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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Bladplukken tomaat : experiment 2015-2016 ‘Tomatenproductie sturen van blad naar vrucht’
Elings, Anne ; Gelder, Arie van; Janse, Jan - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen Plant Research rapport WPR-789) - 33
Various leaf removal treatments were applied during winter and summer to tomato variety Brioso. The standardwinter treatment knew 33% removal of small leaves in the top of the canopy while in total 11-12 leaves per stemwere maintained. The two other winter treatments each knew 55% leaf removal and maintaining 8-9 and 10-11leaves, respectively. The standard summer treatment was the same as in winter. One summer treatment had noleaf removal and therefore a high leaf area, and one summer treatment had 66% leaf removal at the 4th to 5thtruss with approximately the same leaf number as the standard. It was concluded that 55% leaf removal in winterunder the ambient weather conditions has weakened the crop towards the end of winter. This is therefore a riskystrategy. Production was in the first place related to fruit weight and in the second place to the number of fruits.Leaf removal in winter results in a better dry matter partitioning to the fruits, while leaf removal mid-way canopydepth in summer results in a poorer dry matter partitioning to the fruits. An important question is how the excessof assimilates that is accumulated during summer by a small-fruited tomato can be utilized for production.
Energiebesparing door 2e scherm bij onbelichte tomaat : monitoring bij vier tomatenafdelingen met verschillende schermconfiguraties
Raaphorst, Marcel - \ 2018
Wageningen : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-779) - 38
The question whether a second screen is an interesting investment for tomato crops without supplementallighting, is examined by monitoring four greenhouse departments. In addition to the purchase of a secondscreen, the heat use turns out to be mainly influenced by the settings for temperature and humidity. It has beenfound that a second screen saved 3 to 4.5 m3/m2 per year and reduced the peak consumption of heat by 15%.This makes the second energy screen only interesting if it also gives advantages to the cultivation.
Actief koolfiltratie voor de glastuinbouw : Technologie voor behandeling van lozingswater in de glastuinbouwOnderdeel A: Ontwikkelen toepassing actief koolfiltratie, Onderdeel B: Technologie effectiever maken
Koeman-Stein, Nienke ; Palmen, Luc ; Ruijven, Jim van - \ 2018
Nieuwegein : KWR (KWR rapport 2018.033) - 50
Nieuwe methoden voor bestrijding vanbodemplagen in de glastuinbouw. Deel 1: Biologie en bestrijding van Lyprauta sp. /
Kruidhof, Marjolein ; Woelke, Joop ; Vijverberg, Ruben ; Català-Senent, Laura ; Vijverberg, Roland - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-784) - 54
In de teelt van Phalaenopsis orchideeën wordt belangrijke schade veroorzaakt door zogenaamde ‘potwormen’, feitelijk muggenlarven van de familie Keroplatidae (langhoornmuggen). Deze larven, welke zich in het substraat bevinden, prederen in eerste instantie op bodemorganismen. Ze veroorzaken echter ook vraatschade aan wortelpunten, wat leidt tot een algehele groeivertraging. Zelfs bij lage aantallen langhoornmug larven - meestal zit er maar één larve in een pot - wordt de schadedrempel al overschreden door het relatief lage aantal wortels van Phalaenopsis. In dit rapport is het onderzoek beschreven naar a) de biologie van langhoornmuggen, met name naar Lyprauta cambria, en b) verschillende manieren om L. cambria te bestrijden, en/of ervoor te zorgen dat de larven minder schade berokkenen aan de wortelpunten van Phalaenopsis---In the cultivation of Phalaenopsis orchids important damage is caused by so-called ‘potworms’, which in reality are the larvae of the Keroplatidae family (fungus gnats). These larvae live in the substrate, and primarily predate on soil-dwelling organisms. However, they also cause feeding damage to the root tips, leading to a reduction in overall plant growth. Even at low Keroplatidae density – mostly only a single larva per pot is present – the damage threshold is often exceeded in Phalaenopsis because of its relatively low number of roots. In this report research addressing a) the biology of Keroplatidae larvae, with special focus on Lyprauta cambria, and b) different ways to control L. cambria, and/or reduce the damage that the larvae cause to the root tips of Phalaenopsis is described
Actieve kool voor verwijdering gewasbeschermingsmiddelen : uit lozingswater van de glastuinbouw
Ruijven, J.P.M. ; Staaij, M. van der; Eveleens-Clark, B. ; Beerling, E.A.M. ; Koeman, N. ; Palmen, L. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-726) - 42
