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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Using yield gap analysis to give sustainable intensification local meaning
Silva, João Vasco - \ 2017
Wageningen University. Promotor(en): M.K. Ittersum, co-promotor(en): K.E. Giller; P. Reidsma. - Wageningen : Wageningen University - ISBN 9789463437141 - 361
crops - yields - crop yield - modeling - simulation models - cereals - farming systems - yield losses - gewassen - opbrengsten - gewasopbrengst - modelleren - simulatiemodellen - graansoorten - bedrijfssystemen - oogstverliezen

Yield gap analysis is useful to understand the relative contribution of growth-defining, -limiting and -reducing factors to actual yields. This is traditionally performed at the field level using mechanistic crop growth simulation models, and directly up-scaled to the regional and global levels without considering a range of factors intersecting at farm and farming system levels. As an example, these may include farmers' objectives and resource constraints, farm(er) characteristics, rotational effects between subsequent crops or decisions on resource allocation and prioritization of crop management. The objective of this thesis is to gain insights into yield gaps from a farm(ing) systems perspective in order to identify opportunities for sustainable intensification at local level.

Three contrasting case studies representing a gradient of intensification and capturing a diversity of agricultural systems were selected for this purpose, namely mixed crop-livestock systems in Southern Ethiopia, rice based-farming systems in Central Luzon (Philippines) and arable farming systems in the Netherlands. A theoretical framework combining concepts of production ecology and methods of frontier analysis was developed to decompose yield gaps into efficiency, resource and technology yield gaps. This framework was applied and tested for the major crops in each case study using crop-specific input-output data for a large number of individual farms. In addition, different statistical methods and data analyses techniques were used in each case study to understand the contribution of farmers' objectives, farm(er) characteristics, cropping frequency and resource constraints to yield gaps and management practices at crop level.

Yield gaps were largest for maize and wheat in Southern Ethiopia (ca. 80\\% of the water-limited yield), intermediate for rice in Central Luzon (ca. 50\\% of the climatic potential yield) and smallest for the major arable crops in the Netherlands (ca. 30\\% of the climatic potential yield). The underlying causes of these yield gaps also differed per case study. The technology yield gap explained most of the yield gap observed in Southern Ethiopia, which points to a lack of adoption of technologies able to reach the water-limited yield. The efficiency yield gap was most important for different arable crops in the Netherlands, which suggests a sub-optimal timing, space and form of the inputs applied. The three intermediate yield gaps contributed similarly to the rice yield gap in Central Luzon meaning that sub-optimal quantities of inputs used are as important in this case study as the causes mentioned for the other case studies.

Narrowing the yield gap of the major crops does not seem to entail trade-offs with gross margin per unit land in each case study. However, the opposite seems to be true for N use efficiency and labour productivity particularly in Southern Ethiopia and Central Luzon, and to a less extent in the Netherlands. This means that (sustainable) intensification of smallholder agriculture in the tropics needs to go hand-in-hand with agronomic interventions that increase land productivity while ensuring high resource use efficiency and with labour-saving technologies that can reduce the drudgery of farming without compromising crop yields.

Other insights at farm(ing) system level were clearer in Southern Ethiopia than in Central Luzon or in the Netherlands. For example, alleviating capital constraints was positively associated with intensification of maize-based farming systems around Hawassa and increases in oxen ownership (an indicator of farm power) was associated with extensification of wheat-based farming systems around Asella. In Central Luzon, farm and regional factors did not lead to different levels of intensification within the variation of rice farms investigated and the most striking effect was that direct-seeding (and thus slightly lower rice yields) was mostly adopted in larger farms, and used lower amounts of hired labour, compared to transplanting. In the Netherlands, the analysis of rotational effects on crop yields provided inconclusive results but confounding effects with e.g. rented land do not allow to conclude that these are not at stake in this farming system.

This thesis broadens the discussion on yield gaps by moving from the technical aspects underlying their estimation towards the broader farm level opportunities and constraints undermining their closure. Overall, insights from contrasting case studies support conventional wisdom that intensification of agriculture needs to occur in the 'developing South', where yield gaps are large and resource use efficiency low, while a focus on improving sustainability based on sustainable intensification (or even extensification) is more appropriate in the 'developed North', where yield gaps are small and resource use efficiency high.

