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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Autonomous Greenhouse Challenge, First Edition (2018)
Hemming, S. ; Zwart, H.F. de; Elings, A. ; Righini, I. ; Petropoulou, Anna - \ 2019
climate set points - crop management - cucumber - greenhouse climate - harvest - irrigation - outside weather - pruning - resource consumption
The dataset contains data on greenhouse climate, irrigation, outside weather, greenhouse climate set points, harvest and crop management, resource consumption. Data were collected during a 4-month cucumber production (cv. Hi Power) in 6 glasshouse compartments (96 m2), located in Bleiswijk (The Netherlands). The dataset contains raw and processed data. Raw data were collected via climate measuring boxes, climate and irrigation process computer, manual registrations, outside weather station. The dataset was produced during the first edition of Autonomous Greenhouse Challenge, an international competition aiming at using Artificial Intelligence algorithms for the remote control of greenhouse horticulture production. Five international teams consisting of scientists, professionals and students participated in this experiment. The teams' names are: iGrow, deep_greens, AiCU, Sonoma, Croperators. They developed AI algorithms to remotely determine the Climate control set points and they additionally sent instructions for the crop pruning strategy. They had to realize the highest yield with minimal use of resources (e.g. water, CO2). The achievements in AI-controlled compartments were compared with a reference compartment, operated manually by three Dutch commercial growers (named Reference).
Location and external characteristics of the Oecophylla smaragdina queen nest
Itterbeeck, J. Van; Sivongxay, N. ; Praxaysombath, B. ; Huis, A. van - \ 2015
Insectes Sociaux 62 (2015)3. - ISSN 0020-1812 - p. 351 - 356.
weaver ant oecophylla - hymenoptera-formicidae - biological-control - green ant - fabricius - colony - harvest - citrus
The Asian weaver ant Oecophylla smaragdina is of importance to Southeast Asian livelihoods as a source of human food and animal feed and as biological control agent in tree crops including mango and citrus. The introduction of weaver ants in plantations requires the inclusion of the reproductive queen. We report on locating the gravid queen in a mature O. smaragdina colony in Laos. The queen tree could be identified by considering tree height and number of nests in the tree: no tree was taller and housed more nests than the queen tree. The queen nest was a small nest, located near the tree top and near the trunk, and with more workers patrolling its exterior than at other small nests in the queen tree. The queen nest can be highly inconspicuous in dense tree crowns. Queen nest identification was ascertained by tapping and shaking nests, supporting branches, or entire trees, which elicits queen evacuation with retinue.
Unexpectedly high catch-and-release rates in European marine recreational fisheries: implications for science and management
Ferter, K. ; Weltersbach, M.S. ; Strehlow, H.V. ; Graaf, M. de; Hammen, T. van der - \ 2013
ICES Journal of Marine Science 70 (2013)7. - ISSN 1054-3139 - p. 1319 - 1329.
salmon salmo-salar - atlantic salmon - length limits - circle hooks - mortality - anglers - fish - harvest - recall - norway
While catch-and-release (C&R) is a well-known practice in several European freshwater recreational fisheries, studies on the magnitude and impact of this practice in European marine recreational fisheries are limited. To provide an overview of the practice and magnitude of C&R among marine recreational anglers in Europe, the existing knowledge of C&R and its potential associated release mortality was collected and summarized. The present study revealed that in several European countries over half of the total recreational catch is released by marine anglers. High release proportions of >60% were found for Atlantic cod (Gadus morhua), European sea bass (Dicentrarchus labrax), pollack (Pollachius pollachius), and sea trout (Salmo trutta) in at least one of the studied European countries. In the case of the German recreational Baltic Sea cod fishery, release proportions varied considerably between years, presumably tracking a strong year class of undersized fish. Reasons for release varied between countries and species, and included legal restrictions (e.g. minimum landing sizes and daily bag limits) and voluntary C&R. Considering the magnitude of C&R practice among European marine recreational anglers, post-release mortalities of released fish may need to be accounted for in estimated fishing mortalities. However, as the survival rates of European marine species are mostly unknown, there is a need to conduct post-release survival studies and to identify factors affecting post-release survival. Such studies could also assist in developing species-specific, best-practice guidelines to minimize the impacts of C&R on released marine fish in Europe.
