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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Frankincense in peril
Bongers, Frans ; Groenendijk, Peter ; Bekele, Tesfaye ; Birhane, Emiru ; Damtew, Abebe ; Decuyper, Mathieu ; Eshete, Abeje ; Gezahgne, Alemu ; Girma, Atkilt ; Khamis, Mohamed A. ; Lemenih, Mulugeta ; Mengistu, Tefera ; Ogbazghi, Woldeselassie ; Sass-Klaassen, Ute ; Tadesse, Wubalem ; Teshome, Mindaye ; Tolera, Motuma ; Sterck, Frank J. ; Zuidema, Pieter A. - \ 2019
Nature Sustainability 2 (2019). - ISSN 2398-9629 - p. 602 - 610.
The harvest of plant parts and exudates from wild populations contributes to the income, food security and livelihoods of many millions of people worldwide. Frankincense, an aromatic resin sourced from natural populations of Boswellia trees and shrubs, has been cherished by world societies for centuries. Boswellia populations are threatened by over-exploitation and ecosystem degradation, jeopardizing future resin production. Here, we reveal evidence of population collapse of B. papyrifera—now the main source of frankincense—throughout its geographic range. Using inventories of 23 populations consisting of 21,786 trees, growth-ring data from 202 trees and demographic models on the basis of 7,246 trees, we find that over 75% of studied populations lack small trees, natural regeneration has been absent for decades, and projected frankincense production will be halved in 20 yr. These changes are caused by increased human population pressure on Boswellia woodlands through cattle grazing, frequent burns and reckless tapping. A literature review showed that other Boswellia species experience similar threats. Populations can be restored by establishing cattle exclosures and fire-breaks, and by planting trees and tapping trees more carefully. Concerted conservation and restoration efforts are urgently needed to secure the long-term availability of this iconic product.
The implications of ignoring smallholder agriculture in climate-financed forestry projects: empirical evidence from two REDD+ pilot projects
Duker, A.E.C. ; Tadesse, T.M. ; Soentoro, T. ; Fraiture, C. de; Kemerink-Seyoum, J.S. - \ 2019
Climate Policy 19 (2019)sup1. - ISSN 1469-3062 - p. S36 - S46.
deforestation - Ethiopia - Indonesia - livelihoods - REDD+ - smallholder agriculture

Changes in agricultural practices can play a pivotal role in climate change mitigation by reducing the need for land use change as one of the biggest sources of GHG emissions, and by enabling carbon sequestration in farmers’ fields. Expansion of smallholder and commercial agriculture is often one of the main driving forces behind deforestation and forest degradation. However, mitigation programmes such as REDD+ are geared towards conservation efforts in the forestry sector without prominently taking into account smallholder agricultural interests in project design and implementation. REDD+ projects often build on existing re- and afforestation projects without major changes in their principles, interests and assumptions. Informed by case study research and interviews with national and international experts, we illustrate with examples from Ethiopia and Indonesia how REDD+ projects are implemented, how they fail to adequately incorporate the demands of smallholder farmers and how this leads to a loss of livelihoods and diminishing interest in participating in REDD+ by local farming communities. The study shows how the conservation-based benefits and insecure funding base in REDD+ projects do not compensate for the contraction in livelihoods from agriculture. Combined with exclusive benefit-sharing mechanisms, this results in an increased pressure on forest resources, diverging from the principal objective of REDD+. We note a gap between the REDD+ narratives at international level (i.e. coupling development with a climate agenda) and the livelihood interests of farming communities on the ground. We argue that without incorporating agricultural interests and a review of financial incentives in the design of future climate finance mechanisms, objectives of both livelihood improvements and GHG emission reductions will be missed. Key policy insights REDD+ is positioned as a promising tool to meet climate, conservation and development targets. However, these expectations are not being met in practice as the interests of smallholder farmers are poorly addressed. REDD+ policy developers and implementers need more focus on understanding the interests and dynamics of smallholder agriculturalists to enable inclusive, realistic and long-lasting projects. For REDD+ to succeed, funders need to consider how to better ensure long-term livelihood security for farming communities.

Nitrogen allocation and recycling in peri-urban mixed crop–livestock farms in Ethiopia
Tadesse, Solomon Tulu ; Oenema, Oene ; Beek, Christy van; Ocho, Fikre Lemessa - \ 2019
Nutrient Cycling in Agroecosystems 115 (2019)2. - ISSN 1385-1314 - p. 281 - 294.
Circular economy - Crop–livestock ratio (CLS) - Food security - NUE - Smallholder

Mixed crop–livestock (MC–LS) farms are assumed to be more environmental friendly than specialized livestock systems, due to their better options for internal nutrient recycling. However, there are large differences among MC–LS farms in nutrient allocation and recycling. Here, we posit that the relative allocation of nitrogen to crop and livestock compartments, expressed as crop–livestock ratio (CLS), determines the performance of MC–LS farms. Among 300 urban and peri-urban farms studied in 2014, 42 MC–LS farms (Addis Ababa: 20; Jimma: 22) were re-interviewed in 2016, using MonQIt (monitoring tool) questionnaire. The performances of these farms were evaluated using partial nitrogen balance (PNB), N use efficiency (NUE), N recycling index and net farm income (NFI). CLS was negatively related to N input, PNB and NFI. Livestock oriented MC–LS farms had 4–5 times higher N input and 7 times higher PNB than crop oriented MC–LS farms, because they had 2–4 times higher NFI and purchased more external N input. This indicated that N allocation has significant environmental and economic implications. Sensitivity analyses suggested that NUE at farm system level can be improved by 20–25% and N recycling (NR) by 10–20% over the current condition. In conclusion, MC–LS farms are diverse, and much of the diversity can be captured by the CLS indicator. NUE and NR of peri-urban MC–LS farms in Ethiopia can be significantly improved through NUE enhancing measures: targeted exchange of crop residues and manure between crop and livestock activities within and between farms and improving animal NUE through breeding and precision feeding.

Potatoes and livelihoods in Chencha, southern Ethiopia
Tadesse, Yenenesh ; Almekinders, Conny J.M. ; Schulte, Rogier P.O. ; Struik, Paul C. - \ 2019
NJAS Wageningen Journal of Life Sciences 88 (2019). - ISSN 1573-5214 - p. 105 - 111.
Agronomy - Asset - Consumption pattern - Food security - Log-linear analysis - Potato - Production - Wealth category

Potato is highly productive crop and can provide a cheap and nutritionally-rich staple food. Its potential as a cash generator and source of food is much under-utilized in many emerging economies. In this paper we study the impact of an intervention that introduced improved potato technologies in Chencha, Ethiopia on the livelihoods of smallholder farmers. We collected information through in-depth interviews in order to explore possible pathways of impact on farmers’ livelihoods; and used this information as the basis for designing a household survey. The results show changes in agronomic practices and consumption; these changes were most pronounced among wealthy farmers who participated in the intervention. Farmers used the additional income from potato in different ways: wealthier farmers improved their houses and increased their livestock, whereas poor farmers mainly invested in furniture, cooking utensils, tools and in developing small businesses like selling and buying cereals, milk and weaving products in the local markets. Some wealthy farmers, who did not participate in the project, also derived some indirect benefits from the intervention. This underscores: i) interventions that promote uniform farming technologies in themselves are not always sufficient to improve the livelihoods of poor farmers, and ii) the need to broaden the scope of interventions so as to take into account the resources available to farmers in different wealth categories, and the diversity of strategies that they employ for improving their livelihoods. Our approach allows to understand and describe the different developmental effects of a single technological intervention on the different aspects of farmers’ livelihoods.

