae) in The Netherlands
    Piron, P.G.M. - \ 2010
    Entomologische Berichten 70 (2010)1. - ISSN 0013-8827 - p. 10 - 12.
    aphididae - gewasbescherming - allium - allium cepa - bieslook - allium fistulosum - allium sativum - knoflook - plant protection - chives - garlic
    Neotoxoptera formosana (Takahashi) is a pest of wild and cultivated Allium species, but never iwht disastrous consequences. In 1984, N. formosana was found in France. This was the first finding in Europe. Since then, N. formosana has been observed also in other European countries. The first record for The Netherlands dates from 1993. Hoever, this finding is very doubful, because the aphids found were not properly identified; rather the names of three species known to occur on the food plant were suggested, including N. formosana. To my knowledge the present report documents the first occurrence of N. formosana in The Netherlands
    Effect van borium op de hardheid van uien
    Brink, L. van den - \ 2010
    Lelystad : PPO AGV - 12
    allium cepa - uien - borium - boriummeststoffen - kwaliteit - gewaskwaliteit - onions - boron - boron fertilizers - quality - crop quality
    Dit rapport beschrijft de resultaten van een experiment waarbij gekeken is naar het effect van bemesting met borium op de hardheid van uien.
    Inventarisatie hulpstoffen : onderzoek naar het effect van toevoeging hulpstoffen bij bestrijding van valse meeldauw (Peronospora destructor) en bladvlekken (Botrytis squamosa) in ui
    Meier, R. ; Schepers, H.T.A.M. - \ 2010
    Lelystad : Praktijkonderzoek Plant & Omgeving, Business unit Akkerbouw, Groen ruimte en Vollegondsgroenten (AGV) - 15
    allium cepa - uien - peronospora destructor - plantenziektebestrijding - fungiciden - hulpstoffen - onions - plant disease control - fungicides - adjuvants
    Voor de bestrijding van valse meeldauw in ui is de inzet van fungiciden vooralsnog onontbeerlijk. Om de emissie naar het milieu en de kosten zoveel mogelijk te beperken is in een veldproef in zaaiui onderzocht of door toevoeging van hulpstoffen aan fungiciden de effectiviteit tegen schimmelziektes wordt verhoogd en de dosering van de fungiciden daardoor verlaagd kan worden. Voor de toevoeging van een aantal hulpstoffen blijkt dat inderdaad het geval te zijn.
    Genoeg mycorrhiza's in bodem
    Bos, J.F.F.P. - \ 2009
    Boerderij 95 (2009)9. - ISSN 0006-5617 - p. 58 - 58.
    uien - allium cepa - rizosfeer - mycorrhizae - mycorrhizaschimmels - opname (uptake) - onions - rhizosphere - mycorrhizas - mycorrhizal fungi - uptake
    Uit onderzoek van Wageningen Universiteit blijkt dat in het verleden uienrassen onbewust al geselecteerd zijn op hun goede samenwerking met mycorrhiza's
    Fosfaatonderzoek Powerstart in zaaiuien 2008 : op kleigrond
    Paauw, J.G.M. - \ 2009
    Lelystad : Praktijkonderzoek Plant & Omgeving, Business Unit Akkerbouw, Groene Ruimte en Vollegrondsgroenten - 12
    allium cepa - uien - mengmeststoffen - fosfaten - magnesium - kalium - zink - opbrengsten - bemesting - onions - compound fertilizers - phosphates - potassium - zinc - yields - fertilizer application
    In dit rapport staat het resultaat van een onderzoek naar de fosfaatwerking van Powertstart in het gewas zaaiuien. Powerstart is een vloeibare meststof die de mineralen fosfaat, kalium, magnesium en zink bevat. De meststof is tijdens het zaaien toegediend.
