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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Effectbeoordeling van het voorstel voor een nieuwe Europese Meststoffenverordening : analyse van de aanvoer van zware metalen de landbouwbodem en gevolgen voor vrije verhandeling van nationale meststoffen
Römkens, Paul ; Rietra, René ; Ehlert, Philip - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2766) - 99
kunstmeststoffen - wetgeving - dierlijke meststoffen - zware metalen - effecten - milieuwetgeving - europa - fertilizers - legislation - animal manures - heavy metals - effects - environmental legislation - europe
De Europese Commissie (COM) heeft een nieuw pakket voor de circulaire economie goedgekeurd om de overgang naar een circulaire economie in Europa te stimuleren. Oogmerk is om een stimulans en een versterking te geven aan het mondiale concurrentievermogen en duurzame economische groei en nieuwe werkgelegenheid te creëren. Het pakket stelt maatregelen voor die uitgewerkt zijn in een actieplan. Deze maatregelen sturen aan op een overgang van een lineaire economie naar een circulaire economie. Tot uitvoering van het pakket heeft COM maatregelen aangewezen. Een van de maatregelen is een herziening van de Europese meststoffenverordening (CEP, 2016) om de erkenning van organische meststoffen en op afval gebaseerde meststoffen in een geharmoniseerde markt te vergemakkelijken Deze studie onderzoekt de effecten van dit voorstel en richt zich daarbij vooral op mogelijke consequenties van de door CEP 2016 voorgestelde criteria voor meststoffen, waaronder organische en anorganische reststoffen op de gewaskwaliteit en op de belasting van de bodem met contaminanten waaronder Cadmium (Cd), Chroom (Cr), Kwik (Hg), Nikkel (Ni), Lood (Pb), en Arseen (As) en micronutriënten Koper (Cu) en Zink (Zn). Daarnaast wordt via een generieke analyse in kaart gebracht of huidige nationale meststoffen kunnen voldoen aan de door de nieuwe Europese meststoffenverordening voorgestelde eisen voor waardegevende bestanddelen en contaminanten. Tevens is onderzocht of mest en producten van mestverwerking kunnen ressorteren onder de voorgestelde CEPbepalingen (2016). Ten slotte is onderzocht of de huidige afval- en reststromen die als co-vergistingsmateriaal toegelaten zijn, aangemerkt kunnen worden als bioafval conform Richtlijn 2008/98/EG.
The neurotoxin BMAA in aquatic systems : analysis, occurrence and effects
Faassen, E.J. - \ 2016
University. Promotor(en): Marten Scheffer, co-promotor(en): Miguel Lurling. - Wageningen : Wageningen University - ISBN 9789462577855 - 194 p.
cum laude - neurotoxins - aquatic environment - urban areas - effects - environmental impact - daphnia magna - elisa - water quality - analytical methods - aquatic ecology - neurotoxinen - aquatisch milieu - stedelijke gebieden - effecten - milieueffect - waterkwaliteit - analytische methoden - aquatische ecologie

Eutrophication is a major water quality issue and in many aquatic systems, it leads to the proliferation of toxic phytoplankton species. The neurotoxin β-N-methylamino-L-alanine (BMAA) is one of the compounds that can be present in phytoplankton. BMAA has been suggested to play a role in the neurodegenerative diseases Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis, although this hypothesis still needs to be confirmed. It is expected that the main human exposure pathways to BMAA are through direct contact with BMAA containing phytoplankton and through ingestion of BMAA contaminated food, such as fish and shellfish. However, reports on the occurrence of BMAA in aquatic systems have been conflicting and the cause of these reported differences was heavily debated. The use of different analytical methods seems to play a crucial role in the observed discrepancies, but initially, there was little consensus on which method produced most reliable results. The objectives of the work presented in this thesis therefore were to find out what has caused the differences in published results on BMAA concentrations, and to identify and produce reliable data on the presence of BMAA in aquatic systems. In addition, I aimed to determine the effect of BMAA exposure on a key species in many freshwater ecosystems, the grazer Daphnia magna.

The performances of different analytical techniques were compared, and LC-MS/MS analysis, either preceded by derivatisation or not, was found to produce most reliable results. LC-FLD and ELISA should not be used for BMAA analysis, as both methods risk misidentifying BMAA or overestimating its concentrations due to their low selectivity. When reviewing literature on the presence of BMAA in aquatic systems, it was found that the observed discrepancies in results could be explained by the use of unselective analytical methods in some studies, and by severe reporting deficiencies in others. When only studies that used appropriate analytical techniques and that correctly reported their work were taken into account, it was shown that BMAA could be present in phytoplankton and higher aquatic organisms, in concentrations of µg/g dry weight or lower. These results are in agreement with our findings of BMAA in cyanobacterial scums from Dutch urban waters. In a 2008 screening, BMAA was found to be present in 9 out of 21 analysed cyanobacterial scums, at concentrations ranging from 4 to 42 µg/g dry weight. When this screening was repeated 8 years later with 52 similar samples, BMAA was detected below the quantification limit in one sample and quantified in another sample at 0.6 µg/g dry weight.

