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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    Transport and storage of cut roses: endless possibilities? : guide of practice for sea freight of cut roses developed within GreenCHAINge project
    Harkema, Harmannus ; Paillart, Maxence ; Lukasse, Leo ; Westra, Eelke ; Hogeveen, Esther - \ 2017
    Wageningen : Wageningen Food & Biobased Research (Wageningen Food & Biobased Research rapport 1699) - ISBN 9789463430609 - 48
    roses - refrigerated transport - air transport - sea transport - transporting quality - postharvest losses - vase life - rozen - koeltransport - luchttransport - zeetransport - vervoerskwaliteit - verliezen na de oogst - vaasleven
    Geïntegreerde bestrijding van plagen in de sierteelt onder glas : een systeembenadering met preventieve biologische bestrijding als basis
    Messelink, G.J. ; Leman, A. ; Ghasemzadeh Dizaji, Somaiyeh ; Bloemhard, C.M.J. ; Holstein, R. van; Vijverberg, Roland ; Muñoz-Cárdenos, Karen - \ 2016
    Bleiswijk : WageningenUR Glastuinbouw (Rapport GTB 1420) - 98
    siergewassen - glastuinbouw - kasgewassen - rozen - chrysanten - alstroemeria - biologische bestrijding - organismen ingezet bij biologische bestrijding - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - thrips - neoseiulus cucumeris - trialeurodes vaporariorum - aleyrodes - bemisia tabaci - amblyseius swirskii - euseius - iphiseius - roofmijten - orius - cryptolaemus montrouzieri - anagyrus pseudococci - planococcus citri - ornamental crops - greenhouse horticulture - greenhouse crops - roses - chrysanthemums - alstroemeria - biological control - biological control agents - integrated control - integrated pest management - thrips - neoseiulus cucumeris - trialeurodes vaporariorum - aleyrodes - bemisia tabaci - amblyseius swirskii - euseius - iphiseius - predatory mites - orius - cryptolaemus montrouzieri - anagyrus pseudococci - planococcus citri
    The control of greenhouse pests in ornamental crops is getting more difficult because of the decreasing number of available pesticides. Alternative methods of pest control, based on biopesticides and natural enemies is promising, but not yet robust and reliable enough. In this project we developed and evaluated several methods to enhance the biological control of western flower thrips, Echinothrips americanus, whiteflies and mealybugs. Most studies were focused on preventive control measures that promote the establishment and efficacy of natural enemies by using top layers, alternative food, artificial domatia and a banker plant system. Furthermore we studied the interaction between parasitoids and predatory beetles for curative control of mealybugs. Finally, a number of (bio)pesticides was evaluated for their potential use as a correction tool against western flower thrips.
    LED’s zijn geschikt om snel dips en pieken in natuurlijk licht op te vangen
    Gelder, Arie de - \ 2016
    led lamps - roses - heat exchangers - heat - thermal radiation - light - artificial light - greenhouse horticulture
    Duurzaamheid als leidraad voor roos : vervolg onderzoek Perfecte Roos: energiezuinig geteeld
    Gelder, Arie de; Warmenhoven, Mary ; Knaap, Edwin van der; Burg, Rick van der - \ 2016
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1412) - 50
    rozen - teelt onder bescherming - kasgewassen - glastuinbouw - duurzame landbouw - energiebesparing - elektriciteit - assimilatie - kunstlicht - kunstmatige verlichting - verlichting - koelen - meeldauw - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - roses - protected cultivation - greenhouse crops - greenhouse horticulture - sustainable agriculture - energy saving - electricity - assimilation - artificial light - artificial lighting - lighting - cooling - mildews - integrated control - integrated pest management
    The project Sustainable rose cultivation aimed to achieve a sustainable and energy efficient rose cultivation by a controlled use of assimilation lighting, an optimum use of the cooling and an integrated control strategy for mildew. The production came to 320 stems.m-2 average weight 54 grams. The branch length and bud size varied through the season. There was no saving on electricity. There was a significant saving on heat. The improvement of the energy efficiency was totally determined by the reduction of the heat consumption. The light utilization efficiency was 2:44 g.mol-¹ and increased compared to the previous year. Cooling and forced ventilation had a positive effect on the stem elongation in the autumn. The installation with forced ventilation from above combined with the screen had a favourable effect on the climate, especially in the humidity control under a largely (95-98%) closed screen. The payback period of the investment in airconditioning is within 3 years.
    ‘ Lucht aanzuigen boven scherm moet klimaat verbeteren’ : goede productie in onderzoek naar ‘de perfecte roos’
    Gelder, Arie de - \ 2016
    horticulture - greenhouse horticulture - greenhouse technology - cut flowers - roses - agricultural research - mildews - spraying - climatic factors - crop production - heat exchangers - ventilators - illumination