Organising trade : a practice-oriented analysis of cooperatives and networks trading cereals in South Mali
Mangnus, E.P.M. - \ 2015
Wageningen University. Promotor(en): Cees Leeuwis, co-promotor(en): Sietze Vellema. - Wageningen : Wageningen University - ISBN 9789462574311 - 178
coöperaties - voedselcoöperaties - graansoorten - handel - katoen - geschiedenis - platteland - landbouw - agrarische handel - mali - west-afrika - cooperatives - food cooperatives - cereals - trade - cotton - history - rural areas - agriculture - agricultural trade - mali - west africa

Abstract

Farmer organisations have become the centrepiece of pro-poor market development strategies in Africa. Assumed to facilitate scale, quality of produce and professionalism they are regarded as a solution for farmers that are hampered from economic opportunities. In Mali public as well as private actors encourage farmers to trade through one specific organisational form, namely cooperatives. Nevertheless, in reality the landscape is much more diverse. A wide array of organisations can be observed and the models stimulated by external actors do not always succeed in improving the position of farmers. Considering the gap in knowledge, this dissertation poses the following question:

How and in what ways do people organise trading of cereals in South Mali?

The central aim of this thesis is to contribute to a better understanding of organisation of food trade in rural markets, by examining how and in what ways people in South Mali organise trade in cereals and sesame. Trading includes the procurement of cereals or sesame, organisation of finance, information gathering, bargaining, the organisation of transport and selling.

Organisation of trade has been studied from different angles. Studies taking a structural approach explain organisation as emerging from context. Studies that approach organisations from an instrumental perspective regard organisation as a means for efficiently solving a shared problem. Both strands provide insights for understanding organisational functioning and performance but leave open questions regarding how people organise to realise trading and why this results in organisational diversity. This thesis examines organising trade by adopting a practice-oriented approach, which has as entry point that organisation takes shape in the realization of everyday practice. Focus is on what people actually do to realise trading.

Two case study organisations are central to the study. Both are typical for how trade in rural Mali is organised. The first is a cooperative engaged in the trading of sesame in Miena, South-East Mali. The second is a cereal trading network in N’golobougou, in the centre of South Mali. Both provide an example of people collaborating and coordinating to perform trading and as such are excellent cases for tracing the formation of organisational traits that explain performance and diversity in trading cereals in South Mali.

Empirical Chapters

Chapter 2 presents a historical overview of how the organisation of trade of cereals and cotton at farmer level developed in Mali on extensive literature research. It focuses on the efforts of the Malian state to organise rural society, how producers responded, and how the interaction between the two shaped organisation. The analysis starts in the 18th century, in which cotton and cereal trade was intertwined and likewise organised. From the colonial period onwards, organisation dynamics in food and export crops evolved distinctly. For both sectors the most important events and changes are detailed. The chapter found that the political economy at stake influences the set of organisational options people can choose from and that imposed models rarely get adopted in practice.

Chapter 3 traces the emergence and development of the sesame cooperative in Miena. It builds on two strands of literature that emphasize the specific socio-historical context of an organisation. The first body highlights the resilience of existing relations and institutions by showing how these get reproduced in new organisations. The second body of literature claims that individuals involved in collective action have the capacity to influence which institutions get reproduced and which new ones get adopted, also called ‘blended’. To collect the data 35 in depth interviews with cooperative members, (ex) officials from the cotton company CMDT, local officers and NGO-workers active in the research location were collected over a period of three months. Time was spent at the weekly market, in village meetings and at peoples’ homes. Moreover 20 informal talks with villagers and traders on the market were afterwards noted down. Three distinct processes - the historical organisation of cotton farmers, the interaction between state and society and the local trade practices - are found to underlie the current functioning of the cooperative. This chapter shows how both the reproduction and blending happen purposively; in order to (continue) performance in trading.

Chapter 4 addresses the question: How do traders in Mali perform collectively? Following the methodological orientation, labelled as technography, the chapter zooms in on the use of skills and know-how by a group of people coordinating the collection and trade of cereals. Data were collected through 24 in-depth interviews with traders and 37 semi-structured interviews with pisteurs and interviews with key resource persons. Moreover, trade practices were observed during 10 market days in a row. The analysis shows that the success of the traders’ network can be explained by: (i) the use of skills and know-how for adapting to changing economic, social and environmental contexts; (ii) the network’s ability to select capable people and distribute the many trading tasks; and (iii) the network’s effective governance, based on a strict code of conduct specific to each role. The chapter shows how rules steering the distribution of tasks and collaboration in the traders’ network emerge out of the daily practice of trading.

