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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Bepaling samenstelling van vaste mest met NIRS
Rietra, R.P.J.J. ; Oenema, O. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2837) - 27
dierlijke meststoffen - stikstof - fosfor - nabij infrarood spectroscopie - referentienormen - analyse - betrouwbaarheid - analytische methoden - animal manures - nitrogen - phosphorus - near infrared spectroscopy - reference standards - analysis - reliability - analytical methods
Dynamic photosynthesis under a fluctuating environment: a modelling-based analysis
Morales Sierra, Alejandro - \ 2017
University. Promotor(en): Paul Struik; Jaap Molenaar, co-promotor(en): Xinyou Yin; Jeremy Harbinson. - Wageningen : Wageningen University - ISBN 9789463430456 - 282
photosynthesis - modeling - analysis - environmental factors - light - canopy - leaves - crop physiology - metabolism - fotosynthese - modelleren - analyse - milieufactoren - licht - kroondak - bladeren - gewasfysiologie - metabolisme

In their natural environment, leaves are exposed to rapid fluctuations of irradiance. Research on CO2 assimilation under fluctuating irradiance often relies on measurements of gas exchange during transients where irradiance is rapidly increased or decreased, after the leaf has adapted to a particular set of environmental conditions. In the field, such increases and decreases occur mostly because of sunflecks (rapid increases in irradiance on a low irradiance background) created by gaps in the canopy and plant movement by wind, and cloudflecks (rapid decreases in irradiance on a high irradiance background) generated by clouds that transiently block the sun.

In this dissertation, the metabolic regulation of photosynthesis and how this may limit dynamic CO2 assimilation is studied in silico with the development and application of simulation models. In order to support the development of the models, a review of the literature was performed as well as an experiment designed to generate data on dynamic CO2 assimilation for different photosynthetic mutants of Arabidopsis thaliana. In addition to providing these models to the research community, this dissertation also identifies multiple targets that may be used for improving dynamic CO2 assimilation in plants. It further demonstrates that the dynamic responses of CO2 assimilation to changes in irradiance has a significant effect on canopy CO2 assimilation, even for dense canopies exposed to open skies, resembling the conditions of commercial crops.

In Chapter 1, the context of this dissertation is presented. The societal relevance of this research is argued, making reference to the role that photosynthesis could play in addressing global problems such as food and energy security. The necessary background on the physiology of photosynthesis is provided, with special emphasis on the terminology and concepts required to understand the rest of the dissertation, with the aim of making the contents more accessible to a wider audience. Then, prior literature on the specific topics of this dissertation (i.e., photosynthesis in a dynamic environment and its mathematical modelling) is presented, with a chronological approach that analyses the evolution of ideas and methodologies up to the present.

In Chapter 2, the current literature on dynamic CO2 assimilation is reviewed, with an emphasis on the effects of environmental conditions ([CO2], temperature, and air humidity) on the rates of photosynthetic induction and loss of induction. This review reveals major knowledge gaps, especially on the loss of induction. The little data available indicates that rates of photosynthetic induction increase with [CO2], which could be explained by a weak effect on Rubisco activation and a strong effect on stomatal opening. Increases in temperature also increase the rates of photosynthetic induction, up to an optimum, beyond which a strong negative effect can be observed, which could be attributed to deactivation of Rubisco activase.

In Chapter 3, an experiment is presented that makes use of several photosynthetic mutants of A. thaliana. Downregulating non-photochemical quenching and sucrose synthesis did not have any significant effect on dynamic CO2 assimilation, whereas CO2 diffusion and Rubisco activation exerted stronger limitations. Further analysis reveals that whether stomatal opening limits CO2 assimilation after an increase in irradiance depends on the stomatal conductance prior to the change in irradiance. A threshold value of 0.12 mol m−2 s−1 (defined for fluxes of water vapour) could be defined, above which stomata did not affect the rates of photosynthetic induction. The comparison of measurements across irradiance levels also indicated that the apparent rate constant of Rubisco activation is irradiance-dependent, at least for irradiance levels below 150 μmol m−2 s−1.