    Resistance to Fusarium basal rot and response to arbuscular mycorrhizal fungi in Allium
    Galvan Vivero, G.A. - \ 2009
    Wageningen University. Promotor(en): Rolf Hoekstra; Thomas Kuijper, co-promotor(en): Olga Scholten; Chris Kik. - [S.l. : S.n. - ISBN 9789085854760 - 160
    allium cepa - allium - fusarium oxysporum f.sp. cepae - fusarium proliferatum - glomus intraradices - ziekteresistentie - genetische analyse - vesiculair-arbusculaire mycorrhizae - symbiose - plantenveredeling - resistentieveredeling - allium cepa - allium - fusarium oxysporum f.sp. cepae - fusarium proliferatum - glomus intraradices - disease resistance - genetic analysis - vesicular arbuscular mycorrhizas - symbiosis - plant breeding - resistance breeding
    Onion (Allium cepa L.) cultivation in low input and organic farming systems is hampered by Fusarium basal rot (FBR) and the limited ability of onion to take up nutrients like phosphorus. The symbiosis with arbuscular mycorrhizal fungi (AMF) contributes to plant acquisition of phosphorus, among other benefits. This PhD research studied the potential contributions from A. fistulosum and A. roylei to breed onion cultivars with resistance to FBR and enhanced benefit from the symbiosis with AMF. The genetic basis of these traits was studied in an A. cepa x (A. roylei x A. fistulosum) population. A collection of Fusarium isolates was analysed using AFLP markers. The most abundant species was F. oxysporum (with isolates clustered in two clades) followed by F. proliferatum. The Allium species were screened for FBR resistance using one F. oxysporum isolate from each clade, and one F. proliferatum isolate. Allium fistulosum showed high levels of resistance to these three isolates and A. roylei intermediate levels of resistance. High level of resistance from A. fistulosum was dominantly expressed in the A. roylei x A. fistulosum hybrid and the tri-hybrid population. A molecular linkage map based on AFLP markers was developed for the A. roylei x A. fistulosum hybrid. A QTL for FBR resistance from A. roylei was mapped on chromosome 2, and a QTL from A. fistulosum on chromosome 8. Each QTL separately had significant effect on FBR but did not confer complete resistance, thus more QTLs from A. fistulosum remain to be discovered. Regarding Allium-AMF relationship, a first step of research studied genetic diversity and colonization levels of naturally occurring AMF, comparing organic and conventional onion farming in the Netherlands. All plants were colonized with 60% average arbuscular colonization. Onion yields were positively correlated with colonization. AMF phylotypes were identified by rDNA sequencing. The number of phylotypes per field ranged from one to six. Two Glomus-A phylotypes were the most abundant, whereas other phylotypes were infrequently found. Organic and conventional fields had similar number of phylotypes and Shannon diversity indices. A few organic and conventional fields had larger number of phylotypes, which suggested that specific environmental conditions or agricultural practices influence AMF diversity. The genetic basis for the response to AMF in the tri-hybrid Allium population was evaluated in two independent greenhouse experiments. The weights of mycorrhizal plants were significantly larger than the non-mycorrhizal plants. Mycorrhizal Responsiveness (MR) was negatively correlated with plant weight in the non-mycorrhizal condition and was therefore considered unsuitable as an index for plant breeding purposes. Two new indices were proposed: mycorrhizal benefit (MB) and mycorrhizal breeding value (MV). Tri-hybrid genotypes showed transgressive segregation for plant weight, MB, and MV. Two QTLs from A. roylei for these traits were detected on chromosomes 2 and 3. A QTL from A. fistulosum for MV (but not MB), plant weight and the number of stem-borne roots was found on linkage group 9. Positive correlations between plant weight, rooting system and benefit from mycorrhiza were observed, which open prospects to combine these traits in the development of more robust onion cultivars.