Chapter 5 uses evidence from a network of cereal traders in the market of N’golobougou to examine how the characteristics of traders, their positions within different networks, and different kinds of relationships between traders influence performance in trading. 26 traders were extensively interviewed on the history, functioning and the size of their business. Semi-structured interviews focused on their relations in trading. A social network analysis (SNA) is applied to describe the positions of individual traders in the networks and the type of relations that link them. Qualitative analysis is used to understand the motivations underlying their position and collaboration. The findings demonstrate that trading is a complex and multifaceted activity. Within the network distinct networks have emerged to organise the collection of cereals, to arrange finance and to acquire information. Pre-existing social relations facilitate trading but do not guarantee individual success. Proven ability and reputation are equally important in cooperation and relate to the way powerful members of the network acquire a central position, which goes stepwise and takes time.

Conclusions

Collaboration is crucial for trading under the circumstances of rural Mali. Both case studies highlight the role of key individuals who spotted opportunities and mobilised others to collaborate. Different trading activities require specific skills, know-how and tools and people tend to specialise. Most skills are acquired in practice; few of them can be taught by instruction. Accordingly to what is present in terms of capacities, people’s availability and know-how, and tools, groups will distribute tasks among their members.

People also need to coordinate how skills, know-how and tools are distributed over time and space. Trading in South Mali requires bridging of long distances, adaptation to seasonality, securing finance and transport, and finding buyers. The temporal dimension of trading is visible in how traders adapt to seasonality and to how it is adjusted to people’s availability in time. Trading is also spatially situated. Poor infrastructure and long travel distances are characteristic of rural South Mali. Both the cooperative as well as the trading network therefore have a layered structure of actors close to the field, actors in the central village or market where the sesame or cereals are collected, and actors in the city to which the sesame or cereals are transported.

People do not organise in a random constellation. The range of options they can choose from are importantly influenced by the institutions active in decision-making at village level, the relationship between state and rural communities, the social networks people operate in, and the historically developed rules and regulations in market transactions. Also, previous ways of organising play a role in today’s way of organising. The empirical analyses demonstrate that organising trade is ‘path dependent’. Nevertheless, people only reproduce those procedures, habits and actions that are deemed necessary to perform. They blend old and new ways of coordination and collaboration to allow the practice of trade to continue.

The findings in this thesis show that collaboration does not rely on social relations only. Cooperating to achieve a practical end, i.e. to trade, is also skill and competence based. Organisational sustainability depends on how grouped or networked actors coordinate actions in response to changing circumstances and opportunities. Hence, organisational diversity can be understood from the fact that organisation emerges from a situated practice.

Recommendations

Organisation in trade emerges gradually and adaptively from what is present in terms of skills, capacities, know-how and experience in trading. As this is situation specific it is essential to recognize the uniqueness of each organisational form and suggests reconsidering the one-size-fit-all approaches often promoted in development interventions. Imposed organisational structures may be enabling to some extent but they leave little room for exploring the range of possible ways to achieve trading. For understanding how people organise trade it is important to understand the way they perform the actual practice in the specific social and material circumstances. The empirical chapters argue in favour of tutor–apprentice relations between experienced actors and new members, leaving decision-making power and rule setting in the hands of the most experienced traders. Current development projects supporting links between farmers and buyers often aim to be ‘inclusive’ and ‘pro-poor’, meaning that they should be accessible to anyone. The field research shows that organisations in trade in Mali are very selective in membership to assure the group achieves its objectives. Governments and other development actors should be aware of the trade-offs between inclusive, democratic organisational models, and effectiveness and performance in trading.