In order to perform the work presented in this thesis, sensitive and selective analytical methods, mostly based on LC-MS/MS analysis without derivatisation, were developed. This resulted in a standard operating procedure for the underivatised LC-MS/MS analysis of BMAA in cyanobacteria. Also, a CYANOCOST initiated workshop was given, in which a group of scientists from 17 independent laboratories evaluated LC-MS/MS based methods in different matrices. A bound BMAA from found in the supernatant was the most abundant fraction in the positive samples that were tested: cycad seed, seafood and exposed D. magna. In addition, it was found that the deuterated internal standard used for quantification was not a good indicator for the release of BMAA from bound forms, resulting in unprecise quantification of total BMAA.

BMAA was found to reduce survival, somatic growth, reproduction and population growth in D. magna. Animals did not adapt to BMAA exposure: exposed animals born from exposed mothers had a lower brood viability and neonate weight than animals exposed to BMAA, but born from unexposed mothers. In addition, D. magna was shown to take up BMAA from the growth medium and to transfer it to its offspring. D. magna therefore might be an important vector for BMAA transfer along the pelagic food chain, but whether BMAA plays a role in preventing zooplankton from controlling cyanobacterial blooms needs further investigation.

Although BMAA research has much progressed between the start of this thesis’ work and its completion, some important questions still require an answer. Most urgently, it should be determined whether BMAA is indeed involved in the neurological diseases mentioned above, and if so, which doses trigger the onset of these diseases. Human exposure pathways should then be more systematically quantified, and it might be prudent to investigate if the occurrence of BMAA is restricted to aquatic systems, or whether sources from terrestrial systems contribute to BMAA exposure as well.

Targeted and non-targeted effects in cell wall polysaccharides from transgenetically modified potato tubers
Huang, J.H. - \ 2016
University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462576292 - 126 p.
potatoes - cell walls - polysaccharides - transgenic plants - pectins - tubers - xyloglucans - genetically engineered foods - galactans - characteristics - nontarget effects - effects - aardappelen - celwanden - polysacchariden - transgene planten - pectinen - knollen - xyloglucanen - genetisch gemanipuleerde voedingsmiddelen - galactanen - karakteristieken - onbedoelde effecten - effecten

The plant cell wall is a chemically complex network composed mainly of polysaccharides. Cell wall polysaccharides surround and protect plant cells and are responsible for the stability and rigidity of plant tissue. Pectin is a major component of primary cell wall and the middle lamella of plants. However, pectin biosynthesis in planta and the mechanisms underlying the influence of structural differences arising from a modified biosynthesis machinery on functional properties remain poorly understood. In our research, the changes in the chemical structures of cell wall polysaccharides after transgenic modification of potato tuber polysaccharides were examined. The cell wall material from potato wild-type varieties, from known and from new potato transgenic lines targeting changes of the homogalacturonan or rhamnogalacturonan I backbone were isolated and characterized. The modified cell wall polysaccharides were examined by determining their individual monosaccharide levels on fresh weight base and their cell wall characteristic parameters, and levels of acetylation and methyl esterification of cell wall pectin. Data for both targeted and non-targeted structures of cell wall polysaccharides from wild-type and transgenic potatoes were obtained. A shorter galactan side chain was found from the buffer soluble pectin and calcium bound pectin of β-galactosidase (β-Gal) transgenic lines. All pectin fractions from rhamnogalacturonan lyase (RGL) transgenic lines had less galactan chains attached to their rhamnogalacturonan I backbones. Two uridine diphosphate-glucose 4-epimerase (UGE) transgenic lines, UGE 45 and UGE 51, had diverse effects on length of the galactan side chain. The xyloglucans from the RGL and UGE transgenic lines retained its XXGG building blocks but differed in the proportion of repeating units compared to the respective wild-type varieties. In contrast, the β-Gal transgenic lines predominantly consisted of XXXG-type xyloglucan in the 4 M alkali extract, but showed XXGG-type building blocks in 1 M alkali extract. In addition, a quick-screening method was validated and used to analyze 31 transgenic lines and their respective wild-type potato varieties. An overall comparison of pectin backbone, pectin side chains, acetylation and methyl-esterification of pectin, pectin content and (hemi)cellulose content of cell wall polysaccharides from these transgenic lines provided a better insight in the frequency, level and combination of both targeted and non-targeted structural changes compared to that of their respective wild-type varieties. The same evaluation method was used to correlate cell wall composition in wild-type and selected transgenic lines and their established gene expression with the texture of corresponding cooked potato cubes. Changed physical properties for the genetically modified tubers could be connected to specific cell wall characteristics. Tubers from transgenic lines containing cell wall pectin with short galactan side chains were less firm after cold processing compared to wild-type tubers. The enhanced understanding of transgenic modifications of potato tubers resulting into significant targeted and non-targeted modifications in cell wall polysaccharides will lead to a better selection of potato lines with tailored cell wall characteristics and desired properties of the tubers during processing.