In Chapter 4, a phenomenological model of leaf-level CO2 assimilation is presented. The model is described in detail and all the parameters are first estimated with published data, and later refined by fitting the model to the data from Chapter 3. Additional data from the experiment in Chapter 3 is used to validate predictions of CO2 assimilation under lightflecks for the different photosynthetic mutants. The model predicts accurately dynamic CO2 assimilation for the different photosynthetic mutants by only modifying those parameters that are affected by the mutation. This demonstrates that the model has a high predictive power and that the equations, although phenomenological in nature, have a solid physiological basis.

The model is further used to analyse, in silico, the limitations imposed by different photosynthetic processes on dynamic CO2 assimilation at the leaf and canopy level, allowing a more in depth analysis than in Chapter 3. The analysis demonstrates that results obtained at the leaf level should not be extrapolated directly to the canopy level, as the spatial and temporal distribution of irradiance within a canopy is more complex than what is achieved in experimental protocols. Both at the leaf and canopy level, CO2 diffusion is strongly limiting, followed by photoinhibition, chloroplast movements and Rubisco activation.

In Chapter 5, a mechanistic model of the dynamic, metabolic regulation of the electron transport chain is presented. The model is described in detail and all the parameters are estimated from published literature, using measurements on A. thaliana when available. Predictions of the model are tested with steady-state and dynamic measurements of gas exchange, chlorophyll fluorescence and absorbance spectroscopy on A. thaliana, with success.

The analysis in silico indicates that a significant amount of alternative electron transport is required to couple ATP and NADPH production and demand, and most of it is associated with nitrogen assimilation and export of redox power through the malate shuttle. The analysis also reveals that the relationship between ATP synthesis and the proton motive force is highly regulated by the concentrations of substrates (ADP, ATP and inorganic phosphate), and this regulation facilitates an increase in non-photochemical quenching under conditions of low metabolic activity in the stroma.

In Chapter 6, the findings of Chapters 2–5 are summarised and employed to answer in detail the four research questions formulated in Chapter 1. Of great interest is the identification of six potential targets that may be used to improve dynamic CO2 assimilation. These targets are: (i) regulation of Rubisco activity through changes in the amount or regulation of Rubisco activase, (ii) acceleration of stomatal opening and closure, (iii) a lower /ATP for ATP synthesis, (iv) faster relaxation of non-photochemical quenching, (v) reduced chloroplast movements, and (vi) reduced photoinhibition by increased rates of repair of Photosystem II.

Ethiopian soil laboratory infrastructure : CASCAPE scoping mission
Bakker, G. ; Okx, J.P. ; Assen, M. ; Solomon, T. - \ 2016
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2722) - 35 p.
soil - laboratory methods - soil analysis - analysis - laboratory tests - ethiopia - bodem - laboratoriummethoden - grondanalyse - analyse - laboratoriumproeven - ethiopië
Food security is one of the main issues in Ethiopia. Large amounts of money are spent on food security programs set up by federal- and regional governments and other organisations. Decisionmakers, as well as researchers, share a dependency upon reliable data on soils, water and crops. The authors of this report believe that the data from the Ethiopian soil laboratories are not reliable enough for decision-making purposes. Ethiopian laboratories need to improve their analytical services. The main problems concern the organisational set-up, and not merely a lack of budgets for facilities. Apart from organisational problems, managerial-, human resources-, technical-, instrumental- and supply issues were identified.
Mogelijkheden voor de implementatie van het biomassawerf concept in de Greenport Gelderland : deel 3: Logistieke cases
Annevelink, E. ; Oever, M.J.A. van den; Gogh, J.B. van; Dam, J.E.G. van - \ 2015
Wageningen : Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research 1546) - 75
biobased economy - biomassa - reststromen - beschikbaarheid - logistiek - biomassa productie - biomassaconversie - verzamelen - analyse - betuwe - biomass - residual streams - availability - logistics - biomass production - biomass conversion - collection - analysis
Het project ‘Biomassawerf – verwerken van reststromen’ (BO-21.03-001-002) vormt een onderdeel van het Biobased gedeelte van het BO-programma Keteninnovaties Plantaardig (KIP) van het Ministerie van Economische Zaken. Deze nota is het derde deel van de rapportage uit dit project, en is een vervolg op de nota’s: ‘Deel 1. Stakeholder analyse & biomassabeschikbaarheid’ (Annevelink et al., 2013) en ‘Deel 2. Het biomassawerf concept: voorbeelden, theorie & checklist’ (Annevelink et al., 2014a). Het specifieke doel van dit derde deelrapport is om de logistiek rond mogelijke biomassawerven in beeld te brengen d.m.v. specifieke cases. Dit rapport start in Hoofdstuk 2 met feedback vanuit de logistieke praktijk op het biomassawerf concept zoals dat is beschreven in Rapport Deel 2. Vervolgens wordt in Hoofdstuk 3 beschreven hoe de logistieke case studies zijn uitgevoerd. Daarna volgen de resultaten van drie verschillende case studies in de Greenport Gelderland, n.l. rond houtige reststromen in de fruitteelt (Hoofdstuk 4), houtige reststromen uit de laanbomenteelt (Hoofdstuk 5) en het afscheiden van fosfaat en andere componenten uit champost (Hoofdstuk 6). Tenslotte worden algemene conclusies en aanbevelingen uit de cases studies gegeven in Hoofdstuk 7.
