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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Duurzaamheid als leidraad voor roos : vervolg onderzoek Perfecte Roos: energiezuinig geteeld
Gelder, Arie de; Warmenhoven, Mary ; Knaap, Edwin van der; Burg, Rick van der - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1412) - 50
rozen - teelt onder bescherming - kasgewassen - glastuinbouw - duurzame landbouw - energiebesparing - elektriciteit - assimilatie - kunstlicht - kunstmatige verlichting - verlichting - koelen - meeldauw - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - roses - protected cultivation - greenhouse crops - greenhouse horticulture - sustainable agriculture - energy saving - electricity - assimilation - artificial light - artificial lighting - lighting - cooling - mildews - integrated control - integrated pest management
The project Sustainable rose cultivation aimed to achieve a sustainable and energy efficient rose cultivation by a controlled use of assimilation lighting, an optimum use of the cooling and an integrated control strategy for mildew. The production came to 320 stems.m-2 average weight 54 grams. The branch length and bud size varied through the season. There was no saving on electricity. There was a significant saving on heat. The improvement of the energy efficiency was totally determined by the reduction of the heat consumption. The light utilization efficiency was 2:44 g.mol-¹ and increased compared to the previous year. Cooling and forced ventilation had a positive effect on the stem elongation in the autumn. The installation with forced ventilation from above combined with the screen had a favourable effect on the climate, especially in the humidity control under a largely (95-98%) closed screen. The payback period of the investment in airconditioning is within 3 years.
Understanding photosynthesis important for CO2-dosing and lighting : CAM-plants difficult to deal with
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)1. - ISSN 2215-0633 - p. 14 - 15.
horticulture - greenhouse horticulture - carbon dioxide - dosage - cam pathway - illumination - photosynthesis - assimilation - kalanchoe - ornamental bromeliads - phalaenopsis - tuinbouw - glastuinbouw - kooldioxide - dosering - cam cyclus - belichting - fotosynthese - assimilatie - bromelia's als sierplanten
It used to be rare to come across plants that bind CO2 mainly at night: CAMplants. But it’s no longer an exception in the horticultural sector. Nowadays the best-selling pot plant in the Netherlands – phalaenopsis – belongs to this group. This then raises questions such as: When do CAM-plants behave according to the book and when don’t they? And when does it make sense to dose with CO2 and provide lighting?
Minder blad in winter bij veel meer groente- én sierteeltgewassen mogelijk : Leo Oprel pleit voor denken vanuit de winter
Kromwijk, Arca ; Gelder, Arie de - \ 2015
horticulture - greenhouse horticulture - vegetable growing - ornamental horticulture - tomatoes - anthurium - leaf area - biomass - greenhouse experiments - assimilation - winter - energy saving

Onderzoek met een relatief ‘kale’ tomatenplant gaf vorige winter verrassende resultaten: iets meer productie, iets minder gasverbruik. Dit jaar is een nieuwe proef ingezet. Maar waarom zo’n systeem alleen toepassen bij tomaat? Leo Oprel (Kas als Energiebron) ziet nog veel meer mogelijkheden, ook bij siergewassen. Hij gaat in discussie met de onderzoekers Arca Kromwijk en Arie de Gelder.

Sturen op balans source en sink ingewikkelde zaak : temperatuur aanpassen aan de beschikbare straling
Elings, A. ; Heuvelink, E. ; Kierkels, T. - \ 2015
Onder Glas 2015 (2015)4. - p. 36 - 37.
glastuinbouw - cultuurmethoden - teelt onder bescherming - lichtregiem - assimilatie - temperatuur - groenten - snijbloemen - plantenontwikkeling - energiebesparing - greenhouse horticulture - cultural methods - protected cultivation - light regime - assimilation - temperature - vegetables - cut flowers - plant development - energy saving
‘Met het licht meetelen’ is een bekend principe binnen Het Nieuwe Telen. Het betekent dat je de temperatuur aanpast aan het beschikbare licht. De insteek daarbij is vaak energiebesparing, maar ook vanuit plantkundig oogpunt is dat verstandig. Zo breng je source en sink meer in balans.