Zuivering met actief kool is in potentie een interessante techniek voor toepassing op lozingswater van de glastuinbouw. Doel van het project was het ontwikkelen en testen van een simpele en robuuste installatie op basis van poeder actief kool (PAC), die kan concurreren met alternatieve zuiveringstechnieken die reeds op de markt zijn. Een benchmark voor kosten van de installatie is berekend met een nieuw ontwikkelde rekentool (gekoppeld aan het model waterstromen), die voor situaties van individuele telers de investerings- en jaarkosten van de beschikbare zuiveringsinstallaties kan vergelijken. Deze rekentool is ook online beschikbaar gemaakt voor telers. De ontworpen installatie bestaat uit een doseerunit voor PAC, een geroerd reactorvat, een doseerunit voor vlokmiddel en nafiltratie met een doekfilter. Voor drie doseringen en drie contacttijden is voor SAE Super en Pulsorb WP235 het zuiveringsrendement bepaald. Verhogen van contacttijd en dosering verhoogt het zuiveringsrendement. Het gewenste zuiveringsrendement van 95% werd niet voor alle werkzame stoffen gehaald. Daarnaast was de toegepaste nafiltratie niet effectief genoeg en heeft nog optimalisatie nodig. Als spinoff van het project is inmiddels een installatie van WaterQ op basis van PAC en ultrafiltratie goedgekeurd voor het zuiveren van glastuinbouw lozingswater---Water purification using activated carbon is potentially an interesting technology for the removal of plant protection products from greenhouse discharge water. Goal of this project was development and testing of a simple and robust powdered activated carbon installation (PAC), that is competitive with already available technologies. A newly developed tool (connected with the ‘model waterstromen’ ) is capable of calculating a benchmark for cost of purification equipment for individual practical situations. This tool is publicly available online for growers. The developed installation consists of a PAC dosing unit, a stirred reaction tank, a dosing unit for flocculation of chemicals and filtration with a paper band filter. The purification efficacy is measured with this installation for three dosages and three contact times for SAE Super and Pulsorb WP235 PAC. Increasing the contact time and dosage increased the purification efficacy. The minimal purification efficacy of 95% was not reached for all active ingredients. In addition to that, chosen filtration needs optimisation to achieve a reasonable efficacy for application in practice. Project partner WaterQ in the meantime achieved an approval for an installation with PAC and ultrafiltration for purification of greenhouse discharge water as a spin-off from this project
Tomaten telen in een Chinese muurkas, in Nederland en in China
Zwart, Feije de - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 778) - 26
Gloablly, the largest area of protected cultivation consists of small scale greenhouses growing crops at a low technology level. The Chinese Solar Greenhouse is a good example of such greenhouses. Also in this market, Dutch horticultural and technological knowledge can contribute substantially to an improvement of the cropping result and resource efficiency.This report describes the monitoring of the performance of a tomato crop in a Chinese Solar Greenhouse in the Shandong Province and a comparison with a similar crop in a similar greenhouse in Bleiswijk, the Netherlands. The project is carried out by a consortium consisting of Ludvig Svensson, Ridder–Hortimax, Hoogendoorn, Delphy and Wageningen University & Research, Business unit Glastuinbouw. The project was funded by the Rijksdienst Voor Ondernemend Nederland (RVO) and the Metropole region Rotterdam Den Haag (MRDH).The project has shown that also for simple greenhouses like the Chinese Solar Greenhouse the growth of the crop can be planned as a function of light availability. This analyses showed that the production is likely to be increased by 50% if the growth at the start of the cycle is accelerated. This can be achieved by earlier sowing and using white soil covering foil.
Prei op water : overzicht resultaten 2013 - 2017
Os, E.A. van; Verhoeven, J. ; Wilms, J. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport Wageningen Plant Research, Business unit Glastuinbouw WPR-764) - 42
Within the 2nd programme Cultivation-out-of-the-soil for field crops (2014-2017) research f°Cussed onoptimisation of the cultivation, sowing on water, the use of a protective tunnel and upscaling. The robustnessof the growing system could be improved by these experiments. Economically the cost of traditional open fieldcropping is almost comparable with the cultivation on water (deep flow technique). In the plant raising stage adecrease in the growing period can be achieved to 60 instead of 84 days. Uniformity is important for a once overharvesting crop but still variation is big, grading of young plants helps a little. Oxygenation of larger ponds isimportant.