Ketenanalyse residu gewasbeschermingsmiddelen : Bloembollen, boomkwekerijproducten en vaste planten
Werd, H.A.E. de; Dalfsen, P. van; Kuik, A.J. van - \ 2015
Randwijk : Praktijkonderzoek Plant en Omgeving, Bloembollen, Boomkwekerij & Fruit - 87
pesticiden - bloembollen - sierplanten - houtachtige planten - apidae - honingbijen - bijensterfte - bemonsteren - insecticidenresiduen - analyse - fungiciden - acariciden - pesticides - ornamental bulbs - ornamental plants - woody plants - honey bees - bee mortality - sampling - insecticide residues - analysis - fungicides - acaricides
Greenpeace heeft in het voorjaar van 2014 bloembol- en knolproducten en tuinplanten in pot op residuen van gewasbeschermingsmiddelen en biociden laten onderzoeken. PPO Wageningen UR heeft op verzoek van KAVB, Anthos en de LTO Vakgroep Boomkwekerij en Vaste planten, de herkomst van de gevonden residuen geanalyseerd. Hierbij is voor 18 van de bemonsterde en 2 extra gewassen in beeld gebracht wat het toegelaten gebruik van fungiciden, insecticiden en acariciden in Nederland is. Vervolgens zijn voor dezelfde 18 gewassen de gevonden residuen vergeleken met de te verwachten residuen op basis van het toegelaten gebruik. Ook de herkomst van de residuen die niet te verklaren zijn op basis van het in Nederland toegelaten gebruik is geanalyseerd. Binnen deze studie zijn geen nieuwe proeven of metingen uitgevoerd, maar zijn schattingen van het verloop van de ordegrootte van residugehaltes gemaakt op basis van de eigenschappen van de betreffende stoffen.
Analyse trend en hotspots Alsemambrosia
Beringen, R. ; Odé, B. ; Vliet, A.J.H. van - \ 2014
Floron
ambrosia - ambrosia artemisiifolia - invasieve exoten - verspreiding van planten - kenmerken - onkruiden - analyse - detectie - populaties - nederland - invasive alien species - plant dispersal - traits - weeds - analysis - detection - populations - netherlands
Alsemambrosia is de meest voorkomende Ambrosiasoort in Nederland. Na bundeling van de gegevens van de belangrijkste bronnen van waarnemingen door FloravanNederland.nl, De Natuurkalender Wageningen UR, NDFF en Waarneming.nl is een analyse gedaan naar verspreiding en trend van Alsemambrosia in de periode 1975 t/m 2013. Tevens is op basis van de beschikbare gegevens een analyse gedaan naar de omvang van populaties in de periode 2000-2013.