Belichtingsapplicatie : rapportage tot Go/No Go moment
Gelder, A. de - \ 2014
Bleiswijk : Wageningen UR Glastuinbouw (Rapport / Wageningen UR Glastuinbouw 1331) - 26
tuinbouw - kastechniek - glastuinbouw - rozen - belichting - assimilatie - fotosynthese - energiebesparing - internet - computer hardware - horticulture - greenhouse technology - greenhouse horticulture - roses - illumination - assimilation - photosynthesis - energy saving
In dit project wordt een belichtingsapplicatie ontwikkeld voor op internet waarmee tuinders op belichting kunnen besparen. Het model geeft op basis van de behoefte van de plant, bedrijfsspecifieke informatie en de weersverwachting een dagelijks advies over het gewenste aantal uren belichting.
Belichting, CO2 en stuurlicht in de lelieteelt: een strategie voor energiebesparing
Hogewoning, S.W. ; Trouwborst, G. ; Slootweg, G. ; Aanholt, J.T.M. van; Pot, C.S. ; Kok, B.J. - \ 2014
Bunnik : Plant Lighting - 42
glastuinbouw - lilium - cultuurmethoden - kooldioxide - dosering - belichting - assimilatie - plantenontwikkeling - groeistadia - lichtsterkte - effecten - greenhouse horticulture - cultural methods - carbon dioxide - dosage - illumination - assimilation - plant development - growth stages - light intensity - effects
In de lelieteelt wordt langdurig belicht met een aanzienlijke intensiteit SON-T licht (6000-8000 lux ofwel ~78-104 μmol/m2s). Dit heeft een fors energieverbruik tot gevolg. Het doel van de belichting is (1) zwaardere takken, (2) remming van takstrekking (voorkomen slapheid), (3) verkorting van de teeltduur en (4) voorkomen van knopval en knopverdroging. CO2 dosering wordt niet toegepast in de lelieteelt. Eerder onderzoek van PPO heeft namelijk aangetoond dat CO2-dosering geen effect heeft op het takgewicht van Oriëntal-lelies en slechts een klein effect bij Longiflorums, Aziaten en LA-hybriden. Recent onderzoek door Plant Lighting en Plant Dynamics heeft echter aangetoond dat de fotosynthese van Oriëntals flink toeneemt bij aanvullend CO2. Dit is een schijnbare tegenstelling: Wel meer fotosynthese, maar niet meer takgewicht. Echter, mogelijk heeft lelie slechts een beperkte hoeveelheid assimilaten nodig voor een maximaal takgewicht en gaan extra aangemaakte assimilaten naar de bol. Als dat zo is, dan heeft CO2 dosering inderdaad geen zin bij voldoende belichting, maar wél bij lagere lichtniveaus. Daarom ligt aan dit onderzoek de volgende hoofdhypothese ten grondslag: Bij een suboptimale intensiteit belichting kan met CO2 dosering eenzelfde takgewicht gerealiseerd worden als bij een optimale lichtintensiteit zonder CO2 dosering.
Optimal leaf area leads to higher production and higher income : Don't prune too many tomato leaves
Heuvelink, E. ; Kierkels, T. - \ 2014
In Greenhouses : the international magazine for greenhouse growers 3 (2014)2. - ISSN 2215-0633 - p. 52 - 53.
glastuinbouw - solanum lycopersicum - plantenontwikkeling - bladoppervlakte - ontbladering - assimilatie - netto-assimilatiesnelheid - groenten - greenhouse horticulture - plant development - leaf area - defoliation - assimilation - net assimilation rate - vegetables
Good light interception is the first step to good production. For that you need sufficient leaf area in the greenhouse. But it’s difficult for a grower to determine how much leaf surface area is present. Research is shedding new insight into this aspect.