De perfecte chrysant teelt 1-4 : energiezuinige demonstratieteelten bij Delphy Improvement Centre
Raaphorst, M. ; Zwart, Feije de; Schuddebeurs, L. ; Veld, Paul de - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport Wageningen Plant Research, Business unit Glastuinbouw WPR-752) - 46
With funding from ‘Kas als Energiebron’, ChrIP and suppliers, four chrysanthemums crops have been carried outat the Delphy Improvement Centre in 2017. These crops had the following targets:• A heat use up to 475 MJ/m2.yr.• This heat must be extracted from harvesting heat (cooling).• A CO2-use of 25 kg/m2.yr.• A yearly electricity usage for lighting of 121 kWh/m2.yr.• 5% more production than professional growers.The most important means to achieve this objective are hybrid lighting, diffuse glass with 2 AR-coatings, anextra energy screen, 8 air handling units, well pumps and a heat pump. The crops are run under the name ‘ThePerfect Chrysanthemum’ (DPC). The realised use of CO2 and heat turn out to be lower than the target. Theamount of heat (cooling) harvested is much higher and the amount of lighting is almost equal to the target.It is concluded that an investment in air handling units, heat pump and source pumps, an extra screen andLED lighting makes it technically possible to grow chrysanthemums without gas, if an alternative is found fordisinfection by steaming.
Ontwikkeling en validatie van computer vision technologie ten behoeve van een broccoli oogstrobot
Blok, Pieter M. ; Tielen, Antonius P.M. - \ 2018
Wageningen : Stichting Wageningen Research, Wageningen Plant Research, Business unit Agrosysteemkunde (Rapport WPR 799) - 19
De selectieve en handmatige oogst van broccoli is arbeidsintensief en omvat ongeveer 35% van de totale productiekosten. Dit onderzoek is uitgevoerd om te bepalen of computer vision kan worden gebruikt om broccoli kronen te detecteren, als eerste stap in de ontwikkeling van een autonome selectieve broccoli oogstrobot. Een op textuur en kleur gebaseerde beeld detectie is gebruikt om de broccoli kronen van de achtergrond te scheiden. De computer vision is gevalideerd met een ground truth dataset van 200 afbeeldingen. In deze beelden zijn 228 werkelijke broccoli kronen van verschillende groottes aangewezen door twee menselijke experts gebruikmakend van het GrabCut-algoritme. De broccoli detectie van de computer vision is op twee verschillende manieren beoordeeld. De eerste was een pixel-gebaseerde overlap tussen de computer vision en de werkelijke broccoli objecten, wat resulteerde in een gemiddelde overlap van 93.8%. De tweede waarde was op basis van de detectie van de individuele broccoli kronen. Deze toonde een precisie van 99.5%, met een slechts één onterecht aangemerkte broccoli. De specificiteit was 97.9%, de negative predictive value was 69.7% en de gemiddelde nauwkeurigheid was 92.4%. In het totaal zijn 208 broccoli kronen gedetecteerd door de computer vision, wat wijst op een sensitiviteit van 91.2%. De gemiddelde grootte van de
gemiste kronen was kleiner dan de gemiddelde grootte van de gedetecteerde kronen. Indien de broccoli kronen slechter zichtbaar zijn of overschaduwd worden door omringende bladeren is het mogelijk dat de computer vision misclassificaties levert.
Lichtmetingen op komkommerbedrijven met LED-tussenbelichting : begeleiden en monitoren van energie-innovaties in de praktijk
Janse, Jan ; Weerheim, Kees ; Dieleman, Anja - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw : WPR-763) - 25
Light interception was measured by Wageningen University & Research Greenhouse Horticulture at two nurseries with cucumbers in a high wire system and a different orientation of the LED-interlighting. The canopy density appeared to be very important for the light interception and up and down light loss. The total light loss to the greenhouse cover and floor was 17 en 34% on both nurseries, respectively. In the middle of the path between crop rows, 17 and 34% of the LED light was still measured, respectively. However, this light will largely be captured by plants of the neighbouring row. The measured interception of the sunlight by the plants, was on both nurseries respectively 96 and 87%. Per 1% additional LED light, a production increase of 0.8% was realised. The project was funded by Kas als Energiebron.