Rapid tomato volatile profiling by using proton-transfer reaction mass spectrometry (PTS-MS)
Farneti, B. ; Cristescu, S.M. ; Costa, G. ; Harren, F.J.M. ; Woltering, E.J. - \ 2012
Journal of Food Science 77 (2012)5. - ISSN 0022-1147 - p. C551 - C559.
electronic nose - lycopersicon-esculentum - quality attributes - organic-compounds - flavor compounds - aroma volatiles - kidney beans - shelf-life - cultivars - harvest
The availability of rapid and accurate methods to assess fruit flavor is of utmost importance to support quality control especially in the breeding phase. Breeders need more information and analytical tools to facilitate selection for complex multigenic traits such as flavor quality. In this study, it is shown that proton-transfer reaction mass spectrometry (PTR-MS) is a suitable method to monitor at high sensitivity the emission of volatiles determining the tomato aromatic profile such as hexanal, hexenals, methanol, ethanol, and acetaldehyde. The volatiles emitted by 14 tomato varieties (at red stage) were analyzed by 2 solvent-free headspace methods: solid-phase microextraction/gas chromatography MS and PTR-MS. Multivariate statistics (principal component analysis and cluster analysis) of the PTR-MS results allow an unambiguous separation between varieties, especially with a clear fingerprinting separation between the different tomato types: round truss, cocktail, and cherry tomatoes. PTR-MS was also successfully used to monitor the changes in volatile profiles during postharvest ripening and storage.
Public perceptions of the attractiveness of restored nature
Marwijk, R.B.M. van; Elands, B.H.M. ; Kampen, J.K. ; Terlouw, S. ; Pitt, D.G. ; Opdam, P.F.M. - \ 2012
Restoration Ecology 20 (2012)6. - ISSN 1061-2971 - p. 773 - 780.
landscape preferences - aesthetic preferences - scenic quality - restoration - conservation - naturalness - information - management - harvest
Ecological restoration efforts often encounter public resistance. Recreational visitors resist imposition of restoration efforts they fear may result in a visually unattractive area. Public support is, however, essential for restoration efforts on public lands. This study seeks insight into hiker perceptions of perceived attractiveness of nature before and after efforts to restore exotic conifer plantations to native communities containing bog and wet forest communities. Visitors (N = 247) to a Dutch National Park sorted 32 photographs depicting landscapes before and after restoration efforts. Findings show that the most attractive landscape types (bog and wet forest communities containing visible water) are results of restoration efforts and the least attractive landscape types (young deciduous and coniferous forest) are representative of traditional nature before restoration. However, the “middle category” consists of landscape types existing both before and after restoration efforts. Visitors value old coniferous and old deciduous forests as much as products of restoration that lack water. These perceptions are unrelated to either visitor characteristics or the provision of information to visitors explaining restoration goals. The continued existence of resistance to restoration strategies despite their effect on perceived landscape attractiveness implies that the experience of nature has more than only visual dimensions. We expect that more acceptable results of restoration efforts will emerge from the active engagement of the public before restoration practices take place in processes that specifically address feelings of attachment and resistance to change
Evaluation of alternative management strategies of muskrat Ondatra zibethicus population control using a population model
Bos, D. ; Ydenberg, R.C. - \ 2011
Wildlife Biology 17 (2011)2. - ISSN 0909-6396 - p. 143 - 155.
experimental marshes - dynamics - habitat - harvest - mink
Muskrats Ondatra zibethicus are considered a pest species in the Netherlands, and a year-round control programme is in effect. Currently, the agency responsible for the management of muskrat populations in the Netherlands (the LCCM) is preparing for field studies to compare alternative strategies of control. In order to decide on the specific design of such field studies, a population dynamic model was built. The model compares the current management strategy with alternatives in which the effort is focused in space or in time. The model allows us to prioritise future research questions. The major gaps in knowledge at this moment are: 1) insight into the costs of harvesting at different harvest rates, and 2) the relationship between population density on the one hand and (financial damage or) safety risk on the other hand. We suggest continuing the current management, and to test our hypothesis that intensifying harvest will lead to lower numbers of animals killed in the medium term than more extensive harvest rates. The muskrat control programme offers excellent opportunities for applied biological studies of which the benefits are likely to outweigh the costs
Chilling injury in stored nectarines and its detection by time-resolved reflectance spectroscopy
Lurie, S. ; Vanoli, M. ; Dagar, A. ; Weksler, A. ; Eccher Zerbini, P.C. ; Spinelli, L. ; Torricelli, A. ; Lovati, F. ; Feng, R. ; Rizzolo, A. - \ 2011
Postharvest Biology and Technology 59 (2011)3. - ISSN 0925-5214 - p. 211 - 218.