Veterinary medicinal product usage among food animal producers and its health implications in Central Ethiopia
Tufa, Takele Beyene ; Gurmu, Feraol ; Beyi, Ashenafi Feyisa ; Hogeveen, Henk ; Beyene, Tariku Jibat ; Ayana, Dinka ; Woldemariyam, Fanos Tadesse ; Hailemariam, Eyerusalem ; Gutema, Fanta Desissa ; Stegeman, J.A. - \ 2018
BMC Veterinary Research 14 (2018)1. - ISSN 1746-6148
Antimicrobial resistance - Antimicrobial usage - Central Ethiopia - Farmers' knowledge, awareness, and practices - Food animals

Background: Antimicrobials and anthelmintics are the most commonly used veterinary drugs to control animal diseases. However, widespread use of these drugs could contribute to the emergence of drug resistance. Information on the practice of antimicrobial usage among food animal raising communities in Central Ethiopia is scarce. We used a standardised questionnaire survey to assess knowledge, awareness, and practices related to drug use and resistance in food animals among the farmers in and around Bishoftu town. Results: Of the total of 220 livestock owners interviewed, around 80% of the respondents were not able to define what antimicrobials are and for what purposes they are used. Only 14.1% (n = 31) of the respondents had awareness about antimicrobial resistance (AMR) and its consequences; and 35.5% (n = 11/31) and 9.7% (n = 3/31) of them agreed that the irrational use of antimicrobials in animals could lead to AMR in animals and humans. Oxytetracycline was the most commonly available antibiotic in veterinary drug shops/pharmacies and the most widely used drug in the area. However, 43.3% of the respondents did not see clinical improvements after using antibiotics. Similarly, the respondents explained that no response was observed in 73.3, 70.8 and 52.5% of the cases after medication with anthelmintics, antiprotozoal and acaricides, respectively. About 56.7% of the respondents considered traditional medicines equally important to modern medicines. It was also noted that there were illegal drug vendors, dispensing medicines under unfavourable conditions which include a direct exposure to sunlight, which practice violates the drug handling and storage recommendations given by WHO. Conclusion: The study revealed that there is a general lack of awareness among food animal owners about the correct use of antibiotics and anthelmintics. The widespread misuse and improper drug dispensing and handling practices observed in this study can affect the drug quality and can also contribute to the development of drug resistance in central Ethiopia.

Sharing benefits or fueling conflicts? The elusive quest for organizational blue-prints in climate financed forestry projects in Ethiopia
Kemerink-Seyoum, J.S. ; Tadesse, T.M. ; Mersha, W.K. ; Duker, A.E.C. ; Fraiture, C. de - \ 2018
Global environmental change : human and policy dimensions 53 (2018). - ISSN 0959-3780 - p. 265 - 272.
Climate financing - Conflicts over natural resources - Land grab - Livelihoods - Market environmentalism - REDD+

Despite euphoria at international level there is a growing concern that participatory forest conservation projects established with climate finance might not lead to the assumed win-win solution expressed in policy rhetoric of addressing both forest degradation and persistent poverty. Based on two climate financed forestry (pilot) projects in Ethiopia, this paper shows that the strong reliance on organizational blueprints and the focus on crafting institutions concealed the more pertinent issues at stake, in particular the unequal distributions of natural resources as result of the enclosure of the commons. The logic and rules on which the projects have been designed have been superimposed on existing social relations of power and prevailing organizational configurations, leading to aggravation of conflicts over resources as result of social exclusion, elite capture and even state-sanctioned land grab. This does not only points to the elusiveness of the quest for the best organizational model to implement such forestry projects, but also questions the faith in climate finance mechanisms at international level and the effectiveness of the efforts made by advocacy groups to establish safeguards to minimize possible negative outcomes at local level.

