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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    How to measure health improvement? : assessment of subtle shifts in metabolic phenotype
    Fazelzadeh, Parastoo - \ 2017
    Wageningen University. Promotor(en): A.H. Kersten; J.P.M. van Duynhoven, co-promotor(en): M.V. Boekschoten. - Wageningen : Wageningen University - ISBN 9789463430739 - 187
    health promotion - improvement - measurement - metabolic profiling - elderly - obesity - microarrays - rna - peripheral blood mononuclear cells - gezondheidsbevordering - verbetering - meting - metabolische profilering - ouderen - obesitas - microarrays - rna - perifere mononucleaire bloedcellen

    Human health is impacted by a complex network of interactions between biological pathways, mechanisms, processes, and organs, which need to be able to adapt to a continuously changing environment to maintain health. This adaptive ability is called ‘phenotypic flexibility’. It is thought that health is compromised and diseases develop when these adaptive processes fail. As the product of interactions between several factors such as genetic makeup, diet, lifestyle, environment and the gut microbiome, the ‘metabolic phenotype’ provides a readout of the metabolic state of an individual. Understanding these relationships will be one of a major challenges in nutrition and health research in the next decades. To address this challenge, the development of high-throughput omics tools combined with the application of elaborate statistical analyses will help characterize the complex relationship of (bio) chemicals in human systems and their interaction with other variables including environment and lifestyle to produce the measured phenotype. An important aim of this thesis was to identify phenotype shifts by looking at effect of prolonged resistance-type exercise training on skeletal muscle tissue in older subjects and the possible shift toward the features of younger subjects as a reference for a healthier phenotype. A second aim was to identify phenotype shifts by looking at the response to a challenge in obese subjects and the possible shift toward lean subjects as a reference for a healthier phenotype.

    Chapter 2 and 3 of this thesis show how the significant remaining plasticity of ageing skeletal muscle can adapt to resistance-type exercise training. The data indicate that frail and healthy older subjects have two distinct phenotypes according to the skeletal muscle tissue metabolite profiles and that exercise training shifts aged muscle towards a younger phenotype. We showed that the effect of exercise on amino acid derived acylcarnitines (AAAC’s) in older subjects points towards decreased branched chain amino acid catabolism, likely due to compromised activation of the branched chain α-keto acid hydrogenase (BCKDH) complex. Furthermore, we found that the protocadherin gamma gene cluster might be involved in aged-muscle denervation and re-innervation. Finally, plasma was found to be a poor indicator of muscle metabolism, emphasizing the need for direct assessment of metabolites in muscle tissue.

    Chapter 4 of this thesis examines whether a mixed meal challenge response provides a readout for a shift in phenotype upon weight loss in obese male subjects. We concluded that weight loss moderately affects the mixed meal challenge response of both plasma metabolome and transcriptome of peripheral blood mononuclear cells in obese subjects. Measurements at the fasted and postprandial state also provide us with a different type of information.

    In Chapter 5 it is demonstrated that the global testing of pathways could provide a concise summary of the multiple univariate testing approach used in Chapter 4. In Chapter 6 it is discussed how the findings of this thesis increase our understanding of how to measure phenotypic flexibility as a proxy of health. In this thesis it is shown that the correlations between tissue and plasma metabolites are rather weak, emphasising the need to perform organ-specific studies. Availability of less invasive/painful sampling techniques and the use of small amounts of tissue would enable larger scale human studies on adipose tissue and skeletal muscle to more accurately define phenotypical shifts due to diet or lifestyle interventions. With respect to the assessment of phenotypical flexibility by omics approaches, significant complications can be expected in trying to relate plasma metabolism to PBMC gene expression. Organ-focussed approaches that integrate multiple omics levels using system biology approaches are considered to be a lot more promising.

    Production efficiency of mussel bottom culture
    Capelle, Jacob J. - \ 2017
    Wageningen University. Promotor(en): Aad Smaal; P.M.J. Herman, co-promotor(en): Jeroen Wijsman. - Wageningen : Wageningen University - ISBN 9789463430869 - 240
    mussels - mussel culture - bottom culture - efficiency - population dynamics - culture techniques - biomass production - improvement - shellfish culture - aquaculture - mossels - mosselteelt - bodemcultuur - efficiëntie - populatiedynamica - kweektechnieken - biomassa productie - verbetering - schaal- en schelpdierenteelt - aquacultuur

