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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    Vochtbeheersing Cymbidium
    Raaphorst, Marcel - \ 2012
    cultural methods - greenhouse horticulture - greenhouse technology - energy saving - humidity - artificial ventilation - cymbidium - ornamental horticulture
    Transport van perkplanten kan in details nog beter
    Harkema, H. ; Westra, E.H. - \ 2012
    Vakblad voor de Bloemisterij 67 (2012)9. - ISSN 0042-2223 - p. 38 - 39.
    sierplanten - transport - kwaliteitszorg - gewaskwaliteit - houdbaarheid (kwaliteit) - optimalisatie - licht - vochtigheid - ornamental plants - transport - quality management - crop quality - keeping quality - optimization - light - humidity
    De perkgoedsector pakt veel zaken die de kwaliteit betreffen goed aan. Er zijn alleen nog wat details die beter kunnen. Te denken valt aan licht geven tijdens tranport en lage luchtvochtigheid voorkomen.
    Effect of increasing temparature on space requirements of group housed finishing pigs
    Spoolder, H.A.M. ; Aarnink, A.J.A. ; Vermeer, H.M. ; Riel, J.W. van - \ 2012
    Applied Animal Behaviour Science 138 (2012)3-4. - ISSN 0168-1591 - p. 229 - 239.
    dierenwelzijn - dierlijke productie - varkens - huisvesting, dieren - diergedrag - temperatuur - groepshuisvesting - varkensstallen - varkenshouderij - animal welfare - animal production - pigs - animal housing - animal behaviour - temperature - group housing - pig housing - pig farming - lying behavior - growing-pigs - allowance - humidity - welfare
    For groups of pigs to cope adequately with their housing conditions they need sufficient static space (occupied by the body of the pig), activity space (for movement between different functional areas and behaviours relating to these) and interaction space (for appropriate social behaviour). Estimates for static space have been presented for thermoneutral conditions, but are expected to increase substantially as temperature increases. The present paper models the relationship between ambient temperatures above the comfort zone, and thermoregulatory lying behaviour in finishing pigs. Estimates of the effect of posture on floor occupation were obtained and presented as ‘k-values’ (k = floor area occupied (m2)/body weight2/3 (kg)) to correct for the effect of pig size. A literature review was conducted to collect information on three aspects of lying behaviour: lying frequency, posture (lateral, semi lateral or ventral lying) and level of space sharing (huddling) in response to increasing temperatures. The lowest and highest values found were: increase in lying down: 0.2–0.66%, reduction in space sharing: 1.7–4.9% and increase in lateral vs sternal lying: 0.8–2.3% per °C temperature increase. Extrapolation of k values in the comfort zone to T = 31 °C suggests a range of k-values from k = 0.0331 to k = 0.0385 for static space. In the second part of this paper we analyse video data from a pig building in which groups of 18 pigs were kept in large pens (1.67 m2 per animal) at temperatures ranging from 16 to 32 °C. We find a value of k = 0.0339 at T = 31 °C for static space, which is at the lower end of the range predicted from literature. A possible explanation for this relatively low additional space requirement is that the animals coped by increasingly using the slatted area (with sprinkler system) as a lying area. The study confirms earlier suggestions that the amount of space required by EU legislation is insufficient for pigs at the end of the finishing period, even at relatively low temperatures. In situations where the average room temperature exceeds the comfort zone, pigs need additional space to cope with their housing system, or alternative methods to cool themselves down.
    On Monin–Obukhov Scaling in and Above the Atmospheric Surface Layer: The Complexities of Elevated Scintillometer Measurements
    Braam, M. ; Bosveld, F.C. ; Moene, A.F. - \ 2012
    Boundary-Layer Meteorology 144 (2012)2. - ISSN 0006-8314 - p. 157 - 177.