fruit - peach - prediction - firmness - maturity - quality - harvest
Nectarine fruit after cold storage soften normally, but become dry instead of juicy and can develop flesh browning, bleeding and a gel-like or glassy formation of the flesh near the pit. An experiment was conducted to see if time-resolved reflectance spectroscopy could distinguish these internal disorders non-destructively. The optical parameters of absorption coefficient (µa) and reduced scattering coefficient (µ's) were measured at 670 nm and 780 nm, on nectarine (Prunus persica cv. Morsiani 90) fruit held at 20 °C after harvest or after 30 d of storage at 0 °C or 4 °C. Each day for 5 d 30 fruit were examined both non-destructively and destructively. Other measurements were firmness with a penetrometer, peel colour on the blush and non-blush side, expressible juice, weight loss, and visual rating of internal browning, bleeding, and gel. The fruit had been sorted at harvest according to the value of µa670 so that each batch had a similar spread of fruit maturity. More mature fruit (lower µa670 values) developed internal browning and bleeding with more severe symptoms compared to less mature ones (higher µa670 values). It was found that µa780 could distinguish healthy fruits from the chilling injured ones. Canonical discriminant analysis indicated that fruit without cold storage had low µa780, less water loss, low firmness, but high µa670 and high expressible juice compared with cool stored fruit. Fruit cool stored at 4 °C had high µa780 and less expressible juice, lower water loss and lower firmness compared with fruit cool stored at 0 °C. It was concluded that time resolved reflectance spectroscopy could detect internal woolliness and internal browning in nectarines after storage
Prediction ability of firmness decay models of nectarines based on the biological shift factor measured by time-resolved reflectance spectroscopy
Rizzolo, A. ; Vanoli, M. ; Eccher Zerbini, P.C. ; Jacob, S. ; Torricelli, A. ; Spinelli, L. ; Schouten, R.E. ; Tijskens, L.M.M. - \ 2009
Postharvest Biology and Technology 54 (2009)3. - ISSN 0925-5214 - p. 131 - 140.
peach - harvest - fruit
The maturity of nectarines at harvest can be assessed by measuring the absorption coefficient at 670 nm (µa) with the non-destructive technique of time-resolved reflectance spectroscopy (TRS). A kinetic model links µa, converted into the biological shift factor (BSF), to firmness decrease during ripening; in this way the firmness decay model includes the variations in maturity at harvest, thereby allowing prediction of shelf-life for individual fruit. In order to study how this methodology could be practically used at the time of harvest, when µa can be measured non-destructively on all fruit, while the destructive measurement of firmness can only be done on a small sample, various firmness decay models were developed using either data at harvest or within 1–2 d after harvest from previous experimental research with nectarines carried out over a 5-year period. These models were then tested for prediction and classification ability by comparing the predicted firmness and class of usability to the actual ones measured during ripening and their performance compared to that of models based on data during the whole shelf-life. Our results suggest that the methodology might be used as a management tool in the nectarine supply chain. Independently from the actual softening rate, the classification at harvest based on µa is able to segregate fruit of different quality and maturity according to their softening behaviour during shelf-life. Among the various models, those estimated using data at harvest and after 24 h of shelf-life had better performance than those based only on data at harvest. In the 2002 and 2005 seasons, this model showed a classification ability very close to that of models based on data during the whole shelf-life. However, its performance in the 2004 season was not so good, because it could not take into account the influence of cold storage periods prior to shelf-life. All the steps necessary to apply this methodology are detailed
Time-resolved Reflectance Spectroscopy as a management tool in the fruit supply chain: an export trail with nectarines
Echer Zerbini, P. ; Vanoli, M. ; Rizzolo, M.M. ; Jacob, A. ; Torricelli, A. ; Spinelli, L. ; Schouten, R.E. - \ 2009
Biosystems Engineering 102 (2009)3. - ISSN 1537-5110 - p. 360 - 363.
At harvest, fruit shows variation in maturity stage. With Time-resolved Reflectance Spectroscopy (TRS), the maturity of nectarines at harvest can be assessed by measuring the absorption coefficient at 670 nm (¿a), near the chlorophyll peak, in the fruit flesh. A kinetic model has been developed linking the absorption coefficient, expressed as the biological shift factor (¿t*), to firmness decrease during ripening. As the decrease in ¿a in nectarines is linked with softening, shelf life for individual fruit can be predicted. In order to verify the applicability of this methodology in the supply chain, about 1000 nectarines were measured at harvest by TRS, graded into six classes of usability based on the prediction of their individual softening (`will never ripe¿, `dangerously hard¿, `transportable¿, `ready to eat-firm¿, `ready to eat-ripe¿, `overripe¿) and transported from Italy to the Netherlands by a regular temperature-controlled truck. On arrival, fruit was kept at 20 °C and tested for sensory softness (finger feeling) after 5 and 13 days of shelf life. The classes `will never ripe¿, `dangerously hard¿ and `overripe¿ were correctly predicted, as the first two did not soften and the last one was too soft and subject to rot. The intermediate classes showed sufficient firmness to be transported and sufficient ripening potential to satisfy consumers
Influence of storing rough rice with high moisture content on subsequent drying characteristics and milling quality
Manski, J.M. ; Matsler, A.L. ; Siebenmorgen, T.J. - \ 2005
Cereal Chemistry 82 (2005)2. - ISSN 0009-0352 - p. 204 - 208.