Food systems for healthier diets in Ethiopia : toward a research agenda
Gebru, Mestawet ; Remans, Roseline ; Brouwer, Inge ; Baye, Kaleab ; Melesse, M.B. ; Covic, Namukolo ; Habtamu, Fekadu ; Abay, Alem Hadera ; Hailu, Tesfaye ; Hirvonen, Kalle ; Kassaye, Tarik ; Kennedy, Gina ; Lachat, Carl ; Lemma, Ferew ; McDermott, John ; Minten, Bart ; Moges, Tibebu ; Reta, Fidaku ; Tadesse, Eneye ; Taye, Tamene ; Truebswasser, Ursula ; Berg, Marrit van den - \ 2018
International Food Policy Research Institute (IFPRI) (IFPRI Discussion Paper 01720) - 51 p.
Ethiopia - food systems - dietary diversity - nutrition
While dietary energy supply has improved, diets in Ethiopia remain low in diversity and provide insufficient amounts of protein, vitamin A, and zinc. Poor dietary quality contributes to the multiple burden of malnutrition in the country, with 38% stunting among children under five years and 24% anemia and 8% overweight among adult women.
Recent Ethiopian government policies and programs call for sustainable food systems approaches aimed at achieving better nutrition for all. Such food systems approaches imply actions that include but also go beyond agriculture to consider the many processes and actors involved in food production, processing, storage, transportation, trade, transformation, retailing, and consumption.
In this paper, we identify research streams to support the operationalizing of such food systems approaches in Ethiopia. To this end, we engaged with stakeholders, reviewed the literature, and applied a food systems framework to research priorities in the Ethiopian context. We develop an initial food systems profile of Ethiopia and identify 25 priority research questions, categorized into three main areas. A first area focuses on diagnosis and foresight research, for example, to further characterize dietary gaps and transitions in the context of the variety of Ethiopian settings, and to understand and anticipate which food system dynamics contribute positively or negatively to those trends. A second area includes implementation research and focuses on building a base of evidence on the dietary impact of combined demand-, market-, and supply-side interventions/innovations that focus on nonstaples; potential trade-offs in terms of economic, social, and environmental outcomes; and interactions between food system actors. A third area focuses on institutional and policy processes and explores enabling factors and private or public anchors that can take food systems approaches for healthier diets to a regional or national scale.
The paper contextualizes the case of Ethiopia within global food systems thinking and thereby aims to stimulate in- and cross-country learning.
The burden of cardiovascular diseases among us states, 1990-2016
Roth, Gregory A. ; Johnson, Catherine O. ; Abate, Kalkidan Hassen ; Abd-Allah, Foad ; Ahmed, Muktar ; Alam, Khurshid ; Alam, Tahiya ; Alvis-Guzman, Nelson ; Ansari, Hossein ; Ärnlöv, Johan ; Atey, Tesfay Mehari ; Awasthi, Ashish ; Awoke, Tadesse ; Barac, Aleksandra ; Bärnighausen, Till ; Bedi, Neeraj ; Bennett, Derrick ; Bensenor, Isabela ; Biadgilign, Sibhatu ; Castañeda-Orjuela, Carlos ; Catalá-López, Ferrán ; Davletov, Kairat ; Dharmaratne, Samath ; Ding, Eric L. ; Dubey, Manisha ; Faraon, Emerito Jose Aquino ; Farid, Talha ; Farvid, Maryam S. ; Feigin, Valery ; Fernandes, João ; Frostad, Joseph ; Gebru, Alemseged ; Geleijnse, Johanna M. ; Gona, Philimon Nyakauru ; Griswold, Max ; Hailu, Gessessew Bugssa ; Hankey, Graeme J. ; Hassen, Hamid Yimam ; Havmoeller, Rasmus ; Hay, Simon ; Heckbert, Susan R. ; Irvine, Caleb Mackay Salpeter ; James, Spencer Lewis ; Jara, Dube ; Kasaeian, Amir ; Khan, Abdur Rahman ; Khera, Sahil ; Khoja, Abdullah T. ; Khubchandani, Jagdish ; Kim, Daniel ; Kolte, Dhaval ; Lal, Dharmesh ; Larsson, Anders ; Linn, Shai ; Lotufo, Paulo A. ; Razek, Hassan Magdy Abd El; Mazidi, Mohsen ; Meier, Toni ; Mendoza, Walter ; Mensah, George A. ; Meretoja, Atte ; Mezgebe, Haftay Berhane ; Mirrakhimov, Erkin ; Mohammed, Shafiu ; Moran, Andrew Edward ; Nguyen, Grant ; Nguyen, Minh ; Ong, Kanyin Liane ; Owolabi, Mayowa ; Pletcher, Martin ; Pourmalek, Farshad ; Purcell, Caroline A. ; Qorbani, Mostafa ; Rahman, Mahfuzar ; Rai, Rajesh Kumar ; Ram, Usha ; Reitsma, Marissa Bettay ; Renzaho, Andre M.N. ; Rios-Blancas, Maria Jesus ; Safiri, Saeid ; Salomon, Joshua A. ; Sartorius, Benn ; Sepanlou, Sadaf Ghajarieh ; Shaikh, Masood Ali ; Silva, Diego ; Stranges, Saverio ; Tabarés-Seisdedos, Rafael ; Atnafu, Niguse Tadele ; Thakur, J.S. ; Topor-Madry, Roman ; Truelsen, Thomas ; Tuzcu, E.M. ; Tyrovolas, Stefanos ; Ukwaja, Kingsley Nnanna ; Vasankari, Tommi ; Vlassov, Vasiliy ; Vollset, Stein Emil ; Wakayo, Tolassa ; Weintraub, Robert ; Wolfe, Charles ; Workicho, Abdulhalik ; Xu, Gelin ; Yadgir, Simon ; Yano, Yuichiro ; Yip, Paul ; Yonemoto, Naohiro ; Younis, Mustafa ; Yu, Chuanhua ; Zaidi, Zoubida ; Sayed Zaki, Maysaa El; Zipkin, Ben ; Afshin, Ashkan ; Gakidou, Emmanuela ; Lim, Stephen S. ; Mokdad, Ali H. ; Naghavi, Mohsen ; Vos, Theo ; Murray, Christopher J.L. - \ 2018
JAMA Cardiology 3 (2018)5. - ISSN 2380-6583 - p. 375 - 389.
Importance: Cardiovascular disease (CVD) is the leading cause of death in the United States, but regional variation within the United States is large. Comparable and consistent state-level measures of total CVD burden and risk factors have not been produced previously. Objective: To quantify and describe levels and trends of lost health due to CVD within the United States from 1990 to 2016 as well as risk factors driving these changes. Design, setting, and participants: Using the Global Burden of Disease methodology, cardiovascular disease mortality, nonfatal health outcomes, and associated risk factors were analyzed by age group, sex, and year from 1990 to 2016 for all residents in the United States using standardized approaches for data processing and statistical modeling. Burden of disease was estimated for 10 groupings of CVD, and comparative risk analysis was performed. Data were analyzed from August 2016 to July 2017. Exposures: Residing in the United States. Main outcomes ans measures: Cardiovascular disease disability-Adjusted life-years (DALYs). Results: Between 1990 and 2016, age-standardized CVD DALYs for all states decreased. Several states had large rises in their relative rank ordering for total CVD DALYs among states, including Arkansas, Oklahoma, Alabama, Kentucky, Missouri, Indiana, Kansas, Alaska, and Iowa. The rate of decline varied widely across states, and CVD burden increased for a small number of states in the most recent years. Cardiovascular disease DALYs remained twice as large among men compared with women. Ischemic heart disease was the leading cause of CVD DALYs in all states, but the second most common varied by state. Trends were driven by 12 groups of risk factors, with the largest attributable CVD burden due to dietary risk exposures followed by high systolic blood pressure, high body mass index, high total cholesterol level, high fasting plasma glucose level, tobacco smoking, and low levels of physical activity. Increases in risk-deleted CVD DALY rates between 2006 and 2016 in 16 states suggest additional unmeasured risks beyond these traditional factors. Conclusions and relevance: Large disparities in total burden of CVD persist between US states despite marked improvements in CVD burden. Differences in CVD burden are largely attributable to modifiable risk exposures.
Measuring corporate sustainability performance– the case of European food and beverage companies
Engida, Tadesse G. ; Rao, Xudong ; Berentsen, Paul B.M. ; Oude Lansink, Alfons G.J.M. - \ 2018
Journal of Cleaner Production 195 (2018). - ISSN 0959-6526 - p. 734 - 743.
Composite indicator - Corporate sustainability - Data envelopment analysis - Indicator - Principal component analysis

Measuring corporate sustainability performance is necessary to guide sustainability improvements. Although many indicators exist that capture the different dimensions of sustainability, a composite indicator that integrates across all indicators is important as it helps to summarize multi-dimensional issues and provide synthesized information. This paper discusses and evaluates a method that builds on a combinantion of prinicipal component analysis and data envelopment analysis for developing a composite indicator of corporate sustainability. Principal component analysis is used to reduce the number of indicators and remove correlations among the indicators. The composite indicator of sustainability for each company is then obtained by using data envelopment analysis with a bootstrapping procedure. The method is illustrated for companies in the European food and beverages sector, using data from Sustainalytics. The paper also shows how the composite indicator of sustainability can be complemented by a decomposition analysis to identify priorities for sustainability improvements. The approach is valuable for stakeholders who aim to enhance corporate sustainability.

