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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Multi-level socioecological drivers of agrarian change: Longitudinal evidence from mixed rice-livestock-aquaculture farming systems of Bangladesh
Aravindakshan, Sreejith ; Krupnik, Timothy J. ; Groot, Jeroen C.J. ; Speelman, Erika N. ; Amjath- Babu, T.S. ; Tittonell, Pablo - \ 2020
Agricultural Systems 177 (2020). - ISSN 0308-521X
Coastal systems are facing natural and human-driven change coupled with a rising population. With increasing shifts in socioecological conditions during the past several decades, it is important to understand how socioecological drivers at different hierarchical levels: -micro, -meso, and -macro affect coastal farming systems, which play a crucial role in the livelihoods of coastal dwellers. Mixed rice-livestock-aquaculture farming in Southern Bangladesh exemplifies the rapid change occurring in many of the world's coastal farming systems in response to these drivers. We used panel data observations from the above study area and modeled trajectories of farm typologies, and the impact of multi-level socioecological drivers by a novel approach. Our approach integrates: (1) a well-articulated conceptual frame of change observed using (2) a temporal view of the potential drivers, change process and farm type outcomes, with the twenty years panel data of 502 households that is analyzed by means of (3) multivariate statistics in conjunction with panel data models that operationalize the conceptual frame. Our approach allows (a) estimating dynamic effects over time that typically cannot be estimated in a cross-sectional data set, (b) distinguishing between time-invariant fixed and time dependent random effects of multi-level socioecological drivers, and (c) controlling for omitted variables to a certain extent. Considering farming systems both within and outside of polder embankment systems intended to protect against oceanic water intrusion, we found a gradual shift from heterogeneous, rice-livestock farm types to more homogenous farms with less livestock and more off-farm activities. Micro-level factors including farm plot fragmentation, farmers' experience in cropping, machinery, salinity and soil fertility were influencing changes in farming systems. Meso-level factors including markets, road infrastructure, labor availability, access to extension and land tenure also affect the trajectory of farming systems change. Among macro-level drivers, increasing population density positively and significantly influenced cropping intensity among farms outside polder systems. Within polders, a positive but non-significant trend was observed for the influence of population density on cropping intensity. Our data also indicate negative and significant influence of cyclonic storms on cropping intensity over time in both areas. Our results underscore the importance of accounting for multiple levels of socioecological drivers of change when developing appropriate policy options for sustainable development in South Asia's coastal farming systems.
The fertilization effect of global dimming on crop yields is not attributed to an improved light interception
Shao, Liping ; Li, Gang ; Zhao, Qiannan ; Li, Yabing ; Sun, Yutong ; Wang, Weinan ; Cai, Chuang ; Chen, Weiping ; Liu, Ronghua ; Luo, Weihong ; Yin, Xinyou ; Lee, Xuhui - \ 2019
Global Change Biology (2019). - ISSN 1354-1013
acclimation - diffuse radiation - fertilization effect - global dimming - radiation use efficiency - rice - wheat - yield

Global dimming, a decadal decrease in incident global radiation, is often accompanied with an increase in the diffuse radiation fraction, and, therefore, the impact of global dimming on crop production is hard to predict. A popular approach to quantify this impact is the statistical analysis of historical climate and crop data, or use of dynamic crop simulation modelling approach. Here, we show that statistical analysis of historical data did not provide plausible values for the effect of diffuse radiation versus direct radiation on rice or wheat yield. In contrast, our field experimental study of 3 years demonstrated a fertilization effect of increased diffuse radiation fraction, which partly offset yield losses caused by decreased global radiation, in both crops. The fertilization effect was not attributed to any improved canopy light interception but mainly to the increased radiation use efficiency (RUE). The increased RUE was explained not only by the saturating shape of photosynthetic light response curves but also by plant acclimation to dimming that gradually increased leaf nitrogen concentration. Crop harvest index slightly decreased under dimming, thereby discounting the fertilization effect on crop yields. These results challenge existing modelling paradigms, which assume that the fertilization effect on crop yields is mainly attributed to an improved light interception. Further studies on the physiological mechanism of plant acclimation are required to better quantify the global dimming impact on agroecosystem productivity under future climate change.