Potato cell walls are composed of pectin, hemicellulose and cellulose. Cell wall polysaccharides are responsible for the stability, rigidity and flexibility of plant tissue. Pectin, a major component of primary plant cell walls, primarily consists of homogalacturonan (HG) and rhamnogalacturonan I (RG-I). To understand the structure–function relationships of potato cell wall pectin, this study aimed to identify the characteristics of both pectin and other polysaccharides as present in cell wall material (CWM) and of individual polysaccharide populations from wild-type potato varieties and their respective transgenic potato lines.

Chapter 1 gives a general introduction to the fine chemical structures of potato cell wall polysaccharides, the main models of cell wall architecture and the cell wall-degrading enzymes, which include pectinases, hemicellulases and cellulases. In addition, transgenic modification of the cell wall through the heterologous expression of various enzymes from fungal or plant origin that could modify potato cell wall polysaccharides in planta is addressed. Transgenic modifications of potato cell wall polysaccharides that targeted pectin structures and cellulose levels are summarised. However, due to unsuccessful starch removal during CWM isolation and incomplete analysis of CWM yield and composition, characteristics regarding the different cell wall polysaccharides from previously-studied transgenic potato lines are hardly available.

CWMs were extracted from the Karnico (wild-type) potato and its transgenic lines that expressed either β-galactosidase or rhamnogalacturonan lyase (Chapter 2). Improved starch removal procedures proved to be successful. Pectic polysaccharides were fractionated from CWMs of wild-type potato and its transgenic lines β-Gal-14 and RGL-18. Most β-Gal-14 pectin populations had less galactose (Gal) than wild-type, indicating that the transgenic line had shorter galactan side chains, although the side chain length differed for individual pectin populations. The ratio of HG:RG-I was introduced to evaluate the pectin backbone structure. High HG:RG-I ratios were consistently found in RGL-18 pectic polysaccharide populations. A low level of RG-I segments in combination with lower Gal contents indicated the removal of the galactan-rich RG-I segments in all pectin populations of RGL transgenic lines. In addition, RGL-18 transgenic modification increased the methyl-esterification and lowered the acetylation of pectins present in hot buffer extracts, when compared to wild-type. No effect on pectin esterification was found for β-Gal transgenic lines. Side effects of the mutation generated unexpected changes in the various pectin populations.

The xyloglucan structure was extensively modified after transgenic modification of the pectin structure. Two xyloglucan extracts were obtained from the Karnico and its β-Gal-14 and RGL-18 transgenic lines (Chapter 3). The extracts of the Karnico and RGL-18 lines were mainly comprised of the XXGG-type xyloglucan as represented by XXGG and XSGG as predominant repeating units. In contrast, the XXXG-type xyloglucan was primarily present in the β-Gal-14 4 M alkali extract built up by LLUG repeats, although XXGG type of xyloglucan was present in the 1M alkali extract. Both the RGL and β-Gal transgenic lines had different proportions of xyloglucan building blocks (XSGG/XXGG ratios) than wild-type. After transgenic modification of pectin backbone or pectin side chains, the xyloglucan structures has been biosynthetically modified by plant itself.

Uridine diphosphate (UDP)-glucose 4-epimerase (UGE) catalyses the conversion of UDP-glucose into UDP-galactose, which hypothetically should lead to more galactose being built into the cell wall polysaccharides. CWMs from the Kardal (wild-type) potato and its UGE45-1 and UGE51-16 transgenic lines were isolated, fractionated and characterised (Chapter 4). Both the UGE45 and UGE51 genes encoded for UGE enzymes, but the corresponding transgenic lines exhibited different modifications of the galactan side chains and of other cell wall structures. The Gal content of CWM from the UGE45-1 transgenic line was 38% higher than that of the wild-type and resulted in longer pectin side chains. The Gal content present in CWM from UGE51-16 was 17% lower than that of wild-type, which resulted in a slightly shorter galactan side chains for most pectin populations. Both UGE transgenic lines showed a decreased acetylation and an increased methyl-esterification of the cell wall pectin. Side effects were found in the xyloglucan structures of the transgenes as reflected by different proportions of XSGG/XXGG repeating units in comparison to wild-type. Pectin side chain biosynthesis had not only a varying level of galactan side chain modification, but also influenced the structure and possibly the interaction of other cell wall polysaccharides.