Belichtingsapplicatie; een tussenstand
Gelder, A. de - \ 2014
glastuinbouw - kasgewassen - belichting - assimilatie - zonne-instraling - lichtregiem - bedrijfsapplicaties - software-ontwikkeling - behoeftenbepaling - greenhouse horticulture - greenhouse crops - illumination - assimilation - insolation - light regime - business software - software engineering - needs assessment
Assimilatiebelichting op basis van stralingsverwachting en behoefte van het gewas maakt de teler meer bewust van de belichtingsstrategie. Het doel van dit project is de bouw van een applicatie voor advies over belichtingsduur afgestemd op de assimilatenvraag van een gewas en besparing op energie vraag van 10 % voor belichting bij gebruik van de applicatie.
Biosphere model simulations of interannual variability in terrestrial 13C/12C exchange.
Velde, I.R. van der; Miller, J.B. ; Schaefer, K. ; Masarie, K.A. ; Denning, S. ; White, J.W.C. ; Krol, M.C. ; Peters, W. ; Tans, P.P. - \ 2013
Global Biogeochemical Cycles 27 (2013)3. - ISSN 0886-6236 - p. 637 - 649.
carbon-isotope discrimination - ocean co2 sink - stomatal conductance - c-13 discrimination - atmospheric co2 - cycle - climate - fires - photosynthesis - assimilation
Previous studies suggest that a large part of the variability in the atmospheric ratio of (CO2)-C-13/(12)CO(2)originates from carbon exchange with the terrestrial biosphere rather than with the oceans. Since this variability is used to quantitatively partition the total carbon sink, we here investigate the contribution of interannual variability (IAV) in biospheric exchange to the observed atmospheric C-13 variations. We use the Simple Biosphere - Carnegie-Ames-Stanford Approach biogeochemical model, including a detailed isotopic fractionation scheme, separate C-12 and C-13 biogeochemical pools, and satellite-observed fire disturbances. This model of (CO2)-C-12 and (CO2)-C-13 thus also produces return fluxes of (13)CO(2)from its differently aged pools, contributing to the so-called disequilibrium flux. Our simulated terrestrial C-13 budget closely resembles previously published model results for plant discrimination and disequilibrium fluxes and similarly suggests that variations in C-3 discrimination and year-to-year variations in C(3)and C-4 productivity are the main drivers of their IAV. But the year-to-year variability in the isotopic disequilibrium flux is much lower (1 sigma=1.5PgCyr(-1)) than required (12.5PgCyr(-1)) to match atmospheric observations, under the common assumption of low variability in net ocean CO2 fluxes. This contrasts with earlier published results. It is currently unclear how to increase IAV in these drivers suggesting that SiBCASA still misses processes that enhance variability in plant discrimination and relative C-3/C(4)productivity. Alternatively, C-13 budget terms other than terrestrial disequilibrium fluxes, including possibly the atmospheric growth rate, must have significantly different IAV in order to close the atmospheric C-13 budget on a year-to-year basis.
How much CO was emitted by the 2010 fires around Moscow?
Krol, M.C. ; Peters, W. ; Hooghiemstra, P. ; George, M. ; Clerbaux, C. ; Hurtmans, D. ; McInerney, D. ; Sedano, F. ; Bergamaschi, P. ; Hajj, M. El; Kaiser, J.W. ; Fisher, D. ; Yeshov, V. ; Muller, J.P. - \ 2013
Atmospheric Chemistry and Physics 13 (2013). - ISSN 1680-7316 - p. 4737 - 4747.
russian wildfires - emissions - pollution - summer - iasi - assimilation - retrieval - satellite - algorithm - transport
The fires around Moscow in July and August 2010 emitted a large amount of pollutants to the atmosphere. Here we estimate the carbon monoxide (CO) source strength of the Moscow fires in July and August by using the TM5-4DVAR system in combination with CO column observations of the Infrared Atmospheric Sounding Interferometer (IASI). It is shown that the IASI observations provide a strong constraint on the total emissions needed in the model. Irrespective of the prior emissions used, the optimised CO fire emission estimates from mid-July to mid-August 2010 amount to approximately 24 TgCO. This estimate depends only weakly (<15 %) on the assumed diurnal variations and injection height of the emissions. However, the estimated emissions might depend on unaccounted model uncertainties such as vertical transport. Our emission estimate of 22-27 TgCO during roughly one month of intense burning is less than suggested by another recent study, but substantially larger than predicted by the bottom-up inventories. This latter discrepancy suggests that bottom-up emission estimates for extreme peat burning events require improvements.