The acclimation of leaf photosynthesis of wheat and rice to seasonal temperature changes in T-FACE environments
Cai, Chuang ; Li, Gang ; Di, Lijun ; Ding, Yunjie ; Fu, Lin ; Guo, Xuanhe ; Struik, Paul C. ; Pan, Genxing ; Li, Haozheng ; Chen, Weiping ; Luo, Weihong ; Yin, Xinyou - \ 2019
Global Change Biology (2019). - ISSN 1354-1013
climate change - free-air CO enrichment - growth temperature - leaf nitrogen content - Oryza sativa L. - photosynthesis model - stomatal conductance - Triticum aestivum L.

Crops show considerable capacity to adjust their photosynthetic characteristics to seasonal changes in temperature. However, how photosynthesis acclimates to changes in seasonal temperature under future climate conditions has not been revealed. We measured leaf photosynthesis (An) of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) grown under four combinations of two levels of CO2 (ambient and enriched up to 500 µmol/mol) and two levels of canopy temperature (ambient and increased by 1.5–2.0°C) in temperature by free-air CO2 enrichment (T-FACE) systems. Parameters of a biochemical C3-photosynthesis model and of a stomatal conductance (gs) model were estimated for the four conditions and for several crop stages. Some biochemical parameters related to electron transport and most gs parameters showed acclimation to seasonal growth temperature in both crops. The acclimation response did not differ much between wheat and rice, nor among the four treatments of the T-FACE systems, when the difference in the seasonal growth temperature was accounted for. The relationships between biochemical parameters and leaf nitrogen content were consistent across leaf ranks, developmental stages, and treatment conditions. The acclimation had a strong impact on gs model parameters: when parameter values of a particular stage were used, the model failed to correctly estimate gs values of other stages. Further analysis using the coupled gs–biochemical photosynthesis model showed that ignoring the acclimation effect did not result in critical errors in estimating leaf photosynthesis under future climate, as long as parameter values were measured or derived from data obtained before flowering.

Is triose phosphate utilization involved in the feedback inhibition of photosynthesis in rice under conditions of sink limitation
Fabre, Denis ; Yin, Xinyou ; Dingkuhn, Michael ; Clément-Vidal, Anne ; Roques, Sandrine ; Rouan, Lauriane ; Soutiras, Armelle ; Luquet, Delphine ; Lawson, Tracy - \ 2019
Journal of Experimental Botany 70 (2019)20. - ISSN 0022-0957 - p. 5773 - 5785.
Climate change - CO enrichment - photosynthesis - rice - sink feedback - source-sink - sucrose - triose phosphate utilization

This study aimed to understand the physiological basis of rice photosynthetic response to C source-sink imbalances, focusing on the dynamics of the photosynthetic parameter triose phosphate utilization (TPU). Here, rice (Oriza sativa L.) indica cultivar IR64 were grown in controlled environment chambers under current ambient CO2 concentration until heading, and thereafter two CO2 treatments (400 and 800 μmol mol-1) were compared in the presence and absence of a panicle-pruning treatment modifying the C sink. At 2 weeks after heading, photosynthetic parameters derived from CO2 response curves, and non-structural carbohydrate content of flag leaf and internodes were measured three to four times of day. Spikelet number per panicle and flag leaf area on the main culm were recorded. Net C assimilation and TPU decreased progressively after midday in panicle-pruned plants, especially under 800 μmol mol-1 CO2. This TPU reduction was explained by sucrose accumulation in the flag leaf resulting from the sink limitation. Taking together, our findings suggest that TPU is involved in the regulation of photosynthesis in rice under elevated CO2 conditions, and that sink limitation effects should be considered in crop models.