Jaarverslagen van de KNPV-werkgroepen over 2014: Werkgroep Bodempathogenen en bodemmicrobiologie
Os, G.J. van; Postma, J. - \ 2015
Gewasbescherming 46 (2015)2. - ISSN 0166-6495 - p. 46 - 46.
jaarverslagen - werkgroepen - gewasbescherming - bodempathogenen - bodemmicrobiologie - fusarium - oömyceten - onkruidkunde - nematoda - pathogenen - resistentie tegen insecticiden - resistentie tegen herbiciden - weerstand - bacteriologie - graansoorten - annual reports - working groups - plant protection - soilborne pathogens - soil microbiology - oomycetes - weed science - pathogens - insecticide resistance - herbicide resistance - resistance - bacteriology - cereals
Dit artikel omvat de jaarverslagen van de volgende KNPV-werkgroepen over 2014: Bodempathogenen en bodemmicrobiologie; Fusarium; Oömyceten; Nematoden; Onkruidbeheersing; Middelenresistentie; Fytobacteriologie; Gewasbescherming en Maatschappelijk Debat; Jongeren; Fytobacteriologie; Graanziekten.
Survey on sterigmatocystin in food
Mol, J.G.J. ; Pietri, A. ; MacDonald, S.J. ; Anagnostopoulos, C. ; Spanjer, M. - \ 2015
Parma, Italy : EFSA (EFSA supporting publiation 2015 EN-774) - 56
sterigmatocystine - mycotoxinen - graansoorten - bieren - noten - voedselveiligheid - voedselanalyse - sterigmatocystin - mycotoxins - cereals - beers - nuts - food safety - food analysis
A total of 1 259 samples of cereal grains, cereal products, beer and nuts were analysed for the presence of the mycotoxin sterigmatocystin. Samples were mainly collected at processing plants, storage facilities, wholesale and retail between August 2013 and November 2014, in nine European countries (mostly Greece, Italy, the Netherlands and the United Kingdom (UK), additionally in Cyprus, Germany, Latvia, Lithuania, and Poland). The products originated from 27 European countries and 18 other countries (mostly rice and nuts). The samples comprised cereal grains (221 wheat, 35 rye, 33 maize, 59 barley, 51 oats, 2 spelt, 117 rice), grain milling products (125), pasta (115), bread/rolls (143), breakfast cereals/muesli (97), fine bakery ware (90), cereal-based infant food (54), beer (53), peanuts (28) and hazelnuts (36). All samples were analysed by methods based on liquid chromatography with tandem mass spectrometry (LC-MS/MS).
Proficiency test for allergens in food 2014
Bremer, M.G.E.G. ; Alamenou, P. ; Elbers, I.J.W. - \ 2015
Wageningen : RIKILT Wageningen UR (RIKILT report 2015.002) - 38
graansoorten - zuigelingenvoedsel - allergenen - voedselallergieën - laboratoriumproeven - tests - cereals - infant foods - allergens - food allergies - laboratory tests
In the autumn of 2014 a proficiency test for allergens in baby cereal was organized by RIKILT, Wageningen UR. This PT-test enabled laboratories to evaluate their competence for the analysis of allergens in baby cereal. Both quantitative and qualitative methods were accepted. The proficiency test was carried out according to ISO/IEC 17043, however this specific test is not part of the accreditation.
Mengteelten graan met erwten of veldbonen
Beeckman, A. ; Govaerts, W. - \ 2014
Biokennis bericht Dierlijke sectoren (2014)1. - 4 p.
gemengde teelt - graansoorten - erwten - tuinbonen - voedergewassen - eiwitleverende planten - peulvruchten - biologische landbouw - rassenkeuze (gewassen) - mixed cropping - cereals - peas - faba beans - fodder crops - protein plants - grain legumes - organic farming - choice of varieties
Door de stijgende krachtvoederprijzen – voornamelijk bij de eiwitrijke componenten – stijgt de interesse in eiwitteelten van eigen bodem. De teelt van peulvruchten zoals lupinen, erwten en veldbonen in monocultuur blijft echter een risicovolle onderneming. De voorbije jaren werd zowel in Vlaanderen als in Nederland ruime ervaring opgedaan met mengteelten. Hieronder een aantal praktische wenken gebaseerd op de ervaring en proefresultaten van voorbije jaren.
Meerjarig graan; Mogelijkheden van meerjarige graanachtigen voor erosiebestrijding
Wander, J.G.N. ; Crijns, S. ; Duijzer, F. ; Emmens, E. ; Russchen, H.J. ; Meuffels, G.J.H.M. - \ 2014
Dronten : DLV Plant - 38
akkerbouw - graansoorten - thinopyrum - duurzaam bodemgebruik - teeltsystemen - bodemvruchtbaarheid - bemesting - watererosie - winderosie - meerjarige teelt - rassen (planten) - tarwe - nederland - zuid-limburg - veenkolonien - arable farming - cereals - sustainable land use - cropping systems - soil fertility - fertilizer application - water erosion - wind erosion - perennial cropping - varieties - wheat - netherlands
Meerjarige granen, waaronder Thinopyrum intermedium, wortelen dieper en intensiever en houden daardoor bodem, voedingsstoffen en water goed vast. Voor Nederlandse omstandigheden zou de teelt van dergelijke gewassen dan ook kunnen zorgen voor minder water en/of winderosie, minder milieubelasting (minder uitspoeling) en zuiniger gebruik van inputs.
Proficiency test for tropane alkaloids in food en feed
Pereboom-de Fauw, D.P.K.H. ; Elbers, I.J.W. ; Mulder, P.P.J. ; Nijs, W.C.M. de - \ 2014
Wageningen : RIKILT Wageningen UR (RIKILT report 2014.008) - 35
voer - voedsel - voedselproducten - geldigheid - betrouwbaarheid - laboratoriummethoden - graansoorten - voedselconsumptie - voedselveiligheid - tropaanalkaloïden - feeds - food - food products - validity - reliability - laboratory methods - cereals - food consumption - food safety - tropane alkaloids
Proficiency testing is conducted to provide laboratories with a powerful tool to evaluate and demonstrate the reliability of the data that are produced. Next to validation and accreditation, proficiency testing is an important requirement of the EU Additional Measures Directive 93/99/EEC [1] and is required by ISO 17025:200. The proficiency test for tropane alkaloids was organized by RIKILT, Wageningen UR in accordance with ISO 17043. The primary goal of this study was to provide laboratories with the opportunity to implement a method in their laboratory and to evaluate or demonstrate their performance regarding quantitative analysis of tropane alkaloids in cereals intended for human consumption and in animal feed.