yield reduction - long-grain - storage - temperature - respiration - harvest
The objective of this research was to determine the influence on drying characteristics and resultant milling quality of storing high moisture content (MC) rough rice (Oryza sativa L. 'Bengal' and 'Cypress') under various conditions and durations before drying. Immediately after harvest, drying experiments were performed with samples of both cultivars using two drying air conditions: 52°C with 25% rh and 60°C with 17% rh. Rough rice from each cultivar also was stored for 27 and 76 days at -9 or 4°C. After storage, all samples were dried under the same two drying air conditions as at harvest. Head rice yields (HRY) were determined for all dried samples. There were no significant differences between the drying rates or resultant HRY of Bengal or Cypress rice samples stored for either 27 or 76 days at both storage temperatures and then dried compared with the HRY of samples dried immediately after harvest. This research shows that it may be possible to store high MC rice for extended periods of time without detrimental effects on HRY.
Feasiblity of collecting naturally leached rice straw for thermal conversion
Bakker, R.R. ; Jenkins, B.M. - \ 2003
Biomass and Bioenergy 25 (2003)6. - ISSN 0961-9534 - p. 597 - 614.
reed canary grass - quality - harvest
The practical application of field or natural leaching to rice straw was evaluated with the goal of improving biomass fuel value. Observations on three rice farms in the Sacramento Valley, California indicated that potassium, chlorine and total ash are leached from rice straw by rainfall regardless of rice variety, grain harvest method, straw arrangement, or stubble length. Leaching of sulfur by natural precipitation was not clearly established. In selected field plots leached straw was successfully collected in spring, even though biomass yields were variable (2.2¿3.4 Mgha¿1) and equipment had to operate in difficult conditions. Total costs for collecting leached straw on an area basis ($77.07 ha¿1) are 31¿igher compared to collecting crude straw in the fall ($58.67 ha¿1), due to reduced performance of machinery and addition of field curing operations. Analysis of historical rainfall data for the Sacramento Valley revealed that there is an 85¿robability of receiving sufficient rainfall (250 mm or more) for substantial natural leaching of straw during the winter period. The available period for mechanized collection of rice straw after the winter period ranges from 0 to 45 days, depending on drying time needed to accomplish favorable field conditions, and planting date of the next crop. The feasibility of spring collection of rice straw could be improved if straw collection equipment were better equipped to operate under wet field conditions. The commercial implementation of natural leaching of rice straw as a strategy to improve fuel quality depends on a combination of factors that include grain harvest and straw collection practices, rainfall intensity and distribution, and field-specific factors.
Cloning, expression and characterisation of two tyrosinase cDNAs from Agaricus bisporus
Wichers, H.J. ; Recourt, K. ; Hindriks, M. ; Ebbelaar, C.E.M. ; Biancone, G. ; Hoeberichts, F.A. ; Mooibroek, A. - \ 2003
Applied Microbiology and Biotechnology 61 (2003)4. - ISSN 0175-7598 - p. 336 - 341.
polyphenol oxidase - activation - isoform - harvest - plant - gene
Using primers designed on the basis of sequence homologies in the copper-binding domains for a number of plant and fungal tyrosinases, two tyrosinase encoding cDNAs were cloned from an Agaricus bisporus U1 cDNA-library. The sequences AbPPO1 and AbPPO2 were, respectively, 1.9 and 1.8 kb in size and encoded proteins of approximately 64 kDa. The cDNAs represent different loci. Both AbPPO1 and AbPPO2 occur as single copies on the genomes of the U1 parental strains H39 and H97. The genomic size of AbPPO1 and AbPPO2 is minimally 2.3 and 2.2 kb, respectively. Alignment and phylogenetic analysis of 35 tyrosinase and polyphenol oxidase sequences of animal, plant, fungal, and bacterial origin indicated conserved copper-binding domains, and stronger conservation within genera than between them. The translation products of AbPPO1 and AbPPO2 possess putative N-glycosylation and phosphorylation sites and are recognised by antibodies directed against a 43-kDa tyrosinase. The observations are consistent with previously proposed maturation and activation models for plant and fungal tyrosinases.
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