Plant host and drought shape the root associated fungal microbiota in rice
Andreo-Jimenez, Beatriz ; Vandenkoornhuyse, Philippe ; Lê Van, Amandine ; Heutinck, Arvid ; Duhamel, Marie ; Kadam, Niteen ; Jagadish, Krishna ; Ruyter-Spira, Carolien ; Bouwmeester, Harro - \ 2019
PeerJ 2019 (2019)9. - ISSN 2167-8359
Drought - Fungi - Host - Microbiota - Oryza sativa (rice) - Yield

Background and Aim. Water is an increasingly scarce resource while some crops, such as paddy rice, require large amounts of water to maintain grain production. A better understanding of rice drought adaptation and tolerance mechanisms could help to reduce this problem. There is evidence of a possible role of root-associated fungi in drought adaptation. Here, we analyzed the endospheric fungal microbiota composition in rice and its relation to plant genotype and drought. Methods. Fifteen rice genotypes (Oryza sativa ssp. indica) were grown in the field, under well-watered conditions or exposed to a drought period during flowering. The effect of genotype and treatment on the root fungal microbiota composition was analyzed by 18S ribosomal DNA high throughput sequencing. Grain yield was determined after plant maturation. Results. There was a host genotype effect on the fungal community composition. Drought altered the composition of the root-associated fungal community and increased fungal biodiversity. The majority of OTUs identified belonged to the Pezizomycotina subphylum and 37 of these significantly correlated with a higher plant yield under drought, one of them being assigned to Arthrinium phaeospermum. Conclusion. This study shows that both plant genotype and drought affect the rootassociated fungal community in rice and that some fungi correlate with improved drought tolerance. This work opens new opportunities for basic research on the understanding of how the host affects microbiota recruitment as well as the possible use of specific fungi to improve drought tolerance in rice.

Developing parasitic weed control strategies for rainfed rice production environments
Tippe, Dennis Erro - \ 2019
Wageningen University. Promotor(en): N.P.R. Anten, co-promotor(en): L. Bastiaans; J. Rodenburg. - Wageningen : Wageningen University - ISBN 9789463434881 - 146
Quality characteristics and consumer acceptance of bread from wheat and rice composite flour
Adeyeye, S.A.O. ; Bolaji, O.T. ; Abegunde, T.A. ; Adebayo-Oyetoro, A.O. ; Tiamiyu, H.K. ; Idowu-Adebayo, F. - \ 2019
Current Research in Nutrition and Food Science 7 (2019)2. - ISSN 2347-467X - p. 488 - 495.
Bread - Composite flour - Consumer Acceptance - Rice flour - Wheat flour

The quality characteristics and consumer acceptance of wheat-rice composite flour bread were evaluated. Substitution of rice flour was done in wheat flour from 0 to 100% and the composite flour was used to produce bread. The bread samples were subjected to proximate, physical, and sensory analyses. The results showed significant differences (p ≤ 0.05) between the proximate compositions of bread samples studied. Bread from control (100% wheat flour) had moisture content of 28.61±0.28%. Bread from 10-50% wheat-rice composite flour had moisture contents ranged from 28.04±0.41 - 24.81±0.40%. The oven spring of the samples from control (100% wheat flour) had the highest value of 1.12±0.28 cm. The oven spring of wheat-rice composite bread ranged between 1.00±0.22 and 0.82±0.38 cm. There was inverse relationship between loaf weight (g), loaf volume and specific volume and the quantities of rice flour added to the wheat flour. The results of consumer acceptance showed that bread with 70:30 wheat: Rice flour ratio was acceptable to the consumers. In conclusion, bread of good quality and good consumer acceptance could be made from wheat-rice composite flour.