    Opbrengst en kwaliteit van belang
    PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2009
    Boerderij 94 (2009)48. - ISSN 0006-5617 - p. 56 - 56.
    allium cepa - uien - rassen (planten) - cultivars - opbrengsten - gewaskwaliteit - nederland - rassenlijsten - onions - varieties - yields - crop quality - netherlands - descriptive list of varieties
    Overzicht van de uienrassenlijsten. Deze zijn gebaseerd op gegevens na bewaring en voor de teler een basis om tot een weloverwogen rassenkeuze te komen
    Possibilities for breeding to improve responsiveness to arbuscular mycorrhizal fungi in onion
    Galvan Vivero, G.A. ; Burger, K. ; Kuyper, T.W. ; Kik, C. ; Scholten, O.E. - \ 2009
    allium cepa - uien - mycorrhizaschimmels - low input landbouw - allium fistulosum - onions - mycorrhizal fungi - low input agriculture
    Arbuscular mycorrhizal fungi (AMF) play an important role in the uptake of nutrients and water from soil. However, some crops, for example onion, Allium cepa L., have a poorly developed root system. As a result, onion plants need a lot of fertiliser for growth, and they are sensitive to drought. The aim of this project is to study the beneficial effects of mycorrhizal fungi on the growth and development of Allium species and to determine whether it is possible to improve onions for mycorrhizal responsiveness by breeding. Variation among Allium species indicated that selection and thus breeding for high responsiveness to AMF is possible. Two years of experiments with genotypes of a population segregating for mycorrhiza responsiveness indicated that increase in dry matter may be a more reliable trait than responsiveness
    Voorkomen en beheersen van Fusarium in uien
    Blok, H. ; Visser, L. ; Broek, R.C.F.M. van den - \ 2009
    Lelystad : PPO AGV (Rapport / PPO Akkerbouw, Groene Ruimte en Vollegrondsgrondsgroente ) - 27
    fusarium oxysporum - fusarium oxysporum f.sp. cepae - bodemschimmels - gewasbescherming - allium cepa - ziektebestrijdende teeltmaatregelen - ziektebestrijding - agrarisch praktijkonderwijs - fusarium oxysporum - fusarium oxysporum f.sp. cepae - soil fungi - plant protection - allium cepa - cultural control - disease control - on-farm training
    Literatuurstudie uitgevoerd door studenten van CAH Dronten, naar 'Fusarium oxysporum formae speciale cepae', de schimmel die de meeste problemen geeft in de uienteelt. Het hoofddoel van het onderzoek is, om de beschikbare kennis over deze bodemschimmel te bundelen waarbij de nadruk wordt gelegd op het voorkomen, beheersen of te bestrijden van de ziekte in de uienteelt. In hoofdstuk 1 wordt de inleiding van het verslag uitgewerkt aan de hand van de omschrijving, omvang van het probleem en de aanleiding en doel van het verslag. In het tweede hoofdstuk worden de twee bodemschimmels beschreven die grote problemen veroorzaken in de Nederlandse uienteelt namelijk witrot en Fusarium. In hoofdstuk 3 wordt Fusarium verder gedefinieerd en worden de kenmerken en symptomen uitgewerkt. In het vierde hoofdstuk is het effect van Fusarium op de uienteelt uitgewerkt aan de hand van de geschatte economische verliezen, overzicht van probleemgebieden, besmettingsbronnen en gevolgen van de aanwezigheid in de bodem. In het vijfde hoofdstuk wordt de beheersing en bestrijding uitgewerkt, met daarbij ook de mogelijkheden om de ziekte te voorkomen. In het laatste hoofdstuk is een aanbeveling gemaakt hoe Fusarium in de uienteelt voorkomen of beperkt kan worden, dit wordt zowel voor de biologische als de gangbare teelt beschreven.