Correction to: Diversity and nutrient balances of urban and peri-urban farms in Ethiopia
Tadesse, Solomon Tulu ; Oenema, Oene ; Beek, Christy van; Ocho, Fikre Lemessa - \ 2018
Nutrient Cycling in Agroecosystems 111 (2018)1. - ISSN 1385-1314 - p. 19 - 19.
In the original publication, in Table 6, the asterisks (***) indicating the P values appeared under the column of use efficiency for N
Diversity and nutrient balances of urban and peri-urban farms in Ethiopia
Tadesse, Solomon Tulu ; Oenema, Oene ; Beek, Christy van; Ocho, Fikre Lemessa - \ 2018
Nutrient Cycling in Agroecosystems 111 (2018)1. - ISSN 1385-1314 - p. 1 - 18.
Agriculture - Farm income - Farm management - Soil fertility - Urbanization
Urban and peri-urban agriculture (UPA) is important for food security in fast growing cities of developing countries. UPA also may have an important role in nutrient re-cycling at the interface of rural and urban areas. However, little is known about this role and whether it is different for different UPA systems. Here, we report on diversity and nutrient balances of UPA systems in three main cities of Ethiopia. Data collected from 425 households (Addis Ababa: 175, Adama: 126 Jimma: 124) were subjected to categorical principal component analysis and cluster analysis to classify the households. Four farm types per city and overall six: commercial livestock (cLS), commercial vegetable crop (cVC), subsistence field crop (sFC), cLScVC, cLScVCsFC and sVCsFC were identified across the three cities. Two types, cLS and cLScVC were common to the three cities. The farm types differed in resource endowment, income, soil fertility management and nutrient balances. cLS systems accumulated 450, 85 and 260 kg N, P and K ha−1 year−1 and had 26% N and P and 15% K use efficiency, respectively while sFC systems depleted − 30 kg N and − 17 kg K ha−1 year−1 and had 155% N and > 100% K use efficiency. There was little exchange of manure and crop residue between LS, FC and VC systems. To use the potential role of UPA in nutrient re-cycling, a directive that imposes LS systems to distribute their surplus manure resources to proximate FC and VC systems and improve their nutrient use efficiency should be put in place.
Making interventions work on the farm : Unravelling the gap between technology-oriented potato interventions and livelihood building in Southern Ethiopia
Tadesse, Yenenesh - \ 2017
Wageningen University. Promotor(en): P.C.. Struik, co-promotor(en): C.J.M. Almekinders; R.P.O. Schulte. - Wageningen : Wageningen University - ISBN 9789463436847 - 120
potatoes - crop production - crop physiology - technology - intervention - livelihood strategies - livelihoods - ethiopia - east africa - aardappelen - gewasproductie - gewasfysiologie - technologie - interventie - strategieën voor levensonderhoud - middelen van bestaan - ethiopië - oost-afrika

Poor adoption of modern technologies in sub-Saharan Africa is one of the major factors that limit food production and thereby threaten food security of smallholder farmers. This is despite the potential and emerging success stories of new technologies in increasing productivity of smallholder agriculture. Explanations for low uptake of technologies are diverse. Some studies associated it with characteristics of the farmers and their farm; others attributed it to poor access to information about a particular technology, while some others recognize the importance of technology attributes. Farmers’ adoption decision is shaped socially and the farming practices are changing, not only because of the technical changes introduced, but also because of changes in social circumstances among smallholders. All these possible reasons did, however, miss largely important insights on how local complexities influence adoption. The research presented in this thesis analyses the social dynamics of technology-oriented interventions. More specifically, the study assessed the influence of technology introduction strategies, social networks and social differentiation on the adoption, dissemination and effects of potato technologies. As a case, it used interventions introducing improved potato technologies in Chencha, Southern Ethiopia. The field work combined individual and group in-depth interviews, household surveys and field observation for data collection.

Results show that the efforts to introduce technologies for improved potato production to progressive farmers with the assumption that farmers will eventually adopt, once they become familiar with the technology is a distant prospect. Some of the production practices - agronomic field and storage practices - failed to spread to poor farmers as expected, while the majority of agronomic practices fitted well with wealthy farmers. This resulted in diverse outcomes and strategies for livelihood improvement at household level. Access to the technologies and the necessary resources and diverse needs for technology were important factors in explaining variation in adoption and effects of technology across wealth categories. Tracing the seed diffusion through farmers’ networks showed that not all households had equal access to improved seed potatoes, mainly because of social barriers formed by differences in wealth, gender and religion, and because the type of personal relationship (relatives, neighbours, friends and acquaintance) between seed providers and seed recipients affected farmer to farmer seed sharing. In addition, the set-up of farmer-group based seed production demands resources and faces contextual challenges, which could be addressed through a long-term approach that engages continually in diagnosis and responding to the emerging social as well as material challenges. Development practitioners, however, took organizing group initiatives as a one-time process of design and start-up activity. Thus, clean seed potato production and dissemination through farmers’ organizations could not be sustainable. In conclusion, the present study has indicated that through providing special attention to the social dynamics researchers can arrive at better understanding of constraints affecting technology adoption. This implies effective interventions for a range of farm contexts involve not only finding technical solutions but also integrated understanding of farmers’ production conditions and existing social dynamics.

Understanding farmers’ potato production practices and use of improved varieties in Chencha, Ethiopia
Tadesse, Yenenesh ; Almekinders, Conny J.M. ; Schulte, Rogier P.O. ; Struik, Paul C. - \ 2017
Journal of Crop Improvement 31 (2017)5. - ISSN 1542-7528 - p. 673 - 688.
Adoption - farm realities - point score analysis - technology characteristics - wealth class
This study was carried out to better understand non-adoption of improved varieties of potato (Solanum tuberosum) and associated technologies by smallholder farmers in Chencha, Ethiopia. Data were collected through a survey (n = 47) and in-depth interviews (n = 20). It shows how wealth status was a factor of major importance. Most wealthy and some medium-wealthy farmers adopted improved potato varieties and many of the improved production practices; they had access to seed, associated knowledge and support, and sufficient resources that were necessary to apply the improved practices. Non-adoption was common among many medium-wealthy and most poor farmers: they lacked—next to access to the technologies and knowledge—cash, land, and labor. Results indicated the need to rethink research and intervention efforts. Next to paying attention to differences in the access to technology and the related knowledge, there is a need to consider the variation in technology needs, supporting microcredit services, and room to experiment. As a result, different combinations of improved production practices may be adopted.
Prevalence of Escherichia coli O157 : H7 in beef cattle at slaughter and beef carcasses at retail shops in Ethiopia
Abdissa, Rosa ; Haile, Woynshet ; Fite, Akafete Teklu ; Beyi, Ashenafi Feyisa ; Agga, Getahun E. ; Edao, Bedaso Mammo ; Tadesse, Fanos ; Korsa, Mesula Geloye ; Beyene, Takele ; Beyene, Tariku Jibat ; Zutter, Lieven De; Cox, Eric ; Goddeeris, Bruno Maria - \ 2017
Bmc Infectious Diseases 17 (2017)1. - ISSN 1471-2334
Antimicrobial resistance - Beef cattle - Carcass - E. coli O157:H7 - Skins

Background: There is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia. Methods: Various samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods. Results: At the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested. Conclusions:E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7.