    Na een goed voorjaar heeft het rozengewas bij het in Bleiswijk gevestigde Improvement Centre in de zomer en het begin van de herfst meeldauw opgelopen. Door verandering van klimaat en verbeterde spuittechniek is dit weer onder controle. De warmtewisselaars kunnen nu lucht boven het energiescherm aanzuigen, zodat de schermen optimaal inzetbaar zijn.

    Lichtspectrum als middel voor energiezuinige rozenteelt : praktijkproef bij Van der Arend Roses
    Garcia Victoria, N. ; Pot, S. - \ 2015
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1368) - 68
    teelt onder bescherming - glastuinbouw - rozen - kunstlicht - led lampen - lichtsterkte - productie - kwaliteit - energiebesparing - energy economics - protected cultivation - greenhouse horticulture - roses - artificial light - led lamps - light intensity - production - quality - energy saving - energy economics
    During the winter 2014-2015 a research was conducted at a commercial rose nursery to learn more about the influence of a special lamp light spectrum on the production and quality of the rose Avalanche. A “hybrid” lighting system was installed with 103 µmol /m2s PAR from High Pressure Sodium and from Valoya LED lamp G1 in two different intensities: 57 or 103 µmol /m2s PAR. Compared with the conventional installation of the company (191 micromol SON-T), the spectrum of the hybrid installation allowed, depending on the intensity of the added LED, a 7.2% to 9% higher light use efficiency (LUE) by the crop. This offers possibilities for energy saving, but therefore the energy efficiency of the lamps used (Valoya G1) needs to increase to an output of 1.7 µmol PAR per watt electric. Valoya is already working on this improvement. The performed plant measurements (SPAD, bud temperature, photosynthesis, leaf area, etc.) do not contribute to explain this positive effect. More research about the effects of light colour on the rose production is needed. Remaining questions are if other rose varieties react the same to the combined spectrum, if the crop can grow more compact in winter when there is more blue in the spectrum, and if a larger proportion of far-red light could make the flowers even heavier, with a larger flower bud. The research was funded by the program “Greenhouse as Energy Source” (Ministry of Economy and the Horticultural Product Board) and Valoya.
    Een perfecte roos energiezuinig geteelt
    Gelder, A. de; Warmenhoven, M.G. ; Knaap, E. van der; Baar, P.H. van; Grootscholten, M. ; Aelst, N. - \ 2015
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1369) - 96
    rozen - teelt onder bescherming - glastuinbouw - gewaskwaliteit - energiebesparing - kooldioxide - verwarming - diffuus glas - koelen - led lampen - ventilatie - meeldauw - botrytis - vaasleven - economische analyse - bloementeelt - roses - protected cultivation - greenhouse horticulture - crop quality - energy saving - carbon dioxide - heating - diffused glass - cooling - led lamps - ventilation - mildews - botrytis - vase life - economic analysis - floriculture
    Within a greenhouse equipped with diffuse glass, cooling from above the crop, LED interlighting, active ventilation with tubes below the gutters and three screens an experiment was conducted to produce good quality roses in an energy effi cient way. After two years research the roses cv Red Naomi! fulfi lled the desired quality marks. This was achieved with less energy for heating compared to a defi ned virtual reference compartment. Combined with heat harvested during cooling there was no need for additional heating energy. The crop management was a key factor in the way to quality. For control of mildew and Botrytis it was necessary to keep the air humidity below 85 %. This is hard to achieve in an energy saving cropping system.
    Combinatie warmtewisselaars en schermen moet kwaliteit waarborgen : zoektocht naar perfecte roos een jaar verlengd
    Gelder, Arie de - \ 2015
    horticulture - greenhouse horticulture - cut flowers - roses - rosaceae - cropping systems - sustainability - crop quality - relative humidity - heat exchangers - lighting - plant protection
    Richtinggevende beelden voor klimaat neutrale glastuinbouw
    Poot, E.H. ; Garcia Victoria, N. ; Gelder, A. de; Kempkes, F.L.K. ; Marcelis, L.F.M. ; Raaphorst, M.G.M. ; Weel, P.A. van; Zwart, H.F. de - \ 2015
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1365) - 50
    glastuinbouw - duurzame landbouw - energiebesparing - klimaatregeling - kastechniek - belichting - kunstmatige verlichting - teeltsystemen - tomaten - rozen - snijbloemen - greenhouse horticulture - sustainable agriculture - energy saving - air conditioning - greenhouse technology - illumination - artificial lighting - cropping systems - tomatoes - roses - cut flowers
    With financial support of the Dutch ministry of EZ and Dutch horticulture product board PT, Wageningen UR Greenhouse Horticulture designed and simulated concepts with savings of 70% on thermal energy in the greenhouse cultivation of tomatoes, and 50% on electricity for artificial light in the greenhouse cultivation of roses. The tomato concept is based on prototypes “VenLow Energy Greenhouse” and “Next Generation Semiclosed Greenhouse”, and is able to produce tomatoes with 12 m3*m-2*year-1 of natural gas equivalents. Options for energy savings on electricity for assimilation lighting for roses cv. ‘Red Naomi!’ were developed regarding a roadmap with five steps. With significantly less hours of artificial lighting, more solar radiation by using less screens during day time, 3-day light integration and application of diffuse glass with AR coating and LED lights, 50% saving on energy for lighting seems possible without concessions to production. However this system seems not economic feasible yet.
    Een perfecte roos - Energiezuinig geteeld : kennisinteractie
    Gelder, Arie de - \ 2015
    cut flowers - roses - cultural methods - energy saving - carbon dioxide - illumination - heating - objectives
    A model based method for evaluation of crop operation scenarios in greenhouses
    Ooster, A. van 't - \ 2015
    Wageningen University. Promotor(en): Eldert van Henten, co-promotor(en): Jan Bontsema; Silke Hemming. - Wageningen : Wageningen University - ISBN 9789462573024 - 169
    kastechniek - glastuinbouw - simulatie - discrete simulatie - simulatiemodellen - arbeid (werk) - rozen - greenhouse technology - greenhouse horticulture - simulation - discrete simulation - simulation models - labour - roses