Graanstoppels en akkervogels
Bos, J.F.F.P. - \ 2013
Limosa 86 (2013)3. - ISSN 0024-3620 - p. 123 - 131.
vogels - bouwland - fauna - agrarische bedrijfsvoering - graansoorten - overwintering - foerageren - verenigd koninkrijk - birds - arable land - farm management - cereals - foraging - uk
Graanstoppels vormen in najaar en winter een bron van voedsel voor vogels, met name als tijdens de voorafgaande graanteelt de inzet van herbiciden wordt beperkt, de stoppelvelden vanaf de nazomer bezet raken met onkruiden en ze niet te vroeg in de winter worden geploegd. In het Verenigd Koninkrijk is veel onderzoek gedaan naar de betekenis van graanstoppels voor overwinterende akkervogels. Dit artikel biedt een samenvatting van de inzichten die dit onderzoek heeft opgeleverd, met een doorkijkje naar kansen voor toepassing in Nederland
Wintergranen voor waterberging
Crijns, J. ; Meuffels, G.J.H.M. - \ 2013
Horst : DLV Plant - 12
erosiebestrijding - heuvels - bodemwater - graansoorten - proefprojecten - akkerranden - zuid-limburg - wintertarwe - akkerbouw - erosion control - hill land - soil water - cereals - pilot projects - field margins - winter wheat - arable farming
Bij aanleg van een graanbufferstrook kan mogelijk het erosieremmend effect gecombineerd worden met plantaardige productie. Via een bevloeiingsproef is gezocht naar het waterbergend vermogen van een graanbufferstrook. In een perceel van proefboerderij Wijnandsrade (Zuid-Limburg) met een hellingspercentage van 4% werd aan de onderzijde van het perceel op de wendakker de proef aangelegd.
Adviesbasis voor de bemesting van akkerbouwgewassen : stikstof
Geel, W.C.A. van; Haan, J.J. de - \ 2013
Kennisakker.nl 2013 (2013)20 maart.
stikstofmeststoffen - akkerbouw - graansoorten - aardappelen - suikerbieten - voedergewassen - uien - grassen - groenbemesters - bemesting - nitrogen fertilizers - arable farming - cereals - potatoes - sugarbeet - fodder crops - onions - grasses - green manures - fertilizer application
De stikstofbemestingsrichtlijnen geven de door de jaren heen gemiddelde optimale stikstofgift. De optimale stikstofgift is echter van veel factoren afhankelijk, zoals voorvrucht, bemestingsverleden, vochtvoorziening en ziektedruk. Op basis van de eigen ervaringen en kennis van percelen en gewassen kan de richtlijn dan ook aan de eigen situatie worden aangepast. Daar waar mogelijk zijn in deze adviesbasis richtlijnen gegeven voor dergelijke aanpassingen (o.a. onderwerken van groenbemesters en oogstresten en gebruik van dierlijke mest).
Dutch survey ergot alkaloids and sclerotia in animal feeds
Mulder, P.P.J. ; Raamsdonk, L.W.D. van; Voogt, H.J. ; Brakel, M.W. van; Horst, G.M. van der; Jong, J. de - \ 2012
Wageningen : Rikilt - Institute of Food Safety (Report / RIKILT, Institute of Food Safety 2012.005) - 45
diervoedering - voer - ergotalkaloïden - claviceps purpurea - graansoorten - toxinen - mycotoxinen - animal feeding - feeds - ergot alkaloids - cereals - toxins - mycotoxins
Ergot alkaloids are toxins produced by members of the fungal family of Clavicipitaceae represented among others by Claviceps purpurea, C. paspali, and C. fusiformis, occurring predominantly on rye, wheat and barley, but also on rice, maize and sorghum, oats and millet.
Gierst- Panicum Miliaceum / Eiwit en oliepad
PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2012
gierst - panicum miliaceum - graansoorten - voedselgewassen - vezelgewassen - gewassen - akkerbouw - biobased economy - millets - cereals - food crops - fibre plants - crops - arable farming
Factsheet van het Eiwit en Oliepad met korte informatie over het gewas gierst. Met het project Eiwit & Oliepad wil Innovatief Platteland samen met de gemeente Venray en andere partners het publiek de gelegenheid geven zich een beeld te vormen van de enorme multifunctionaliteit en de nog steeds verder te ontdekken mogelijkheden van in Europa te telen gewassen als grondstof voor de biobased economie
Graansorghum-SorghumBicolor / Eiwit en oliepad
PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2012
sorghum bicolor - gewassen - graansoorten - voedselgewassen - voedergewassen - brandstofgewassen - vezelgewassen - akkerbouw - biobased economy - crops - cereals - food crops - fodder crops - fuel crops - fibre plants - arable farming
Factsheet van het Eiwit en Oliepad met korte informatie over het gewas Graansorghum. Met het project Eiwit & Oliepad wil Innovatief Platteland samen met de gemeente Venray en andere partners het publiek de gelegenheid geven zich een beeld te vormen van de enorme multifunctionaliteit en de nog steeds verder te ontdekken mogelijkheden van in Europa te telen gewassen als grondstof voor de biobased economie
Faunaschade ganzen 2011 : Inventarisatie van schade en extra kosten op een aantal akkerbouwbedrijven met ganzenvraat in granen en graszaad
Vlaswinkel, M.E.T. ; Wijk, C.A.P. van; Uijthoven, W. - \ 2012
Lelystad : Praktijkonderzoek Plant & Omgeving, AGV - 42
beweidingsschade - ganzen - vogelbestrijding - vogelafweermiddelen - oogstschade - akkerbouw - vergoeding - graansoorten - graszaden - gewasbescherming - browsing damage - geese - bird control - bird repellents - crop damage - arable farming - compensation - cereals - grass seeds - plant protection
In 2010 en 2011 zijn in dit project op 6 praktijkbedrijven in totaal 15 praktijkpercelen gevolgd op schade door ganzen en de extra kosten voor verjaging. Het doel was de financiële gevolgen van ganzenschade voor granen en graszaad door een praktijkinventarisatie beter te onderbouwen. Het ging in eerste instantie om schade door overzomerende ganzen. Er zijn diverse waarnemingen gedaan en bij meerdere percelen is bij de oogst de opbrengst bepaald. Verder zijn de maatregelen geïnventariseerd die genomen zijn om de schade te beperken.
The relationship between strigolactones and Striga hermonthica infection in cereals
Jamil, M. - \ 2012
Wageningen University. Promotor(en): Harro Bouwmeester. - S.l. : s.n. - ISBN 9789461731388 - 184
graansoorten - striga hermonthica - parasitaire planten - wortelexudaten - cereals - striga hermonthica - parasitic plants - root exudates

