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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    40 kg Paprika
    Eveleens-Clark, B.A. ; Lagas, P. ; Driever, S.M. ; Zwinkels, J. ; Vaate, J. Bij de; Kaarsemaker, R.C. - \ 2010
    Bleiswijk/Wageningen/Delfgauw : Wageningen UR Glastuinbouw/DLV Plant/Groen Agro Control - 87
    capsicum - gewasproductie - productiegroei - glasgroenten - tuinbouw - assimilatie - groeimodellen - teeltsystemen - brix - diffuus glas - snoeien - teelt in rijen - capsicum - crop production - production growth - greenhouse vegetables - horticulture - assimilation - growth models - cropping systems - brix - diffused glass - pruning - alley cropping
    Rapport beBestaand uit de volgende onderdelen: 1. Een kasproef, waarin het doel was de productie te verhogen door een combinatie van maatregelen; diffuus glas, verneveling en gewashandelingen 2. Praktijktoepassing en ontwikkeling van een plantmodel dat zetting voorspelt 3. Toetsing van een nieuwe methode om beschikbaarheid van assimilaten voor zetting te meten
    Workshop Freesia Groeimodel: Inzicht in fotosynthese en groei van freesia
    Visser, Pieter de - \ 2010
    horticulture - floriculture - freesia - growth models - growth - developmental stages - growth analysis - climatic factors - photosynthesis - optimization methods - greenhouse horticulture
    Grassland simulation with the LPJmL model : version 3.4.018
    Boons-Prins, E.R. - \ 2010
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 172) - 174
    graslanden - graslandbeheer - gewassen - groeimodellen - landgebruik - simulatiemodellen - gewasgroeimodellen - grasslands - grassland management - crops - growth models - land use - simulation models - crop growth models
    One third of the land surface is covered with natural and cultivated grasslands. Most of these grasslands are intensively or extensively exploited by humans to feed animals. With growing wealth, causing an increase of meat consumption, there is a need to better understand the processes that influence the grass production of these ecosystems. The project aims to improve the knowledge basis regarding grassland productivity and the relationship between management of grasslands and productivity. The research will led to modification of the Dynamic global vegetation model with natural and managed land (LPJmL, version 3.4.018, 2010) for the simulation of grassland and grassland management. Crop growth models such as LPJmL can help to clarify and understand grass production processes. A checked and calibrated model gives useful insights in the carrying capacity of grasslands and enables us to estimate the risk for environmental damage with increase of grass and/or meat production.
    Automatiseerder en onderzoekers inspireren elkaar
    Verkerke, W. - \ 2010
    Syscope Magazine 2010 (2010)26. - p. 7 - 8.
    kassen - teelt onder bescherming - plantenontwikkeling - groeimodellen - computertechnieken - automatisering - planning - teeltsystemen - glastuinbouw - logistiek - greenhouses - protected cultivation - plant development - growth models - computer techniques - automation - planning - cropping systems - greenhouse horticulture - logistics
    De glastuinbouw gebruikte tot voor kort alleen plantengroeimodellen om de gewasgroei te beschrijven. Ze waren niet goed te koppelen aan de logistieke processen op moderne bedrijven. Hier komt verandering in door het project Plant-iT. Voor het eerst werken logistieke ICT-ers en plantenfysiologen samen aan een nieuwe generatie bedrijfsoplossingen, waarin groene kennis en logistiek echt geïntegreerd worden.
    Detection, occurence, growth and inactivation of Cronobacter spp. (Enterobacter sakazakii)
    Kandhai, M.C. - \ 2010
    Wageningen University. Promotor(en): Leon Gorris; Marcel Zwietering, co-promotor(en): Martine Reij. - [S.l. : S.n. - ISBN 9789085855569 - 240
    enterobacter sakazakii - flesvoedingsamenstelling - detectie - groeianalyse - groeimodellen - inactivatie - risicoschatting - voedselveiligheid - microbiële besmetting - blootstellingsbepaling - enterobacter sakazakii - infant formulae - detection - growth analysis - growth models - inactivation - risk assessment - food safety - microbial contamination - exposure assessment
    The genus Cronobacter consists of Gram-negative, motile, non-spore forming, facultative anaerobic bacteria, and was originally defined as one species “Enterobacter sakazakii” within the genus Enterobacter in 1980. Cronobacter spp. have been documented as a rare cause of outbreaks and sporadic cases of neonatal meningitis, necrotizing enterocolitis, and sepsis in infants with a high mortality. Among these infants, those at greatest risk are infants less than 2 months of age, particularly pre-term infants, low birth weight (LBW) infants (< 2500 g), and immuno-compromised infants.