    This research initiated a model-based method to analyse labour in crop production systems and to quantify effects of system changes in order to contribute to effective greenhouse crop cultivation systems with efficient use of human labour and technology. This method was gradually given shape in the discrete event simulation model GWorkS, acronym for Greenhouse Work Simulation. Model based evaluation of labour in crop operations is relatively new in greenhouse horticulture and could allow for quantitative evaluation of existing greenhouse crop production systems, analysis of improvements, and identification of bottlenecks in crop operations. The modelling objective was a flexible and generic approach to quantify effects of production system changes. Cut-rose was selected as a case-study representative for many cut-flowers and fruit vegetables.

    The first focus was a queueing network model of the actions of a worker harvesting roses in a mobile cultivation system. Data and observations from a state-of-art mobile rose production system were used to validate and test the harvesting model. Model experiments addressed target values of operational parameters for best system performance. The model exposed effects of internal parameters not visible in acquired data. This was illustrated for operator and gutter speed as a function of crop yield. The structure and setup of the GWorkS model was generic where possible and system specific where inevitable.

    The generic concept was tested by transferring GWorkS to harvesting a greenhouse section in a static growing system for cut-roses and extending it with navigation in the greenhouse, product handling, and multiple operator activity (up to 3 workers). Also for rose harvesting in a static growing system, the model reproduced harvesting accurately. A seven workday validation for an average skilled harvester showed a relative root mean squared error (RRMSE) under 5% for both labour time and harvest rate. A validation for 96 days with various harvesters showed a higher RRMSE, 15.2% and 13.6% for labour time and harvest rate respectively. This increase was mainly caused by the absence of model parameters for individual harvesters. Work scenarios were simulated to examine effects of skill, equipment, and harvest management. For rose yields of 0.5 and 3 harvested roses per m2, harvest rate was 346 and 615 stems h-1 for average skilled harvesters, 207 and 339 stems h-1 for new harvesters and 407 and 767 stems h-1 for highly skilled harvesters. Economic effects of trolley choice are small, 0-2 € per 1000 stems and two harvest cycles per day was only feasible if yield quality effects compensate for extra costs of 0.2-1.1 eurocents per stem.