Cereal production in Africa is under increasing constraint due to the obligate, out-crossing, hemiparasitic weed Striga hermonthica (Del.) Benth, a member of the Scrophulariaceae family. Striga parasitizes roots of cereals like sorghum, pearl millet, maize and upland rice. It has infested about 40% of the African agricultural land, resulting in severe yield losses or even complete crop failure worth US billion per annum. The subsistence farmers or approximately 300 million African people lose about 20-80% of their crop because of this weed. This considerable damage by Striga is due to the fact that existing control measures are often ineffective. Since much of the damage occurs underground during the early stages of parasitism, there is a need to develop control strategies that target the weed prior to attachment and emergence. A crucial step in the lifecycle of Striga is the induction of germination by strigolactones, signalling molecules secreted by the roots of its host. These strigolactones could be an important target to control this weed at the pre attachment phase. Control methods targeted at the germination and attachment phase, based on low strigolactones, might prove to be more effective and result in reduced infestation of this weed in cereal crops. In present thesis we studied the relationship between strigolactones and Striga infection in cereals and explored opportunities for lowering Striga damage at the germination or attachment phase. To this end different aspects like strigolactone biosynthetic inhibitors, genetic variation for strigolactone production, and the effect of fertilizers on strigolactone production were investigated in laboratory studies and – when possible - in the field in Kenya and Mali.

