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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    Purifying manure effluents with duckweed
    Timmerman, M. ; Hoving, I.E. - \ 2016
    Wageningen UR Livestock Research (Livestock Research rapport 942) - 27
    animal manures - effluents - lemna - aquatic weeds - feeds - nutrients - ingredients - animal feeding - animal nutrition - waste water - biogas - biomass production - cultivation - biobased economy - dierlijke meststoffen - afvoerwater - lemna - schadelijke waterplanten - voer - voedingsstoffen - ingrediënten - diervoedering - diervoeding - afvalwater - biogas - biomassa productie - teelt - biobased economy
    The objective of this study was to perform a short literature survey to provide information about purifying manure effluents with duckweed with regard to varieties, cultivation, harvesting methods, utilization and valorisation of duckweed. The results of the study show that duckweed can be used to recuperate nutrients from manure effluents and that the concerning duckweed can be utilized as a source of feed, energy and ingredients
    Project Kleinschalige bioraffinage : Inventarisatie innovatieve digestaatverwerking in combinatie met teelt aquatische biomassa - Beschrijving teeltsystemen en monitoringsplan
    Dijk, W. van; Hoeksma, P. ; Weide, R.Y. van der - \ 2014
    Lelystad : PPO AGV (Deliverables D5.7) - 16
    teeltsystemen - algenteelt - lemna - digestaat - mineralen - plantenvoeding - melkveehouderij - geïntegreerde bedrijfssystemen - voer - biomassa productie - biobased economy - aquatische biomassa - cropping systems - algae culture - lemna - digestate - minerals - plant nutrition - dairy farming - integrated farming systems - feeds - biomass production - biobased economy - aquatic biomass
    Aquatische teelten (o.a. algen, eendenkroos) staan op dit moment volop in de belangstelling. Eén van de factoren voor een voldoende groei is de nutriëntenvoorziening. Uit oogpunt van duurzaamheid en het sluiten van kringlopen is er een voorkeur voor mest(producten) of afvalwater als nutriëntenbron. Naast technische beperkingen (o.a. troebelheid) zijn er ook wettelijke aspecten die de aandacht behoeven bij toepassing van deze nutriëntenbronnen. Dit betreft zowel de mestwetgeving als toelatingseisen voor gebruik als veevoer. Binnen het werkpakket aquatische biomassa van de TKI kleinschalige bioraffinage is nagegaan welke oplossingen mogelijk zijn en welke informatie hiervoor nodig is. Dit doen we aan de hand van twee lopende pilots: algenteelt bij bedrijf Kelstein en eendenkroosteelt bij bedrijf Algaecom. In dit rapport worden de productiesystemen en de monitoringsplannen beschreven.
    Inkuilen van eendenkroos als veevoer met verschillende additieven = Ensiling Duckweed for feed with different additives
    Hoving, I.E. ; Schooten, H.A. van; Holshof, G. ; Houwelingen, K.M. van; Geest, W. van de - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 528) - 30
    waterplanten - lemna - vochtgehalte - droging - kuilvoerbereiding - voedertoevoegingen - kuilvoerfermentatie - aquatic plants - lemna - moisture content - drieration - silage making - feed additives - silage fermentation
    Ferment duckweed as silage is a cheap and sustainable alternative for drying. Without an additive, no satisfying preservation result was reached. Molasses gave a good preservation result and is relatively cheap and practical. Common methods of forage ensilaging are not suitable for duckweed as they have too little product structure to facilitate wrapping. The use of an airtight container or silo may lead to good preservation results, and prevent losses.
    Eendenkroos nu ook voor de koe
    Holshof, G. - \ 2008
    V-focus 5 (2008)3. - ISSN 1574-1575 - p. 30 - 33.
    rundveehouderij - rundveevoeding - krachtvoeding - lemna - lemnaceae - plantaardig eiwit - vervangmiddelen - waterplanten - cattle husbandry - cattle feeding - force feeding - lemna - lemnaceae - plant protein - substitutes - aquatic plants
    Eendenkroos is geschikt als eiwitgrondstof voor krachtvoer en is bij de productie van mengvoer goed uitwisselbaar met gangbare grondstoffen als soja. Voor de veehouderij zijn vanwege de hoge prijzen alternatieve eiwitbronnen welkom; daarbij staat het gebruik van soja maatschappelijk ter discussie. In een pilot is kroos verwerkt tot 3 verschillende krachtvoerproducten. Oogsten van Spakenburg en Stolwijk zijn bemonsterd op zware metalen en voederwaarden. De eerste resultaten wijzen op een perspectiefvolle nieuwe grondstof voor veevoeders
    Eendenkroos als veevoer : kijken met een ander oog naar kroos
    Hoving, Idse - \ 2007
    livestock farming - fodder - lemna - feed industry - fodder plants - applied research - dairy cattle nutrition
    A simple equation for describing the temperature dependent growth of free-floating macrophytes
    Heide, Tj. van; Roijackers, R.M.M. ; Nes, E.H. van; Peeters, E.T.H.M. - \ 2006
    Aquatic Botany 84 (2006)2. - ISSN 0304-3770 - p. 171 - 175.
    salvinia-molesta - water macrophytes - climate-change - azolla - responses - nitrogen - ditches - lemna - model
    Temperature is one of the most important factors determining growth rates of free-floating macrophytes in the field. To analyse and predict temperature dependent growth rates of these pleustophytes, modelling may play an important role. Several equations have been published for describing temperature responses of macrophytes and algae. But they are often complex or are only applicable in a limited range of temperatures. In this paper, we present a simple three-parameter equation for describing the temperature dependent growth rates of pleustophytes. The equation that we developed is tested using results from laboratory growth experiments conducted with three different species of pleustophytes (Lemna minor, Salvinia molesta and Azolla filiculoides). The equation is simple and demonstrates reliable fits (adjusted R2 reaching from 0.89 to 0.95). Additionally, our equation primarily uses parameters of biological significance, resulting in estimates of useful cardinal temperatures (minimum and maximum)