    Mussel bottom culture is an extensive type of aquaculture; it depends on natural resources for feed, seed and space. It consists of the translocation of seed from natural beds to designed culture areas, where mussel farmers try to improve production efficiency. Production efficiency is measured by the relative biomass production (RBP) expressed as units of biomass harvested from one unit of biomass seeded, it increases with mussel growth and decreases with mussel mortality. Mussel bottom culture makes use of nature and also depends on nature. Cultured mussels are subject to similar environmental factors that influence growth and mortality on natural mussel beds, with additional effects of anthropogenic factors. In this thesis we focus on dynamics of mussel beds and the impact and effectivity of culture activities on mussel production yield. The major objectives are stated as: (1) to better understand the population dynamics of subtidal mussel populations, (2) to analyze what factors determine production efficiency in mussel bottom culture and how this can be improved. On natural mussel beds mussels organise in patterns that enhance food delivery and resilience of the bed. On culture plots mussels are seeded in concentric seeding patterns. Seeding techniques concentrate mussels locally within the culture plot area, resulting in high local mussel densities; this increases competition and limits the spatial re-organisation of mussels in the bed. Consequently, seeding on culture plots is followed by a large size and density dependent seeding loss that ranges from about 40% for seed from fishery to 69% for smaller SMC seed. This loss was the major factor in determining the maximum RBP. Losses in the grow-out stage were substantially lower, a subsequent density dependent loss was found for smaller mussels (<30 mm), and a non-density dependent loss for larger mussels (>30 mm). Shore crab predation is an important factor contributing to the higher losses at seeding. The effect of shore crab predation on mussel biomass production is higher than expected from previous studies. In an experiment on an intertidal culture plot in the Oosterschelde (NL), we observed that shore crab predation peaks directly after seeding and accounted for 33% of the total losses within five weeks after seeding. Spatial patterns in the survival rates of natural mussel beds in the Wadden Sea show better seed survival in areas with intermediate salinity (mean annual salinity 17.5-22.5 mg l-1). This suggests that mussel survival is negatively related to sea star distribution, which is largely controlled by salinity. Natural beds that escape predation are found at lower salinities and mussels on these beds showed low growth rates, also because of a lower food quality in these areas. Mussel culture strongly affects the population dynamics of the subtidal mussel population, through relaying of mussels from natural mussel beds to culture plots. Culture plots are located in more saline regions of the Wadden Sea (mean annual salinity 25.8 mg l-1), compared to natural mussel beds. This activity increased mussel growth and survival because food quality on culture plots is high and predation is prevented. As a result, average biomass production is higher on culture plots than on natural mussel beds and this difference increases over time. A more efficient seed use on the available area, that can be obtained by reducing seeding losses will increase RBP, maximum biomass production and increases maximum profit. Our results suggest that this can be achieved by seeding homogeneously in low densities.

    Greening of Ethiopian Dairy Value Chains: evaluation of environmental impacts and identification of interventions for sustainable intensification of dairy value chains
    Vries, Marion de; Yigrem, Sintayehu ; Vellinga, Theun - \ 2016
    Wageningen : Wageningen UR Livestock Research (Livestock Research report 948) - 69
    dairy herds - dairy performance - improvement - dairy industry - sustainability - nutrient use efficiency - environmental impact - intensification - ethiopia - melkveestapel - melkresultaten - verbetering - zuivelindustrie - duurzaamheid (sustainability) - nutriëntengebruiksefficiëntie - milieueffect - intensivering - ethiopië
    5 jaar Wageningen Potato Centre (WPC)
    Brouwer, T.A. ; Tramper, M. ; Visser, R.G.F. - \ 2015
    Wageningen : Wageningen UR
    akkerbouw - aardappelen - wetenschappelijk onderzoek - landbouwbedrijven - proefbedrijven - kennisoverdracht - verbetering - arable farming - potatoes - scientific research - farms - pilot farms - knowledge transfer - improvement
    Het kennisplatform Wageningen Potato Centre (WPC) is een initiatief van Wageningen UR om een brug te slaan tussen wetenschap en bedrijfsleven. Strategisch en fundamenteel wordt toegankelijk én toepasbaar gemaakt voor de partners van WPC.
    Weerbaarheid, ook tegen plantenvirussen!
    Stijger, C.C.M.M. ; Verbeek, M. - \ 2015
    Wageningen UR
    gewasbescherming - tuinbouw - plagenbestrijding - virussen - bodemweerbaarheid - verbetering - conferenties - biologische bestrijding - plant protection - horticulture - pest control - viruses - soil suppressiveness - improvement - conferences - biological control
    Minder virus (schade) in een economisch rendabele en duurzame teelt door: 1. Afbraak virusdeeltjes door bacteriën/schimmels. 2. Vatbaar wordt onvatbaar door genetische aanpassing van de plant. 3. Symptoomonderdrukking. Poster van PlantgezondheidEvent 12 maart 2015.
    Various ways for successful Cultivar introduction in the market
    Nuijten, H.A.C.P. ; Zeelenberg, A. ; Janmaat, L. ; Lammerts Van Bueren, E. - \ 2015
    Louis Bolk Instituut
    marketing - marketingkanalen - appels - gevalsanalyse - cultivars - ziekteresistentie - fruitteelt - agro-industriële ketens - verbetering - biologische productie - biologische landbouw - marketing - marketing channels - apples - case studies - cultivars - disease resistance - fruit growing - agro-industrial chains - improvement - biological production - organic farming
    In this brochure key obstacles and opportunities for market introduction of disease-resistant cultivars of apple and potato are described. Various solution pathways have been compared. The comparison focuses strongly on apple because many experiences have been gained with the introduction of scab resistant cultivars. Four solution pathways are described with four case studies.
    Get a taste of new talented Robust potato cultivars
    Lammerts Van Bueren, E. ; Janmaat, L. - \ 2015
    Louis Bolk Instituut
    marketing - aardappelen - consumptieaardappelen - verbetering - ziekteresistentie - biologische landbouw - phytophthora - cultivars - akkerbouw - marketing - potatoes - table potatoes - improvement - disease resistance - organic farming - phytophthora - cultivars - arable farming
    In the potato breeding programme Bioimpuls, the Louis Bolk Institute and Wageningen UR are working together with breeding companies and farmer-breeders to develop robust cultivars that are resistant to Phytophthora. Thanks to these new cultivars, organic growers now have more chance of yield security. The next step is to collaborate with organic wholesalers and retailers to make sure that the new cultivars reach the shop shelves and consumers’ plates. In the Netherlands, the organic market has already accepted new cultivars such as Bionica, Sarpo Mira and Carolus, but other cultivars are still relatively unknown, and additional promising cultivars will become available for the European market in the near future. Together, these cultivars will offer a complete assortment of boiling, baking and multi-purpose potatoes in various colours and shapes. The new talents are presented in this brochure.
    Using agronomic tools to improve pineapple quality and its uniformity in Benin
    Fassinou Hotegni, V.N. - \ 2014
    Wageningen University. Promotor(en): Paul Struik; Jack van der Vorst, co-promotor(en): Willemien Lommen. - Wageningen : Wageningen University - ISBN 9789462570382 - 302
    ananas comosus - ananassen - fruitteelt - gewaskwaliteit - plantmateriaal - heterogeniteit - verbetering - gewasfysiologie - benin - ananas comosus - pineapples - fruit growing - crop quality - planting stock - heterogeneity - improvement - crop physiology - benin