The first investigation was on the use of carotenoid inhibitors to see the possibilities of strigolactone reduction in the roots of plants by blocking carotenoid biosynthesis. We postulated in this study that the (mild) inhibition of carotenoid biosynthesis by carotenoid inhibitors, could lead to a reduced production of strigolactones and decreased Striga germination and infection. Very low concentrations of four different carotenoid inhibitors (fluridone, norflurazon, clomazone and amitrole) were applied to rice either through irrigation or through foliar spray. Irrigation application of all carotenoid inhibitors and spray application of amitrole significantly decreased strigolactone production. Application of carotenoid inhibitors caused 61-75% reduction in Striga germination and 65-94% reduction in Striga attachment. The study shows thatthe reducing effect of carotenoid inhibitors (which, in much higher concentrations are widely used as herbicides) on strigolactone secretion and subsequent Striga germination and attachment may be developed into an attractive Striga control technology.

Another experiment was aimed at assessing the pre-attachment Striga resistance based on low strigolactone production. We hypothesized that low strigolactones producing crop cultivars might possess pre-attachment Striga resistance due to less germination. For this purpose a set of 18 upland cultivars of NERICA and their parents were screened for strigolactones production and Striga infection parameters like germination, attachment, emergence and Striga dry biomass. NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection while NERICAs 7, 8, 11 and 14 produced the highest amounts of strigolactones and showed the most severe Striga infection. This study shows that genetic variation for pre-attachment Striga resistance exists in NERICA rice due to variation in strigolactones. This could be highly relevant for breeding programs aimed at the development of Striga resistant cultivars. In another similar study we hypothesized that variation in strigolactone production in rice might be interconnected with the tillering phenotype and that this link could affect Striga infection. In this study the genetic variation was tested in a series of rice varieties collected from all over the world for strigolactone production, tillering phenotype and Striga infection. Rice cultivars like IAC 165, IAC 1246, Gangweondo and Kinko produced high amounts of the strigolactones, displayed low amounts of tillers and induced high Striga germination, attachment, emergence as well as Striga biomass. In contrast to this, rice cultivars such as Super Basmati, TN 1, Anakila and Agee showed low production of strigolactones and also low Striga germination and infection but high tillering. These results show that genetic variation in strigolactone production results in variation in tillering and also in Striga infection. The tillering phenotype could possibly be used as an easy indicator of the strigolactone production in a breeding programme for Striga resistance.

Some experiments were also designed with the aim to quantify the relationship between strigolactones and Striga germination and attachment and to explore the mechanism responsible for the reported reduction in Striga parasitism in the field after fertilizer application. Different levels of nitrogen and phosphorous were applied under greenhouse conditions using rice, maize and sorghum. For maize and sorghum, a parallel study was carried out under field conditions in Kenya and Mali to study the translation of greenhouse results to the field. Application of N and P effectively suppressed Striga infection in the greenhouse in all three crop species and the reduction strongly correlated with reduced secretion of strigolactones into the rhizosphere and the Striga germination induced by these exudates. Although the field results with maize in Kenya were less consistent than in the greenhouse, especially with respect to P effect, still there was a trend that fertilizer application reduced Striga infection. These results show that the positive effect of fertilizer against Striga is at least partly due to a reduction in strigolactone production and as a consequence of that lower Striga germination and subsequent attachment.

Overall it can be concluded that there is a good correlation between strigolactones andStriga germination, attachment and biomass. We found this using strigolactone biosynthesis inhibitors, genetic variation and using fertilizer application. These technologies can hence be exploited as an important tool to target Striga at a very early phase of its life cycle. The practical field application of these strategies requires further research but could lead to effective Striga control components that can be used in Integrated Striga Management.