    Experiments with duckweed-moth systems suggest global warming may reduce rather than promote herbivory
    Heide, Tj. van; Roijackers, R.M.M. ; Peeters, E.T.H.M. ; Nes, E.H. van - \ 2006
    Freshwater Biology 51 (2006)1. - ISSN 0046-5070 - p. 110 - 116.
    biological-control - south-africa - temperature - ditches - lemna
    1. Wilf & Labandeira (1999)suggested that increased temperatures because of global warming will cause an increase in herbivory by insects. This conclusion was based on the supposed effect of temperature on herbivores but did not consider an effect of temperature on plant growth. 2. We studied the effect of temperature on grazing pressure by the small China-mark moth (Cataclysta lemnata L.) on Lemna minor L. in laboratory experiments. 3. Between temperatures of 15 and 24 degrees C we found a sigmoidal increase in C. lemnata grazing rates, and an approximately linear increase in L. minor growth rates. Therefore, an increase in temperature did not always result in higher grazing pressure by this insect as the regrowth of Lemna changes also. 4. At temperatures below 18.7 degrees C, Lemna benefited more than Cataclysta from an increase in temperature, causing a decrease in grazing pressure. 5. In the context of global warming, we conclude that rising temperatures will not necessarily increase grazing pressure by herbivorous insects.
    The strength of limiting factors for duckweed during algal competition
    Szabo, S. ; Roijackers, R.M.M. ; Scheffer, M. ; Borics, G. - \ 2005
    Archiv für Hydrobiologie 164 (2005)1. - ISSN 0003-9136 - p. 127 - 140.
    voedingsstoffen - verwijdering - lemna - algen - groeitempo - concurrentie tussen planten - eutrofiëring - waterkwaliteit - nutrients - removal - lemna - algae - growth rate - plant competition - eutrophication - water quality - waste-water treatment - common duckweed - lemna-gibba - performance - growth - ph - macrophytes - toxicity - nitrogen
    Duckweed (Lemna gibba) growth was found to be strongly reduced by unicellular green algae (Scenedesmus conspicua, Chlorella sp., Chlamydomonas sp.) in indoor experiments. These algae reduced N, P, Fe and Mn concentrations of the medium drastically, moreover they increased the pH beyond 10. Subsequent additions of nutrients and pH neutralisation removed the growth inhibition of duckweed. This growth inhibition is, therefore, concluded to be due to pH increase and N, P and trace element (Fe, Mn) removal. Of the five factors significantly inhibiting duckweed growth, depletion of N was strongest, increase in pH was second, followed by reduction of P > Fe > Mn.
    Nutrients valorisation via duckweed-based wastewater treatment and aquaculture
    El-Shafai, S.A.A.M. - \ 2004
    Wageningen University. Promotor(en): H.J. Gijzen; F. El-Gohary, co-promotor(en): Johan Verreth; P. van der Steen. - [S.l.] : Balkema - ISBN 9789058089564 - 174
    afvalwaterbehandeling - aquacultuur - lemna - voedingsstoffen - egypte - waste water treatment - aquaculture - lemna - nutrients - egypt
    Experimental analysis of the competition between algae and duckweed
    Roijackers, R.M.M. ; Szabo, S. ; Scheffer, M. - \ 2004
    Archiv für Hydrobiologie 160 (2004)3. - ISSN 0003-9136 - p. 401 - 412.
    lemna - concurrentie tussen planten - eutrofiëring - algen - voedingsstoffen - beschaduwen - nederland - gelderland - lemna - plant competition - eutrophication - algae - nutrients - shading - netherlands - gelderland - ditches - lake
    We performed indoor competition experiments between algae and Lemna gibba L. in order to unravel mechanisms of competition. To separate effects of shading and physical interference from nutrient competition we grew the two groups physically separated while sharing the same water. A multifactorial design was used with five levels of initial nitrogen concentration (0.1- 50 mg N l-1) and four shade levels mimicking 0 -100 % duckweed shade on the algal compartment
    We performed indoor competition experiments between algae and Lemna gibba L. in order to unravel mechanisms of competition. To separate effects of shading and physical interference from nutrient competition we grew the two groups physically separated while sharing the same water. A multifactorial design was used with five levels of initial nitrogen concentration (0.1-50mg N l(-1)) and four shade levels mimicking 0-100% duckweed shade on the algal compartment. In the experiments in which algae were not shaded, the growth rate of Lemna was reduced strongly (60-62%) at moderate initial nitrogen concentrations (0.1-1 mg N l(-1)). The impact of algae was less at high N-loading and if algae were shaded. The reduction in the chlorophyll content of the fronds was even more dramatic (72-80%). Analyses of nutrients and pH indicated that algae inhibited the growth of Lemna by the removal of N, P and Fe, but also by their photosynthetic effect on pH. When algae and duckweeds were grown together, floating algae occurring at high nutrient levels partly covered the duckweeds and reduced the growth further than in the absence of physical contact. Since under those conditions Lemna growth was still marked, it seems likely that on the long run Lemna will always expand sufficiently to outcompete the algae at high nutrient levels.
    Nitrogen transformations and removal mechanisms in algal and duckweed stabilisation ponds
    Zimmo, O. - \ 2003
    Wageningen University. Promotor(en): H.J. Gijzen, co-promotor(en): N.P. van der Steen. - S.l. : Balkema - ISBN 9789058088116 - 143
    afvalwaterbehandeling - stikstof - verwijdering - algen - lemna - bezinkingsvijvers - waste water treatment - nitrogen - removal - algae - lemna - stabilization ponds