    In a sensitivity analysis and uncertainty analysis, parameters with strong influence on labour performance in harvesting roses in a static system were identified as well as effects of parameter uncertainty on key performance indicators. Differential sensitivity was analysed, and results were tested for linearity and superposability and verified using the robust Monte Carlo method. The model was not extremely sensitive for any of the 22 tested input parameters. Individual sensitivities changed with crop yield. Labour performance was most affected by greenhouse section dimensions, single rose cut time, and yield. Throughput was most affected by cut time of a single rose, yield, number of harvest cycles, greenhouse length and operator transport velocity. In uncertainty analysis the coefficient of variation for the most important outputs labour time and throughput is around 5%. The main sources of model uncertainty were in parallel execution of actions and trolley speed. The uncertainty effect of these parameters in labour time, throughput and utilisation of the operator is acceptably small with CV less than 5%. The combination of differential sensitivity analysis and Monte Carlo analysis gave full insight in both individual and total sensitivity of key performance indicators.

    To realise the objective of model based improvement of the operation of horticultural production systems in resources constrained system, the GWorkS-model was extended for simultaneous crop operations by multiple workers analysis. This objective was narrowed down to ranking eight scenarios with worker skill as a central theme including a labour management scenario applied in practise. The crop operations harvest, disbudding and bending were considered, which represent over 90% of crop-bound labour time. New sub-models on disbudding and bending were verified using measured data. The integrated scenario study on harvest, disbudding and bending showed differences between scenarios of up to 5 s per harvested rose in simulated labour time and up to 7.1 € m-2 per year in labour costs. The simulated practice of the grower and the scenario with minimum costs indicated possible savings of 4 € m-2 per year, which equals 15% of labour cost for harvest, disbudding and bending. Multi-factorial assessment of scenarios pointed out that working with low skilled, low paid workers is not effective. Specialised workers were most time effective with -17.5% compared to the reference, but overall a permanent team of skilled generalists ranked best. Reduced diversity in crop operations per day improved labour organisational outputs but ranked almost indifferent. The reference scenario was outranked by 5 scenarios.

    Discrete event simulation, as applied in the GWorkS-model, described greenhouse crop operations mechanistically correct and predicts labour use accurately. This model-based method was developed and validated by means of data sets originating from commercial growers. The model provided clear answers to research questions related to operations management and labour organisation using the full complexity of crop operations and a multi-factorial criterion. To the best of our knowledge, the GWorkS-model is the first model that is able to simulate multiple crop operations with constraints on available staff and resources. The model potentially supports analysis and evaluation of design concepts for system innovation.