    Keywords: Ananas comosus; Benin; cultural practices; fruit quality; hapas; heterogeneity; planting material; slips; suckers; supply chain; variation in quality; variation within crop; vigour.

    Poor average quality and uniformity in quality have become major issues in agri-food chains. This is also the case in the pineapple sector in Benin where less than 2% of the fresh pineapple is exported to international markets. The average quality of pineapple delivered to other markets, local and regional, is poor. The present thesis studied the improvement options in the pineapple sector which will help pineapple producers to produce higher pineapple quality for different markets, including international ones. This thesis aimed at (1) understanding how fresh pineapple supply chains are organised in Benin and identifying the bottlenecks for delivering the right pineapple to the right market; (2) increasing our knowledge on the agronomic tools used by pineapple producers to produce pineapple fruits; (3) understanding how agronomic factors affect pineapple quality and harvesting time, and (4) proposing and discussing the trade-offs between cultural practices. Research included analysis of supply chains and cropping systems and field experimentation.

    To understand how fresh pineapple supply chains are organised, 54 semi-structured interviews were held with key informants and 173 structured interviews with actor groups. Results indicated six main actor groups in the fresh pineapple chains: primary producers, exporters, wholesalers (those selling at local markets and those selling at regional markets), processors, retailers, and middlemen. Two pineapple cultivars were grown: Sugarloaf and Smooth Cayenne, with Sugarloaf being dominant in local and regional markets and Smooth Cayenne in European markets. The main constraints hampering the effectivity of the chains were: the non-controlled conditions under which the pineapple was transported from one actor group to another, the lack of appropriate storage facilities at wholesaler’s and processor’s levels, the unavailability of boxes for export and the non-concordance between actor groups in which quality attributes and criteria they valued most. In addition, most respondents interviewed affirmed that the pineapple quality was highly heterogeneous, emphasising the need to understand how pineapple is grown in Benin and what the constraints for producing high pineapple quality are.

    To find out the agronomic tools in use by pineapple producers in Benin, interviews were held with 100 producers in the pineapple production areas. Pineapple production practices proved diverse for both cultivars in planting density, flowering induction practice and fertiliser application. The production systems of the two pineapple cultivars differed in planting material used (slips in cv. Sugarloaf; hapas plus suckers in cv. Smooth Cayenne); the use of K2SO4 (not commonly used in cv. Sugarloaf and commonly used in cv. Smooth Cayenne); the number of fertiliser applications (lower in cv. Sugarloaf than in cv. Smooth Cayenne) and in the maturity synchronisation practice by means of Ethephon (not commonly used in cv. Sugarloaf and commonly used in cv. Smooth Cayenne). Constraints for high quality production were the unavailability of planting material, unavailability and high costs of fertilisers and the heterogeneity in planting material weight.

    To understand how agronomic factors affect pineapple quality and harvesting time, four on-farm experiments were conducted in commercial pineapple fields. Results first indicated that the heterogeneity in fruit weight was a consequence of the heterogeneity in plant vigour at artificial flowering induction time. The plant vigour at flowering induction was mainly related with the infructescence weight and less or not with crown weight. Second, results indicated that artificial flowering induction gave fruits with lower infructescence weight and heavier crown than natural flowering induction. Artificial maturity induction reduced the total soluble solids (TSS) concentration in the fruits. Finally, results showed that the reason why a high proportion of fruits in cv. Sugarloaf was not exportable to Europe was the high value in the ratio crown: infructescence height (above 1.5); in cv. Smooth Cayenne, reasons were a ratio crown: infructescence height as well as a TSS below 12 ºBrix.

    To come up with improvement options for high pineapple quality production with low heterogeneity in quality, the possibility of pruning slips on selective plants as means to improve uniformity in fruit quality was evaluated through two on-farm experiments on commercial fields with cv. Sugarloaf. Results revealed that pruning of slips did not significantly improve average fruit quality attributes and was not successful in achieving more uniform fruit quality at harvesting time. Through one experiment per pineapple cultivar, we investigated how fruit quality and its variation were affected by weight (in both pineapple cultivars) and type (in cv. Smooth Cayenne only) of planting material. Results showed that fruits from heavy planting material had heavier infructescence and fruit weights, longer infructescence height, but shorter crown height and smaller ratio crown: infructescence height than those from light planting material. In cv. Sugarloaf fruits from heavy planting material had higher variation in crown weight and lower variation in infructescence height than fruits from light and mixed (light plus heavy) planting materials. In cv. Smooth Cayenne, fruits from heavy planting material had a lower variation in fruit height than fruits from other classes of planting material. The type of planting material (in cv. Smooth Cayenne) had no effect on the average fruit quality attributes except on the crown height where fruits from hapas had shorter crowns than those from suckers. The type of planting material had in overall no significant effect on the variation in the fruit quality attributes.