    At the onset of the work for this thesis, Cronobacter spp. had been isolated from milk-based powdered formulae which have a direct link to the sub-population at greatest risk. However, there was a need to more closely investigate whether and where Cronobacter spp. occurs in environments in which these powdered are manufactured and packed but also to investigate other sources which could lead to exposure of vulnerable sub-populations. The main objective of this study was to develop isolation and detection methods that would allow quick and reliable investigation into the occurrence of the micro-organism in potential sources. Furthermore, more insight into the growth behavior of Cronobacter spp. in reconstituted infant formula was necessary in order to provide data to be used in Microbiological Risk Assessment (MRA) dedicated to this particular food product.
    A selective enrichment method was developed for the rapid and reliable enrichment and detection of Cronobacter spp. in environmental samples. The detection method which was developed is based on two features of Cronobacter spp. combined: their yellow pigmented colonies when grown on tryptone soy agar and their constitutive -glucosidase, which can be detected in a 4-h colorimetric assay. The initially developed method and refinements thereof were applied for routine screening for the presence of Cronobacter spp. in environmental samples and a variety of food products manufactured or marketed in The Netherlands. The detection method described in this thesis has been the basis for a series of media for Cronobacter spp. that have recently been commercialized.
    Quantitative data on product contamination at manufacture, during preparation, and also growth after reconstitution are required in order to assess the risk associated with Cronobacter spp. exposure. Next to that, tools are needed to asses the micro-organisms growth potential as well as its inactivation (thus, its survival) due to specific control measures applied. In this thesis, predictive growth models were developed that capture key growth parameters. Minimum– and maximum temperatures estimated with the Secondary Rosso equation were 3.6 ºC and 47.6 ºC, respectively. The estimated lag time of the micro-organisms was found to vary from 83.3 ± 18.7 h at 10 ºC to 1.73 ± 0.43 h at 37 ºC and could be described with the hyperbolic model and reciprocal square root relation. The models for growth rates and lag times as a function of temperatures obtained during this study allow estimating the potential growth of Cronobacter spp. in reconstituted infant formula stored at any temperature below 47 C.
    As growth rates of Cronobacter at refrigeration temperatures are relatively small, caregivers are advised to store reconstituted infant at low temperature as a control measure to prevent microbial growth. It is evident that storage of reconstituted formula in a refrigerator may require a significant amount of the time before the formula reach the targeted refrigeration temperature. Therefore, a mathematical model was built to predict the temperature profile and the resulting growth of Cronobacter spp. during cooling, i.e. under dynamic temperature conditions. Predictions showed that proliferation of Cronobacter spp. during cooling strongly depends on the size of the container used for storage and that it may be prevented by limiting the volume to be cooled to portion-size only or by reconstituting at temperatures of 25 °C or lower.
    The survival of two Cronobacter strains in dry powdered infant formula (PIF) was tested and compared to the survival of six other bacterial strains after inoculation and storage at several temperatures between 7 and 42 ºC. The effect of temperature on survival in PIF, was described using both the Weibull distribution model and the log-linear model. Differences were found in the rate of survival that can be due to difference in the resistance to inactivation in dry environments between Cronobacter species, which could be relevant to consider when establishing quantitative risk assessments on consumer risks related to PIF.
    The research described in this thesis contributes to the existing knowledge on the natural habitat of Cronobacter spp. and its occurrence and behavior in PIF. The models developed for quantifying the growth of Cronobacter spp. in reconstituted formulae under various conditions can be applied in risk assessments set-up to estimate the probability of vulnerable sub-populations becoming ill after consuming infant formulae. International and national governmental bodies may use these predictive models in risk assessments and to establish guidelines for health care professionals to provide effective hygiene training to parents and professional caregivers to ensure that PIF is prepared handled and stored appropriately.