Rapport : bemonsteren en analyseren van dierlijke mest op een vrachtauto
Zedde, H.J. van de; Kekem, C. van; Boer, E.P.J. - \ 2014
Wageningen : Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research 1432) - ISBN 9789461737014 - 47
dierlijke meststoffen - analyse - bemonsteren - nabij infrarood spectroscopie - analytische methoden - trucks - betrouwbaarheid - animal manures - analysis - sampling - near infrared spectroscopy - analytical methods - reliability
Dierlijke mest is uitermate lastig materiaal om te analyseren met NabijInfraRood Spectroscopie (NIRS), want het is donker materiaal, hoofdzakelijk bestaand uit vocht en het is niet homogeen qua samenstelling. Toch wordt in literatuur beschreven, en ook in eerder onderzoek onder gecontroleerde omstandigheden aangetoond, dat stikstof- en fosfaatgehaltes in dierlijke mest kan worden gemeten met behulp van NIR spectroscopie met acceptabele niveaus qua betrouwbaarheid. De doelstellingen van het in dit rapport beschreven project waren: - Kan met Nabij Infrarood Spectroscopie bij belading en tijdens het lossen van mesttransport vrachtwagens een analyse van stikstof en fosfaat worden gerealiseerd die zich qua betrouwbaarheid ten minste kan meten met de huidige laboratorium-analyses? - Is de Nabij Infrarood Spectroscopie geschikt om toe te passen op voertuigniveau waarbij behoud van de betrouwbaarheid van analysen een voorwaarde is? - Is de Nabij Infrarood Spectroscopie een techniek die qua kosten en handhaving op grotere schaal in de praktijk toegepast kan worden?
Analyse van residugegevens en spuitschema's in kleinfruit (rode bes)
Wenneker, M. - \ 2013
Randwijk : Praktijkonderzoek Plant en Omgeving, Bloembollen, Boomkwekerij & Fruit (PPO 2013-04) - 23
fruitteelt - bessen - kleinfruit - pesticidenresiduen - residuen - kwaliteitscontroles - spuiten - analyse - landbouwkundig onderzoek - fruit growing - berries - small fruits - pesticide residues - residues - quality controls - spraying - analysis - agricultural research
Residuen van gewasbeschermingsmiddelen op vruchten zijn in toenemende mate een probleem voor de afzet. Door retailers worden steeds hogere eisen gesteld aan het aantal verschillende residuen dat mag worden aangetroffen en aan het residuniveau dat geaccepteerd wordt (bovenwettelijke eisen). In kleinfruit (m.n. rode bessen) zijn hierdoor in de afgelopen jaren problemen ontstaan, omdat veel verschillende actieve stoffen in de residu-analyses worden teruggevonden, en de hoeveelheid residu soms de MRL-waarde nadert. Om aan de eisen van de retail te kunnen voldoen is het noodzakelijk dat het aantal stoffen dat bij residu-analyses wordt aangetoond vermindert én het residuniveau wordt verlaagd. Tevens werden bijbehorende spuitschema’s geanalyseerd.
Differences in leaf litter, ascospore production and infection of pear scab (Venturia pirina) in Dutch organic orchards
Timmermans, B.G.H. ; Jansonius, P.J. - \ 2012
In: Eco-fruit : 15th international conference on cultivation technique and phytopathological problems in organic fruit-growing and viticulture, 20-22 February 2012, Hohenheim. - Weinsberg : Foerdergemeinschaft Oekologischer Obstbau e.V. - p. 253 - 259.
venturia pyrina - peren - fruitteelt - epidemiologie - plantenziekteverwekkende schimmels - schimmelziekten - plantenziekten - biologische landbouw - analyse - ziektebestrijdende teeltmaatregelen - regen - ascosporen - pears - fruit growing - epidemiology - plant pathogenic fungi - fungal diseases - plant diseases - organic farming - analysis - cultural control - rain - ascospores
In 2010 and 2011 the amounts of leaf litter and ascospore production per unit of leaf litter area in 7 organic pear orchards throughout the Netherlands were measured. In one of the orchards, adapted managements strategies were implemented, being grass/clover that is grown as ground cover on the tree-strip, and organic cattle-manure that replaces chicken manure pellets, in order to stimulate the earthworm population and change the palatability of the leaf litter. First results indicate large differences between orchards in percentage of ground covered by dead leaves at the time of major ascospore infections, but also in number of ascospores per cm2 leaf litter and in resulting potential ascospore dose. These data, together with weather data (temperature, rainfall), were used in a simple multivariate analysis to gain insight in the dynamics of the system. The first results show that, to a limited degree, leaf litter was indeed important for the scab epidemic in 2011, whereas in 2010 the high amount of rainfall in the second part of the growing season must have led to a high conidial infection pressure. Surprisingly, in both years ascospore number per unit leaf area was of more importance than leaf litter area or potential ascospore dose.