    The present study is a step towards the improvement of the whole pineapple sector in Benin. It identified constraints for high pineapple quality production but also tested and proposed improvement options for high pineapple quality production.

    Improving the quality of crude palm oil: transdisciplinary research on artisanal processing in Kwabibirem District, Ghana
    Osei-Amponsah, C. - \ 2013
    Wageningen University. Promotor(en): Leontine Visser; M.K. Abekoe, co-promotor(en): Tjeerd-Jan Stomph; O. Sakyi-Dawson. - Wageningen : Wageningen UR - ISBN 9789461737588 - 146
    palmoliën - kwaliteit - verbetering - verwerking - olieproducten - plattelandsontwikkeling - ghana - palm oils - quality - improvement - processing - oil products - rural development - ghana
    Coordination mechanisms for quality improvement and market access in Ethiopian potato value chains
    Abebe, G.K. - \ 2013
    Wageningen University. Promotor(en): Onno Omta; Ruerd Ruben, co-promotor(en): Jos Bijman. - S.l. : s.n. - ISBN 9789461735713 - 220
    ketenmanagement - voedselketens - aardappelen - kwaliteitszorg - verbetering - agro-industriële ketens - solanum tuberosum - boeren - gewasproductie - marketing - ethiopië - supply chain management - food chains - potatoes - quality management - improvement - agro-industrial chains - solanum tuberosum - farmers - crop production - marketing - ethiopia

    Market access for smallholders in developing countries often requires the improvement of product quality. As products are traded in value chains, quality improvement entails the coordination of activities and decisions by all actors in the chain. Thus, enhancing smallholders’ commercialization requires, for instance, making significant investment in production technologies, availing market oriented varieties, and establishing well-functioning input and output markets. Markets are one form of institutions providing coordination functions. From the perspective of new institutional economics (NIE), there are also other types of institutions (e.g., contract farming, producer organizations, etc.) facilitating economic exchange,

    This thesis aims to gain insights into the factors affecting smallholders to improve quality and market access by analyzing their relationship with upstream and downstream actors and generateinformation relevant for the development of sustainable value chains in the potato sector.

    The thesis has demonstrated that farmers’ assessment of production- and market-related attributes of local potato varieties strongly influence their decision to adopt improved varieties (IVs). Thus, enhancing the uptake of IVs requires development of varieties with market-related quality attributes, adequate information exchanges, and joint (or delegated) decision-making. Regarding smallholders’ downstream relationship, most transactions are carried out at farmgate. This type of arrangement has provided a better opportunity for buyers to closely monitor quality and for smallholders to minimize the risk of opportunism in the spot market. In farmer-buyer relationships, coordination is largely enforced through reputation effects and repeated interactions.

    Although farmgate and trust-based contractual relationships can provide better incentives to improve quality, smallholder commercialization in highly ruminative markers, such as the regional market, needs more integrated type of coordination, such as contract farming arrangement.To this effect, the thesis provides an analytical framework to analyse contractual relations in a contract farming scheme by conceptualizing smallholders’ preferences as a multi-category discrete choice problem, where the choice of a contract is modelled as a set of different contract design attributes. Smallholders’ preferences for specific contract design attributes can largely be explained from the perspective of smallholders’ risk aversion behaviour and entrepreneurship traits. The findings showed that smallholders’ willingness to participate in a contract farming scheme increases if the contractual relationship is based on a written form; inputs, technical assistance, and seed supplied by the buyer firm; and variable output quality and variable price specifications. While the uncertainty in the input market motivates farmers for participation, the risk of underpayment (when accepting a fixed-price contract) and the lack of freedom to make autonomous decisions in the output market tend to refrain them from participation. In this regard, the thesis has provided an argument about the significance of institutional support (for instance, supplying the necessary inputs through farmer organizations) and flexible contracts to ease the tension and thus to stimulate smallholders to participate in contract farming.

    Assuring dairy cattle welfare : towards efficient assessment and improvement
    Vries, M. de - \ 2013
    Wageningen University. Promotor(en): Imke de Boer; Eddy Bokkers; T. Dijkstra. - [S.l.] : s.n. - ISBN 9789461735669 - 130
    melkkoeien - melkvee - dierenwelzijn - verbetering - beoordeling - indicatoren - kwaliteit - evaluatie - modellen - melkveestapel - huisvesting van koeien - rundveehouderij - melkveehouderij - dairy cows - dairy cattle - animal welfare - improvement - assessment - indicators - quality - evaluation - models - dairy herds - cow housing - cattle husbandry - dairy farming