Respiration is necessary for growth and maintenance : growth rate is ten times higher in summer than in winter
Heuvelink, E. - \ 2013
In Greenhouses : the international magazine for greenhouse growers 2 (2013)1. - ISSN 2215-0633 - p. 40 - 41.
glastuinbouw - snijbloemen - sierteelt - plantenontwikkeling - assimilatie - plantenfysiologie - gesloten systemen - seizoengroei - greenhouse horticulture - cut flowers - ornamental horticulture - plant development - assimilation - plant physiology - closed systems - seasonal growth
Does respiration divert energy away from production or does it lead to more production? The answer is both. Steering plant growth based on respiration is very complicated. However, in a closed greenhouse is should be possible to better control the maintenance respiration.
What eddy-covariance measurements tell us about prior land flux errors in co 2-flux inversion schemes
Chevallier, F. ; Wang, T. ; Ciais, P. ; Maignan, F. ; Bocquet, M. ; Moors, E.J. - \ 2012
Global Biogeochemical Cycles 26 (2012)1. - ISSN 0886-6236 - 9 p.
carbon-dioxide exchange - interannual variability - soil respiration - atmospheric co2 - pine forests - water-vapor - oak forest - assimilation - uncertainty - grassland
To guide the future development of CO2-atmospheric inversion modeling systems, we analyzed the errors arising from prior information about terrestrial ecosystem fluxes. We compared the surface fluxes calculated by a process-based terrestrial ecosystem model with daily averages of CO2flux measurements at 156 sites across the world in the FLUXNET network. At the daily scale, the standard deviation of the model-data fit was 2.5 gC·m-2·d-1; temporal autocorrelations were significant at the weekly scale (>0.3 for lags less than four weeks), while spatial correlations were confined to within the first few hundred kilometers (
Observation uncertainty of satellite soil moisture products determined with physically-based modeling
Wanders, N. ; Karssenberg, D. ; Bierkens, M.F.P. ; Parinussa, R. ; Jeu, R. de; Dam, J.C. van; Jong, S. de - \ 2012
Remote Sensing of Environment 127 (2012). - ISSN 0034-4257 - p. 341 - 356.
passive microwave measurements - improving runoff prediction - vegetation optical depth - ers scatterometer - amsr-e - retrieval - assimilation - validation - algorithm - index
Accurate estimates of soil moisture as initial conditions to hydrological models are expected to greatly increase the accuracy of flood and drought predictions. As in-situ soil moisture observations are scarce, satellite-based estimates are a suitable alternative. The validation of remotely sensed soil moisture products is generally hampered by the difference in spatial support of in-situ observations and satellite footprints. Unsaturated zone modeling may serve as a valuable validation tool because it could bridge the gap of different spatial supports. A stochastic, distributed unsaturated zone model (SWAP) was used in which the spatial support was matched to these of the satellite soil moisture retrievals. A comparison between point observations and the SWAP model was performed to enhance understanding of the model and to assure that the SWAP model could be used with confidence for other locations in Spain. A timeseries analysis was performed to compare surface soil moisture from the SWAP model to surface soil moisture retrievals from three different microwave sensors, including AMSR-E, SMOS and ASCAT. Results suggest that temporal dynamics are best captured by AMSR-E and ASCAT resulting in an averaged correlation coefficient of 0.68 and 0.71, respectively. SMOS shows the capability of capturing the long-term trends, however on short timescales the soil moisture signal was not captured as well as by the other sensors, resulting in an averaged correlation coefficient of 0.42. Root mean square errors for the three sensors were found to be very similar (± 0.05 m3m- 3). The satellite uncertainty is spatially correlated and distinct spatial patterns are found over Spain.