Vegetable chains in Kenya: Production and consumption of vegetables in the Nairobi metropolis
Lans, C.J.M. van der; Snoek, H.M. ; Boer, F.A. de; Elings, A. - \ 2012
Bleiswijk : Wageningen UR Greenhouse Horticulture (Rapporten WUR GTB 1130) - 86
voedselconsumptie - consumptiepatronen - groenten - analyse - internationale samenwerking - stedelijke bevolking - afrika - kenya - food consumption - consumption patterns - vegetables - analysis - international cooperation - urban population - africa
Vegetable consumption in African countries such as Kenya is low, which has a negative impact on the nutritional condition of the population, and on the production by smallholders. The goals of the project were to determine the potentials for consumption and cultivation in the Nairobi metropolitan region, to analyse the reasons for low consumption and to define strategies to stimulate consumption and production. Vegetable consumption can be increased, especially during the dry season when availability is low, and for low-income groups. Production can be increased through technical interventions and improvement of skills. Important is to improve the leverage of producers in the value chain and the efficiency of the value chain. Key elements are: stimulate urban farming; reduce the cost price throughout the value chain and make the value chain more transparent, accountable, shorter with less transaction costs; reduce post-harvest losses, develop a revenue system that better rewards farmers; improve cold storage and logistics, improve irrigation in the dry season; offer dry-season solutions through food processing; and pay attention to a number of life-style issues. The Netherlands can contribute in the fields of re-structuring the value chain, brokering between parties, food processing, consumer behaviour, production and product quality (irrigation, quality seeds, crop management), and R&D.
Analyzing efficiency of vegetable production in Benin
Singbo, A.G. - \ 2012
University. Promotor(en): Alfons Oude Lansink, co-promotor(en): Grigorios Emvalomatis. - S.l. : s.n. - ISBN 9789461732774 - 128
groenten - productie - landbouwproductie - boerenmarkten - efficiëntie - analyse - benin - afrika ten zuiden van de sahara - vegetables - production - agricultural production - farmers' markets - efficiency - analysis - africa south of sahara
The objective of this research is to investigate the production technology and efficiency of vegetable production and marketing at the farm level in Benin. Using recent advances in cross sectional efficiency analysis, we analyze two samples of vegetable producers following different perspectives. First, the empirical results show that farms’ inefficiency in lowland farming systems is the most diverse. Second, the results suggest that vegetable producers are more inefficient with respect to marketing than production and that marketing inefficiency is affected by the type of marketing arrangements. Third, the analysis shows that vegetable producers have an incentive for specialization and that the degree of specialization has a positive effect on technical efficiency. Finally, the results on pesticide use provide evidence that pesticides are overused while there is no evidence of technical interdependence between pesticides and productive inputs
Grasraffinage in de veehouderij
Pol, A. van den; Durksz, D.L. ; Klop, A. ; Gosselink, J.M.J. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 556) - 11
grasmaaisel - grassen - raffineren - haalbaarheidsstudies - toegevoegde waarde - melkveehouderij - agrarische bedrijfsvoering - analyse - biobased economy - grass clippings - grasses - refining - feasibility studies - value added - dairy farming - farm management - analysis
This report presents a SWOT-analysis of grass refinery on livestock farms in the Netherlands. Grass refinery is still in its infancy, yet it has prospects.
Systeembiologie leidt tot nieuwe inzichten in de plant : processen sturen op niveau van genen, celprocessen en plantorganen
Heuvelink, E. ; Kierkels, T. ; Molenaar, J. - \ 2012
Onder Glas 9 (2012)2. - p. 34 - 35.
glastuinbouw - systeembiologie - plantenontwikkeling - analyse - groeistudies - landbouwkundig onderzoek - innovaties - kasgewassen - greenhouse horticulture - systems biology - plant development - analysis - growth studies - agricultural research - innovations - greenhouse crops
Met klimaatregeling kun je de bloei van planten beïnvloeden. Eigenlijk ben je dan bezig om processen te sturen op het niveau van genen, celprocessen, plantorganen, hele plant en omgeving. Systeembiologie maakt het mogelijk het inzicht in de samenhang daartussen op een hoger plan te brengen. Daar heeft de veredelaar baat bij en de teler op termijn ook.