Vergelijking klimaat Paprika : Analyse van Het Nieuwe Telen Paprika bij Delphy Improvement Centre in vergelijking met een praktijkbedrijf
Raaphorst, Marcel - \ 2018
Wageningen : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 747) - 34
The indoor climate, the heat use and the production of a demonstration trial with sweet pepper are compared with a commercial grower. With intensive use of the screens a 59% lower use of heat is achieved. The intensive use of screens has decreased the amount of light with 4% in comparison to the commercial grower. The biggest difference was during the first three (winter) months of cultivation. The roof also showed 4% less light transmission. By dosing 64% less CO2, a lower CO2 concentration was obtained, which should have led to 4% less photosynthesis according to the CO2-rule of thumb. Despite the lower light intensity and lower CO2 concentration, the production was just 10% lower than at the commercial grower. This indicates that CO2 and light have been a little less restrictive than what would be expected from the rules of thumb.
Fytosanitaire na-oogst behandel- en detectietechnieken voor plaagorganismen in tuinbouw
Qiu, Y. ; Hogeveen-van Echtelt, Esther ; Verschoor, J.A. ; Rozen, K. van; Ruizendaal, J.L. ; Helsen, H.H.M. ; Booij, C.J.H. ; Dam, M.F.N. van; Sluis, A.A. van der; Pekkeriet, E.J. ; Vreeburg, P.J.M. ; Vijn, M.P. ; Spoorenberg, P.M. - \ 2018
Wageningen University & Research (Rapport WPR 751) - 81 p.
Klimaat, energieverbruik en bloem temperatuur bij twee Gerbera telers : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-741) - 38
This report provides an overview of the Gerbera companies -Holstein Flowers and Zuijderwijk Witzier. Both growers have a blackout screen, energy screen and an illumination system. Holstein Flowers dehumidifies the greenhouse air by means of blowing in heated outside air (using air ducts) and Zuijderwijk Witzier uses a Ventilation Jet system. Both growers screen a lot using a screen gap and they close very rare the screens for 100%. At Holstein Flowers the calculated energy consumption is 22.7 m3/m2/year and at Zuijderwijk 23.8 m3/ m2/year. With a thermal camera, the crop and flower temperatures were measured and they were rarely below the dew point. By carrying out plant sap analyses at 4 growers, a statistical relationship between the plant sap composition and the chance of rot heads (‘rotkoppen’) has been demonstrated. However, it is unknown whether this relationship is also a causal relationship, other factors could also have caused the rot heads. If the mechanism behind the development of Botrytis/rot heads were known, then a grower could - depending on the plant balance, evaporation and the chance of getting Botrytis/rot heads –grow with lower moisture deficits, which could then lead to energy savings
Vergelijking tomatenteelten met een Ventilation Jet systeem : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-744) - 26
De belichte tomatenbedrijven Greenco en Gardener’s Pride telen een kleine tomaat en zijn uitgerust met een: Ventilation Jet (VJ) systeem, SON-T belichting systeem, verduisteringsscherm en een energiescherm. Het berekende energieverbruik wat via de buizen bij Gardener’s Pride de kas in was gebracht was tussen 1 december 2016– 1 december 2017 37.8 m3/m2/jaar en bij Greenco 25.4 m3/m2/jaar. Het hogere energieverbruik bij Gardener’s Pride kon verklaard worden doordat: (1) Sunstream een ras is dat generatief gestuurd wordt; (2) Gardener’s Pride niet zo’n hoge relatieve vochtigheden durfde aan te houden door het ontbreken van het werkende VJ systeem en (3) Gardener’s Pride minder heeft geschermd. Met de Ventilation Jets waren de tuinders goed in staat om het verduisteringsdoek (bijna) 100% gesloten te houden op momenten dat er belicht werd. Gedurende bepaalde periodes hebben beide tuinders besloten om het Ventilation Jet systeem minder te gebruiken. De telers hebben het vermoeden dat de luchtbeweging die veroorzaakt wordt door de recirculatieventilator soms zorgt voor een te generatieve gewasreactie. Bij Gardener’s Pride bleek dat nog geen 3% van de lucht die ingeblazen wordt door de VJ, de kas verlaat via de kier op het middenpad. Onder deze omstandigheden kan dus geconcludeerd worden dat deze kier niet nodig is---The tomato companies Greenco and Gardener’s Pride grow a small tomato and are equipped with a: Ventilation Jet (VJ) system, SON-T lighting system, blackout screen and an energy screen. The energy consumption that was brought into the greenhouse by the heating pipes at Gardener’s Pride was 37.8 m3/m2/year between 