    In many countries, there is an increasing interest to assure the welfare of production animals. On-farm assessment of dairy cattle welfare, however, is time-consuming and, therefore, expensive. Besides this, effects of housing and management interventions that are aimed at improving welfare can be conflicting for different indicators of dairy cattle welfare. The research described in this thesis aimed to contribute to assurance of dairy cattle welfare by evaluating strategies to improve time-efficiency of welfare assessment and by identifying housing and management interventions for welfare improvement. Results presented are based on an observational study among 194 selected Dutch dairy herds. From these herds, data relating to housing, management, and indicators of the Welfare Quality (WQ) protocol for dairy cattle was collected on-farm, and routine herd data (RHD), relating to demography, management, milk production, milk composition, and fertility, was extracted from several national databases. Because in many countries RHD are regularly collected from dairy farms, it was hypothesized that RHD could be used to identify herds with potentially poor animal welfare and, therefore, reduce the number of on-farm assessments that are needed to identify these herds. Results of the literature review showed that variables of RHD have been associated with almost half of the welfare indicators in the WQ protocol for dairy cattle. When RHD and welfare data collected in the observational study were used to evaluate the value of RHD for predicting dairy cattle welfare at the herd level, predictions based on RHD for welfare indicators varied from less to highly accurate. For most welfare indicators, therefore, RHD can serve as a pre-screening test for detecting herds with poor welfare and reduce the number of on-farm assessments. In order to decide whether a herd should be visited following a pre-screening, however, value judgments about the overall welfare of herds need to be made. This requires combining welfare indicators in an overall score that reflects the multidimensional nature of welfare and the relative importance of indicators. The relative importance of indicators was evaluated for welfare classification of our study herds based on the WQ multicriteria evaluation model. Results showed that a limited number of indicators had a strong influence on classification of herds, and classification was not very sensitive to indicators of good health, such as prevalence of severely lame cows. As a different strategy for improving time-efficiency of welfare assessment, reduction of the time per on-farm assessment of the WQ protocol for dairy cattle was explored. Reduction of on-farm assessment time was simulated by omitting welfare indicators from the WQ protocol, and replacing observed values of omitted indicators by predictions based on remaining welfare indicators in the protocol. Because results showed that agreement between predicted and observed values of indicators was poor to moderate, it was concluded that this strategy has little potential to reduce on-farm assessment time. To contribute to knowledge of housing and management interventions that may lead to improvement of dairy cattle welfare, housing and management factors associated with various indicators in the WQ protocol were identified and compared. Surface of the lying area and pasturing in summer were commonly associated with the prevalence of lameness, lesions or swellings, and dirty hindquarters, but no common risk factors were identified for the average frequency of displacements and other welfare indictors. In conclusion, the present work shows that routine herd data can be used to improve time-efficiency of welfare assessment, whereas replacing welfare indicators by predictions based on other welfare indicators cannot. The WQ multicriteria evaluation model for classification of dairy cattle welfare has limitations in its current form. A softer surface of the lying area and pasturing in summer can enhance simultaneous improvement of multiple welfare indicators.