In Chapter 5, a new screening strategy is introduced to evaluate higher numbers of transgenic potato tubers via CWM yield and sugar composition. A total of four wild-type potato varieties and 31 transgenic lines were evaluated to determine the effects on targeted structures including RG-I or HG pectin backbone elements, galactan or arabinogalactan side chains, acetyl groups of pectin and cellulose levels. Modification of the pectin backbone or pectin side chains in the transgenic lines has either a simultaneous increase or simultaneous decrease of HG:RG-I ratio, side chain length and methyl-esterification of pectin. The pectin esterification transgenic line exhibited only limited side effects. The cellulose level targeted lines had also high HG:RG-I ratios, longer galactan chains and similar pectin content compared to the wild-type, indicative for a less branched pectin backbone with longer side chains. From the monosaccharide composition data, various pectin and cell wall characteristics parameters are suggested as powerful indicators of cell wall polysaccharide structure.

In Chapter 6, the achievements of this research are summarised and discussed in the context of potato cell wall architecture. The strategy and outcome of a quick screening method for multiple transgenic lines and an in-depth analysis of individual pectin and xyloglucan populations for the evaluation of potato CWMs is discussed. Furthermore, the texture of steam-cooked potatoes and the stability of potato cubes after freeze-thaw cycles are correlated with gene expression and cell wall composition in wild-type and selected transgenetically modified potato tubers. CWMs from transgenetically modified potatoes showed different physical properties during processing. In isolated CWMs, acetylation of cell wall pectin, molar Gal levels and starch content were the main parameters that could be related to the texture or firmness of tubers. Tubers from transgenic lines that resulted in shorter pectin side chains felt apart more easily after several freeze-thaw cycles than wild-type tubers and tubers with an increased length of pectin side chains. The modification of both targeted as well as non-targeted structures have now been shown to occur in many different potato transgenic lines, but precise mechanisms and consequences for the cell wall architecture remain unclear. Research performed so far, as well as research needed for getting a better understanding of plant cell wall architecture, is discussed.