1 December 2016 and 1 December 2017 and 25.4 m3/m2/year at Greenco. The higher energy consumption at Gardener’s Pride could be explained by: (1) Sunstream is a variety that is grown very generative; (2) Gardener’s Pride did not dare to hold high relative humidity levels due to the lack of a working VJ system and (3) Gardener’s Pride had fewer screening hours. Thanks to the Ventilation Jets, the growers were able to keep the blackout screen (almost) 100% closed at times when the lighting system was on. During certain periods both growers have decided to use the Ventilation Jet system less. The growers suspect that the air movement caused by the recirculation fan ensures sometimes undesired extra generativity. At Gardener’s Pride, it turned out that less than 3% of the air blown in by the VJ leaves the greenhouse through the gap at the central path. It can therefore be concluded that under these circumstances this gap is not necessary
Ervaringen met het Ventilation Jet systeem bij Dekker Chrysanten : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-743) - 22
The purpose of the Ventilation Jet (VJ) system at Dekker Chrysanten is to reduce the temperature of the grow pipe in order to save energy. Dekker Chrysanten encountered problems with circles in the crop in the VJ compartment in many cultivation rounds in 2016 and 2017. Early flowering took place at these circles, which occasionally resulted in poorer quality and shorter stems. Due to these cultivation problems, Dekker Chrysanten did not want to reduce yet the minimum grow pipe in the Ventilation Jet compartment. Due to the efforts of the growers and the monitoring project, potential causes have been identified and solved such as (1) the prevention of dry spots in the soil by: switching off the VJ when there is irrigation, switching on the VJ later in the short day period and by irrigating more (this is done companywide); (2) lowering the relative humidity setpoint in the VJ compartment at night so that a higher night evaporation is achieved; (3) improving the air flow profile of the bottom fan and (4) adjusting the climate computer software, resulting in a much more stable temperature and RH in the VJ compartment. The above learning experiences are now applied which has resulted in a good quality chrysanthemum in the past cultivation period (harvest January 2018).
Perchloraat in kasgrond Bioteelt : Resultaat uitspoelproef voor vermindering perchloraat concentratie in de biologische kasteelt
Voogt, Wim ; Winkel, Aat van - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 765) - 22
certain fertilisers. This ion can be taken up by plants quite easily and will be transported partly into fruits, hence the norms for ClO4 - will be exceeded easily. Experiments have been carried out to leach out the soil by flushing. It appeared that ClO4 - can be leached out quite easily, but it requires a lot of water and the strategy has to be adapted to the soil type.
Precisietechnologie Tuinbouw: PPS Autonoom onkruid verwijderen : D2.4 Literatuurstudie spectrale reflectie-eigenschappen van planten en onkruiden; D2.5 Lab en veldexperimenten spectrale reflectie-eigenschappen van planten en onkruiden
Blok, Pieter ; Hemming, Jochen ; Holterman, Henk-Jan ; Michielsen, Jean-Marie ; Ruizendaal, Jos - \ 2018
Bleiswijk : Wageningen Plant Research, Business unit Glastuinbouw (Rapport WPR 751) - 118
This report contains the two deliverables of the research project “autonomous weed removal” that deal with the topic hyper- and multispectral weed detection. In the literature of the past 10 to 15 years, there are sufficient indications that a good distinction on the basis of spectral characteristics can be made between various plant species. For the hyperspectral lab measurements, various crops and weeds have been cultivated. The reflection spectrum of all plants was measured between 400 and 1000 nm and between 900 and 1700 nm on different growing stages in the laboratory. In particular the reflection in the chlorophyll range (650-670 nm) and in the green range (around 550 nm), red-edge (700 nm) and near-infrared (800 nm) show a distinctive power between the crops and weeds studied. With field measurements it was investigated whether it is possible to detect green weeds in a green lettuce crop using hyperspectral camera images. The accuracy of a correct classification on both measurement days was 6.9% and 9.9%, respectively, below the previously set target value of 90%. In order to exclude the effect of the use of different cameras on the test result, a comparative follow-up study is recommended.