Generating spatial precipitation ensembles: impact of temporal correlation structure
Rakovec, O. ; Hazenberg, P. ; Torfs, P.J.J.F. ; Weerts, A.H. ; Uijlenhoet, R. - \ 2012
Hydrology and Earth System Sciences 16 (2012)9. - ISSN 1027-5606 - p. 3419 - 3434.
distributed hydrological model - radar rainfall estimation - ourthe catchment - real - bias - assimilation - resolution - region
Sound spatially distributed rainfall fields including a proper spatial and temporal error structure are of key interest for hydrologists to force hydrological models and to identify uncertainties in the simulated and forecasted catchment response. The current paper presents a temporally coherent error identification method based on time-dependent multivariate spatial conditional simulations, which are conditioned on preceding simulations. A sensitivity analysis and real-world experiment are carried out within the hilly region of the Belgian Ardennes. Precipitation fields are simulated for pixels of 10 km x 10 km resolution. Uncertainty analyses in the simulated fields focus on (1) the number of previous simulation hours on which the new simulation is conditioned, (2) the advection speed of the rainfall event, (3) the size of the catchment considered, and (4) the rain gauge density within the catchment. The results for a sensitivity analysis show for typical advection speeds > 20 km h(-1), no uncertainty is added in terms of across ensemble spread when conditioned on more than one or two previous hourly simulations. However, for the real-world experiment, additional uncertainty can still be added when conditioning on a larger number of previous simulations. This is because for actual precipitation fields, the dynamics exhibit a larger spatial and temporal variability. Moreover, by thinning the observation network with 50 %, the added uncertainty increases only slightly and the cross-validation shows that the simulations at the unobserved locations are unbiased. Finally, the first-order autocorrelation coefficients show clear temporal coherence in the time series of the areal precipitation using the time-dependent multivariate conditional simulations, which was not the case using the time-independent univariate conditional simulations. The presented work can be easily implemented within a hydrological calibration and data assimilation framework and can be used as an improvement over currently used simplistic approaches to perturb the interpolated point or spatially distributed precipitation estimates.
Bloei-inductie bij Chrysant onder lange dag : toepassing van LED-licht technologie
Ieperen, W. van; Hogewoning, S.W. ; Dam, E. ten - \ 2011
Wageningen : Wageningen Universiteit, Leerstoelgroep Tuinbouwketens - 23
tuinbouw - glastuinbouw - chrysanthemum - led lampen - klimaatkamerproeven - fotoperiode - bloei-inductie - assimilatie - potplanten - snijbloemen - teeltsystemen - lichtregiem - horticulture - greenhouse horticulture - led lamps - growth chamber experiments - photoperiod - flower induction - assimilation - pot plants - cut flowers - cropping systems - light regime
Deze publicatie beschrijft een onderzoek naar daglengte verlenging tijdens de korte dag bij chrysant met behoud van bloei door sturing met speciale LED belichting. In klimaatkamerproeven met LEDs (zonder natuurlijk licht) kon bij Chrysant bloemknopaanleg worden geïnduceerd onder een lange dag (LD), door de laatste paar uur van de lichtperiode alleen blauw LED-licht te geven. De rest van de lichtperiode werd een combinatie van rood en blauw LED-licht gegeven. Omdat blauw licht fotosynthetisch actief is leverde dit aanzienlijke extra groei op. Echter, wanneer overdag natuurlijk zonlicht of kunstlicht met een zonlichtspectrum werd gegeven, bleek het doorbelichten met blauw LED-licht niet te resulteren in bloei. Langdurig blauw LED-licht kan dus niet zondermeer worden toegepast in de commerciële teelt van pot- en snijchrysant in kassen. Voor toekomstige meerlagen- en andere teeltsystemen zonder natuurlijk licht is het wel een optie. Deze experimenten laten voor het eerst zien dat ook de spectrale samenstelling van het licht overdag invloed heeft op de bloei-inductie bij chrysant.