    large-aperture scintillometer - boundary-layer - structure parameters - sonic anemometer - refractive-index - sensible heat - water-vapor - temperature - fluxes - humidity
    In scintillometry Monin–Obukhov similarity theory (MOST) is used to calculate the surface sensible heat flux from the structure parameter of temperature (CT2)(CT2) . In order to prevent saturation a scintillometer can be installed at an elevated level. However, in that case the observation level might be located outside the atmospheric surface layer (ASL) and thus the validity of MOST questioned. Therefore, we examine two concepts to determine the turbulent surface sensible heat flux from the structure parameter at elevated levels with data obtained at 60-m height on the Cabauw tower (the Netherlands). In the first concept (MOSTs) CT2CT2 is still scaled with the surface flux, whereas in the second (MOSTl) CT2CT2 is scaled with the local sensible heat flux. The CT2CT2 obtained from both concepts is compared with direct observations of CT2CT2 using a sonic anemometer/thermometer. In the afternoon (when the measurement height is located within the ASL) both concepts give results that are comparable to the directly observed values of CT2CT2 . In the morning (data outside the ASL), our data do not unequivocally support either of the two concepts. First, the peak in CT2CT2 that occurs when the measurement height is located in the entrainment zone disqualifies the use of MOST. Second, during the morning transition, local scaling shows the correct pattern (zero flux and a minimum in CT2CT2) but underestimates CT2CT2 by a factor of ten. Third, from the best linear fit a we found that the slope of MOSTl gave better results, whereas the offset is closer to zero for MOSTs. Further, the correlation between the direct observations and MOST-scaled results is low and similar for the two concepts. In the end, we conclude that MOST is not applicable for the morning hours when the observation level is above the ASL.
    Risicobeperking van ziekten en plagen bij energiezuinige maatregelen
    Hofland-Zijlstra, J.D. ; Messelink, G.J. ; Slooten, M.A. van; Groot, E.B. de; Stevens, L.H. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1153) - 34
    glastuinbouw - plantenplagen - plantenziekten - klimaatregeling - kooldioxide - vochtigheid - natuurlijke vijanden - gewasbescherming - ziekteresistentie - plaagresistentie - greenhouse horticulture - plant pests - plant diseases - air conditioning - carbon dioxide - humidity - natural enemies - plant protection - disease resistance - pest resistance
    This study gives an overview on the impact of climatic conditions, e.g. moisture deficit and CO2, on the plant defense system in the greenhouse. Higher CO2 dosages or increased moisture levels have a strong influence on the pest control. Partly, by direct effects on biological control agents and partly through effects on the plant quality. The outcome depends on the prey-predator system.
    Vochtafvoer met verwarmde buitenlucht slaat aan in tulpenbroei : hoge luchtvochtigheid door verdamping van gewas en watersysteem (interview met Jouke Campen)
    Staalduinen, J. van; Campen, J.B. - \ 2012
    Onder Glas 9 (2012)3. - p. 5 - 7.
    glastuinbouw - teelt onder bescherming - tulpen - forceren van planten - vochtigheid - klimaatregeling - beluchting - verwarmingssystemen - kastechniek - snijbloemen - greenhouse horticulture - protected cultivation - tulips - forcing - humidity - air conditioning - aeration - heating systems - greenhouse technology - cut flowers
    Vochtregulering met aangezogen en verwarmde buitenlucht maakt opgang in de tulpenbroeierij op water. Wagemaker Flowers in Hoogkarspel deed er als eerste ervaring mee op. Bolbloementeler Jeffrey Wagemaker en klimaatspecialist Jouke Campen van Wageningen UR Glastuinbouw doen verslag van de ervaringen.
    Vochthuishouding in perencellen : maatregelen voor een beter bewaarseizoen
    Geijn, F.G. van de - \ 2011
    De Fruitteelt 101 (2011)34. - ISSN 0016-2302
    fruitgewassen - peren - fruitbewaarplaatsen - opslagloodsen - maatregelen - vochtigheid - fruit crops - pears - fruit stores - stores - measures - humidity
    Het bewaren van Conference vraagt op allerlei vlakken om maatregelen. Een juiste vochthuishouding is daarbij zeer bepalend.