    Kwaliteit roos: relaties vaasleven en kasklimaat
    Benninga, J. ; Barendse, J. ; Vermeulen, C. ; Garcia Victoria, N. ; Raaphorst, M.G.M. ; Hofland-Zijlstra, J.D. - \ 2015
    snijbloemen - rozen - rassen (planten) - vaasleven - duurzaamheid (durability) - proeven - cultivars - relatieve vochtigheid - cut flowers - roses - varieties - vase life - durability - trials - cultivars - relative humidity
    Kwaliteit is het sterke punt van Nederlandse ten opzichte van buitenlandse rozen. Vanuit de markt bestaat een toenemende vraag naar kwaliteit garanties. Gebleken is dat, vooral in de periode vanaf half december tot half februari, veel partijen Nederlandse rozen niet kunnen voldoen aan de verwachting van zeven dagen vaasleven, zo blijkt uit het project “vaasleven getest” van FloraHolland, waar 60% van de Nederlandse aanvoerders om de week aan deelnemen. Om het vaasleven in de kritische periode (winter) te verbeteren is in de winters 2012/2013 en 2013/2014 een onderzoek uitgevoerd bij acht rozenteeltbedrijven: 4 teelden het ras Red Naomi! en 4 het ras Avalanche+.
    Inleiding tripsbrainstorm
    Messelink, Gerben - \ 2015
    thrips - insect control - plant protection - roses - greenhouse experiments - plant disease control - natural enemies - biological control - predatory mites - workshops (programs)
    Bijvoeren van blad- en bodemroofmijten voor de bestrijding van trips in roos
    Messelink, G.J. ; Leman, A. ; Muñoz-Cardénas, K. ; Janssen, A. - \ 2015
    kasproeven - sierteelt - glastuinbouw - gewasbescherming - biologische bestrijding - organismen ingezet bij biologische bestrijding - rozen - roofmijten - conferenties - greenhouse experiments - ornamental horticulture - greenhouse horticulture - plant protection - biological control - biological control agents - roses - predatory mites - conferences
    Doelstelling van dit onderzoek is om te bepalen of de bestrijding van trips verbeterd kan worden door 1) een gecombineerde inzet van bodem- en bladroofmijten en 2) het bijvoeren van deze roofmijten in zowel de bodem als op het gewas. Poster van PlantgezondheidEvent 12 maart 2015.
    Geurdetectie als middel om wolluishaarden op te sporen
    Kogel, Willem Jan de - \ 2015
    plant protection - horticulture - workshops (programs) - odours - greenhouse experiments - greenhouse horticulture - roses - tetranychidae - pseudococcidae
    Kwaliteitsplan roos : onderdeel klimaatregistratie en statistiek
    Benninga, J. ; Barendse, H. ; Vermeulen, C. ; Garcia Victoria, N. ; Raaphorst, M.G.M. ; Hofland-Zijlstra, J.D. - \ 2015
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1336) - 41
    snijbloemen - rozen - vaasleven - gewaskwaliteit - houdbaarheid (kwaliteit) - kwaliteit na de oogst - temperatuur - winter - landbouwkundig onderzoek - cut flowers - roses - vase life - crop quality - keeping quality - postharvest quality - temperature - winter - agricultural research
    Dutch roses can’n always guarantee a vase life of seven days. A study was conducted in the winters 2012/2013 and 2013/2014 in eight roos nurseries in order to find ways to improve the vase life in the critical period (winter). Four nurseries cultivated the variety Red Naomi! and four Avalanche+. For the study collaborated growers, FloraHolland, Wageningen UR Greenhouse Horticulture and Wageningen UR LEI. Financial support was granted by the Topsector T & U (Ministry of EL & I). The vase life of the roses varied between 3.5 and 17.7 days. Differences were found among the growers in vase life, bud opening, the occurrence of leaf and Botrytis problems, and the Botrytis spore pressure in the greenhouse. An explanation for these differences is found in greenhouse climate parameters: For Red Naomi! a decrease in vase life is explained mainly by high average humidity and little temperature fluctuations > 1°C . For Avalanche+ the differences in vase life are explained by the length of the dark period and the RV: the longer the dark period, and the lower the RH, the better the vase life. Bud opening is in both varieties explained and negatively impacted by RV’s higher than 93%. The vase life results are representative of the average quality of Dutch roses, as they correlate well with those of the FloraHolland project “vase life tested”. This correlation will be useful for the proposed implementation in practice.
    Belichtingsapplicatie : rapportage tot Go/No Go moment
    Gelder, A. de - \ 2014
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport / Wageningen UR Glastuinbouw 1331) - 26
    tuinbouw - kastechniek - glastuinbouw - rozen - belichting - assimilatie - fotosynthese - energiebesparing - internet - computer hardware - horticulture - greenhouse technology - greenhouse horticulture - roses - illumination - assimilation - photosynthesis - energy saving - internet - computer hardware
    In dit project wordt een belichtingsapplicatie ontwikkeld voor op internet waarmee tuinders op belichting kunnen besparen. Het model geeft op basis van de behoefte van de plant, bedrijfsspecifieke informatie en de weersverwachting een dagelijks advies over het gewenste aantal uren belichting.
    Towards marker assisted breeding in garden roses: from marker development to QTL detection
    Vukosavljev, M. - \ 2014
    Wageningen University. Promotor(en): Richard Visser; Rene Smulders, co-promotor(en): Paul Arens. - Wageningen : Wageningen University - ISBN 9789462571341 - 245
    rosa - rozen - siergewassen - tuinen - marker assisted breeding - loci voor kwantitatief kenmerk - genetische merkers - rosa - roses - ornamental crops - gardens - marker assisted breeding - quantitative trait loci - genetic markers