Een verkenning van het effect van stadslandbouw: de case Almere
Dekking, A.J.G. ; Veen, E.J. ; Jansma, J.E. - \ 2015
Stichting Dienst Landbouwkundig Onderzoek (DLO) (PPO/PRI 673)
landbouw - stadslandbouw - effecten - omgevingsverrijking - stedelijke gebieden - streekgebonden producten - voedsel - lokale netwerken - hobbyboeren - agriculture - urban agriculture - effects - environmental enrichment - urban areas - regional specialty products - food - local area networks - hobby farmers
Onderzoek in het kader van de PPS ‘Multifunctionele Landbouw’ Wat is de omvang en dynamiek rond stadslandbouw in Nederland, is de betekenis van stadslandbouw nader te duiden? De casus is in Almere uitgevoerd.
Auswirkungen der Erhöhung des Mehrwertsteuersatzes für Zierpflanzenerzeugnisse : Situation im Jahr 2015
Bunte, F. ; Galen, M.A. van - \ 2015
LEI Wageningen UR (Rapport / LEI Wageningen UR 2015-103) - ISBN 9789086157167 - 25 p.
ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
Effects of increased VAT rates for ornamentals : situation 2015
Bunte, F. ; Galen, M.A. van - \ 2015
LEI Wageningen UR (Report / LEI Wageningen UR 2015-103) - ISBN 9789086157174 - 23 p.
ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
Effets de l'augmentation du taux de TVA pour les produits d'horticulture ornementale : situation 2015
Bunte, F.H.J. ; Galen, M.A. van - \ 2015
Wageningen : LEI Wageningen UR (Rapport / LEI Wageningen UR 2015-103) - ISBN 9789086157167 - 25 p.
ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
Effecten van verhoging btw-tarief voor sierteeltproducten : situatie 2015
Bunte, F.H.J. ; Galen, M.A. van - \ 2015
Wageningen : LEI Wageningen UR (LEI rapport 2015-103) - ISBN 9789086157167 - 25 p.
sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland - ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands
This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
Impact of the water matrix on the effect and the side effect of MP UV/H2O2 treatment for the removal of organic micropollutants in drinking water production
Martijn, A.J. - \ 2015
University. Promotor(en): Ivonne Rietjens, co-promotor(en): J.P. Malley; J.C. Kruithof. - Wageningen : Wageningen University - ISBN 9789462575882 - 172
water treatment - pollutants - toxins - pretreatment - drinking water - pressure treatment - ultraviolet radiation - hydrogen peroxide - effects - waterzuivering - verontreinigende stoffen - toxinen - voorbehandeling - drinkwater - drukbehandeling - ultraviolette straling - waterstofperoxide - effecten
More than 30 per cent energy savings possible with LEDs in gerbera : substantial energy savings and little loss in production
Helm, F.P.M. van der - \ 2015
In Greenhouses : the international magazine for greenhouse growers 4 (2015)1. - ISSN 2215-0633 - p. 12 - 13.
glastuinbouw - snijbloemen - gerbera - led lampen - belichting - energiebesparing - effecten - proeven - greenhouse horticulture - cut flowers - led lamps - illumination - energy saving - effects - trials
By installing LED-lighting and limiting it to 80 instead of 100 μmol gerbera growers can save 30 per cent on energy without any great loss in production, according to research. Light integration and interlighting don’t yet deliver any savings.
Efficiëntere bemestingsstrategie mogelijke opslossing Lyprauta in potorchidee : gezonde plant toont minder schade van potworm
Rodenburg, J. ; Kruidhof, H.M. - \ 2015
Onder Glas 12 (2015)2. - p. 29 - 31.
orchidaceae - phalaenopsis - plantenplagen - potplanten - insectenplagen - effecten - bemesting - landbouwkundig onderzoek - mestgiften - glastuinbouw - plant pests - pot plants - insect pests - effects - fertilizer application - agricultural research - dressings - greenhouse horticulture
Zijn potwormen in orchidee misschien minder schadelijk dan altijd werd gedacht? Adviseur René ‘t Hoen denkt van wel. Hij claimt dat ondanks de aanwezigheid van potwormen, een gezonde plant zonder problemen kan uitgroeien tot een prima verkoopbaar product. Dit zou betekenen dat de teeltstrategie belangrijker is dan bestrijding van de schadelijke muggenlarven. Tegelijkertijd vindt hij dat zijn waarnemingen moeten worden gestaafd door onderzoek. Er is namelijk nog zeer weinig bekend over de biologie van potwormen.
Geweldige producties lisianthus op substraat blijven nog uit : eerste conclusie na één jaar los van ondergrond telen
Velden, P. van; Raaphorst, M.G.M. - \ 2015
Onder Glas 12 (2015)5. - p. 43 - 43.
glastuinbouw - vollegrondsteelt - substraten - teeltsystemen - effecten - kastechniek - recirculatiesystemen - doelstellingen - energiebesparing - proeven op proefstations - snijbloemen - greenhouse horticulture - outdoor cropping - substrates - cropping systems - effects - greenhouse technology - recirculating systems - objectives - energy saving - station tests - cut flowers
Een volveldse teelt met recirculatie bij lisianthus is zeker haalbaar, maar het is nog zoeken naar het meest effectieve teeltsysteem. Besparing op energie en met name belichting leidde tot groeivertraging, zo blijkt. Toch is er al veel bereikt in één jaar intensief praktijkonderzoek en er is nog meer mogelijk.
Aparte toediening geeft betere resultaten : alternatief voor ijzerchelaat in praktijk getoetst met positief resultaat
Hoogstraten, K. van; Voogt, W. - \ 2015
Onder Glas 12 (2015)5. - p. 23 - 25.
glastuinbouw - plantenvoeding - sporenelementen - polyfosfaten - bemesting - toepassing - opname (uptake) - effecten - ijzerhoudende meststoffen - chelaten - meststofdragers - greenhouse horticulture - plant nutrition - trace elements - polyphosphates - fertilizer application - application - uptake - effects - iron fertilizers - chelates - fertilizer carriers
IJzer is een onmisbaar voedingselement, dat nodig is voor de vorming van bladgroen en zo chlorose voorkomt. Omdat het element normaal niet opgelost blijft – en dan niet beschikbaar is voor de plant – zijn al jaren ijzerchelaten voorhanden. Bij een nieuwe meststof is het ijzer op een andere manier gebonden, namelijk met een combinatie van polyfosfaten. Bij toediening via een aparte bak blijkt het in de praktijk goed te werken. De meststof heeft daarnaast andere effecten, zoals minder bladrand en makkelijker UV-ontsmetting. Recent onderzoek en praktijkervaringen geven vergelijkbare resultaten.
Als het gebrek eenmaal zichtbaar is, is het vaak te laat
Voogt, W. ; Heuvelink, E. ; Kierkels, T. - \ 2015
Onder Glas 12 (2015)5. - p. 13 - 17.
glastuinbouw - bemesting - toediening op blad - bladvoeding - effecten - controle - plantenfysiologie - dosering - potplanten - greenhouse horticulture - fertilizer application - foliar application - foliar nutrition - effects - control - plant physiology - dosage - pot plants
Planten halen nutriënten normaal gesproken binnen via hun wortels. Het opname- en transportsysteem is daar volledig op ingericht. Bij bemesting via het blad is er niet zo’n gestroomlijnde route. Dat maakt het resultaat van bladbemesting erg wisselend. Immobiele elementen blijven snel steken bij de plek waar ze terecht zijn gekomen.
Een evaluatiekader voor ontgrondingen : Een studie naar de maatschappelijke gevolgen van ontgrondingen