    Bladrandjes tomaat; achtergronden en oorzaken
    Voogt, Wim - \ 2011
    tomatoes - greenhouse horticulture - calcium - nutrient deficiencies - deficiency diseases - plant disorders - humidity
    Zomerkwaliteit lisianthus
    Helm, Frank van der - \ 2011
    eustoma grandiflorum - ornamental horticulture - cultural methods - air conditioning - greenhouse horticulture - flower induction - light - temperature - humidity
    Luchtvochtigheid en scheuren radijs
    Janse, Jan - \ 2011
    radishes - greenhouse vegetables - cracking - humidity - greenhouse horticulture
    Stomatal response characteristics as affected by long-term elevated humidity levels
    Fanourakis, D. - \ 2011
    Wageningen University. Promotor(en): Olaf van Kooten, co-promotor(en): Ep Heuvelink; Susana Pinto de Carvalho. - [S.l.] : S.n. - ISBN 9789461730015 - 169
    huidmondjes - vochtigheid - tuinbouw - vaasleven - plantenfysiologie - abscisinezuur - cuticula bij planten - plantenanatomie - rosa - stomata - humidity - horticulture - vase life - plant physiology - abscisic acid - plant cuticle - plant anatomy - rosa

    Restriction of leaf water loss, by stomatal closure, is decisive for plant survival, especially under conditions of water deficit. This sensitivity of stomata to low water potential is attenuated by high relative air humidity (RH ≥ 85%) during growth, which impedes the plant’s ability to survive when subsequently exposed to lower humidities due to a negative water balance. This thesis focuses on the extent of the existing variation and the reasons underlying cultivar differences in their tolerance to high RH, as well as the rate and reversibility of stomatal adaptation to elevated RH in the course of leaf ontogeny.

    Cut rose was used as a model plant. An experiment on the postharvest water relations of three contrasting cultivars in their sensitivity to high RH showed that the sensitive cultivar (i.e. steepest decrease in the cut flower longevity) underwent a higher increase in the water loss compared to the tolerant cultivars. Preventing vascular occlusion considerably extended the time to wilting in the sensitive cultivar grown at high RH, showing that the high rate of water loss, as a result of plant growth at high RH, can only be detrimental for keeping quality under limiting water uptake conditions. Further investigation showed a large genotypic variation in the regulation of water loss, as a result of leaf development at high RH, and stomatal closing capacity was the key element in this process. The degree to which the stomatal anatomical features were affected and the extent that their functionality was impaired were not correlated. However, higher stomatal density, longer pore length and depth contributed to the higher water loss of high RH-grown leaves (16–30% of the effect depending on the cultivar). Reciprocal change in RH showed that stomatal functioning was no longer affected by the RH level after full leaf expansion. However, expanding leaves were always able to partly adapt to the new RH level. For leaves that started expanding at high RH but completed their expansion after transfer to moderate RH, the earlier this switch took place the better the regulation of leaf water loss. This behaviour of expanding leaves experiencing a shift from high to moderate RH was related with the increasing population of stomata exceeding a critical stomatal length. Contrary to this, leaves initially expanding at moderate RH and transferred to high RH exhibited poor stomatal functioning, even when this transfer occurred very late during leaf expansion. This suggests that stomata at various developmental stages were similarly prone to loss of closing ability, when these had been exposed to high RH prior to full leaf expansion.

    Key words: abscisic acid, cuticular permeability, heterogeneity, hydraulic conductivity, pore aperture, relative air humidity, Rosa hybrida, stomatal anatomy, stomatal conductance, stomatal growth, stomatal initiation, stomatal malfunctioning, stomatal population, stomatal proximity, vase life.

    Invloed van luchtvochtigheid op het scheuren van radijs
    Janse, J. ; Steenbergen, P. - \ 2011
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1094) - 28
    glastuinbouw - raphanus sativus - radijsjes - splijting - vochtigheid - plantenziektebestrijding - glasgroenten - teelt onder bescherming - kasgewassen - greenhouse horticulture - raphanus sativus - radishes - splitting - humidity - plant disease control - greenhouse vegetables - protected cultivation - greenhouse crops
    Referaat Veel gescheurde radijs bij hoge RV tijdens knolvorming In de winter geeft een hoge luchtvochtigheid tijdens de knolvormingsfase duidelijk meer gescheurde radijsknollen. Dit gebeurt met name als de luchtvochtigheid in de eerste teeltfase juist laag is geweest. Dit bleek uit onderzoek bij Wageningen UR Glastuinbouw in Bleiswijk. Bij oogst in januari scheuren radijsknollen veel gemakkelijker dan bij oogst in februari of maart. Vooral bij een knoldiameter van circa 8 mm zijn radijsjes gevoelig voor een hoge luchtvochtigheid. Om in de wintermaanden gescheurde radijs te voorkomen is het dus gewenst dat telers proberen om de luchtvochtigheid tijdens de knolvormingsfase te verlagen door meer te ventileren en/of wat te verwarmen. Abstract High humidity causes more splitting of radish tubers In winter season, high humidity in the greenhouse causes more cracking or splitting of the tubers of radish. This happens especially when humidity in the first growing phase is low. This became clear in a research by Wageningen UR Greenhouse Horticulture in Bleiswijk. Harvesting in January gives far more splitting of radish tubers than harvesting in February or March. Especially tubers with a diameter around 8 mm seems susceptible for splitting at circumstances with a high humidity. Growers are being advised to try to decrease the humidity in glasshouses by ventilating and or heating.