Hidden Rice Diversity in the Guianas
Andel, Tinde van; Veltman, Margaretha A. ; Bertin, Alice ; Maat, Harro ; Polime, Thomas ; Hille Ris Lambers, Derk ; Tjoe Awie, Jerry ; Boer, Hugo De; Manzanilla, Vincent - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
ethnobotany - French Guiana - landraces - Maroons - PAFTOL - rice - Suriname - traditional agriculture

Traditional crop varieties are an important source of genetic diversity for crop adaptation and modern breeding. Landraces of Asian (Oryza sativa) and African (Oryza glaberrima) rice have been well studied on the continents where they were domesticated. However, their history of cultivation in northern South America is poorly understood. Here, we reveal the rice diversity that is maintained by Maroons, descendants of enslaved Africans who fled to the interior forests of the Guianas ca. 300 years ago. We interviewed subsistence farmers who practice shifting cultivation along the Maroni and Lawa rivers that form the natural border between French Guiana and Suriname, and used ethnobotanical and morphological methods to identify around 50 varieties, of which 15 were previously undocumented. The genetic origin of these varieties was explored using the Angiosperms353 universal probe set. Despite the large distances between sites and relative inaccessibility of the area, phenotypic and genetic diversity did not display any geographic structure, which is consistent with knowledge of seed exchange among members of the same ethnolinguistic group. Although improved US cultivars were introduced in Maroon villages in the 1940s, these have not displaced the traditional landraces, which are cherished for their taste and nutritious qualities and for their importance in Maroon spiritual life. The unique agricultural and ritual practices of Maroons confirm their role as custodians of rice diversity, a role that is currently under threat from external pressures and encroaching globalization. We expect that the rice diversity uncovered in this study represents only a fraction of the total diversity in the Guianas and may constitute a large untapped resource that holds promise for future rice improvement. Further efforts to inventory and preserve these landraces will help to protect a precious cultural heritage and local food security.

Slaves' rice varieties found
Andel, Tinde van; Maat, H. - \ 2019
Do diverse landscapes provide for effective natural pest control in subtropical rice?
Zou, Y. ; Kraker, Joop de; Bianchi, F.J.J.A. ; Xiao, Haijun ; Huang, Jikun ; Deng, Xiangzheng ; Hou, Lingling ; Werf, W. van der - \ 2019
Wageningen University & Research
agroecosystem - biological pest control - China - natural enemy - pest - planthopper - yield
This datasets comprises data from 20 rice fields embedded in a gradient of landscapes from crop-dominated to semi-natural habitat-dominated, in the Jiangxi Province in China in 2014 and 2015. Each field was split into two plots: in one plot no pesticides were applied and in the other plot farmers applied pesticides according to their normal pest management practices. The dataset comprises information on the focal rice fields, the land use surrounding the focal rice fields, arthropod abundances and diversity, crop damage, an exclusion experiment to assess the potential of natural enemies to suppress pests, pest management practices and rice yield
The Cost of Postponement of Bt Rice Commercialization in China
Jin, Yan ; Drabik, D. ; Heerink, N.B.M. ; Wesseler, J.H.H. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Bt rice - cost of postponement - China - technology - trade
To maintain self-sufficiency in rice production and national food security, the Chinese government strongly supports research that aims at increasing the productivity of rice cultivation. Rice with genetic material from Bacillus thuringiensis (Bt rice) is transgenic rice that can reduce lepidopteran pest damage and the use of insecticides. It was developed in the 1990s and earned biosafety certificates in 2009. However, because of political reasons, its commercialization in China has been postponed, and, to date, Bt rice is not grown in China. We assess the opportunity cost of postponement of Bt rice
commercialization in China between the years 2009 and 2019 and consider the external costs of pesticide use and potential technology spill-overs of Bt rice. We estimate the cost of postponement of Bt rice over the analyzed period to be 12 billion United States (US) dollars per year.
Evidence of Toxoplasma gondii in rodents from Bangladesh
Krijger, I.M. ; Cornelissen, J.B.W.J. ; Belmain, Steven R. ; Begum Shafali, R. ; Meerburg, B.G. - \ 2019
Vector-Borne and Zoonotic Diseases (2019). - ISSN 1530-3667
Rodents contribute to the life cycle of the protozoan parasite Toxoplasma gondii as an intermediate host and key prey animal of cats, the definitive host. As there is limited scientific knowledge available about the incidence and prevalence of T. gondii in commensal rodents in many Asian countries, we tested rodents from a commercial rice mill and eight local villages in Bangladesh for the presence of T. gondii DNA using rodent brain material preserved in ethanol. Overall, 10 of 296 (3.4%) rodent samples tested positive for Toxoplasma DNA. Our results indicate that rodents present in food production and food storage facilities may carry T. gondii.
Shoot sodium exclusion in salt stressed barley (Hordeum vulgare L.) is determined by allele specific increased expression of HKT1;5
Bezouw, Roel F.H.M. van; Janssen, Elly M. ; Ashrafuzzaman, Md ; Ghahramanzadeh, Robab ; Kilian, Benjamin ; Graner, Andreas ; Visser, Richard G.F. ; Linden, Gerard van der - \ 2019
Journal of Plant Physiology 241 (2019). - ISSN 0176-1617
Barley - Gene expression - HKT1;5 - Naexclusion - Salt tolerance