    This thesis describes the results of a comparative study of the performance of algae-based ponds (ABPs) and duckweed-based ponds (DBPs) for wastewater treatment, with emphasis on nitrogen transformations and removal mechanisms.

    Batch experiments simulating algae and duckweed ( Lemna gibba ) stabilisation ponds for domestic wastewater treatment were conducted to quantify the importance of various nitrogen removal mechanisms under controlled conditions of pH and DO. N-removal in both systems by different mechanisms are more dependent on the pH variations than on the oxygen variations. Significantly higher N-removal efficiency in the duckweed system (26-33%) than in the algae system (14-24%) was found at lower pH range of 5 to 7. At high pH values of 7 to9, the increase in N-removal by sedimentation and volatilisation in the algae system and the decrease in N-uptake by duckweed in the duckweed system resulted in significantly higher N-removal efficiency in the algae system (45-60%) than the duckweed system (38-41%).

    Further research was carried out in pilot scale algae-based and duckweed-based systems that consisting of 4 similar ponds in series for each system, fed with wastewater with hydraulic retention time of 7 days in each pond.

    Tracer experiments showed that the hydraulic characteristics were similar in both ABPs and DBPs. Actual retention times were observed to be higher than the theoretical retention times due to the spurious tracer curves resulting in negative dead spaces. This suggests that the higher density of LiCl solution compared to pond wastewater density, probably caused LiCl to pass onto the bottom of the pond and slowly dissolved into pond water where it leached out at a much longer period and thus giving spurious tracer curves. The hydraulic behaviour of the ponds was neither plug-flow nor completely mixed, but rather showed a dispersed flow. A tracer experiment in larger scale algae and duckweed-based ponds in Colombia showed lesser short-circuiting and more plug flow conditions in the duckweed pond than the algae pond. For larger surface areas the presence of duckweed cover improved the hydraulic performance of pond. The better hydraulic behaviour of the pond with duckweed cover may be explained by reduced wind-induced short circuiting and reduced mixing caused by the absence of algae biomass activities.

    Higher BOD and TSS removal efficiencies were achieved in DBPs compared to ABPs. In both systems, the removal of BOD and TSS did not differ significantly during the different seasons of warm and cold weather. Total-P was more effectively reduced in DBPs than in ABPs, irrespective of the season due to phosphorus uptake of duckweed and subsequent removal from the system via harvesting.

    Increase in organic loading resulted in an increase in BOD and TSS removal rates in both ABPs and DBPs. Phosphorous removal was similar during the two experimental periods in ABPs. DBPs behaved likewise. Removal of FC in ABPs was higher than in DBPs. FC removal in the ABPs and in the DBPs was significantly higher during low organic loading period compared to high organic loading period. FC removal in ABPs during the low and high organic loading periods was 3.8 and 3.4 log units, respectively. Corresponding values for DBPs were significantly lower at 2.2 and 1.8 log units. Lower FC removal was found during the cold period in both systems.