Quality assurance for animal feed analysis laboratories
Balthrop, J. ; Brand, B. ; Cowie, R.A. ; Danier, J. ; Boever, J.L. de; Jonge, L.H. de; Jackson, F. ; Makkar, H.P.S. ; Piotrowski, C. - \ 2011
Rome : FAO (FAO animal production and health manual 14) - ISBN 9789251070505 - 193
voer - diervoedering - analyse - kwaliteitszorg - kwaliteitsnormen - goede laboratoriumpraktijk - feeds - animal feeding - analysis - quality management - quality standards - good laboratory practices
Every sector of the livestock industry, the associated services and the wellbeing of both animals and humans are influenced by animal feeding. The availability of accurate, reliable and reproducible analytical data is imperative for proper feed formulation. Only reliable analysis can lead to the generation of sound scientific data. This document gives a comprehensive account of good laboratory practices, quality assurance procedures and examples of standard operating procedures as used in individual specialist laboratories. The adoption of these practices and procedures will assist laboratories in acquiring the recognition of competence required for certification or accreditation and will also enhance the quality of the data reported by feed analysis laboratories. In addition, ensuring good laboratory practices presented in the document will enhance the safety of the laboratory workers. The document will be useful for laboratory analysts, laboratory managers, research students and teachers and it is hoped that it will enable workers in animal industry, including the aquaculture industry, to appreciate the importance of proven reliable data and the associated quality assurance approaches. An additional effect of implementing and adopting these approaches will be strengthening of the research and education capabilities of students graduating from R&D institutions and promotion of a better trading environment between developing and developed economies. This will have long-term benefits and will promote investment in both feed industries and R&D institutions.
Analysing agriculture and rural areas in Europe; A synthesis of research programmes in 20 countries
Brouwer, F.M. ; Sas-Paszt, L. - \ 2011
The Hague : LEI, part of Wageningen UR (Report / LEI : Research area Natural resources ) - ISBN 9789086155323 - 83
landbouw - duurzaamheid (sustainability) - analyse - landbouwkundig onderzoek - duurzame ontwikkeling - platteland - europa - agriculture - sustainability - analysis - agricultural research - sustainable development - rural areas - europe
The existing research programmes in Europe dealing with the new relationships between rural areas, agriculture and sustainable development, cover a wide range of topics in the domains of ecology and economy.
Quantification of net exudation for the plant-microbial fuel cell
Kuijken, R.C.P. ; Snel, J.F.H. ; Bouwmeester, H.J. ; Marcelis, L.F.M. - \ 2011
wortelexudaten - analyse - microbiële brandstofcellen - biobased economy - biochemie - root exudates - analysis - microbial fuel cells - biochemistry
The objective of this project is to develop a simple procedure to estimate net root exudation to study genetic and environmental effects on exudation.
Omgevingsanalyse, Thema: Teelt de grond uit BO-12.03-009-004
Slobbe, R.B. - \ 2011
S.n.
cultuur zonder grond - tuinbouw - vollegrondsteelt - milieufactoren - plattelandsomgeving - analyse - teeltsystemen - soilless culture - horticulture - outdoor cropping - environmental factors - rural environment - analysis - cropping systems
Informatieposter getiteld "Omgevingsanalyse" met thema "Teelt de grond uit". Het zoeken is naar gewassen uit de vollegrondstuinbouw die geen volle grond meer nodig hebben om te groeien. Voor een succesvolle ontwikkeling van deze teeltinnovatie is het belangrijk, om rekening te houden met omgevingsfactoren en de belangen van stakeholders. In dit project zijn omgevingsfactoren verkend die invloed hebben op het welslagen van de nieuwe teeltsystemen en die andersom ook beïnvloed worden door deze ontwikkeling
Parapluplan Gerbera "Beheersing van botrytis door efficiënter energiegebruik": Bestrijding van Botrytis in gerbera tijdens de teelt en in de na-oogstfase: Deelproject 4 van Parapluplan Gerbera: kasklimaat, energie en botrytis bij gerbera; oorzaak, verband en maatregelen
Os, E.A. van; Hofland-Zijlstra, J.D. ; Hamelink, R. ; Leeuwen, G.J.L. van - \ 2010
Wageningen : Wageningen UR Glastuinbouw (Rapporten GTB-1057_JV) - 35
gerbera - sierteelt - botrytis cinerea - plantenziektebestrijding - laboratoriumproeven - kwaliteit na de oogst - analyse - methodologie - bestrijdingsmethoden - ornamental horticulture - plant disease control - laboratory tests - postharvest quality - analysis - methodology - control methods