High affinity potassium transporters (HKT) are recognized as important genes for crop salt tolerance improvement. In this study, we investigated HvHKT1;5 as a candidate gene for a previously discovered quantitative trait locus that controls shoot Na+ and Na+/K+ ratio in salt-stressed barley lines on a hydroponic system. Two major haplotype groups could be distinguished for this gene in a barley collection of 95 genotypes based on the presence of three intronic insertions; a designated haplotype group A (HGA, same as reference sequence) and haplotype group B (HGB, with insertions). HGB was associated with a much stronger root expression of HKT1;5 compared to HGA, and consequently higher K+ and lower Na+ and Cl concentrations and a lower Na+/K+ ratio in the shoots three weeks after exposure to 200 mM NaCl. Our experimental results suggest that allelic variation in the promoter region of the HGB gene is linked to the three insertions may be responsible for the observed increase in expression of HvHKT1;5 alleles after one week of salt stress induction. This study shows that in barley - similar to wheat and rice - HKT1;5 is an important contributor to natural variation in shoot Na+ exclusion.

Information systems and actionable knowledge creation in rice-farming systems in Northern Ghana
Nyamekye, Andy Bonaventure ; Dewulf, Art ; Slobbe, Erik Van; Termeer, Katrien - \ 2019
African Geographical Review (2019). - ISSN 1937-6812
actionable knowledge - credibility - information systems - Informational governance - legitimacy - salience

Rice farmers in the Kumbungu District in Northern Ghana interact with information systems. Of interest here is the degree to which knowledge derived from such interaction is actionable. The paper addresses the overall question: what information systems are currently providing agricultural information to rice farmers, and to what extent does this result in actionable knowledge creation? Findings revealed that Farmer-to-Farmer systems contribute most to actionable knowledge creation. We conclude that systems integration and local actor participation are essential for actionable knowledge creation in information systems.

Effect of market production on rural household food consumption: evidence from Uganda
Ntakyo, Proscovia Renzaho ; Berg, Marrit van den - \ 2019
Food Security 11 (2019)5. - ISSN 1876-4517 - p. 1051 - 1070.
Food security - Market-oriented production - Propensity score matching - Uganda

Food access is an important element of food security that has since long been a major concern of rural households. One intervention to improve food access has been increased promotion of market production in the hope that households will get increased income and access to food through the market rather than through self-sufficiency characteristic of subsistence production. We examine the effect of market production on household food consumption using a case of rice in western Uganda, where rice is largely a cash crop. Our analysis is based on propensity score matching and instrumental variable approach using survey data collected from 1137 rural households. We find evidence of negative significant effects of market production on calorie consumption; More commercialized households are more likely to consume less than the required calories per adult equivalent per day. This implies that the substitution effects due to higher shadow prices of food outweigh the income effects of additional crop sales. On the contrary, we find positive significant effects on household dietary diversity. We suggest a mixed approach combining policies targeted at market production as well as production for own consumption, and nutrition sensitization.