    Sunergiekas toont prima teeltresultaat en netto energieproductie (Onderzoekspagina Wageningen UR Glastuinbouw)
    Wageningen UR Glastuinbouw, - \ 2009
    Onder Glas 6 (2009)12. - p. 63 - 63.
    kassen - tomaten - teeltsystemen - smaakpanels - leerlingen - klimaatregeling - groeimodellen - plantenontwikkeling - gewasbescherming - botrytis - glastuinbouw - semi-gesloten kassen - duurzame energie - groenten - greenhouses - tomatoes - cropping systems - taste panels - pupils - air conditioning - growth models - plant development - plant protection - botrytis - greenhouse horticulture - semi-closed greenhouses - sustainable energy - vegetables
    Onderzoek bij WUR Glastuinbouw : sunergiekas toont positieve resultaten in de tomatenteelt, de ontwikkeling van een kispanel als smaakteam in Bleijswijk en een groeimodel voor freesia om de effecten van de verschillende klimaatfactoren op groei en ontwikkeling te structureren en botrytisvoorspeller gerbera nu beschikbaar als rekenmodel
    Crop models: main developments, their use in CGMS and integrated modeling
    Wolf, J. ; Ittersum, M.K. van - \ 2009
    Agro Informatica 22 (2009)2. - ISSN 0925-4455 - p. 15 - 18.
    gewassen - groeimodellen - oogstvoorspelling - gewasopbrengst - monitoring - wiskundige modellen - gewasgroeimodellen - crops - growth models - yield forecasting - crop yield - monitoring - mathematical models - crop growth models
    Het artikel beschrijft de voornaamste ontwikkelingen in gewasgroeimodellen (WOFOST), hun gebruik in CGMS en geïntegreerde modellering
    Rekenmodel voor Botrytis en groei
    Visser, Pieter de - \ 2009
    gerbera - growth models - crop quality - plant development - energy consumption - air conditioning - simulation models
    Beheersing intrinsieke kwaliteit potplanten met als pilot Ficus en Anthurium : Deelproject 1b, Bepaling intrinsieke kwaliteit van uitgangsmateriaal Ficus
    Snel, J.F.H. ; Jalink, H. ; Schoor, R. van der; Carvalho, S.M.P. ; Heuvelink, E. ; Dijkhuis, P. ; Verberkt, H. ; Geest, J. van - \ 2008
    Wageningen : Wageningen UR Glastuinbouw (Nota / Wageningen UR Glastuinbouw 556) - 12
    gewaskwaliteit - methodologie - groei - ficus - groeimodellen - glastuinbouw - potplanten - crop quality - methodology - growth - ficus - growth models - greenhouse horticulture - pot plants
    Verslag van onderzoek naar bepaling van intrinsieke productkwaliteit om de groeikracht van Ficus stekken te kunnen voorspellen.
    Sensoren: meten en weten wat de plant wil
    Marcelis, L.F.M. ; Dieleman, J.A. ; Meinen, E. ; Tuijl, B.A.J. van; Gieling, T.H. ; Janssen, H.J.J. ; Voogt, W. - \ 2007
    teelt onder bescherming - groeimodellen - sensors - meetapparatuur - fotosynthese - glastuinbouw - protected cultivation - growth models - sensors - indicating instruments - photosynthesis - greenhouse horticulture
    Wageningen UR Glastuinbouw heeft een breed scala aan sensoren, meetmethodieken en groeimodellen. Daarmee kan de vertaalslag van meting naar bruikbare informatie worden gemaakt
    Groeimodellen: rekenen aan planten
    Marcelis, L.F.M. ; Elings, A. ; Buwalda, F. ; Visser, P.H.B. de; Heuvelink, E. ; Nieboer, S. - \ 2007
    groeimodellen - groei - gewasteelt - teelt onder bescherming - gewasgroeimodellen - glastuinbouw - growth models - growth - crop management - protected cultivation - crop growth models - greenhouse horticulture
    Wat zijn de toepassingen van groeimodellen?
    Virtuele planten: groeimodellen in 3D
    Visser, P.H.B. de; Marcelis, L.F.M. ; Heijden, G.W.A.M. van der; Vos, J.W. ; Heuvelink, E. - \ 2007
    groei - modellen - groeimodellen - planten - plantenontwikkeling - simulatie - growth - models - growth models - plants - plant development - simulation
    Informatie over 3D modellen van planten ('virtuele planten'). Hoe werkt dit en wat is de toepassing van deze 3D modellen?
    Aanvullende COCO-berekeningen in het kader van nazorg van het DynAqua-project (kokkelkweek deel)
    Vries, P. de; Veenstra, F.A. - \ 2007
    Den Helder : IMARES (Rapport / Wageningen IMARES nr. C096/07) - 23
    schaaldieren - kokkels - groei - groeitempo - groeimodellen - watertemperatuur - chlorofyl - zwevende deeltjes - organische stof - mariene ecologie - shellfish - clams - growth - growth rate - growth models - water temperature - chlorophyll - suspended solids - organic matter - marine ecology