Prevalence and antimicrobial susceptibility of Escherichia coli O157 in beef at butcher shops and restaurants in central Ethiopia
Beyi, Ashenafi Feyisa ; Fite, Akafete Teklu ; Tora, Ephrem ; Tafese, Asdesach ; Genu, Tadele ; Kaba, Tamirat ; Beyene, Tariku J. ; Beyene, Takele ; Korsa, Mesula Geloye ; Tadesse, Fanos ; Zutter, Lieven De; Goddeeris, Bruno M. ; Cox, Eric - \ 2017
BMC Microbiology 17 (2017)1. - ISSN 1471-2180
Antimicrobial susceptibility - Beef - Butcher shops - Escherichia coli O157 - Minced beef - Restaurants

Background: Ethiopia bears the largest burden of foodborne diseases in Africa, and diarrheal diseases are the second leading causes of premature deaths. Enterohemorrhagic Escherichia coli O157 causes an asymptomatic infection to severe diarrhea and/or hemolytic-uremic syndrome in humans. Methods: A total of 440 beef carcass and in-contact surface swabs from 55 butcher shops and 85 minced beef samples from 40 restaurants in central Ethiopia were collected and examined for the presence of E. coli O157. Standard microbiological methods were used to isolate and identify E. coli O157 and to characterize the antimicrobial resistance of the isolates. Results: E. coli O157 was detected in 4.5% carcass swabs (n = 5) and 3.6% cutting board swabs (n = 4) samples from butcher shops. E. coli O157 was not detected in any of the minced beef samples obtained from restaurants. All isolates (n = 9) were 100% susceptible to five drugs, but five isolates were resistant to amoxicillin, two isolates to streptomycin and three isolates to chloramphenicol. One isolate was resistant to two drugs and another to three drugs. Conclusions: The present study shows a low prevalence of E. coli O157 in beef sold at butcher shops. Nevertheless, given the low infective dose of this pathogen and the deep-rooted tradition of consuming raw or undercooked beef, the current prevalence should not be considered lightly from a public health perspective.

Tracing the seed : seed diffusion of improved potato varieties through farmers’ networks in Chencha, Ethiopia
Tadesse, Yenenesh ; Almekinders, Conny J.M. ; Schulte, Rogier P.O. ; Struik, Paul C. - \ 2017
Experimental Agriculture 53 (2017)4. - ISSN 0014-4797 - p. 481 - 496.

There are many prerequisites for potato production to meet its full potential as a food security crop for subsistence farmers in Sub-Saharan Africa. One of these is the introduction of improved varieties. Traditionally, the introduction of new varieties is by government agencies or Non-Governmental Organizations (NGOs). To understand the diffusion of seed tubers (seeds) of new potato varieties in farmer networks, we analysed social factors influencing the sharing of seed of improved potato varieties amongst farmers in Chencha, Ethiopia. We interviewed 166 farmers and analysed 146 seed transactions. We used seed flow mapping to visualize seed sharing amongst farmers. We found that the social networks of farmers are differentiated by wealth, gender and religion, and that this differentiation affects the dispersion of new varieties through the farming communities: Wealthier farmers shared seed tubers most frequently and poor farmers did not share seed at all. Seed sharing was influenced by, but not restricted to, gender and religion categories. Most sharing was with relatives (as gifts) and neighbours (in exchange for labour). There weas no equal access to seed for all households because of (i) the targeting of the better off farmers by the NGO (ii) differences in frequency of sharing and (iii) terms and motivation of the transactions. Our results show that wealthy farmers most effectively multiply and share the seed of new varieties with medium wealthy and poor farmers. This study shows that for the introduction of new technologies into a community, its dynamics of social differentiation need to be understood.

Gender Analysis in CASCAPE Interventions : Gender-based roles and constraints in agricultural production
Roo, N. de; Assefa, B. ; Ahmed, A. ; Boka, B. ; Tadesse, M. ; Tariku, J. ; Tekie, H. ; Zelleke, B. ; Spanjer, M. - \ 2016
Centre for Development Innovation - 60 p.
The Analysis of Potato Farming Systems in Chencha, Ethiopia : Input, Output and Constraints
Dersseh, Waga Mazengia ; Gebresilase, Yenenesh Tadesse ; Schulte, R.P.O. ; Struik, Paul C. - \ 2016
American Journal of Potato Research 93 (2016)5. - ISSN 1099-209X - p. 436 - 447.
Improved varieties - Inorganic fertilizer - Labour shortage - Training

A household survey was conducted for mixed farming systems in Chencha, Ethiopia. Goals of the survey were to establish a baseline for the current production system, to quantify the variation in input and output, and to identify constraints hindering expansion of potato production. Descriptive statistics and principal component analysis were computed using SPSS and XLSTAT. Input and product use constraints varied over household characteristics. Using improved varieties, inorganic fertilizers, and selling products strongly and positively correlated with the households’ wealth, adoption, and education levels. Problems of cash and inadequate produce negatively correlated with wealth, adoption factors, and education levels. Access to improved varieties, training, and fertilizer were positively correlated with age, family size and gender. Land and labour shortages and pests were identified as cross-cutting constraints. Results of the analysis identify a need for a pluriform advisory model recognizing and building upon alleviation of the diversity of constraints identified in this analysis.