    Over the last few decades the rose market in Eastern Europe showed a steady growth, which indicates that there is increasing demand for new cultivars that are adapted to the climate as well as to the customs and beauty criterion of that region. One of the possibilities to speed up breeding is to implement marker assisted selection (MAS). Implementation of MAS requires a specific infrastructure (molecular markers, knowledge on genetics of important traits, genetic maps) which is not yet available for tetraploid roses. In this thesis I developed some of the prerequisites for MAS in roses and discuss when and how MAS could have a positive effect on accelerating breeding and/or reducing the costs of the breeding process.

    The first step in understanding the structure of the genepool of garden roses was to evaluate the relatedness among available cultivars. For the first time genetic diversity among modern garden rose cultivars was evaluated (Chapter 2) using a set of 24 microsatellite markers covering most chromosomes. A total of 518 different alleles were obtained in a set of 138 rose cultivars. Genetic differentiation among types of garden roses (Fst=0.022) was four times that found among cut roses, and similar in magnitude to the differentiation among breeders, due to the fact that horticultural groups and breeders overlap largely in classification. In terms of genetic diversity cut roses can be considered as a subgroup of the garden roses. Winter hardy Canadian garden rose cultivars (Explorer roses) showed the least similarities to European roses, and introgression from wild species for winter hardiness was clearly visible. Roses of two breeding programmes (Harkness and Olesen) shared a similar genepool. Comparison of the differentiation among linkage groups indicated that linkage group 5 is potentially a region containing important QTLs for winter hardiness. Linkage group 6 contains the largest amount of genetic diversity, while linkage group 2 is the most differentiated among types of garden roses.

    Garden roses, as well as many other important crops (wheat, potato, strawberry, etc.) are polyploid. Genetic analyses of polyploids is complex as the same locus is present on multiple homologous chromosomes. SSR markers are suitable for mapping in segregating populations of polyploids as they are multi-allelic, making it possible to detect different alleles of the same locus on all homologous chromosomes. If a SSR marker gives fewer alleles than the ploidy level, quantification of allele dosages increases the information content. In Chapter 3 I showed the power of this approach. Alleles were scored quantitatively using the area under the peaks in ABI electropherograms, and allele dosages were inferred based on the ratios between the peak areas for two alleles in reference cases in which these two alleles occurred together. We resolved the full progeny genotypes, generated more data and mapped markers more accurately, including markers with “null” alleles.

    Even though SSR markers are one of the most appropriate marker systems for genetic studies in polyploids still few hurdles complicate (reduce) their implementation. The first major hurdle in developing microsatellite markers, the cloning step, has been overcome by next generation sequencing techniques. The second hurdle is the testing step to differentiate polymorphic from non-polymorphic loci. The third hurdle, somewhat hidden, is that only those polymorphic markers that detect a large effective number of alleles in the germplasm to be studied, are sufficiently informative to be deployed in multiple studies. Both selection steps are laborious and still done manually. In Chapter 4 I present a strategy in which we first screen sequence reads from multiple genotypes for repeats that show the most variation in length, and only these are subsequently developed into markers. We validated our strategy in tetraploid garden rose using Illumina paired-end transcriptome sequences of 11 roses. Out of 48 tested two markers did not amplify but all others were polymorphic. Ten loci amplified more than one locus, indicating duplicated genes or gene families. Completely avoiding this will be difficult, as the range of numbers of predicted alleles of highly polymorphic single- and multi-locus markers largely overlapped. Of the remainder, half were duplicates, indicating the difficulty of correctly filtering short sequence reads containing repeat sequences. The remaining 18 markers were all highly polymorphic, amplifying between 6 and 20 alleles in the 11 tetraploid garden roses. This strategy therefore represents a major step forward in the development of highly polymorphic microsatellite markers.