Haaften, M. ; Heijman, W.J.M. ; Rietveld, M. - \ 2015
Water Governance 5 (2015)3. - ISSN 2211-0224 - p. 24 - 30.
markteconomie - regionaal beleid - maatschappelijk draagvlak - grondverzet - effecten - nadelige gevolgen - vergunningen - gelderland - market economics - regional policy - public support - earth moving - effects - adverse effects - permits
Op 1 februari 2008 verdween de plicht van provincies om van tevoren vastgestelde hoeveelheden zand en grind te leveren Deze beleidswijziging van taakstelling naar marktwerking werd doorgevoerd vanwege een slechte voorspelbaarheid van de behoefte aan zand en grind, een tanend maatschappelijk draagvlak en de wens om beleidskosten te verminderen. In het nieuwe beleid is economisch belang gekoppeld aan het creëren van maatschappelijk draagvlak. Overheden, omwonenden en bedrijven leveren vanuit hun betrokkenheid een bijdrage aan de afweging van gevolgen van ontgrondingen op maatschappelijk en economisch terrein. Deze gevolgen doen zich op kortere of langere termijn voor, op lokaal, regionaal en nationaal niveau. Een afwegingskader dat de gevolgen van het ontgronden beschrijft, inzichtelijk maakt en beoordeelt, ontbreekt tot op heden. Hetgeen het besluitvormingsproces inzake het verlenen van ontgrondingvergunningen niet transparant maakt. Het doel van dit artikel is tweeledig. Eerst worden de mogelijke gevolgen van ontgrondingen geïnventariseerd, daarna wordt ex post geëvalueerd hoe de afweging van gevolgen een plaats heeft gekregen in het beleid van de Provincie Gelderland. Het artikel besluit met een aantal aanbevelingen ter vergroting van het maatschappelijk draagvlak voor ontgrondingen.
Effect van afstromend regenwater op het watersysteem in de Wieringermeer
Slijkerman, D.M.E. ; Bos, R. - \ 2015
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 40 (2015)21. - ISSN 0166-8439 - p. 30 - 32.
riolering - regen - watersystemen - ecosystemen - effecten - waterkwaliteit - hydrologie - stedelijke gebieden - oppervlaktewaterkwaliteit - wieringermeer - sewerage - rain - water systems - ecosystems - effects - water quality - hydrology - urban areas - surface water quality
Voor een grootschalig afkoppelproject in de gemeente Wieringermeer is onderzoek verricht naar de verontreiniging in het afstromende regenwater en de ecologische effecten op het watersysteem. Dat gebeurde in het kader van NORIS (NO Rainwater in Sewers). Dit project wordt gesubsidieerd vanuit het Interreg IIIb North Sea-programma van de Europse Unie. Het Nederlandse deel van het project is uitgevoerd door TNO-IMARES en het Hoogheemraadschap Hollands Noorderkwartier. Het onderzoek toont aan dat locatiespecifiek chemische effecten kunnen optreden (verzoeting en periodieke overschrijding MTR van zink in water), maar dat dit niet direct leidt tot ecologische gevolgen. Landelijk en regionaal bestaan echter grote verschillen in typen ecosystemen en daarmee ook in de lokale veerkracht en gevoeligheid voor uiteenlopende sturende factoren. Daarom wordt gepleit voor een gebiedsgerichte evaluatie bij emissie van regenwater op oppervlaktewater
Nieuwe mogelijkheden voor de bestrijding van wittevlieg in de sierteelt onder glas : onderzoek aan omnivore roofwantsen en gedragsbeïnvloedende geuren
Messelink, G.J. ; Kruidhof, H.M. ; Elfferich, C. ; Leman, A. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1350)
glastuinbouw - sierteelt - organismen ingezet bij biologische bestrijding - reduviidae - thrips - effecten - schade - gerbera - cultivars - limoneen - geurstoffen - greenhouse horticulture - ornamental horticulture - biological control agents - effects - damage - limonene - odours
This study explored new possibilities to control whiteflies in greenhouse ornamental crops with omnivorous predatory bugs and volatiles. Besides the well-known Macrolophus pygmaeus, we tested 4 new species of predatory bugs: Dicyphus errans, Dicyphus eckerleini, Dicyphus maroccanus and Dicyphus tamaninii. We assessed both their potential to control whiteflies and their possible plant damaging effects through plant feeding. The best control of whiteflies was achieved by the species M. pygmaeus, D. tamaninii and D. maroccanus. Significant flower damage was only observed for the predator M. pygmaeus. The degree of flower damage depended strongly on the gerbera cultivar, but damage was observed for both large-flowered and small-flowered types. All 5 species of predatory bugs were able to establish in a winter crop of 2 gerbera cultivars and the exotic plant Lantana camara. The most promising candidate predatory bug for biological control in gerbera is D. maroccanus. This species established well on the 2 tested gerbera cultivars, gave in all cases an excellent control of pests and no significant plant damage was observed. The predatory bugs gave, besides whiteflies, a good control of Echinothrips and in some cases a suppression of aphids and western flower thrips. The volatile limonene showed no significant effect on the oviposition of tobacco and greenhouse whiteflies. Neither did they repel adults of these whiteflies. The mixture of (E)-2-hexenal and 3-hexen-1-ol did not induce a significant attraction response of the adult whiteflies.
Onderzoek stuurlicht Freesia winter 2012-2013 : praktijkonderzoek met lage intensiteit LED belichting tijdens de donkerperiode
Kromwijk, J.A.M. ; Echteld, E. van; Akerboom, T. ; Pronk, H. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1347) - 24
glastuinbouw - freesia - cultivars - belichting - led lampen - verrood licht - plantenontwikkeling - cultuurmethoden - effecten - greenhouse horticulture - illumination - led lamps - far red light - plant development - cultural methods - effects
Low intensity red or far-red LED light (4 µmol.m-2.s-1) during the dark period was tested in a commercial greenhouse (Akerboom Freesia). During the day assimilation lighting was used. The trial showed no clear effect on production. At the first planting date, plants showed symptoms of virus, so no production counts were carried out. At the second planting date, only small differences in production were observed (max. 6% difference in production) and there was no clear correlation with the treatments. This might be a result of low intensities of red and far-red light reaching the control plots and/or the variety used in this experiment (Ambassador). The production increase varied from 5% for the variety Albatros to 22% for the variety Red Beauty in a previous experiment with red and far-red LED light on Freesia. Ambassador maybe less sensitive to low intensity LED light during the dark period than the other cultivars.
Impact of context on food safety management systems in fresh produce chains
Kirezieva, K.K. - \ 2015
University. Promotor(en): Tiny van Boekel, co-promotor(en): Pieternel Luning; L. Jacxsens. - Wageningen : Wageningen University - ISBN 9789462572591 - 244
voedselveiligheid - klimaatverandering - effecten - beleid inzake voedsel - ketenmanagement - verse producten - food safety - climatic change - effects - food policy - supply chain management - fresh products