Lensink, R. ; Asenso-Okyere, K. ; Bahiigwa, G. ; Cao, E. De; Eriksen, S. ; Jemaneh, S. ; Gutu, T. ; Hansen, N. ; Lutz, C. ; Tadesse, G. ; Tefera, W. ; Yirga, C. ; Zerfu, E. ; Berg, M. van der; Klaver, D.C. ; Jacobs, J. ; Hofstede, M. ; Ingen, T. van; Getew, H. ; Tigabu, A. ; Babu, S. ; Buizer, N.N. ; Desalos, C.B. ; Kefyalew, D. ; Kusters, C.S.L. ; Bulte, E. ; Pradhan, M. - \ 2015
Wageningen : Centre for Development Innovation, Wageningen UR (CDI Rapporten ) - 1978
This report on Ethiopia is one of a series of evaluation reports, consisting of ten reports in total, reflecting the results of the jointly-organised MFS II evaluation: - Eight country reports (India, Bangladesh, Ethiopia, Uganda, Indonesia, DR Congo, Liberia, Pakistan); - A synthesis report (covering the eight country studies); and - A report with the results of the international lobbying and advocacy programmes. This series of reports assessed the 2011-2015 contribution of the Dutch Co-Financing System (MFS II) towards achieving the Millennium Development Goals, strengthening international civil society, setting the international agenda and changing decision-makers’ policy and practice, with the ultimate goal of reducing structural poverty. On July 2nd, 2015, the reports were approved by the independent steering committee (see below), which concluded that they meet the quality standards of validity, reliability and usefulness set by the Ministry of Foreign Affairs.
Risk perception and management in smallholder dairy farming in Tigray, Northern Ethiopia
Gebreegziabher, K. ; Tadesse Woeldesenbet, T. - \ 2014
Journal of Risk Research 17 (2014)3. - ISSN 1366-9877 - p. 367 - 381.
tick-borne diseases - kenya highlands - cattle - tanzania - systems - prevalence - economics - adoption - farmers - region
Empirical studies on smallholder dairy farmers' risk perceptions and management strategies have still received little attention in agricultural research of developing countries. This study focuses on farmers' risk perception and management strategies of smallholder dairy farms in urban and peri-urban areas of Tigray in northern Ethiopia. Based on data collected from a sample of 304 smallholder dairy farm households, we used descriptive statistics for analyzing farmers' risk attitude and factor analysis for analyzing and classifying risk sources and management strategies. The majority of dairy farmers considered themselves risk takers towards farm decision that may have a positive impact on technology adoption. Factor analysis identified technological, price/market, production, financial, human, and institutional factor as major sources of risks. In addition, factor analysis indicates that disease reduction, diversification, financial management, and market network are perceived as the most effective risk management strategies. Our findings indicate that perceptions of risk and management strategies are farmer-specific; therefore, policy-makers need to consider tailor-made strategies that would address farmers' individual motives to manage risks and shocks.
Investigation on the cause of tomato fruit discoloration and damage under chilling condition using external antioxidants and hot water treatment
Nardos Tadesse, T. ; Farneti, B. ; Woltering, E.J. - \ 2012
Asian journal of plant sciences 11 (2012)5. - ISSN 1682-3974 - p. 217 - 225.
The color of tomato fruit turns to red from green during ripening. The accumulated lycopene content of red tomato fruits is reduced when the fruits stored in the refrigerator. Therefore, this study was conducted in order to investigate the reason why red color tomato turns to light red when the fruit is stored at chilling temperature. A tomato variety (cv Rotarno) grown under greenhouse condition and harvested at red stage was used to assess color and firmness. Before storage at these temperatures, red tomato fruits were infiltrated by different concentration of antioxidants (Vitamin C, L-galactonic acid-¿-lactone and Butylated hydroxyanisole (BHA) and also treated by hot water. The color and firmness of the fruits were measured by pigment analyzer and Zwick, respectively. Dessicator with vacuum pump was used for infiltration of antioxidants and water. Antioxidants were infiltrated through the scar of the fruits by applying 400 Mbar pressure for 15 sec. for each concentration. Red tomatoes were treated in hot water at 40, 45 and 50°C for 2, 5 and 10 min each. All antioxidant infiltrated and hot water treated fruits were stored at 4°C for three weeks. Statistically significant difference was not observed on color and firmness among different fruits treated by different concentration of antioxidants. Hot water treatment also showed no significant difference on color value between treated and non-treated fruits. However, hot water treated fruits scored significantly higher firmness than non-treated fruits. In general, the results showed that antioxidants as well as hot water treatment did not maintain accumulated lycopene content of the red tomato fruits which, stored at chilling temperature.
Effect of Ethylene and 1-Methylcyclopropene (1-MCP) on color and Firmness of Red and Breaker Stage Tomato Stored at Different Temperatures
Tadesse, T.N. ; Farneti, B. ; Woltering, E.J. - \ 2012
American Journal of Food Technology 7 (2012)9. - ISSN 1557-4571 - p. 542 - 551.
The red color of the tomato fruit during ripening is due to the presence lycopene, a compound known for its antioxidant property. This compound is influenced by temperature, ethylene and 1-Methylcyclopropene (1-MCP) treatment. It was believed that ethylene application at chilling temperature could help increase the amount of lycopene content of tomato fruits. In addition, application of 1-MCP was assumed to reduce the action of ethylene on production of lycopene content and decrease loss of firmness of tomato fruit under chilling temperature. Therefore, the objective of this experiment was to see the effect of ethylene and 1-MCP treatment on color and firmness of tomato fruit under different storage temperatures. A tomato variety (cv. Rotarno) grown under greenhouse condition harvested at red and breaker stage was stored at 4, 8 and 20°C to assess color and firmness. Tomato fruits were treated by ethylene (85.7 ppm) and 1-MCP (2.9 ppm) gases starting from the first day of storage throughout the experimentation period. The color and firmness of the fruits were measured by pigment analyzer and Zwick respectively. Results showed that there was significant difference in color value of ethylene treated breaker stage tomato. 1-MCP treatment reduced the color value of tomato fruits stored at 20°C more than the fruits stored at 4 and 8°C. However, 1-MCP treatment helped to reduce loss of firmness of the fruits. We conclude that external ethylene application on red tomato fruits stored at chilling temperature generally has no effect on the subsequent accumulation of lycopene or to maintain the loss of accumulated lycopene during chilling storage. However, external ethylene treatment on breaker stage tomatoes helps for red color development. In addition, 1-MCP treatment helps to reduce loss of firmness of the fruits.
The contribution of town functions to the development of rural areas: empirical analyses for Ethiopia
Tadesse Woeldesenbet, T. - \ 2012
Wageningen University. Promotor(en): Arie Oskam. - S.l. : s.n. - ISBN 9789461731883 - 211
relaties tussen stad en platteland - steden - nutfunctie - invloeden - gezinsinkomen - inkomen - werkgelegenheid - huishoudens - landbouwhuishoudens - gewassen - bemesting - agrarische handel - overheidsdiensten - wegtransport - telefoons - elektriciteit - drinkwater - ontwikkeling - economische ontwikkeling - plattelandsontwikkeling - platteland - ethiopië - rural urban relations - towns - utility functions - influences - household income - income - employment - households - agricultural households - crops - fertilizer application - agricultural trade - public services - road transport - telephones - electricity - drinking water - development - economic development - rural development - rural areas - ethiopia
Rural areas in many developing countries often lack infrastructure and institutions. However, rural towns and towns possess some of the major services that rural and town households can use to advance their economic activities. The study of the contribution that towns and their functions make to different economic activities is still in development. The thesis sought to add to the literature by conceptually discussing the role of town functions and empirically examining the influence on income, employment opportunities, rural household crop marketing and fertilizer application. For these purposes, data from households in four major regional states of Ethiopia are used. Results show that shorter distances to roads, transport services and telephone centers, and connection to electricity and tap water are likely to increase income and non-farm wage employment. We find also that proximity to roads and markets and strong network connections are associated with improved input-output exchange among rural households
What the Future Holds for Forestry Development in Ethiopia? Foresight Through Scenarios Construction