    Despite that garden roses are economically very important ornamentals, breeding is still mostly conventional, mainly due to tetraploidy and the lack of genetic maps and knowledge about the genetic base of important traits. Furthermore, crosses with unintended parents occur regularly and detection of these is not always straightforward, especially when genetically related varieties are used. Moreover, in polyploids detection of off-type offspring often relies on detecting differences in allele dosage rather than the presence of new alleles. In Chapter 5 I applied the WagRhSNP Axiom rose SNP array to generate 10,000s of SNPs for parentage analysis and to generate a dense genetic map in tetraploid rose. I described a method to separate progeny into putative populations which share parents, even if one of the parents is unknown, using PCO analysis and sets of markers for which allele dosages are incompatible. Subsequently, dense SNP maps were generated for a biparental and a self-pollinated mapping population with one parent in common. I confirmed a tetrasomic mode of inheritance for these crosses and created a starting point for implementation of marker-assisted breeding in garden roses by QTL analysis for important morphological traits (recurrent blooming and prickle shape).

    Winter hardiness is a complex trait and one of the most important limiting factors for garden rose growth and distribution in areas characterized by a continental climate. In Chapter 6 research was undertaken to determine the genetic regions underlying winter hardiness of garden roses, and to generate markers linked to them. For this purpose we exposed two segregating populations, RNDxRND and RNDxHP, to temperatures below -15C in a cold chamber and in the field in Serbia. The frost damage in the hardened plants was estimated directly at the phenotypic level (proportion of dieback) and at the non-visible physiological level indirectly (through the potential for meristem production in spring; regrowth). For winter hardiness we detected two tentative QTLs in the RNDxRND population and two tentative QTLs in the RNDxHP population, of which one was the same in both populations. The ability of plants to regrow in spring was associated to genomic regions on three linkage groups of the RNDxRND population, and on two different linkage groups in the RNDxHP population. A comparison of the ability for regrowth and level of damage caused by low temperature revealed that these two traits are inherited independently and that the final cold tolerance depends on the plant’s ability to withstand low temperature and to regrow fast in spring.

    In résumé, this thesis resulted in the development of basic tools (a fast strategy for polymorphic SSR marker development), basic methods/concepts for genetic analyses in polyploids (quantification of SSR allele dosage, distinguishing outliers from population in polyploid crops, dense SNP map generation and QTL study in tetraploids), and knowledge on genetics of important traits in rose (relatedness among modern garden roses (genetic diversity approach), mode of inheritance, occurrence of selfing, QTLs for morphological traits (recurrent blooming and prickle shape) and dissection of winter hardiness (level of damage caused by low temperature and regrowth)). Additionally, potential use of markers in every phase of rose breeding was discussed (Chapter 7). All these aspects contribute to a solid basis for marker assisted breeding in (garden) rose.