Referaat Botrytis kan veel schade geven in de na-oogstfase van gerberabloemen. Het doel van dit onderzoek is het bepalen van de meest effectieve bestrijdingsmethode in de teelt of in de na-oogstfase. Hiervoor zijn eerst de huidige middelen en methodieken geïnventariseerd en vervolgens zijn de beste methoden geselecteerd en op labschaal uitgetest en daarna onder praktijkomstandigheden getoetst. Het blijkt dat een specifieke botrytis bestrijding het beste in de na-oogstfase kan worden uitgevoerd en niet in de teeltfase. UV belichting en Aquanox (verneveling van een zoutoplossing) bieden hiervoor de meeste perspectieven. Aquanox dient sterk bloemgericht te worden verneveld om >90% reductie in kleine lesies te krijgen. In een laboratoriumopstelling is een dosis effect relatie voor UV belichting vastgesteld. Om meer dan 90% reductie in lesies te krijgen is 200 - 350 mJ/cm2 UV-C licht nodig. Onder hoge intensiteiten bestaat er bij enkele cultivars kans op brandschade (>350 mJ/cm2). Testen zijn uitgevoerd met lage druk lampen. De vereiste intensiteit wordt bereikt door een juiste combinatie van afstand bloem/lamp, tijdsduur en lichtsterkte. Gebruik van UV lampen in een sorteermachine vereist een zeer hoge lichtsterkte omdat de belichtingstijd zeer kort is. Oriënterende proeven met UV middendruklampen geven wel mogelijkheden, maar de warmteontwikkeling is vooralsnog te hoog om direct ingezet te kunnen worden. Lage druk lampen hebben in de sorteemachine het nadeel dat zeer veel lampen achter elkaar nodig zijn, terwijl daar geen ruimte voor is. Voor de gerberatelers is een praktijkadvies opgesteld om UV belichting in de na-oogstfase toe te passen tegen botrytis voor inbouw in een sorteermachine en voor zelfstandige toepassing.
Safety of herbal preparations on the Dutch market
Martena, M.J. - \ 2010
University. Promotor(en): Ivonne Rietjens, co-promotor(en): E.J.M. Konings. - [S.l.] : S.n. - ISBN 9789085858225 - 224
keukenkruiden - azië - voedingsmiddelenwetgeving - toxiciteit - besmetters - analyse - natuurlijke toxinen - culinary herbs - asia - food legislation - toxicity - contaminants - analysis - natural toxins
The use and availability of herbal preparations covered by food law is increasing in the Netherlands and in other European Member States. Correspondingly, safety concerns relating to herbal preparations are growing as well. The aim of the present PhD project was therefore to review the toxicity of selected herbal preparations, to investigate the presence and actual levels of selected naturally-occurring toxic substances and contaminants in herbal preparations on the Dutch market and to estimate the associated risks.
First, an overview is provided of the Dutch and European legal provisions for food commodities with botanical ingredients, the nature and mechanism of action of various toxic botanical ingredients specifically covered by these provisions, and the health concerns defined by risk assessors related to several botanicals for which no specific legal provisions exist. Secondly, data are presented on the actual occurrence in traditional herbal preparations (THPs) of a group of phytotoxins, i.e. aristolochic acids, which were banned by the Dutch Commodities Act Decree ‘Herbal preparations’. Aristolochic acids and derivatives are nephrotoxic, genotoxic and carcinogenic and are present in several plants from the Aristolochiaceae family. Aristolochic acids were found in 25 of 190 THPs used in Traditional Chinese Medicine (TCM) sampled on the Dutch market. This shows that testing for aristolochic acids of Chinese THPs at risk of contamination is essential in the framework of food safety.
Thirdly, the presence of selected toxic contaminants in herbal preparations on the Dutch market was investigated. Lead, mercury and arsenic levels were analyzed in THPs used in several Asian traditional medicine systems, such as Ayurveda, TCM, and Traditional Tibetan Medicine (TTM). These metals and metalloids were present in 186 (64%) of 292 THPs and use at recommended dose levels of 59 THPs (20%) would result in intakes of these contaminants significantly above established toxicological safety limits. It was concluded that the mercury, arsenic and lead contents of these Asian THPs are cause for concern. Because metals such as mercury can exist in various defined chemical species with different toxic properties, a study was performed using selective acid extraction procedures to determine the presence or absence of the relatively non-toxic elemental form of mercury in 19 Ayurvedic THPs, which were shown in the previous study to result in mercury intakes above the safety limit for inorganic mercury when used at the recommended daily dose level. It was concluded that in these THPs the main part of the mercury content is not present in the elemental form, that the mercury detected in Ayurvedic THPs is likely to be present in the inorganic form and that therefore the estimation of the related risks based on the safety limits for inorganic mercury is justified.