Lemenih, M. ; Bongers, F. ; Wiersum, K.F. ; Arts, B.J.M. - \ 2011
In: Research and development in drylands of Ethiopia / Worku, A., Animut, G., Kassa, H., Sintayehu, M., Tadesse, W., Gebru, Y., Addis Ababa : Forum for Environment, Addis Ababa, Ethiopia - p. 101 - 122.
Leaf gas exchange in the frankincense tree (Boswellia papyrifera) of African dry woodlands
Mengistu, T. ; Sterck, F.J. ; Fetene, M. ; Tadesse, W. ; Bongers, F. - \ 2011
Tree Physiology 31 (2011)7. - ISSN 0829-318X - p. 740 - 750.
vapor-pressure deficit - water relations - stomatal conductance - forest tree - seasonal-changes - photosynthesis - traits - transpiration - australia - ethiopia
A conceptual model was tested for explaining environmental and physiological effects on leaf gas exchange in the deciduous dry tropical woodland tree Boswellia papyrifera (Del.) Hochst. For this species we aimed at (i) understanding diurnal patterns in leaf gas exchange, (ii) exploring cause–effect relationships among external environment, internal physiology and leaf gas exchange, and (iii) exploring site differences in leaf gas exchange in response to environmental variables. Diurnal courses in gas exchange, underlying physiological traits and environmental variables were measured for 90 trees on consecutive days at two contrasting areas, one at high and the other at low altitude. Assimilation was highest in the morning and slightly decreased during the day. In contrast, transpiration increased from early morning to midday, mainly in response to an increasing vapor pressure deficit (VPD) and gradual stomatal closure. The leaf water potential varied relatively little and did not influence gas exchange during the measurement period. Our results suggest that the same cause–effect relationships function at contrasting areas. However, leaves at the higher altitude had higher photosynthetic capacity, reflecting acclimation to higher light levels. Trees at both areas nevertheless achieved similar leaf assimilation rates since assimilation was down-regulated by stomatal closure due to the higher VPD at the higher altitude, while it became more light limited at the lower altitude. Gas exchange was thus limited by a high VPD or low light levels during the wet season, despite the ability of the species to acclimate to different conditions
Household demand for improved water supply services in Mekelle City, Northern Ethiopia
Gebreegziabher, K. ; Tadesse Woeldesenbet, T. - \ 2011
Water Policy 13 (2011)1. - ISSN 1366-7017 - p. 125 - 142.
contingent valuation surveys - developing-countries - willingness - pay
With population growth and urbanization, demand for improved water services has been growing. It is imperative therefore to examine different factors that influence demand for improved water services and the resultant welfare changes. Using cross-sectional household survey data collected through structured questionnaire from ten administrative units in Mekelle City, we estimate household willingness to pay models and identify major determinant factors of demand for improved water service. In order to help us do this, we considered selection issues and estimated models using the Heckman Two-Step Estimator. Our results show that the amount of bid (amount of money households would be willing to pay) that households (already connected to private taps) would be willing to pay is positively associated with household income, ownership of the house, price of vended water and the practice of water purification. For households who are not connected to private taps, the amount they would be willing to pay for (improved) private tap connection is positively associated with formal education, housing status and gender. We also investigate the welfare gains and losses as a result of improved water service. Analytical results show that, as the number of households who subscribe to improved water service increases, there is a gain in surplus for households and revenue (producer surplus) for the municipality.
Forest Resources and Challenges of Sustainable Forest Management and Conservation in Ethiopia
Teketay, D. ; Lemenih, M. ; Bekele, T. ; Yemshaw, Y. ; Feleke, S. ; Tadesse, W. ; Moges, Y. ; Hunde, T. ; Nigussie, D. - \ 2010
In: Degraded Forests in Eastern Africa: management and resoration / Bongers, F, Tennigkeit, T, London : The Earthscan Forest Library - ISBN 9781844077670 - p. 19 - 64.
Environmental concern and its implication to household waste separation and disposal: Evidence from Mekelle, Ethiopia
Tadesse Woeldesenbet, T. - \ 2009
Resources, Conservation and Recycling 53 (2009)4. - ISSN 0921-3449 - p. 183 - 191.
solid-waste - behavior - determinants - paradigm - values
Proper understanding of the relationship among concern for the environment, waste separation and disposal can contribute to good waste management and safer environment. This is particularly vital in cities of developing countries (such as Ethiopia) where waste separation is poor and there is widespread illegal dumping, with dire consequences for the environment. In this study, household data are collected in the city of Mekelle in order to identify and analyze the relationship among concern for the environment, waste separation and disposal into communal waste containers. Bivariate probit and Heckman probit selection models are used as tools of analysis. Relevant covariates such as demographic features, waste attributes and environmental attitude are used to get an insight to environmental concern, waste separation and disposal behavior. Results show that the volume of waste generated, NIMBY and NIABY attitudes of households, municipal regulation over the proper use of waste containers and container distance from dwelling houses are positively associated with concern for the environment. Education level of household head, container access, shorter distance to waste containers and household income are found to increase the probability of disposal into containers. In another instance, results indicate that waste separation is positively related with recycling practice, longer container distance, family size and waste attitude. Findings and implications from the relationships can be used to influence and strengthen pro-environment household attitudes and better practices in waste separation and appropriate disposal.
Household waste disposal in Mekelle city, Northern Ethiopia
Tadesse Woeldesenbet, T. ; Ruijs, A.J.W. ; Hagos, F. - \ 2008
Waste Management 28 (2008)10. - ISSN 0956-053X - p. 2003 - 2012.
management - reduction - behavior
In many cities of developing countries, such as Mekelle (Ethiopia), waste management is poor and solid wastes are dumped along roadsides and into open areas, endangering health and attracting vermin. The effects of demographic factors, economic and social status, waste and environmental attributes on household solid waste disposal are investigated using data from household survey. Household level data are then analyzed using multinomial logit estimation to determine the factors that affect household waste disposal decision making. Results show that demographic features such as age, education and household size have an insignificant impact over the choice of alternative waste disposal means, whereas the supply of waste facilities significantly affects waste disposal choice. Inadequate supply of waste containers and longer distance to these containers increase the probability of waste dumping in open areas and roadsides relative to the use of communal containers. Higher household income decreases the probability of using open areas and roadsides as waste destinations relative to communal containers. Measures to make the process of waste disposal less costly and ensuring well functioning institutional waste management would improve proper waste disposal.
Evaluating DEM results with FEM perspectives of load : soil interaction
Tadesse, D. - \ 2004
Wageningen University. Promotor(en): U.D. Perdok, co-promotor(en): A.J. Koolen. - [S.I.] : S.n. - ISBN 9085040116 - 234
grondmechanica - bodemverdichting - bodemstructuur - bodemeigenschappen - simulatiemodellen - deeltjes - dynamische belasting - eindige-elementenmethode - soil mechanics - soil compaction - soil structure - soil properties - simulation models - particles - dynamic loads - finite element analysis
Development of leaf area and leaf number of micropropagated potato plants
Tadesse, M. ; Lommen, W.J.M. ; Putten, P.E.L. van der; Struik, P.C. - \ 2001
Netherlands Journal of Agricultural Science 49 (2001). - ISSN 0028-2928 - p. 15 - 32.
Aboveground leaf area and leaf number development of in vitro produced potato plantlets was studied over three growth phases. In vitro plantlets were produced at 17 or 23°C (normalisation phase, 3 weeks), planted in soil at 18/12 or 26/20°C (transplant production phase, 2 weeks), and later transplanted at 18/12 or 26/20°C (tuber production phase, 6 weeks). Boosts in leaf area increase and leaf appearance occurred in the first days after planting to soil. A shock in leaf area increase occurred after the later transplanting. Both for plant averages and most individual plants, leaf area increase in all growth phases was best described by logistic curves, indicating growth limitations occurred in all phases. These limitations were least severe during the relatively short transplant production phase. Higher temperatures did not significantly increase leaf area during normalisation, increased leaf area during transplant production, and first increased but later reduced leaf area during tuber production. Higher temperatures increased leaf number in all phases. After-effects of normalisation temperature occurred during transplant production but no longer during tuber production. Aftereffects of transplant production temperature occurred during tuber production. After-effects were direct (affecting plants at the beginning of the next phase) or appeared later.