Drought and conflicts at the local level: Establishing a water sharing mechanism for the summer-autumn rice production in Central Vietnam
Huynh, Chuong Van; Scheltinga, Catharien Terwisscha van; Pham, Ty Huu ; Duong, Non Quoc ; Tran, Phuong Thi ; Nguyen, Linh Hoang Khanh ; Pham, Tung Gia ; Nguyen, Ngoc Bich ; Timmerman, Jos - \ 2019
International Soil and Water Conservation Research 7 (2019)4. - ISSN 2095-6339 - p. 362 - 375.
Adaptation - Agriculture - Climate change - Governance - Rice production - Water sharing

In recent years, water for agricultural production gradually became a significant challenge in the context of climate change in Vietnam. Sustainable solutions are required, which consider the use of resources for both human needs and ecology, and that account for the equitable distribution and the livelihood of the farmers now and in the future. In particular, the farmers in the province of Quang Nam facing water shortage in the cultivation of paddy in the summer-autumn season. Conflicts arise regarding the sharing of the water between the farmers, the drinking water company and the hydropower company. In the context of climate change, the water shortage is expected to increase in the future. The article presents the results of participatory action research (PAR) approach to develop a local level mechanism for water sharing, in which stakeholders actively participated. Water sharing mechanism was developed, envisioning a sustainable solution for inclusive water sharing. The mechanism was successfully implemented in two cases, one at commune level (Tho stream) and one at the district level (Mo stream). The participatory approach proved to be successful in setting up a broadly acceptable mechanism that will need to be further incorporated in the institutional set-up.

Long-term sustainability of the Vietnamese Mekong Delta in question : An economic assessment of water management alternatives
Tran, Dung Duc ; Halsema, Gerardo van; Hellegers, Petra J.G.J. ; Hoang, Long Phi ; Ludwig, F. - \ 2019
Agricultural Water Management 223 (2019). - ISSN 0378-3774
flood risk - Mekong - rice production - salinity intrusion - sediment - sustainability

A dense dike system has been built in the upstream floodplains of the Vietnamese Mekong Delta, allowing large scale rice production based on compartmentalized fields and optimized water management. Intensive cultivation has enabled farmers to greatly increase their rice productivity and augment the national food bowl. However, flood-control structures have undermined the water retention capacity, compromising various benefits of floodwaters for delta ecosystems. Effects are both internal and external to farming. Negative internal effects are the large investment requirements and higher farming costs. Negative externalities include increased flood damage, reduced sediment flows, saltwater intrusion and riverbank erosion. In this study, we assessed the effects of three dike–agricultural system scenarios on delta-level sustainability, considering both internal and external effects. Direct and indirect costs were estimated using various methodologies and the literature. Our findings show that extensive development of high dikes on the floodplains is the least economical and most ecologically risky alternative. In this scenario, accelerated high-dike construction exacted a cost 136% greater than the situation represented by the baseline year of 2011. Externalities in this scenario contributed to rising economic losses in both aquaculture and agriculture. The scenario of transforming high-dike into low-dike systems revealed lower water management costs combined with lesser environmental impacts and greater capacity to exploit floodwater benefits. Our findings provide a useful input for decision-makers considering the unintended economic consequences of existing water management strategies. They support a transition to low-dike farming systems for a more sustainable delta.

Prevalence of leptospira infection in rodents from Bangladesh
Krijger, Inge M. ; Ahmed, Ahmed A.A. ; Goris, Marga G.A. ; Groot Koerkamp, Peter W.G. ; Meerburg, Bastiaan G. - \ 2019
International Journal of Environmental Research and Public Health 16 (2019)12. - ISSN 1661-7827
Food safety - Leptospirosis - Reservoir - Rodents - Zoonosis