A comparison of different inverse carbon flux estimation approaches for application on a regional domain
Tolk, L.F. ; Dolman, A.J. ; Meesters, A.G.C.A. ; Peters, W. - \ 2011
Atmospheric Chemistry and Physics 11 (2011). - ISSN 1680-7316 - p. 10349 - 10365.
atmospheric transport - dioxide exchange - european forests - modeling system - surface fluxes - boundary-layer - co2 fluxes - assimilation - sensitivity - tower
We have implemented six different inverse carbon flux estimation methods in a regional carbon dioxide (CO2) flux modeling system for the Netherlands. The system consists of the Regional Atmospheric Mesoscale Modeling System (RAMS) coupled to a simple carbon flux scheme which is run in a coupled fashion on relatively high resolution (10 km). Using an Ensemble Kalman filter approach we try to estimate spatiotemporal carbon exchange patterns from atmospheric CO2 mole fractions over the Netherlands for a two week period in spring 2008. The focus of this work is the different strategies that can be employed to turn first-guess fluxes into optimal ones, which is known as a fundamental design choice that can affect the outcome of an inversion significantly. Different state-of-the-art approaches with respect to the estimation of net ecosystem exchange (NEE) are compared quantitatively: (1) where NEE is scaled by one linear multiplication factor per land-use type, (2) where the same is done for photosynthesis (GPP) and respiration (R) separately with varying assumptions for the correlation structure, (3) where we solve for those same multiplication factors but now for each grid box, and (4) where we optimize physical parameters of the underlying biosphere model for each land-use type. The pattern to be retrieved in this pseudo-data experiment is different in nearly all aspects from the first-guess fluxes, including the structure of the underlying flux model, reflecting the difference between the modeled fluxes and the fluxes in the real world. This makes our study a stringent test of the performance of these methods, which are currently widely used in carbon cycle inverse studies. Our results show that all methods struggle to retrieve the spatiotemporal NEE distribution, and none of them succeeds in finding accurate domain averaged NEE with correct spatial and temporal behavior. The main cause is the difference between the structures of the first-guess and true CO2 flux models used. Most methods display overconfidence in their estimate as a result. A commonly used daytime-only sampling scheme in the transport model leads to compensating biases in separate GPP and R scaling factors that are readily visible in the nighttime mixing ratio predictions of these systems. Overall, we recommend that the estimate of NEE scaling factors should not be used in this regional setup, while estimating bias factors for GPP and R for every grid box works relatively well. The biosphere parameter inversion performs good compared to the other inversions at simultaneously producing space and time patterns of fluxes and CO2 mixing ratios, but non-linearity may significantly reduce the information content in the inversion if true parameter values are far from the prior estimate. Our results suggest that a carefully designed biosphere model parameter inversion or a pixel inversion of the respiration and GPP multiplication factors are from the tested inversions the most promising tools to optimize spatiotemporal patterns of NEE.
How plant architecture affects light absorption and photosynthesis in tomato: towards an ideotype for plant architecture using a functional-structural plant model
Sarlikioti, V. ; Visser, P.H.B. de; Buck-Sorlin, G.H. ; Marcelis, L.F.M. - \ 2011
Annals of Botany 108 (2011)6. - ISSN 0305-7364 - p. 1065 - 1073.
carbon gain - leaf - interception - canopy - morphology - yield - assimilation - efficiency - avoidance - capture
Background and Aims - Manipulation of plant structure can strongly affect light distribution in the canopy and photosynthesis. The aim of this paper is to find a plant ideotype for optimization of light absorption and canopy photosynthesis. Using a static functional structural plant model (FSPM), a range of different plant architectural characteristics was tested for two different seasons in order to find the optimal architecture with respect to light absorption and photosynthesis. Methods - Simulations were performed with an FSPM of a greenhouse-grown tomato crop. Sensitivity analyses were carried out for leaf elevation angle, leaf phyllotaxis, leaflet angle, leaf shape, leaflet arrangement and internode length. From the results of this analysis two possible ideotypes were proposed. Four different vertical light distributions were also tested, while light absorption cumulated over the whole canopy was kept the same. Key Results Photosynthesis was augmented by 6 % in winter and reduced by 7 % in summer, when light absorption in the top part of the canopy was increased by 25 %, while not changing light absorption of the canopy as a whole. The measured plant structure was already optimal with respect to leaf elevation angle, leaflet angle and leaflet arrangement for both light absorption and photosynthesis while phyllotaxis had no effect. Increasing the length : width ratio of leaves by 1·5 or increasing internode length from 7 cm to 12 cm led to an increase of 6–10 % for light absorption and photosynthesis. Conclusions - At high light intensities (summer) deeper penetration of light in the canopy improves crop photosynthesis, but not at low light intensities (winter). In particular, internode length and leaf shape affect the vertical distribution of light in the canopy. A new plant ideotype with more spacious canopy architecture due to long internodes and long and narrow leaves led to an increase in crop photosynthesis of up to 10 %.