In the last study of this PhD thesis, polycyclic aromatic hydrocarbons (PAH) were determined in more than 1500 food supplements sampled on the Dutch market, many of which contained herbal ingredients. Herbal preparations can become contaminated with PAH through various processes including direct atmospheric deposition on plant surfaces and drying practices during manufacturing. Several PAH, such as benzo[a]pyrene are genotoxic and carcinogenic. Supplements containing herbal ingredients such as St. John’s wort and Ginkgo biloba, the phytochemical resveratrol and the bee product propolis showed the highest mean PAH levels. It was shown that individual food supplements can contribute significantly to PAH exposure, whereas on average PAH intake resulting from food supplement use will be at the lower end of the range of contributions of main food groups to PAH exposure.
From the work described in this thesis it can be concluded that for herbal preparations ‘natural’ does not equal ‘safe’. Given that uncertainty exists whether additional European legal measures will be taken in the near future to restrict or prohibit the use of specific toxic herbal substances in foods and the fact that several herbal preparations for which specific provisions are absent in Dutch food safety law raise toxicological concern, would suggest that it is prudent to keep the Dutch Decree ‘Herbal preparations’ and other national legislation up to date in order to protect consumers from serious risks resulting from use of botanicals in food products such as herbal preparations.
Naar een kern voor leerlijnen natuur- en milieueducatie : analyse van bestaande leerlijnen en synthese van een kern-leerlijn NME
Verheijen, S. ; Koppen, C.S.A. van; Wammes, D.F. - \ 2010
Utrecht [etc.] : Universiteit Utrecht [etc.] - 102
onderwijs - leerplan - onderwijsmaterialen - onderwijsmethoden - analyse - leerplanontwikkeling - natuur- en milieueducatie - education - curriculum - resource materials - teaching methods - analysis - curriculum development - nature and environmental education
Op dit moment zijn er veel leerlijnen voor NME in omloop, en nog veel meer onderwijsmaterialen. Dit onderzoek wil bijdragen aan een betere opbouw en een grotere samenhang van leermethoden en -materialen op het gebied van NME. Dit wordt gedaan door kern-principes te formuleren voor de opbouw en structurering van NME-gerelateerde leeractiviteiten in het curriculum van de basisschool. Deze kern-principes zijn gebaseerd op de belangrijkste elementen en invalshoeken binnen de grote verscheidenheid van leerlijnen in het domein NME. In dit onderzoek is een schema met leesvragen ontwikkeld om bestaande leerlijnen met elkaar te kunnen vergelijken. Een selectie van leerlijnen NME en leerlijnen natuuronderwijs is hiermee geanalyseerd. Besloten is om deze analyse op te volgen met de synthese van een zogeheten kern-leerlijn. Vanuit de bevindingen van de analyse kwamen drie startpunten naar voren: verbreden van leerinhouden, verankeren van leerdoelen en verbinden van onderwerpen. Deze startpunten resulteerden in drie componenten voor de kern-leerlijn: een indeling in ontwikkelingsgebieden, een overzicht van leerdoelen en een beschrijving van conceptopbouw. De ontwikkelingsgebieden beschrijven vanuit het perspectief van NME naar welke brede ontwikkeling gestreefd wordt bij leerlingen, zoals 'zorg' of 'onderzoeksvaardigheid'. Bij de leerdoelen die in dit onderzoek worden gepresenteerd wordt aangegeven of ze bij (kunnen) dragen aan die ontwikkelingsgebieden en waar ze bij (kunnen) dragen aan het voldoen aan kerndoelen die voor basisscholen gelden. Tenslotte wordt beschreven dat het expliciteren van voorwaardelijkheid van leerdoelen en begrippen de opbouw voor zowel makers als gebruikers inzichtelijker kan maken.
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