    Humidification - Fogging and other evaporative cooling in greenhouses
    Nederhoff, E.M. ; Weel, P.A. van - \ 2011
    Practical Hydroponics & Greenhouses 2011 (2011)118. - ISSN 1321-8727 - p. 46 - 52.
    kastechniek - glastuinbouw - verdampingskoeling - vochtigheid - binnenklimaat - greenhouse technology - greenhouse horticulture - evaporative cooling - humidity - indoor climate
    Fogging, misting, roof sprinklers, pad-and-fan and other techniques based on water evaporation are effective tools for improving the growing conditions in a greenhouse when humidity is low. They should be used wisely though.
    Buitenluchtaanzuiging en schermen
    Kempkes, Frank - \ 2011
    greenhouse horticulture - greenhouses - blinds - ventilation - temperature - air - humidity - greenhouse technology - energy saving
    Botrytis in de afzetketen van gerbera's
    Westra, E.H. ; Woltering, E.J. ; Boerrigter, H.A.M. - \ 2010
    Gewasbescherming 41 (2010)5. - ISSN 0166-6495 - p. 236 - 238.
    botrytis - gerbera - snijbloemen - verpakkingen - koelen - behandeling na de oogst - vochtigheid - chemische bestrijding - botrytis - gerbera - cut flowers - wrappings - cooling - postharvest treatment - humidity - chemical control
    Bij gerbera is aantasting door Botrytis cinerea het belangrijkste kwaliteitsprobleem in de afzetketen. In het kader van het Parapluplan Gerbera heeft Wageningen UR Food & Biobased Research onderzoek gedaan naar maatregelen in de keten om Botrytis-aantasting te beperken. Door gerbera’s in de afzetketen te koelen vermindert de Botrytis-aantasting, zelfs als door het koelen condensvorming optreedt. Gerbera’s verpakken in netten, in dozen met openingen, remt Botrytis eveneens. Chemische bestrijding na de oogst met Aquanox heeft in de praktijk een klein effect.
    Sturing kasklimaat op basis van modellering van Botrytis
    Körner, O. ; Visser, P.H.B. de - \ 2010
    Gewasbescherming 41 (2010)5. - ISSN 0166-6495 - p. 232 - 235.
    botrytis - microklimaat - vochtigheid - simulatiemodellen - infectie - sporenverspreiding - glastuinbouw - beslissingsondersteunende systemen - energiebesparing - botrytis - microclimate - humidity - simulation models - infection - spore dispersal - greenhouse horticulture - decision support systems - energy saving
    Schade aan kasgewassen door Botrytisaantasting (smet) is één van de belangrijkste knelpunten in de kasteelt. Te hoge luchtvochtigheid en lokale koude plekken met condensvorming zijn de belangrijkste oorzaken van smet. Het instellen van een droog kasklimaat kost veel energie, maar door het gebruik van een waarschuwings- of sturingsmodel is het mogelijk om naast het vermijden van besmetting straks ook energiewinst te behalen ten opzichte van telen zonder model. Met verklarende computermodellen kunnen plantengroei, -kwaliteit en schimmelinfectie berekend worden. De modellen kunnen Botrytis helpen voorkomen door de juiste klimaatinstellingen en de inrichting van de kas.
    Bedrijfsvergelijking geeft inzicht in kansen op Botrytis bij gerbera in de na-oogstfase
    Os, E.A. van; Körner, O. ; Marcelis, L.F.M. ; Slootweg, G. ; Swinkels, G.L.A.M. ; Janssen, Hans ; Tuijl, B.A.J. van - \ 2010
    Gewasbescherming 41 (2010)5. - ISSN 0166-6495 - p. 227 - 231.