    COCO (COmputer COckle model) is ontwikkeld door het voormalig Nederlands Instituut voor Visserij Onderzoek (RIVO), tegenwoordig bekend als Wageningen IMARES. COCO berekent ondermeer de groei van een individuele kokkel, maar kan ook informatie met betrekking tot de productie van pseudo-feces opleveren. Het model bevat feedback loops bij de opname en het metabolisme van voedsel en het verdelen van koolstof naar de verschillende interne toestandsvariabelen: somatisch weefsel, opslag (glycogeen), organische schelpmatrix en gameten. In de eerste plaats is het de bedoeling met deze rapportage een sterkere link van de COCO-modelberekeningen (uitgevoerd in het kader van het DynAqua-project) met de praktijk te leggen. Hieraan wordt vorm gegeven met aanvullende berekeningen, die in dit rapport beschreven worden.
    Hoge kilogramopbrengst gaat niet altijd samen met hoge kwaliteit
    Heuvelink, E. ; Kierkels, T. - \ 2007
    Onder Glas 4 (2007)5. - p. 54 - 55.
    groeimodellen - plantenontwikkeling - plantenfysiologie - gewaskwaliteit - stressfactoren - stress - maximum opbrengst - relatie tussen groei en oogst - milieubeheersing - kwaliteitszorg - secundaire metabolieten - glastuinbouw - growth models - plant development - plant physiology - crop quality - stress factors - stress - maximum yield - growth yield relationship - environmental control - quality management - secondary metabolites - greenhouse horticulture
    Samengaan van hoge productie en een goede kwaliteit vergt drie stappen. Ten eerste moet de fotosynthese optimaal zijn. Ten tweede is een goede verdeling van de assimilaten naar nuttige delen van de plant belangrijk. De derde stap is per gewas anders. Soms is het nodig af te zien van de hoogste productie om een goede kwaliteit te krijgen. Bij tomaat geeft een hogere EC een betere smaal maar minder productie. Bij roos zou continue groeilicht veel meer opbrengst geven, maar bij de consument verwelkt de bloem dan zeer snel. Bij veel gewassen is enige stress niet verkeerd. Bloemisterijgewassen zijn dan sterker; groenten smaken soms beter. In Wageningen wordt getracht nieuwe groeimodellen te maken die tuinder en veredelaar bijstaan in het streven naar meer interne kwaliteit
    Verfijnd rekenmodel voor belichting in rozen blijft toekomst muziek : beslissingsondersteunend model geeft 10-15% besparing
    Staalduinen, Jan van; Raaphorst, M.G.M. - \ 2007
    Onder Glas 4 (2007)5. - p. 78 - 79.
    groeimodellen - groei - rozen - belichting - lichtsterkte - efficiëntie - optimalisatie - groeianalyse - plantenfysiologie - netto-assimilatiesnelheid - beslissingsondersteunende systemen - energiebesparing - glastuinbouw - snijbloemen - growth models - growth - roses - illumination - light intensity - efficiency - optimization - growth analysis - plant physiology - net assimilation rate - decision support systems - energy saving - greenhouse horticulture - cut flowers
    In opdracht van het ministerie van LNV en PT onderzocht Wageningen UR Glastuinbouw de behoefte van rozentelers aan een beslissingsondersteunend model om energie-efficiëntie van belichten te optimaliseren. Onderzoeker Raaphorst ervoer dat sommige telers enthousiast zijn. Ondanks een verwacht besparingspotentieel van 10 tot 15% heeft maar een beperkte groep rozentelers interesse in een beslissingsondersteunend rekenmodel voor het optimaliseren van de belichtingsinstellingen. Eisen aan het rekenmodel zijn eenvoudige bediening, bewezen praktijkwaarde, rasafhankelijke instellingen, input vanuit de bedrijfsadministratie en professionele ondersteuning. Voor vervolgonderzoek is dat een te smalle basis. Onderzoekers en telers verwachten wel dat het draagvlak over enkele jaren breder is
    Macroscopic modelling of solid-state fermentation
    Hoogschagen, M.J. - \ 2007
    Wageningen University. Promotor(en): Hans Tramper, co-promotor(en): Arjen Rinzema. - [S.l.] : S.n. - ISBN 9789085045786 - 120
    fysische modellen - groeimodellen - computersimulatie - aspergillus - tarwe - vast-substraatfermentatie - physical models - growth models - computer simulation - aspergillus - wheat - solid-state fermentation