    Economic and agronomic analysis of the seed potato supply chain in Ethiopia
    Tufa, A.H. - \ 2013
    Wageningen University. Promotor(en): Alfons Oude Lansink; Paul Struik, co-promotor(en): Miranda Meuwissen; Willemien Lommen. - S.l. : s.n. - ISBN 9789461735430 - 170
    pootaardappelen - zaadkwaliteit - verbetering - voedselketens - ketenmanagement - houding van boeren - voedselzekerheid - productie - solanum tuberosum - aardappelen - economische analyse - prestatieniveau - ethiopië - seed potatoes - seed quality - improvement - food chains - supply chain management - farmers' attitudes - food security - production - solanum tuberosum - potatoes - economic analysis - performance - ethiopia
    Production and productivity of potato in Ethiopia are very low because of poor quality seed tubers and unavailability of seed tubers of improved varieties. These poor quality seed tubers and unavailability of seed tubers of improved varieties are caused by economic and agronomic factors. This thesis deals with economic and agronomic aspects that affect quality and availability of seed potatoes in Ethiopia. It encompasses analysis of strengths and weaknesses of seed potato systems currently operating in Ethiopia, elicitation of farmers’ opinions on management attributes that they believed to affect yield and quality of potato, cost-effective seed potato production plans for farmers in Ethiopia, and analysis of performance of existing and potential seed potato supply chains. The results of this thesis indicate that seed quality and availability can be improved by improving economic and agronomic aspects of the seed systems in general and seed supply chains in particular.
    Nog een flinke slag te maken : zuivel goed op weg met duurzaamheid
    Doornewaard, G.J. ; Reijs, J.W. ; Beldman, A.C.G. - \ 2013
    V-focus 10 (2013)3. - ISSN 1574-1575 - p. 32 - 35.
    melkveehouderij - zuivelindustrie - duurzaamheid (sustainability) - verbetering - duurzame veehouderij - dairy farming - dairy industry - sustainability - improvement - sustainable animal husbandry
    De Duurzame Zuivelketen wil Nederland koploper maken op het gebied van duurzaamheid. Om dit te bereiken, zijn doelen geformuleerd op uiteenlopende thema’s. Op basis van gegevens uit 2011 is een nulmeting uitgevoerd, welke inzicht geeft in waar de sector staat en welke uitdagingen er nog liggen.
    Precisie irrigatie: Verbeteren van het irrigatiesysteem voor de chrysantenteelt
    Tuijl, B.A.J. van; Vermeulen, T. ; Winkel, A. van; Lier, G. van - \ 2013
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1229) - 34
    chrysanthemum - irrigatiesystemen - verbetering - teelt onder bescherming - snijbloemen - optimalisatiemethoden - onderhoud - nederland - chrysanthemum - irrigation systems - improvement - protected cultivation - cut flowers - optimization methods - maintenance - netherlands
    Samenvatting Vanwege knelpunten in de irrigatiesystemen is in dit project onderzocht welke knelpunten er zijn, wat de oorsprong is vandeze knelpunten en of er verbeteringen mogelijk zijn op de bestaande systemen, dan wel volledig nieuwe irrigatiesystemen ontworpen kunnen worden. Uit een inventarisatie bleek dat er een grote diversiteit is in de praktijk aan gebruik van nozzles, inrichting en vooral het onderhoud van de irrigatiesystemen. Daarbij bleek dat de on-uniformiteit bij enkele onderzochte bedrijven groter was dan de betrokken ondernemers dachten. Op basis van de beschikbare kennis over irrigatie moest echter geconcludeerd worden, dat niet zozeer de kennis ontbreekt, maar dat deze kennis veelal niet wordt toegepast. Voorbeelden hiervan zijn verkeerde installatie van het hele systeem (doorrekening op papier), te grote drukvallen door verkeerde uitvoering (bv. verkeerde koppelstukken, verkeerde inschatting van de druk bij gebruik van slootwater in plaats van basinwater), te lang gebruik van nozzles en het achterwege blijven van periodieke reiniging en controle. Vanwege deze situatie heeft het project zich gericht op het vergroten van de bewustwording door het ontwerpen van een eenvoudig meetinstrument. Dit instrument stelt ondernemers in staat periodiek en vergelijkbaar (binnen het bedrijf en met andere bedrijven) de uniformiteit van de irrigatieverdeling te bepalen. Op basis van deze informatie kan de ondernemer acties nemen op het gebied van onderhoud. Vervolgens is alternatieve irrigatieprincipes voor doorontwikkeling in de toekomst. Principes als spuitboom, onderlangs druppel irrigatie of ingegraven ‘zweetslangen’ bleken in eerste ronden van toetsing al niet geschikt voor toepassing in de chrysantenteelt. Uit deze inventarisatie kwam wel naar voren dat er mogelijk perspectieven zijn voor het ontwikkelen van (draadloze) vochtsensornetwerken, zodat de kwaliteit van irrigatie kwantitatief gemonitord kan worden op de plek waar het er toe doet: in de wortelzone. Puntsgewijs concluderen we de volgende aanbevelingen voor de praktijk: 1. ga in studiegroepen aan de gang met het meetprotocol en leer de ondergrens - zie Bijlage 1 2. bewuster bezig zijn bij installatie - zie Bijlage 2 en 3 3. op het bedrijf 2-3 maal per jaar de uniformiteit meten en het verloop zien - en daarop inspelen met onderhoud (reiniging, vervangen van doppen, eventueel verdere monitoring van drukverlies in het systeem - en vervanging/reiniging van systeemcomponenten). 4. voer vervolgstudies uit naar de relatie tussen uniformiteit en kwaliteitsverlies: wat kost het om 10% over of onder te irrigeren? 5. verdere ontwikkeling van irrigatiesystemen in de toekomst toespitsen op kwantitatieve sturing van irrigatie -vochtsensoren in de grond.
    Milieurapportage Boom- en Vaste Plantenteelt van 2009 en 2010 : grote afname van de milieubelasting inmiddels gerealiseerd
    Sluis, B.J. van der - \ 2012
    Lisse : Praktijkonderzoek Plant & Omgeving BBF - 72
    boomkwekerijen - vasteplantenkwekerijen - maatregelen - milieubeheer - milieutoets - doelstellingen - innovaties - verbetering - forest nurseries - perennial nurseries - measures - environmental management - environmental assessment - objectives - innovations - improvement