    gerbera - snijbloemen - bloementeelt - botrytis cinerea - tuinbouwbedrijven - microklimaat - vochtigheid - temperatuur - agrarische bedrijfsvoering - glastuinbouw - kwaliteit na de oogst - gerbera - cut flowers - floriculture - botrytis cinerea - market gardens - microclimate - humidity - temperature - farm management - greenhouse horticulture - postharvest quality
    Door op twaalf bedrijven in drie meetronden van zes weken wekelijks te oogsten en de gerealiseerde klimaatdata te analyseren bleek dat het microklimaat rond de plant van grote invloed was op het ontstaan van pokken in de naoogstfase. Hoe vochtiger het is, hoe groter de snelheid van Botrytisontwikkeling. Overdag moeten de omstandigheden rond de bloem zodanig zijn dat sporen òf doodgaan (lage vochtigheid, hoge temperatuur), òf niet kunnen hechten (lage vochtigheid) of verspreid worden. ‘s Nachts moet de vochtigheid tussen de bladeren niet te hoog oplopen om groei en ontwikkeling van de schimmel te remmen.
    Meting van ruimtelijke verdeling van temperatuur en RV met behulp van draadloze minisensoren (Smart Dust). Deel 3: Metingen bij praktijkbedrijven in verschillende seizoenen
    Balendonck, J. ; Os, E.A. van; Schoor, R. van der; Tuijl, B.A.J. van; Keizer, L.C.P. - \ 2010
    Wageningen : Wageningen UR Glastuinbouw (Rapport / Wageningen UR Glastuinbouw 311) - 74
    kassen - temperatuur - vochtigheid - sensors - seizoenen - operationeel onderzoek - tests - klimaatregeling - glastuinbouw - meetsystemen - draadloze sensornetwerken - energiebesparing - greenhouses - temperature - humidity - sensors - seasons - operations research - tests - air conditioning - greenhouse horticulture - measurement systems - wireless sensor networks - energy saving
    Beschrijving van de metingen bij praktijkbedrijven in verschillende seizoenen.
    Meten ruimtelijke verdeling van temperatuur en luchtvochtigheid met draadloze sensoren
    Balendonck, J. - \ 2010
    klimaatregeling - infrastructuur - kassen - vochtigheid - vochtgehalte - glastuinbouw - kastechniek - air conditioning - infrastructure - greenhouses - humidity - moisture content - greenhouse horticulture - greenhouse technology
    Een homogeen klimaat leidt tot een gelijkmatiger gewas, minder ziekten en de mogelijkheid om energie te besparen, en levert daardoor economisch voordeel. Telers proberen daarom koude en natte plekken in hun gewas te voorkomen. Het toepassen van een dicht meetnet van goedkope draadloze sensoren opent mogelijkheden om de horizontale verdeling van temperatuur en luchtvochtigheid in kassen te beïnvloeden, enerzijds door de infra-structuur van de kas aan te passen of door de mogelijkheid te benutten om veel preciezer met de instellingen van de klimaatcomputer, verwarming en ventilatie om te gaan.
    Sodium hypochlorite: A promising agent for reducing Botrytis cinerea infection on rose flowers
    Macnish, A.J. ; Morris, K.L. ; Theije, A. de; Mensink, M.G.J. ; Boerrigter, H.A.M. ; Reid, M.S. ; Jiang, C.Z. ; Woltering, E.J. - \ 2010
    Postharvest Biology and Technology 58 (2010)3. - ISSN 0925-5214 - p. 262 - 267.
    cut roses - chlorine - conidia - preharvest - resistance - bacteria - humidity - disease - mold
    Botrytis cinerea is a fungal pathogen that greatly reduces the postharvest quality of rose flowers. A postharvest dip in 200 µL L-1 sodium hypochlorite (NaOCl) for 10 s at 20 °C provided the greatest control of B. cinerea on ‘Akito’ and ‘Gold Strike’ flowers. NaOCl derived from Clorox® Ultra household bleach solution was more effective than laboratory grade NaOCl in reducing disease symptoms. Lowering the pH of the NaOCl solution from pH 9.7 (unadjusted) to pH 7.0 greatly improved its efficacy. Treating ‘Gold Strike’ flowers in this pH-adjusted NaOCl solution was more effective in reducing the level of infection on petals than postharvest dips in the conventional fungicides Medallion®, Phyton®, Switch® and Vangard®. Applying NaOCl prior to a 3- or 10-d commercial shipment also provided the most consistent disease control for a wide range of rose cultivars as compared to conventional fungicides. Of particular interest, the efficacy of NaOCl and Phyton® was greatest when these compounds were applied to ‘Gold Strike’ flowers after incubation at 20 °C and 90% RH for 6–9 h. Our findings highlight NaOCl as a promising new candidate for the control of B. cinerea on rose flowers.
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