Background and aim

This research was a part of a project of the European Commission called VEG-i-TRADE, aimed at identifying possible impacts of climate change and globalisation on safety of fresh produce. VEG-i-TRADE formed a multidisciplinary team of scientists from different disciplines, representatives from the food industry and other stakeholders from the European Union and third party countries. The objective of this research was to investigate the influence of context on status of food safety management systems (FSMS) in the fresh produce chain. Under context, we aimed to study the broad context in which companies operate, including food safety policy, supply chain, and climate that may directly and indirectly influence the actual set-up and operation of FSMS. Therefore, an interdisciplinary approach was employed to link concepts from different fields, and to provide scientific evidence about the possible role of the systems in the broad context in setting and operating FSMS in companies. The scientific challenge was to employ an interdisciplinary approach and bridge the gap between disciplines such as food technology, quality management, political economy, and supply chain management. The approach that was used could also be defined as transdisciplinary, as it was problem-oriented and involved companies, sector organisations and academia, thus, relating stakeholders/problem owners and scientists.


Chapters 2 and 3 of this thesis describe the development of a diagnostic tool to assess the status of FSMS and riskiness of their company specific context. The tool allows assessment of the FSMS activities, FSMS output and context factors that affect decision-making in the FSMS (so called, FSMS context). The latter include product, production, organisation, and chain characteristics. The tool allows assessment that is independent from implemented legislation, guidelines, or standards. Moreover, the tool provides for mapping of FSMS and their context over supply chains, different countries, and sectors.

The diagnostic tool was applied in three case studies of leafy greens production regions in Belgium, Norway, and Spain (chapter 4). Moreover, a theoretical framework was developed to explore the broad context in which companies operate. The latter was defined as including the sub-systems of: food safety governance, agro-climatic, market and public policy environments. The companies operating in favourable broad context, including favourable climate, big companies in integrated market, and stringent standards as a result of market self-regulation, have demonstrated advanced FSMS, good information about the output and supporting organisational characteristics. The FSMS of the companies that were operating in less favourable broad context, either in fragmented market with small companies or in less favourable climate, have demonstrated less mature FSMS. As a conclusion, we postulate that the FSMS output is a function of the broad context in a country and sector, the FSMS context in a company, and implemented food safety management system.