    Solid-state fermentation is different from the more well known process of liquid fermentation because no free flowing water is present. The technique is primarily used in Asia. Well-known products are the foods tempe, soy sauce and saké. In industrial solid-state fermentation, the substrate usually consists of loose substrate particles, although in research situations agar like substrates are also common. Solid-state fermentations cannot be mixed as easily as liquid fermentations. Because of this, it is difficult to maintain the temperature in the fermentation at an acceptable level and to prevent differences in substrate availability throughout the solid material. An advantage of solid-state fermentation is that the process is cheap, and that products are in some cases easier to separate from the substrate than in liquid. Because of this, the technique is economically interesting. The process has not been studied as extensively as liquid fermentation. This thesis extends the available knowledge by providing several mathematical models for both biological and physical processes that occur in aerated packed beds.

    In aerated packed beds, the metabolic heat that is released in the microbial process is removed by blowing air through the packed material. The effectiveness of the aeration is the result of both the heat uptake capacity of the air itself and of the evaporation of moisture to the air. In fact, the evaporation contributes more to the heat removal than the air itself. A side effect of the evaporation is that the decreasing moisture level in the substrate can become limiting for the microbial process.

    In this thesis, the growth of Aspergillus oryzae and Aspergillus sojae, two related species of fungi, in an aerated packed bed of moist wheat kernels is studied. The study deals with both the microbial and physical aspects of the system.

    Many different types of substrate have been used in studies on solid-state fermentation. Prior to starting the work on the mathematical models, we checked if the fermentation results of A. oryzae on several types of wheat matched, The check was done by matching respiration profiles for several types of wheat and two pretreatment methods. It turned out that considerable differences between the pretreatment methods can exist, which indicated the importance of using the exact same type of substrate and pretreatment in experiments that are to be compared.