    Bestrijding van Verticillium in de bodem : in de teelt van laanbomen (klei) en rozen (zand)
    Hiemstra, J.A. ; Sluis, B.J. van der - \ 2014
    Lisse : Praktijkonderzoek Plant & Omgeving, Business Unit Bloembollen, Boomkwekerij & Fruit - 31
    straatbomen - houtachtige planten - rozen - gewasbescherming - biologische grondontsmetting - verticillium dahliae - pratylenchus penetrans - proeven op proefstations - vergelijkend onderzoek - methodologie - street trees - woody plants - roses - plant protection - biological soil sterilization - verticillium dahliae - pratylenchus penetrans - station tests - comparative research - methodology
    1 Samenvatting en conclusies De in dit rapport beschreven experimenten werden opgezet om een aantal nieuwe methoden (alternatieven voor chemische bodemontsmetting) te testen op hun werkzaamheid voor wat betreft bestrijding van Verticillium dahliae (Vd) en daarnaast ook nematoden (Pratylenchus penetrans: Pp) in de bodem. De aandacht ging daarbij m.n. uit naar biologische grondontsmetting (BGO) en in mindere mate naar biofumigatie (Biofum) omdat op basis van beschikbare ervaringen en literatuur de verwachtingen van de eerste methode het hoogst waren. Op twee proeflocaties (Randwijk: klei, Vredepeel: zand) werden twee veldexperimenten opgezet waarbij beide methoden in een aantal herhalingen werden vergeleken met enkele andere methoden en controlebehandelingen. Op het proefveld op een zandbodem bleek het effect van BGO even sterk of zelfs nog beter dan dat van natte grond ontsmetting, gemeten aan de hoeveelheid Vd en Pp in de bodem na behandeling. Ook Biofum had op zandgrond een zeer sterk bestrijdingseffect, zij het iets minder dan BGO. Dat het effect van beide methoden niet zichtbaar werd in een verminderde aantasting door Verticillium van het testgewas roos (in vergelijking met de niet behandelde veldjes) komt waarschijnlijk doordat voor de proef in Vredepeel op verzoek van de Begeleidingscommissie gebruik is gemaakt van het in de praktijk veel gebruikte ras ‘Pfänder”. Dit ras bleek onder de omstandigheden op het proefveld, ook op de niet behandelde veldjes, ondanks de hoge inoculumdruk van zowel Vd als Pp, in de twee jaar van het experiment weinig zichtbaar zieke planten te geven. In het proefveld op kleigrond hadden beide methoden veel minder effect, zeker wat betreft de hoeveelheid Vd in de bodem. Weliswaar was het aantal zieke planten in het testgewas esdoorn (A. platanoides) na BGO het laagst, maar de verschillen tussen de behandelingen bleken statistisch niet significant en in de twee groeiseizoenen na de behandeling werd nog een substantieel deel van de planten ziek. De oorzaak van de mindere werking van BGO (en Biofum) op een kleibodem is niet geheel duidelijk, mogelijk heeft het echter te maken met verschillen in de poriënstructuur waardoor deze vrij zware kleibodem veel moeilijker doordringbaar was voor de bij de toepassing van BGO en Biofum gevormde toxische producten. Over het algemeen werkt chemische grondontsmetting op kleigronden sowieso minder goed dan op zandgrond. Dit wordt ook in dit experiment geïllustreerd door het feit dat natte grondontsmetting een beperkte werking had. Een opvallende waarneming ten slotte was dat niet alle door Vd geïnfecteerde esdoorns duidelijke bladsymptomen ontwikkelen. Bij een deel van de bomen bleek de schimmel aanwezig in het hout van de stam zonder zichtbare uitwendige symptomen. Waarneming van bladsymptomen alleen kan dus een onderschatting van het aantal geïnfecteerde bomen geven. Een tweede, voor de teelt interessante waarneming, is dat toepassing van BGO zeker geen negatief effect op de groei van het daarna geteelde gewas heeft. Hoewel de verschillen statistisch niet significant waren, waren de planten op de met BGO behandelde veldjes zowel op zand als op klei bij de sterkste groeiers. Tot slot werd een beperkte praktijkproef met BGO uitgevoerd bij een laanboomkweker op zandgrond. De resultaten hiervan vormen een sterke aanwijzing dat BGO in de teelt van laanbomen op zandgrond het optreden van Verticillium sterk kan beperken. In het met BGO behandelde blok was het aantal A. platanoides met symptomen circa 50% lager dan in het referentieblok. Voor een betere onderbouwing van dit effect is het echter nodig om BGO op grotere schaal, onder meer optimale omstandigheden in de praktijk te testen. Daarbij kan dan ook meer aandacht geschonken worden aan de economische haalbaarheid en de praktische inpasbaarheid in de bedrijfsvoering. Een praktijknetwerk wat zich hier op richt is inmiddels van start gegaan.
    Duurzame gewasbescherming roos in 2020 : Kennisdeling in de praktijk - Eindrapport
    Klein, E. ; Hoogendoorn, M. ; Buurma, J.S. - \ 2013
    Zoetermeer : Productschap Tuinbouw - 32
    gewasbescherming - geïntegreerde bestrijding - duurzaamheid (sustainability) - rozen - tuinbouw - sociale netwerken - gedragsveranderingen - plant protection - integrated control - sustainability - roses - horticulture - social networks - behavioural changes
    Doel van dit project is het bewerkstelligen van verminderen van milieubelasting door effectiever gebruik van middelen en methoden en kennishiaten opheffen rondom gewasbescherming middels netwerken en onafhankelijke kennisdeling (digitaal handboek geïntegreerde gewasbescherming Roos). Dit moet mede leiden tot gedragsverandering bij telers.
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