Leaf area development of micropropagated potato plants: effects of leaf area of individual plants on logistic curve parameters and correlations among these parameters
Tadesse, M. ; Lommen, W.J.M. ; Putten, P.E.L. van der; Struik, P.C. - \ 2001
Netherlands Journal of Agricultural Science 49 (2001). - ISSN 0028-2928 - p. 33 - 51.
Leaf area increase of individual, in vitro produced potato plantlets was analysed over three growth phases: in vitro normalisation (3 weeks, 17 or 23°C), transplant production (2 weeks. 18/12 or 26/20°C) and tuber production (6 weeks. 18/12 or 26/20°C). In each phase, initial leaf area (ILA) and final leaf area (FLA) of logistically growing plants were related to parameters describing logistic growth (leaf area = A C/(1 -exp((-Bxtt-M))); A: fitted minimum leaf area, B: fitted initial relative rate of increase, C: fitted maximum increment, M: fitted midpoint, MI: maximum rate of increase at M, MI = BxC/4). Higher ILA was associated with higher FLA during normalisation and transplant production, but not consistently during tuber production. During normalisation, higher ILA led to higher A, C and MI-values, and at 23°C also to higher B and earlier M. During transplant production, higher ILA was associated with higher C.During normalisation, leaf area increase of plants with higher FLAs was characterised by higher A, C and MI-values, and at 23°C also by earlier M. During transplant production, higher FLAs were associated with higher C and MI-values, and at 18/12°C also with higher A. During tuber production, higher FLAs were associated with higher C, M and MI-values.Correlations among parameters characterising logistic growth were of physiological origin, mathematical origin, or resulted from the actual shape of the logistic curve. A and B were positively correlated, likely because clearer S-shaped curves result in higher values of both. Both parameters usually were positively correlated with MI, likely because MI is a function of B, whereas A was correlated to B. Physiologically relevant correlations were found between M and C in the tuber production phase.
Development of micropropagated potato plants over three phases of growth as affected by temperature in different phases
Tadesse, M. ; Lommen, W.J.M. ; Struik, P.C. - \ 2001
Netherlands Journal of Agricultural Science 49 (2001). - ISSN 0028-2928 - p. 53 - 66.
To assess (after)effects of temperature on plant development, in vitro potato plantlets produced at 17 or 23°C (normalization phase, 3 weeks) were planted into soil in growth chambers at 18/12 or 26/20°C (transplant production phase, 2 weeks), and transplanted to glasshouses at 18/12 or 26/20°C (tuber production phase, 6 weeks). The latter phase commonly takes place in the field. Transition from one phase to another, especially from in vitro to in vivo conditions, greatly increased leaf growth and to a smaller extent stem growth. Within a phase, higher temperature stimulated vegetative growth, but delayed tuber formation and reduced tuber yields, harvest index (HI) and tuber dry matter concentration. Temperature during tuber production was more important for high yield than temperatures during earlier phases. Normalization and transplant production temperatures nevertheless showed after-effects in later phases. Lower normalization temperatures advanced plant development: they increased vegetative growth in subsequent phases and finally increased fresh tuber yield and HI. This could have yield advantages at locations where field production seasons are short. Lower transplant production temperatures reduced vegetative growth in the next phase, but enhanced early tuber production. Finally they increased tuber dry weight and HI when tuber production temperatures were high. This may increase yield at locations where field conditions delay tuber formation.
Effects of nitrogen pre-treatment of transplants from in vitro produced potato plantlets on transplant growth and yield in the field
Tadesse, M. ; Lommen, W.J.M. ; Struik, P.C. - \ 2001
Netherlands Journal of Agricultural Science 49 (2001). - ISSN 0028-2928 - p. 67 - 79.
In vitro propagated potato plantlets, cultivars Gloria and Spunta, were pre-treated with 10 or 40 mg nitrogen per plant before transplanting to the field to determine after-effects of nitrogen on field performance of these transplants in two experiments. Yield, ground cover (GC), accumulated intercepted radiation (AIR), radiation use efficiency (RUE) and harvest index (HI) were assessed. Spunta had higher GC, AIR, total dry matter and tuber fresh and dry weights but lower RUE and HI than Gloria at final harvest. Nitrogen pre-treatment had no clear effect on plant growth at the end of the transplant production phase or during early field growth. Later, higher nitrogen pre-treatment resulted in a slightly higher GC and AIR. In one experiment, this resulted in a significantly higher yield. Pre-treatment did not affect HI at the end of the season. Nitrogen pre-treatment can improve seasonal light interception of plantlets of transplant crops from early cultivars.
Effects of temperature pre-treatment of transplants from in vitro produced potato plantlets on transplant growth and yield in the field
Tadesse, M. ; Lommen, W.J.M. ; Struik, P.C. - \ 2001
Potato Research 44 (2001). - ISSN 0014-3065 - p. 173 - 185.
N-acetylglucosamine and glucosamine-containing arabinogalactan proteins control somatic embryogenesis
Hengel, A.J. van; Tadesse, Z. ; Immerzeel, P. ; Schols, H. ; Kammen, A. van; Vries, S.C. de - \ 2001
Plant Physiology 125 (2001). - ISSN 0032-0889 - p. 1880 - 1890.
In plants, complete embryos can develop not only from the zygote, but also from somatic cells in tissue culture. How somatic cells undergo the change in fate to become embryogenic is largely unknown. Proteins, secreted into the culture medium such as endochitinases and arabinogalactan proteins (AGPs) are required for somatic embryogenesis. Here we show that carrot (Daucus carota) AGPs can contain glucosamine and N-acetyl-D-glucosaminyl and are sensitive to endochitinase cleavage. To determine the relevance of this observation for embryogenesis, an assay was developed based on the enzymatic removal of the cell wall from cultured cells. The resulting protoplasts had a reduced capacity for somatic embryogenesis, which could be partially restored by adding endochitinases to the protoplasts. AGPs from culture medium or from immature seeds could fully restore or even increase embryogenesis. AGPs pretreated with chitinases were more active than untreated molecules and required an intact carbohydrate constituent for activity. AGPs were only capable of promoting embryogenesis from protoplasts in a short period preceding cell wall reformation. Apart from the increase in embryogenesis, AGPs can reinitiate cell division in a subpopulation of otherwise non-dividing protoplasts. These results show that chitinase-modified AGPs are extracellular matrix molecules able to control or maintain plant cell fate.
Effects of in vitro treatments on leaf area growth of potato transplants during acclimatisation
Tadesse, M. ; Lommen, W.J.M. ; Struik, P.C. - \ 2000
Plant Cell, Tissue and Organ Culture: an international journal on in vitro culture of higher plants 61 (2000). - ISSN 0167-6857 - p. 59 - 67.
Effects of normalization treatments on the leaf area development of potato transplants during acclimatization
Tadesse, M.H. ; Lommen, W.J.M. ; Struik, P.C. - \ 1999
In: Abstracts of Conference Papers. 14th Triennial Conference of the European Association for Potato Research (EAPR), 2-7 May 1999, Sorrento, Italy - p. 96 - 97.
Effects of N-fertilisation of transplants from in vitro produced potato plantlets on transplant growth and yield in the field
Tadesse, M.H. ; Lommen, W.J.M. ; Struik, P.C. - \ 1999
In: Abstracts of Conference Papers. 14th Triennial Conference of the European Association for Potato Research (EAPR), 2-7 May 1999, Sorrento, Italy - p. 150 - 151.
The relationship between carrot EP3 endochitinases, arabinogalactan proteins (AGPs) and embryogenesis.
Hengel, A.J. van; Tadesse, Z. ; Kammen, A. van; Vries, S.C. de - \ 1997
In: In: Abstractbook 5th International Congress of Plant Molecular Biology, Singapore - p. 178 - 178.
Interrelationship between vitamin A, iodine and iron status in schoolchildren in Shoa Region, Central Ethiopia
Wolde-Gebriel, Z. ; West, C.E. ; Gebru, H. ; Tadesse, A.S. ; Fisseha, T. ; Gabre, P. ; Aboye, C. ; Ayana, G. ; Hautvast, J.G.A.J. - \ 1993
The British journal of nutrition 70 (1993)2. - ISSN 0007-1145 - p. 593 - 607.
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