Market and supply chain governance were further investigated in chapter 5, with a special focus on cooperatives. Case studies were performed in four cooperatives, with different supply chain governance of transactions. Results suggested that high vertical integration has a positive influence on FSMS. However, when cooperatives become too large and complex, horizontal collaboration decreases and may negatively influence FSMS.

Chapter 6 dove into the factors determining differences between companies operating under the European Union laws, and companies in emerging and developing countries exporting to the EU. Data analysis revealed that the main factor that was determining the differences between companies was not their location, but the availability of information, expertise, and collaboration within the supply chain, which was linked to the increased integration of supply chains triggered by the stringent requirements of private standards. Another important factor was linked to the support by sector organisations and NGOs for small and medium companies, in cases when supply chains are less integrated and only national standards or GlobalGAP are followed. The companies with lowest scores of their FSMS were linked to lack of support in supply chain or country, and no standards or guidelines implemented. These companies were only small ones located in developing and emerging countries.

The pressures of climate change on safety management in fresh produce farms were explored in a Delphi study (chapter 7). The experts were from countries in the global North - with industrialized food systems, and in the global South - with structured and traditional food systems. The identified pressures were linked to contamination of water resources and production environment with microorganisms, pesticide residues, mycotoxins and heavy metals. Response strategies were defined for each pressure, including coping strategies immediately after a pressure occurs, and adaptation strategies to increase adaptive capacity. The insights from the study revealed that a first response to climate change will be realised by the FSMS activities implemented in companies. The experts stressed the need to strengthen some of the activities, and validate their effectiveness for the changed circumstances. Likelihood of the most pressures was assessed as higher for the countries from the global south, which was explained by existing adaptations in the global north. It was proposed that the adaptive and coping capacities of companies, regions and sectors are determined by the currently available adaptation and coping strategies.

The role of the broad context for the food safety management research and practice is discussed in chapter 8. It is highlighted that systemic risks can occur at the junction between different social, political and natural systems, and they need to be taken into account in the overall food safety governance. Systems thinking approaches are advocated to explain the relationships between systems and their synergic effects.


The research described in this thesis demonstrated that FSMS are influenced not only by the narrow FSMS context of a company, with its product, production, organisation, and chain, but also by the broad context in a country and sector. The broad context involves the agro-climatic, market and public policy environments that can affect the overall food safety governance. Food safety governance includes different public, private or hybrid organisations aimed at enforcing standards and guidelines into companies’ specific FSMS.

Market and particularly supply chain integration play an important role for capacity building and maturation of the FSMS. The highest degrees of integration are driven by private interests imposed by private (brand) standards, and result in advanced FSMS. Baseline standards putting minimum requirements from a public health perspective result in basic FSMS, not adapted, and tested for own production circumstances. Vertical integration in the supply chain is particularly important in developing and emerging economies, where institutional environments are sometimes weaker – struggling with the set-up and enforcement of legislation, lacking produce, and sector organisations to support farmers. In developed economies in the European Union, cooperatives play an important role to support farmers. However, their vertical expansion may have negative impact on FSMS possibly related to loss of social capital and members’ motivation.

Last but not least, FSMS need to continuously evolve and adapt to new pressures like the ones triggered by climate change. However, this is not always within the capabilities of a single farm or company, and the adaptive capacity dependents on the other systems in the broad context of the countries and sectors.

Moths in illuminated nights : articificial night effects on moth ecology
Geffen, K.G. van - \ 2015
University. Promotor(en): Frank Berendse, co-promotor(en): Elmar Veenendaal; Roy van Grunsven. - Wageningen : Wageningen University - ISBN 9789462572300 - 116
lepidoptera - kunstlicht - nacht - belichting - dierecologie - effecten - geometridae - diergedrag - artificial light - night - illumination - animal ecology - effects - animal behaviour
Almost all terrestrial species on earth have evolved to be active in a certain part of the day, and as a result are adapted to certain light conditions. Diurnal species are active under high light intensities (the period known as the photophase, i.e. daytime), nocturnal species are active in low light intensities (the period known as the scotophase, i.e. night), and crepuscular species are in between, active in twilight (i.e. dusk and dawn). During the course of evolution, light intensity has been a very reliable cue for the on- and offset of activity of all these species, but recently, the night is no longer dark per definition. Mankind illuminates the night with artificial light sources, which has led to world-wide large-scale alterations of night-scapes. Levels of light pollution continuously rise, currently with approximately 6% per year on average
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