Worldwide, Leptospira infection poses an increasing public health problem. In 2008, leptospirosis was recognised as a re-emerging zoonosis of global importance with South-East Asia being one of the most significant centres of the disease. Rodents are thought to be the most important host for a variety of Leptospira serovars. Because Bangladesh offers a suitable humid climate for the survival of these pathogenic bacteria, the presence of rodents could be a serious risk for human infection, especially in peri-urban areas or locations where food is stored. In order to gain more understanding of the multi-host epidemiology, a prevalence study was conducted in Comilla, Bangladesh to determine the presence of pathogenic Leptospira species in rodents. Real-time Polymerase Chain Reaction (qPCR) and sequencing showed that 13.1% (61/465) of the trapped rodents were infected with pathogenic Leptospira. Sequencing of the qPCR products identified the presence of three species: Leptospira interrogans, Leptospira borgpetersenii, and Leptospira kirschneri. Rodents of the genus, Bandicota, were significantly more likely to be positive than those of the genus, Rattus and Mus. Our results confirm the importance of rodents as hosts of pathogenic Leptospira and indicate that human exposure to pathogenic Leptospira may be considerable, also in places where food (rice) is stored for longer times. This study emphasizes the need to improve rodent management at such locations and to further quantify the public health impacts of this neglected emerging zoonosis in Bangladesh.

Inclusiveness of contract farming along the vertical coordination continuum : Evidence from the Vietnamese rice sector
Ba, Hélène A. ; Mey, Yann de; Thoron, Sylvie ; Demont, Matty - \ 2019
Land Use Policy 87 (2019). - ISSN 0264-8377
Adoption - Contract farming - Horizontal coordination - Inclusiveness - Transaction costs - Vertical coordination

The Vietnamese government is currently attempting to upgrade rice value chains in the Mekong River Delta by encouraging (i) vertical coordination between exporters and farmers through contract farming, and (ii) horizontal coordination among farmers through the “small farmers, large field” program. Previous studies on the determinants of contract farming participation assume that firms offer only a single contract type, whereas in reality, farmers may face a continuum of exclusive contract options. Devising correct and targeted policies for fostering contract inclusiveness hence crucially hinges on deploying correct econometric specification of the decision to participate in contract farming. We model contract farming participation and intensity in four different ways along the vertical coordination continuum: as a discrete, categorical, ordered, and continuous choice. We find that older, smaller and horizontally coordinated farmers with higher levels of trust in buyers tend to secure higher levels of buyer investment through increased vertical coordination. In contrast with the common finding in the literature that contract participation is biased towards larger farms, our findings from Vietnam suggest that the scale bias of contract farming could be successfully relaxed through horizontal coordination and even reversed under increasing levels of vertical coordination as smaller farmers are found to secure higher levels of buyer investment. These findings highlight the role both policies can play in fostering inclusiveness of contract farming in rice value chain upgrading in Vietnam.

Effects of feed ingredients on nutrient digestibility, nitrogen/energy balance and morphology changes in the intestine of Nile tilapia (Oreochromis niloticus)
Tran-Ngoc, Kim T. ; Haidar, Mahmoud N. ; Roem, Arjen J. ; Sendão, João ; Verreth, Johan A.J. ; Schrama, Johan W. - \ 2019
Aquaculture Research 50 (2019)9. - ISSN 1355-557X - p. 2577 - 2590.
digestibility - feed ingredient - intestinal morphology - nitrogen and energy balance

The present study assessed the effect of different feed ingredients on nutrient apparent digestibility coefficients (ADC), nitrogen/energy balance and morphology changes in the intestine of Nile tilapia; using a control diet and six test diets, in which the following six ingredients were included at 30%: hydrolysed feather meal (HFM), soybean meal (SBM), rice bran (RB), rapeseed meal (RM), sunflower meal (SFM) and dried distillers grains with solubles (DDGS). The proximal, middle and distal intestine was processed for quantitative histology counting the number of goblet cells (GC), and measuring the thickness of lamina propria (LP) and submucosa (SM). The study showed that the ADC of protein in raw materials were highest in SBM (92.2%), followed by SFM (90.2%), DDGS (89.2%), RM (87.8%), HFM (86.9%) and RB (84.0%). The nutrient ADCs had no correlation with intestinal morphology changes. Only the SBM diet caused noticeable changes in intestinal morphology such as an increase the thickness of SM and LP and the number of GC. The diet composition, however, altered the protein efficiency and the maintenance energy requirement. Protein retention efficiency was the lowest in fish fed HFM and the highest in RB. The highest maintenance energy requirements were observed in HFM and SBM treatments.

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