Fax met DON-advies meestal juist
Schepers, H.T.A.M. ; Spits, H.G. - \ 2011
Boerderij/Akkerbouw 96 (2011)35. - ISSN 0169-0116 - p. E12 - E13.
graansoorten - fusarium - timing - beslissingsondersteunende systemen - mycotoxinen - gewasbescherming - spuiten - opslag - cereals - decision support systems - mycotoxins - plant protection - spraying - storage
Bestrijding van Fusarium in granen kan alleen als tijdens de bloei wordt gespoten, blijkt keer op keer uit PPO-onderzoek. 100 procent bestrijding kan niet.
Bedrijfsinventarisatie van schade en extra kosten van ganzenvraat in granen en graszaad
Wijk, C.A.P. van; Vlaswinkel, M.E.T. - \ 2011
Kennisakker.nl 2011 (2011)8 april.
ganzen - plagenbestrijding - vogelbestrijding - oogstschade - kosten - akkerbouw - graansoorten - graszaden - geese - pest control - bird control - crop damage - costs - arable farming - cereals - grass seeds
Faunaschade is in de akkerbouw een groot probleem en volgens de praktijk wordt faunaschade niet altijd of maar gedeeltelijk vergoed. Op verzoek van het Productschap Akkerbouw is daarom in 2010 op bedrijfsniveau een eerste inventarisatie van de faunaschade uitgevoerd. In 2010 trad er op 4 van de 7 aangemelde percelen daadwerkelijk schade door overzomerende ganzen op, waardoor een groot verschil in opbrengst ontstond. Andere percelen met zichtbare beginschade gaven weinig opbrengstreductie; de periode waarin schade optreedt is erg belangrijk. Ook zat er een groot verschil in de opbrengsten van het stro. Stro is voor veel bedrijven ook een belangrijke bron van inkomsten. De kosten die nodig zijn voor het verjagen van de ganzen bleken uiteen te lopen van € 1.000 tot € 6.000 per perceel. Vooral de tijd die men bezig is met het verjagen ligt vele malen hoger dan vaak wordt ingeschat. Verder is het lastig te achterhalen wanneer iets structuurschade is en wanneer ganzenschade.
Faunaschade ganzen 2010 : eerste inventarisatie van schade en extra kosten op een aantal akkerbouwbedrijven met ganzenvraat in granen en graszaad
Vlaswinkel, M.E.T. ; Wijk, C.A.P. van; Uijthoven, W. - \ 2011
Lelystad : Praktijkonderzoek Plant & Omgeving, AGV - 37
ganzen - plagenbestrijding - vogelbestrijding - kosten - oogstschade - akkerbouw - graansoorten - graszaden - geese - pest control - bird control - costs - crop damage - arable farming - cereals - grass seeds
In 2010 zijn in het kader van het project Faunaschade op 5 praktijkbedrijven 7 praktijkpercelen gevolgd op schade door ganzen en de extra kosten voor verjaging. Het ging in eerste instantie om schade door overzomerende ganzen. Er zijn diverse waarnemingen gedaan en bij meerdere percelen is bij de oogst de opbrengst bepaald. Verder zijn de maatregelen die genomen zijn om de schade te beperken, geïnventariseerd. Het jaar 2010 was het 1e inventarisatie jaar. Van de 7 percelen wintertarwe, traden er in 4 percelen ook daadwerkelijk schade door overzomerende ganzen op. Het bleek dat er op enkele percelen een duidelijke vraatschade was waardoor een groot verschil in opbrengst ontstond. Andere percelen met zichtbare schade, gaven weinig opbrengstreductie. De periode waarin schade optreedt is erg belangrijk. Ook zat er een groot verschil in de opbrengsten van het stro. Stro is voor veel bedrijven ook een belangrijke bron van inkomsten. De kosten die nodig zijn voor het verjagen van de ganzen bleken uiteen te lopen van 1000 tot 6000 euro. Vooral de tijd die men bezig is met het verjagen ligt vele malen hoger dan vaak wordt ingeschat. Verder is het lastig te achterhalen wanneer iets structuurschade is en wanneer ganzenschade. Een tweede inventarisatiejaar is nodig om een breder en beter onderbouwd beeld te krijgen over vraatschade en de gevolgen daarvan voor de hectareopbrengst. Als extra zou het aan te bevelen zijn in 2011 meer te doen met het volgen van schade via GPS. Misschien is het ook mogelijk om via MijnAkker.nl of Cropview vanuit de lucht de opbrengst en schade te bepalen. Ook is het belangrijk opnieuw te inventariseren wat de kosten van het verjagen zijn.
Jaarverslag 2009 KNPV Werkgroep Graanziekten
Schepers, H.T.A.M. - \ 2010
Gewasbescherming 41 (2010)3. - ISSN 0166-6495 - p. 161 - 163.
graansoorten - plantenziekten - excursies - veldproeven - jaarverslagen - cereals - plant diseases - field trips - field tests - annual reports
Jaarverslag 2009 van de KNPV Werkgroep Graanziekten. De excursie naar Rothamsted Research in Harpenden (UK) op 28 mei 2009 wordt beschreven.
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