    In de boomkwekerij en de vaste plantenteelt is de milieubelasting in de periode 1998-2010 met maar liefst 86% gedaald. In de totale land- en tuinbouw is dit 85%. De doelstelling was 95% en is dus niet helemaal gehaald. Duidelijk is dat de boomkwekerij forse inspanningen heeft geleverd en dat de boomkweker blijft innoveren om de milieubelasting verder terug te dringen. Verdere afname zal nog een grote inspanning vergen. De sector geeft tegelijkertijd aan dat verdere maatregelen wel bedrijfseconomisch verantwoord moeten zijn.
    Roofmijten tegen trips in roos
    Pijnakker, J. ; Leman, A. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1201) - 30
    rozen - rosaceae - insectenplagen - thrips - roofmijten - roofinsecten - anthocoridae - phytoseiidae - biologische bestrijding - verbetering - glastuinbouw - nederland - roses - rosaceae - insect pests - thrips - predatory mites - predatory insects - anthocoridae - phytoseiidae - biological control - improvement - greenhouse horticulture - netherlands
    De californische trips Frankliniella occidentalis (Pergande) van de familie van de Thripidae komt oorspronkelijk uit de westkust van Californië (Bryan & Smith, 1956). Haar introductie in Europa dateert van 1984. In de glastuinbouw is californische trips, één van de belangrijkste plagen. Ze vormt het belangrijkste struikelblok voor de verdere uitbreiding van geïntegreerde bestrijding. In roos kan slechts een kleine aantal tripsen belangrijke schade veroorzaken. Veel telers hanteren bij een wekelijkse telling een aantal van 10 tripsen op een blauwe signaalplaat als schadedrempel. Tripsen zijn moeilijk te bestrijden omdat ze zich in het gewas verschuilen en resistent zijn tegen veel insecticiden. De meest gebruikte chemische tripsmiddelen zijn Match (lufenuron), Conserve (spinosad), Vertimec (abamectine), Actara (thiamethoxam) en Mesurol (methiocarb). De laatste 10 jaren heeft geïntegreerde bestrijding zich in roos enorm ontwikkeld. In 2012 introduceert meer dan 70% van de rozentelers roofmijten tegen spint en/of trips en/of kaswittevlieg. In 2002 paste slechts 15% van de Nederlandse rozentelers jaarrond geïntegreerde gewasbescherming toe. Voor het gewas roos is een reeks roofmijtensoorten geschikt gebleken uit onderzoek in voorafgaande projecten. Het project heeft als doel de beste strategie te vinden voor de rozenteelt en met voorkeur voor een roofmijtensoort met affiniteit voor roos (vestiging).
    Verbetering spuittechniek in de teelt van potplanten
    Staaij, M. van der; Weel, P.A. van; Hamelink, R. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1207) - 36
    spuiten - verbetering - technieken - glastuinbouw - potplanten - vergelijkingen - teeltsystemen - optimalisatie - nederland - spraying - improvement - techniques - greenhouse horticulture - pot plants - comparisons - cropping systems - optimization - netherlands
    In de teelt van potplanten is spuittechniek een belangrijk aandachtspunt. Twee type potplantenbedrijven zijn te onderscheiden: teelten op de grond/betonvloer (vaste teelten) of op rolcontainers (mobiele teelten). Beide typen vragen om een verschillende aanpak. Potplanten op rolcontainer (Calathea): Voor potplanten op rolcontainers (mobiele teelt) werden een spuitboom met luchtondersteuning, het Hoge Druk Systeem van Arend-Sosef en het Pieton Systeem van Van der Ende Pompen vergeleken met een conventionele spuitboom. De bedekking van de onderkant van de bladeren verbeterde bij alle spuitconfiguraties t.o.v. de conventionele spuitboom. De percentages bedekking liepen op van 15 naar 30 procent bij grote planten van 50 cm hoogte tot 60 procent op kleine planten van 30 cm hoog. Het heen en weer spuiten leverde bij alle methoden een verbetering van 7 tot 14 procent op t.o.v. een enkelvoudige bespuiting. Hierbij moet worden aan getekend dat dit alleen in grote planten is uitgevoerd. Tijdens de proeven werd stekend gespoten onder een hoek van 45°. Bij grote planten bleek deze hoek te groot. De wolk druppeltjes rolde over het gewas heen in plaats van er doorheen. Verkleinen van de hoek naar 35° en 25° gaf een verbetering van de bedekking van de onderkant van de bladeren. Potplanten op betonvloeren (Bananenplanten): Voor potplanten op beton vloeren (vaste teelt) werden aan een conventionele spuitboom spuitlansen met elk twee spuitkopjes gemonteerd. Met de spuitlansen werd van onderaf in het gewas gespoten (onderdoor spuiten). Met een conventionele spuitboom werd een bedekkingspercentage op de onderkant van de bladeren behaald van 0,5 tot 5 procent. Met het onderdoor-spuiten werden bedekkingspercentages behaald tot 50 procent. Abstract Spraying techniques are a major concern in the cultivation of potted plants. Two types of potted plant cultivation can be distinguished: crops on the ground / concrete floor (immobile culture), or crops on roll containers (mobile culture). Each type requires a different approach. Pot plants on a mobile container (Calathea): For pot plants in mobile containers (mobile culture), two spraybars with air support, were compared to a conventional spraybar. The spraybars with air support were the high pressure system from Arend-Sosef and the Pieton system from Van der Ende Pumps. The deposition of liquid on the untherside of the leaves increased with with both spraybars compared to the conventional spraybar. The coverage rates rose from 15 to 30% for large plants (50 cm high) to 60% for small plants (30 cm high). Spraying back and forth improved coverage by 7 to 14% for all methods compared to a single spraying. It should be noted that this was only performed with large plants. The spray was applied at an angle of 45 degrees during the trials, however this angle was to large for large plants. The droplets passed over the crop, rather than through it. Reduction of the angle to 35 and 25 degrees improved the deposition on the untherside of the leaves. Pot on concrete floors (Banana Plants): For potted plants on concrete floors (immobile culture) spraylances with two spray nozzles were added to a conventional spraybar. The crop was sprayed from below (spraying underneath) with the lances. The covered area on the untherside of the leaves was 0.5 to 5% with the conventional spraybar, whereas the coverage percentages achieved went up to 50% by spraying from below.
    Verbetering uitzetmethode van sluipwespen tegen bladluis