    No accurate model description of the microbial aspects of SSF is available yet. Because the focus of the major part of the thesis is on deriving model descriptions for the physical aspects of cooling and drying-out in aerated packed beds, it was decided that using a temperature-response model for the description of heat development would incorporate too many uncertainties in the overall packed-bed model. The heat development in the further studies presented was therefore based on fitted oxygen consumption profiles instead of on modelled microbial growth.

    For the validation of the physical models in this thesis, experiments were carried out in a packed bed of approximately 50 cm height. This packed bed was insulated thermally, and offered the possibility of taking online temperature measurements and sampling the moisture content. The models that were derived to describe the changes in growth conditions in the packed bed in time and space were based on well-known physical relations. All physical models are composed of heat- and mass balances. As described above, the temperature dependence of the fungus was neglected, and the metabolic heat development was incorporated in the balances by means of fitted respiration profiles. This way, inaccuracies in the heat production in the physical model were prevented, allowing the focus on the correct description of heat and mass transfer.

    The first model presented was based on an existing model, which overestimated the drying out of the solid material. This overestimation was due to the assumption of constant saturation of the gas phase with water vapour. The overestimation of the drying out meant that the assumption of vapour saturation needed to be adjusted. Heat and mass transfer coefficients were determined for the substrate involved, and besides this water activity was introduced as a factor that limited the evaporation of water from the substrate. The addition of water activity was of great influence on the model results.

    The insight in the effect of local water activity on the fermentation was the onset for a study on the response of fungi to changing water activity. A system was designed that allowed the dynamic response of the fungus on decreasing water activity to be measured. The experimental set-up was based on isothermal experiments that were slowly dried out by blowing dry air through them, with simultaneous experiments carried out at aw ~ 1 for comparison with the response to the drying out. Considering the fact that all studies on water activity that preceded this approach were based on static and artificial conditions, this set-up is more similar to the actual conditions in a packed-bed fermentation.

    Contrary to the expectations, the system that was dried out showed a decreased fungal growth rate when the water activity in the substrate was still the same as it was in the reference experiment. We checked two possible causes for this phenomenon. Moisture gradients in the particle were ruled out, because these were too small to be able to cause the difference in growth rate. We found that there is most likely a region of very cold substrate material due to wet-bulb cooling. Wet-bulb cooling is a phenomenon in which the evaporation of water from a system to a passing airflow allows the system to cool to temperatures below the temperature of the air. Because we used dry air in our experiment, the effect was too large to be compensated through conduction. An estimated 5% of the bed could not be fermented because of the low temperature. For a successful series of experiments, we need to obtain drying with a 100% constant bed temperature. For such a series, a good comparison of the effect of drying on fungal behaviour will be possible.

    During the experiments in the packed-bed involving Aspergillus oryzae strong shrinkage of the packed-bed occurred because the fungus tied the substrate particles together. Because of the shrinkage, the aeration lost effectivity and the fermentation results were suboptimal. A model was designed to describe the amount of shrinkage, based on the decrease in water content in the bed. The validation of this model could not be performed with A. oryzae, because it was impossible to carry out controlled fermentations with this fungus. Therefore, A. sojae was used, which has the same growth characteristics as A. oryzae, except for the formation of substrate ties. The model on shrinkage offers a good prediction of the shrinkage that is expected with the combined effect of fungal growth and dehydration. 1f in industrial fermentations a different shrinkage pattern is observed, this is an indication that there is channel formation somewhere in the bed. This observation can be than followed by for instance a mixing event, improving the overall performance of the fermentation.

    In the final chapter of this thesis, an overview of the work that could possibly offer further improvements to the present models is given. It was concluded that the modelling of the microbial aspects offer the biggest chances for success in this respect, since this aspect has of yet been modelled less accurately than the physical part.