    Duurzame bestrijding van valse meeldauw in ui
    Stevens, L.H. ; Davelaar, E. ; Stoopen, G.M. ; Meier, R. ; Schepers, H.T.A.M. - \ 2009
    uien - allium cepa - peronospora farinosa - pesticiden - onions - pesticides
    Poster met informatie uit onderzoek naar de ontwikkeling van een effectief middel tegen valse meeldauw in ui door combinatie van componenten die qua type en toegepaste hoeveelheden nauwelijks milieu-impact hebben
    Geïntegreerde onkruid- en ziektebestrijding in ui
    Schepers, H.T.A.M. - \ 2009
    onkruidbestrijding - ziektebestrijding - herbiciden - fungiciden - geïntegreerde bestrijding - uien - allium cepa - akkerbouw - weed control - disease control - herbicides - fungicides - integrated control - onions - arable farming
    Poster met informatie uit onderzoek om te komen tot vermindering van fungiciden- en herbicidengebruik in de uienteelt (plantuien, pootuien én zaaiuien), door preventie en integratie van chemische en mechanische onkruidbestrijding
    Knelpunten in de biologische veredeling; een stap verder: resultaten onderzoeksprogramma 2004-2007
    Lammerts Van Bueren, E. ; Osman, A.M. ; Tiemens-Hulscher, M. ; Timmermans, B. ; Scholten, O.E. ; Voorrips, R.E. ; Burger, K. ; Steenhuis, M.M. ; Galvan, G. - \ 2008
    Ekoland 2008 (2008)1. - ISSN 0926-9142 - p. 26 - 29.
    biologische landbouw - gewasbescherming - genetische gewasbescherming - plantenveredeling - koolsoorten - daucus - tarwe - allium cepa - onderzoek - biologische plantenveredeling - organic farming - plant protection - genetic control - plant breeding - cabbages - daucus - wheat - allium cepa - research - organic plant breeding
    De biologische landbouw kent voor sommige gewasssen specifieke knelpunten die via de teelt moeilijk aangepakt kunnen worden, maar die via de veredeling wél behandeld kunnen worden. In de afgelopen vier jaar heeft in het kader van Bioconnect een onderzoeksprogramma gelopen om de ontwikkeling van betere rassen te ondersteunen. Het onderzoek heeft zich vooral gericht op de weerbaarheid tegen trips (kool), zwarte vlekken (peen) en fusarium (tarwe) en op het ontwikkelen van nieuwe veredelingsstrategieën (ui)
    Can conventional breeding programmes provide onion varieties that are suitable for organic farming in the Netherlands?
    Osman, A.M. ; Struik, P.C. ; Almekinders, C.J.M. ; Lammerts Van Bueren, E. - \ 2008
    Euphytica 163 (2008)3. - ISSN 0014-2336 - p. 511 - 522.
    biologische landbouw - plantenveredeling - allium cepa - biologische plantenveredeling - organic farming - plant breeding - allium cepa - organic plant breeding - allium-roylei stearn - cepa l - resistance - backcross - systems - fungi
    Main stream commercial onion breeders do not select varieties for organic farming, but solely for conventional farming. Seed companies consider the organic market too small to justify investments in breeding for this sector. In order to study if their varieties also suit organic farmers¿ needs we interviewed four Dutch commercial onion breeders on their breeding programme and selection criteria and compared the outcome with a variety profile composed of the priority traits of Dutch organic farmers. Breeders gave priority to the same storage and bulb quality traits that are demanded by organic farmers, because organic onions are exported to conventional supermarkets that apply the same quality standards to organic and conventional onions. However, organic farmers also need varieties that perform well in the field. Breeders give low priority to field selection. Furthermore, three of the four seed companies only breed hybrids. The cytoplasmic male sterility system used to produce these hybrids does not comply with organic principles. We conclude that at present breeders can provide varieties that meet organic farmers¿ demands for storability and quality traits, but they should give higher priority to field selection to also improve required field traits. The latter will only occur, if in future the organic seed market will grow. If the organic sector wants varieties developed according to its own principles, it should either set up its own onion breeding programme or seek alliances with breeding companies that are prepared to harmonize their breeding methodology with the organic principles
    Genetic variation among Fusarium isolates from onion, and resistance to Fusarium basal rot in related Allium species
    Galván, G.A. ; Koning-Boucoiran, C.F.S. ; Koopman, W.J.H. ; Burger-Meijer, K. ; Gonzáles, P.H. ; Waalwijk, C. ; Kik, C. ; Scholten, O.E. - \ 2008
    European Journal of Plant Pathology 121 (2008)4. - ISSN 0929-1873 - p. 499 - 512.