    During the low organic loading period at warm temperature, nitrogen removal efficiency was higher in ABPs (80%) than in DBPs (55%) despite the fact that approximately one third of the influent nitrogen to the DBPs is removed via duckweed harvesting. Lower N-removal in both systems was obtained during cold season but similar removal was found during periods of low and high organic loading.

    Quantification of N-fluxes in both systems showed that the major fluxes of nitrogen in the ABPs were sedimentation (33-40%) and denitrification (14-24%). Sedimentation and denitrification in DBPs were of equal importance except during the warm season and low organic loading operation, when sedimentation was low. In DBPs, 30-33% and 15% of the total nitrogen was recovered into biomass and removed from the system via duckweed harvesting during the summer and winter period, respectively. During the high organic loading period, nitrogen recovered via duckweed was 19%. Ammonia volatilisation in both treatment systems was found to be a minor N-removal mechanism responsible for less than 1.1 % of total influent nitrogen. Nitrification and denitrification occurred in the aerobic water phase and anaerobic sediment, respectively. Higher DO concentrations in ABPs, especially during the warm season, favoured higher nitrification in ABPs as compared to DBPs. Predictive models for nitrogen removal in ABPs and DBPs were proposed. They presented a good reflection of nitrogen fluxes on overall nitrogen balance under the prevailing experimental conditions. Validation of the models with reported data from literature gave poor results for shallower ponds, while better agreement was obtained using data for deeper ponds. Further elaboration and validation of the model to accommodate pond design and environmental parameters that dictate pond performance is required.

    Effects of light and phytochrome in heterotrophic growth of Lemna minor L.
    Rombach, J. - \ 1976
    Landbouwhogeschool Wageningen. Promotor(en): E.C. Wassink, co-promotor(en): C.J.P. Spruit. - Wageningen : Veenman - 115
    lemnaceae - lemna - fotosynthese - groei - lemnaceae - lemna - photosynthesis - growth

    Axenic cultures of Lemna minor L. were grown on a medium containing sugars and amino acids. In continuous darkness the growth rate was one-tenth of the maximum in continuous light. In darkness early death revealed a thiamine deficiency; this deficiency was counteracted, without increasing the multiplication rate, by feeding the plants thiamine or its thiazole component. The rate of cell division, the rate of frond expansion, and the frond multiplication rate were increased by illumination; at low intensities this increase was in the nature of a photostimulus effect. The increase in growth rate was accompanied by a decrease in dry weight. The sugar uptake from the medium per frond per day was constant, independent of the light intensity and multiplication rate. At intensities of above 100 μW cm -2continuous red light, the multiplication rate increased in proportion to the rate of photosynthesis.

    Periodic brief illuminations yielded a stimulation of the frond multiplication rate of up to 4 times the dark value. Red illuminations of 2 minutes every 48 hours were sufficient to prevent thiamine deficiency; this effect of the red illuminations was reversible by far red. Stimulation of the multiplication rate was likewise reversible by far red; the effect of continuous low intensity red light was reduced by a simultaneous far red irradiation, while the effect of brief illuminations was reduced by far red following the red. From this it was concluded that phytochrome is a photoreceptor for these light effects. The results of experiments with different far red and red illumination schedules suggested that in plants with much phytochrome only a small part of it is active but that the Pfr level in this part decreases at a rate not very different from that of the bulk phytochrome as measured by the spectrophotometer.

    Part of the light effect was not reversible by far red. This part increased by increasing the length of the illumination periods, the light intensity, and the number of illuminations per day. In this increase blue light was much more effective than it was in the far red reversible part of the light effect. This indicates a photoreaction different from phytochrome photoconversion.

    Kinetin specially increased the far red non-reversible part of the photostimulation. Together with the intensity dependency of this part of the stimulation, this gave rise to the supposition that the non-reversible part of the light effect was limited by the supply of substrates in phytochrome controlled reactions during the light periods. Thus it would seem plausible to assume that the far red non-reversible part is built up during the red and the blue light periods, whereas the reversible part is developed during the intervening dark periods.

    The influence of the phytochrome reaction on the growth of Lemna Minor L
    Rombach, J. - \ 1965
    Wageningen : Veenman (Mededelingen van de Landbouwhogeschool Wageningen 65-14) - 11
    lemnaceae - lemna - fytochroom - plantenpigmenten - vacuolen - licht - fotoperiode - fotoperiodiciteit - schaduw - lemnaceae - lemna - phytochrome - plant pigments - vacuoles - light - photoperiod - photoperiodism - shade
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