    Jongschaap: 'Met juiste strategie energie en geld besparen' : 16% energie besparen en toch 2,00 euro per m2 verdienen
    Arkesteijn, Marleen ; Jongschaap, R.E.E. ; Dieleman, J.A. - \ 2006
    Onder Glas 4 (2006)5. - p. 56 - 57.
    plantenontwikkeling - kassen - groeimodellen - belichting - kunstmatige verlichting - rozen - energiekosten - lichtsterkte - optimalisatie - cultuurmethoden - milieubeheersing - toegepast onderzoek - energiebesparing - warmtekrachtkoppeling - glastuinbouw - snijbloemen - plant development - greenhouses - growth models - illumination - artificial lighting - roses - energy expenditure - light intensity - optimization - cultural methods - environmental control - applied research - energy saving - cogeneration - greenhouse horticulture - cut flowers
    Modelbouwer Raymond Jongschaap heeft 200 verschillende belichtingsscenario’s bij roos in een model doorgerekent. Daaruit blijkt dat een belichtingsduur van 16 uur voldoende is behalve in de donkere maanden, want dan is 20 uur nodig. De belichtingsintensiteit mag ‘s zomers lager zijn dan ’s winters. Ook mag de belichting ’s zomers eerder uit dan in de rest van het jaar. Wie per periode van vier weken de meest energie-efficiënte strategie volgt, kan 16% energie besparen en € 2,00 per m2 verdienen
    Proceedings of the Third International Symposium on Models for Plant Growth, Environmental Control and Farm Management in Protected Cultivation (HORTIMODEL)
    Marcelis, L.F.M. ; Straten, G. van; Stanghellini, C. ; Heuvelink, E. - \ 2006
    Leuven : ISHS (Acta horticulturae 718) - ISBN 9789066056091 - 688
    teelt onder bescherming - tuinbouwgewassen - tuinbouw - kassen - modellen - simulatiemodellen - gewasopbrengst - groei - groeimodellen - glastuinbouw - protected cultivation - horticultural crops - horticulture - greenhouses - models - simulation models - crop yield - growth - growth models - greenhouse horticulture
    Vruchtzetting paprika spel van vraag en aanbod
    Marcelis, L.F.M. ; Heuvelink, E. - \ 2005
    Groenten en Fruit. Algemeen (2005)33. - ISSN 0925-9694 - p. 20 - 21.
    capsicum - teelt - cultuurmethoden - vruchtzetting - hormonen - zaadzetting - assimilatie - plantenfysiologie - groeimodellen - gewasopbrengst - relatie tussen groei en oogst - capsicum - cultivation - cultural methods - fructification - hormones - seed set - assimilation - plant physiology - growth models - crop yield - growth yield relationship
    Voor een goede productie bij paprika is niet het aantal bloemen, maar het aantal gezette vruchten de beperkende factor. De zetting wordt vooral bepaald door de beschikbaarheid van assimilaten. Die beschikbaarheid wordt bepaald door de aanmaak van deze suikers en de vraag ernaar van al gezette vruchten. De effecten van vraag en aanbod van assimilaten werden door Plant Research International en Wageningen Universiteit opgenomen in een groeimodel, dat op basis van klimaatgegevens en enkele teeltgegevens de groei en productie berekent. Met behulp van dit groeimodel bleek de zetting van te voren redelijk te voorspellen
    Better insight into the control of Kalanchoe
    Carvalho, S.M.P. ; Heuvelink, E. - \ 2005
    FlowerTECH 8 (2005)5. - ISSN 1388-8439 - p. 24 - 25.
    potplanten - sierplanten - kalanchoe - teelt - cultuurmethoden - groeimodellen - belichting - temperatuur - oogsttijdstip - pot plants - ornamental plants - cultivation - cultural methods - growth models - illumination - temperature - harvesting date
    Productie van planten van hoge kwaliteit volgens een vooropgezet schema is niet eenvoudig, zelfs niet voor een ervaren kalanchoe teler. Wageningen UR ontwikkelde een groeimodel voor dit gewas, dat een beter inzicht in de mogelijkheden tot teeltcontrole geeft. De gevolgde systematische aanpak kan een voorbeeld zijn voor de ontwikkeling van groeimodellen voor andere bloeiende potplanten
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