Lichtmeetprotocol : lichtmetingen in onderzoekskassen meet LED en SON-T belichting
Dueck, T.A. ; Pot, S. - \ 2010
Wageningen : Wageningen UR Glastuinbouw/Plant Dynamics and Wageningen Universiteit (Rapport / Wageningen UR Glastuinbouw nr. 302) - 14
lichtgevende dioden - glastuinbouw - assimilatie - belichting - protocollen - meting - led lampen - light emitting diodes - greenhouse horticulture - assimilation - illumination - protocols - measurement - led lamps
Gedurende de laatste jaren is er in lichtonderzoek projecten een nieuw fenomeen ontstaan, t.w. de introductie van LEDs als assimilatie belichting in de glastuinbouw. Naar aanleiding daarvan heeft LNV en Productschap Tuinbouw in het kader van Kas als Energiebron opdracht gegeven aan WUR Glastuinbouw om een protocol te schrijven voor het meten van licht in SON-T en LED belichtingsystemen in onderzoekskassen. WUR Glastuinbouw heeft dit meetprotocol opgesteld in samenwerking met Plant Dynamics en WU Tuinbouwproductieketens. Dit protocol is vervolgens besproken en vastgesteld in een platform met Philips, Lemnis Lighting, Hortilux, KEMA en TNO.
Space-time geostatistics for geography: a case study of radiation monitoring across parts of Germany
Heuvelink, G.B.M. ; Griffith, D.A. - \ 2010
Geographical Analysis 42 (2010)2. - ISSN 0016-7363 - p. 161 - 179.
spatiotemporal covariance-models - optimization - assimilation - variogram
Many branches within geography deal with variables that vary not only in space but also in time. Therefore, conventional geostatistics needs to be extended with methods that estimate and quantify spatiotemporal variation and use it in spatiotemporal interpolation and stochastic simulation. This article briefly summarizes the main concepts of space–time geostatistics. Kriging in space and time can be done in much the same way as it is in a purely spatial setting. The main difficulties are in defining a realistic stochastic model that is assumed to have generated data and in characterizing and estimating the space–time correlation of that model. This article uses a model-based geostatistical approach to characterize space–time variability. The space–time variable of interest is treated as a sum of independent stationary spatial, temporal, and spatiotemporal components, which leads to a sum-metric space–time variogram model. Methods are illustrated with a case study of space–time interpolation of monthly averages of detected background radiation for a 5-year period in four German states.
40 kg Paprika
Eveleens-Clark, B.A. ; Lagas, P. ; Driever, S.M. ; Zwinkels, J. ; Vaate, J. Bij de; Kaarsemaker, R.C. - \ 2010
Bleiswijk/Wageningen/Delfgauw : Wageningen UR Glastuinbouw/DLV Plant/Groen Agro Control - 87
capsicum - gewasproductie - productiegroei - glasgroenten - tuinbouw - assimilatie - groeimodellen - teeltsystemen - brix - diffuus glas - snoeien - teelt in rijen - crop production - production growth - greenhouse vegetables - horticulture - assimilation - growth models - cropping systems - diffused glass - pruning - alley cropping
Rapport beBestaand uit de volgende onderdelen: 1. Een kasproef, waarin het doel was de productie te verhogen door een combinatie van maatregelen; diffuus glas, verneveling en gewashandelingen 2. Praktijktoepassing en ontwikkeling van een plantmodel dat zetting voorspelt 3. Toetsing van een nieuwe methode om beschikbaarheid van assimilaten voor zetting te meten
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