Precisietechnologie Tuinbouw: PPS Autonoom onkruid verwijderen : Eindrapportage
Hemming, Jochen ; Blok, Pieter ; Ruizendaal, Jos - \ 2018
Bleiswijk : Wageningen Plant Research, Business unit Glastuinbouw (Rapport WPR 750) - 42
Work package 2 of the Precision Technology Horticulture program focuses on autonomous weed removal. This final report contains four deliverables: D2.1 Module for recognition of red lettuce, D2.2 Vision based crop row guidance module, D2.3 Machine for hoeing more than 8 crop rows simultaneously, and D2.6 Actuator for controlling weeds in full field crops. D2.1 reports on the software for an extra colour segmentation algorithm that has been added to the Steketee IC-cultivator. With this algorithm it is possible to adequately detect and distinguish non green plants, such as red lettuce, from weeds. For D2.2 a standalone module for crop row guidance for hoeing between the row has been developed. D2.3 describes is the extension in hardware and software that makes it possible to hoe up to 24 crop rows simultaneously. For D2.6, research has been conducted into different robotic arms to move the end effector to the right spot for weed control in full field crops. Different arms are compared and the maximum possible driving speed was be calculated. A test device for full field weed control was build based on a x-z position unit. The chapter publications and media provides an overview of the dissemination of the project results throughout the duration of the project.
Voorkomen en bestrijden emissies kasteelten : Fase I: 2017
Beerling, Ellen ; Blok, Chris ; Cornelissen, Emile ; Eveleens-Clark, Barbara ; Gozales, Jorge ; Harmsen, Danny ; Koeman, Nienke ; Leyh, Romain ; Os, Eric van; Palmen, Luc ; Roest, Els van der; Ruijven, Jim van; Stijger, Ineke ; Voogt, Wim - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 748) - 46
In this project, solutions are developed to minimise leaching of nutrients and pesticides from greenhouses to the environment (esp. surface water), in order to comply with legislation and societal demands. In 2017 the following questions have been addressed: To prevent emission, drain solutions are reused or purified. Other water flows may deviate in compositionand possibilities for reuse or purification. The option for reuse or purification for these water flows has been investigated, and a working methodology for the end of a cultivation (e.g. cleaning) has been developed. Applications of Forward Osmosis in horticulture have been investigated. Water extracted from the discharge flow with Forward Osmosis using the concentrated nutrient solution holds prospects, but extracting irrigation water from brackish groundwater seems less feasible. In a long-term experiment, sodium (Na) standards for sweet pepper have been reinterpreted. It was shown that an increase in the Na standard up to 8-10 mmol/l causes no damage or loss in pepper production. Inaddition, it was shown that the split-root system can be used for uptake of extra Na without growth hampering. Furthermore, applying humate can prevent negative sodium effects at high sodium levels (Chinese cabbage). Finally, insight was gained into the risks associated with the use of chlorinated cleaning products in zero-discharge cultivations.
Programmeringsstudie Meeldauw : Invloed van bestaande en nieuwe interventies op geïnduceerde weerbaarheid tegen biotrofe schimmel
Hofland-Zijlstra, J.D. ; Breeuwsma, S. ; Noordam, M. ; Stevens, L. - \ 2018
Bleiswijk : Wageningen University & Research, Business unit Glastuinbouw (Wageningen Plant Research rapport WPR-749) - 46
Purpose of this TKI project Programming study powdery mildew is to generate new knowledge about existingand new interventions aimed at prevention of mildew development in horticultural crops. This research isconducted by Wageningen University & Research greenhouse horticulture business unit. The project is supportedby LTO Glaskracht Nederland. To test the impact of existing interventions on the natural defenses of a plant testsin climate chamber were carried out with total daylight sum, CO2 and relative humidity. After three weeks theinfluence on the production of pathogen related proteins, which is a measure for induced resistance, was veryminor. However, it is confirmed that relative humidity and the daily light sum influence the mildew developmentdirectly and to a higher extent than the CO2. In addition, changes in nutritional composition of plants may be oneof the first indicators for enhanced disease risk (e.g. sodium).
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