    Bloemhard, C.M.J. ; Messelink, G.J. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1188) - 27
    insectenplagen - aphidoidea - sluipwespen - uitzettingstechnieken - verbetering - paprika's - glastuinbouw - biologische bestrijding - nederland - insect pests - aphidoidea - parasitoid wasps - release techniques - improvement - sweet peppers - greenhouse horticulture - biological control - netherlands
    Referaat Sluipwespen worden door veel biologische paprikatelers wekelijks preventief ingezet, om zo snel mogelijk bladluishaarden te laten parasiteren. Dit onderzoek heeft laten zien dat de levensduur van sluipwespen met zo’n 6 dagen verlengt kan worden door ze te voorzien van suikers. Zonder deze suikers zijn de meeste wespen na 6-7 dagen al dood. Het is daarom aan te bevelen om de sluipwespen die worden ingezet, vlak na uitkomst suikers aan te bieden. Een mix van sucrose, glucose en fructose is daar zeer geschikt voor. Op het moment dat et al. bladluis in de kas aanwezig is, lijkt een extra suikerbron weinig meer toe te voegen. In een kooiproef met Aphidius matricariae leidde toevoeging van suikers niet tot hogere parasiteringspercentages van rode perzuikluis. Blijkbaar is de honingdauw van de bladluizen zelf ook een belangrijker suikerbron. Een andere manier om sluipwespen in kasteelten in stand te houden is door middel van alternatieve bladluizen die worden aangeboden op bankerplanten. Uit dit onderzoek blijkt dat van de graansoorten wintertarwe zich het beste handhaaft onder zomers kasomstandigheden en de beste productie van de grote graanluis Sitobion avenae geeft. De plantengroei gaat nog beter op een stikstofarm substraat van vermiculiet en potgrond. Dit leverde compactere planten op wat gunstig is voor de bladluizen. Deze graanluis is geschikt voor de vermeerdering van Aphidius ervi, maar in vergelijking met de commercieel gekweekte sluipwespen van deze soort, zijn de wespen van graanluis ca. 30% kleiner. Het is bekend dat kleinere wespen minder nakomelingen produceren. Een voordeel van bankerplanten is dat er een continue stroom van “verse” sluipwespen in de kas terechtkomt. Abstract Most organic sweet pepper growers release aphid parasitoids weekly in their crop, in order to parasitize new aphid colonies as soon as possible. This study has shown that the lifetime of parasitoids can be prolonged with about 6 days by providing parasitoids sugars. Without these sugars, most parasitoids died after 6-7 days. It is therefore recommended to offer parasitoids sugars shortly after they emerge from aphid mummies. A mixture of sucrose, glucose and fructose is very suitable for this purpose. Sugars seems to have less additional value for parasitoids when aphids are present is a crop. In a cage experiment with Aphidius matricariae, the addition of sugars did not results in higher rates of parasitism of red peach aphids. Apparently the honeydew of aphids themselves was an important source of sugar. Another way to maintain parasitoids in greenhouses can be achieved through alternative aphids that are offered on banker plants. This study shows that winter wheat was the most suitable monocotyle plant for producing the cereal aphid Sitobion avenae. The plants performed even better on a substrate of vermiculite and potting soil with low nitrogen levels. This resulted in more compact plants which is favourable for the aphids. This grain aphid species is a suitable host for Aphidius ervi, but parasitoids produced on cereal aphids were approximately 30% smaller than the commercially grown parasitoids of this species. It is known that smaller parasitoids produce less progeny. However, an advantage of the banker plant system is the continuous production of "fresh" parasitoids into the greenhouse.
    Verbetering bloeizekerheid bij potplanten en snijbloemen met behulp van moleculaire toetsen
    Kromwijk, J.A.M. ; Noort, F.R. van; Verhoef, N. ; Balk, P. ; Lamers, R. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1168) - 44
    potplanten - snijbloemen - sierteelt - glastuinbouw - bloei - verbetering - moleculaire technieken - tests - nederland - pot plants - cut flowers - ornamental horticulture - greenhouse horticulture - flowering - improvement - molecular techniques - tests - netherlands
    Abstract In several ornamentals there is insufficient certainty about the flowering results. Wageningen UR Greenhouse Horticulture and NSure have investigated whether flowering results can be improved with the development of molecular tests. In crops such as snowball (Viburnum opulus 'Roseum’), Hydrangea, azalea and Syringa flower buds go into winter dormancy in autumn. Flowering results of these crops can be improved when it is possible to measure when winter dormancy is sufficiently broken to force these crops successfully. For Viburnum a molecular test has been developed and successfully tested. For Hippeastrum, Bromelia, Cymbidium, Miltonia, Nerine and Zantedeschia it was investigated whether development of a molecular test can improve flowering results. For Cymbidium a greenhouse experiment was conducted with 0, 2, 4, 8, 13 and 16 weeks 13 oC from week 44 - 2010 and plant samples were collected at the end of the treatments. As plants stood longer at 13 oC, the number of inflorescences autumn 2011 increased. The collected samples can be used to develop a molecular test in the future.
    Opties voor provinciaal beleid ter verbetering van het welzijn van dieren in Zuid-Holland = Policy options for the improvement of the welfare of animals in the province of Zuid-Holland
    Hopster, H. ; Groot Bruinderink, G.W.T.A. ; Bracke, M.B.M. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 535) - 43
    dierenwelzijn - verbetering - gebiedsgericht beleid - provincies - zuid-holland - laboratoriumdieren - gezelschapsdieren - animal welfare - improvement - integrated spatial planning policy - provinces - zuid-holland - laboratory animals - pets
    For livestock, companion animals, laboratory animals and wildlife, the major threats to animal welfare in the province of Zuid-Holland are appointed. Within the duties and powers of the province 30 recommendations are designed to improve animal welfare.
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