    ziekteresistentie - fusarium - allium - schimmelziekten - allium cepa - onderzoek - aflp - disease resistance - fusarium - allium - fungal diseases - allium cepa - research - amplified fragment length polymorphism - f-sp cepae - root-rot - oxysporum - proliferatum - aflp - genealogies - cultivars - culmorum - disease - complex
    The aim of this research was to study levels of resistance to Fusarium basal rot in onion cultivars and related Allium species, by using genetically different Fusarium isolates. In order to select genetically different isolates for disease testing, a collection of 61 Fusarium isolates, 43 of them from onion (Allium cepa), was analysed using amplified fragment length polymorphism (AFLP) markers. Onion isolates were collected in The Netherlands (15 isolates) and Uruguay (9 isolates), and received from other countries and fungal collections (19 isolates). From these isolates, 29 were identified as F. oxysporum, 10 as F. proliferatum, whereas the remaining four isolates belonged to F. avenaceum and F. culmorum. The taxonomic status of the species was confirmed by morphological examination, by DNA sequencing of the elongation factor 1-¿ gene, and by the use of species-specific primers for Fusarium oxysporum, F. proliferatum, and F. culmorum. Within F. oxysporum, isolates clustered in two clades suggesting different origins of F. oxysporum forms pathogenic to onion. These clades were present in each sampled region. Onion and six related Allium species were screened for resistance to Fusarium basal rot using one F. oxysporum isolate from each clade, and one F. proliferatum isolate. High levels of resistance to each isolate were found in Allium fistulosum and A. schoenoprasum accessions, whereas A. pskemense, A. roylei and A. galanthum showed intermediate levels of resistance. Among five A. cepa cultivars, `Rossa Savonese¿ was also intermediately resistant. Regarding the current feasibility for introgression, A. fistulosum, A. roylei and A. galanthum were identified as potential sources for the transfer of resistance to Fusarium into onion.
    Schimmelbestrijding met driftarme spuitdoppen in aardappel en ui
    Schepers, H.T.A.M. ; Meier, R. - \ 2008
    gewasbescherming - pesticiden - schimmelbestrijding - spuitdoppen - spuiten - drift - veldproeven - botryotinia squamosa - peronospora destructor - phytophthora infestans - fungiciden - toepassing - allium cepa - aardappelen - uien - plant protection - pesticides - fungus control - fan nozzles - spraying - field tests - fungicides - application - potatoes - onions
    Poster met onderzoeksresultaten. Dat driftarme doppen de drift verminderen is duidelijk. Maar de vraag is of de bestrijding van schimmels met deze doppen even effectief is als met de standaard doppen. Er is naar een antwoord gezocht in de gewassen aardappel en ui. Zowel de gewasstructuur als de toegelaten fungiciden zijn verschillend voor deze 2 gewassen. Ook is gekeken naar de rol van hulpstoffen bij de herverdeling en dampremming.
    Breeding for improved responsiveness to arbuscular mycorrhizal fungi in onion
    Galvan Vivero, G.A. ; Burger, K. ; Kuiper, T.W. ; Kik, C. ; Scholten, O.E. - \ 2008
    biologische landbouw - allium cepa - uien - wateropname (planten) - voedingsstoffenopname (planten) - mycorrhizae - mycorrhizaschimmels - biologische plantenveredeling - organic farming - allium cepa - onions - water uptake - nutrient uptake - mycorrhizas - mycorrhizal fungi - organic plant breeding
    Onion (Allium cepa L.) is one of the leading vegetable crops worldwide. Due to its superficial root system that is rarely branched and lacks root hairs, onion is very inefficient in the uptake of water and nutrients. As a result, large amounts of fertilizer are used in onion cultivation. In low-input systems crops need to be nutrient scavengers. To improve nutrient uptake in onions it is possible to breed for larger root systems using A. fistulosum. A complementary approach is to use arbuscular mycorrhizal fungi (AMF), which associate with onion and improve plant growth and the uptake of nutrients and water from soils. Previous research showed high responsiveness of A. fistulosum with AMF. The aim of the present research was to study possibilities to improve onions for mycorrhizal responsiveness by breeding.
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