Browsing by Subject "Cassava"

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Public attitudes towards genetically modified provitamin A Cassava in Brazil
(2010) Gonzalez Rojas, María Carolina; Qaim, Matin
Cassava is a basic staple food crop with worldwide distribution, mainly in developing countries. A fundamental source of energy for the poor, cassava grows well on marginal soils and resists pests and drought. In Latin America, Brazil is the largest cassava producer and consumer. The crop is especially important in the northeastern (NE) part of the country, where poverty and malnutrition rates are higher than in the rest of the country. However, despite the crop?s dietary importance, relatively little is known about consumer preferences, which holds true not only for Brazil but also for other developing countries. Understanding consumer preferences is crucial for technology and market development, especially in the context of provitamin A biofortification, as this entails a yellow-colored cassava root. The first article, titled ?Consumer Preferences for Cassava Characteristics in Pernambuco, Brazil?, addresses this research gap. Consumer preference for different cassava attributes are analyzed using household survey data and econometric techniques. A hedonic price model is specifically developed to estimate the values that consumers place on specific product attributes. Results show the most important characteristics for local consumers are ease of peeling, time of cooking, and texture; however, root color and size as well as market location are other relevant attributes in determining price. The second article, titled ?Consumer Acceptance of Second-Generation GM Foods: The Case of Biofortified Cassava in the Northeast of Brazil?, examines whether consumers would appreciate provitamin A biofortification and accept GM cassava. For this purpose, stated preference data, collected as part of the household survey, are used. Findings suggest that attitudes towards GM biofortified cassava are generally quite positive among local consumers. Three-quarters of all respondents in the survey said they would support the introduction of this new technology. Using contingent valuation techniques, consumers were shown to be willing to pay an average price premium of 64% for GM biofortified cassava. This is high but not unrealistic, given that vitamin A deficiency and related health problems are widespread in NE Brazil. In addition, a contingent ranking choice experiment was used to better understand the trade-offs between different cassava characteristics and estimate the partial willingness to pay (WTP) for each relevant attribute. For the provitamin A attribute alone, the average consumer is willing to pay a large premium of 160%. However, a discount is required for the color change of cassava from white to yellow (-29%), and an additional discount results from the fact that the cassava is genetically modified (-61%). These are important findings for biofortification research programs that have to make choices between conventional and GM breeding techniques. It is noted that a significantly positive WTP does not imply that GM provitamin A cassava will indeed be sold at a premium. The technology is being developed by the public sector with the aim to reduce malnutrition among the poor, so a low price should be sought to enable easy access. Hence, the WTP survey is a tool to better understand consumer attitudes rather than an approach to develop a pricing strategy for a new commercial product. The third article, titled ?Stakeholder Positions toward GM Food: The Case of Vitamin A Biofortified Cassava in Brazil?, gathers experiences from around the world and shows that stakeholder positions can crucially influence the efficiency of GM regulatory approaches and the success of new technologies. This research builds on a survey of a large range of local stakeholders. Overall, stakeholder perceptions about GM foods are relatively positive in Brazil. Statistical analysis shows that three groups of stakeholders can be distinguished: those in favor of GM crops, those against, and those that have a more or less neutral position. Representatives of local and multinational industries and those of several governmental entities belong mostly to the first group; international and national NGOs form the second group, while scientists are mostly found in the third group. Information sources and institutional/personal relationships influence individual stakeholder positions, as do socio-demographic characteristics, such as the level of education and age. An important result is also the high level of trust that stakeholders in Brazil have, in general, in the country?s research and academic sectors. Therefore, taking into account the relevance of information and the role played by the research sector, an effective system of distributing GM crop information via government agencies and/or public media is necessary to complement the knowledge of consumers so that they can make their own informed decisions.
Soil erosion in Andean Cropping Systems: The impact of Rainfall Erosivity
(2002) Sonder, Kai; Leihner, Dietrich
Rationale and methods The Andean region of Colombia, 30% of the country, has about 15% of the tot. population and 50% of the rural population. A great part of the countries food-crops are grown on the hillsides of the region, which are severely degraded or threatened by degradation. The objectives of the present study were: a) to determine the applicability of the USLE rainfall erosivity factor to the Andean Region, particularly the energy-intensity term b) to calculate long-term erosivity data c) to establish the long-term erosivity of two soil types in the research area d) to evaluate the yield and soil conservation performance of several cassava-based cropping systems. Research was carried out at two sites in the Cauca department in the southwest of Colombia. Santander de Quilichao is located at 3o 6' N, 76 o 31' W, at an altitude of 990 m a.m.s.l., with an annual precipitation of 1,789 mm and an average temperature of 23.7 o C. Mondomo, which lies 2o 53' N, 76 o 35' W at an altitude of 1,450 m a.m.s.l., has an annual precipitation of 2,133 mm and an average temperature of 18.2 o C. The soils at both sites belong to the inceptisols, which form about 77% of the soils of the Cauca departments. In 1987 erosion plots were established at both sites on slopes of between 7% and 20% consisting of 8 treatments and 3 repetitions at Quilichao with 2 at Mondomo. During the research in this study, the 8 treatments comprised: 1) Continuous bare fallow, 2) Traditional cassava-based rotation, 3) Continuous sole cassava, 4) Cassava-based rotation with minimum tillage and mulch, 5) Cassava-based rotation with two previous years of bush fallow, 6) Cassava-based rotation with vetiver grass barriers, 7) Cassava-based rotation with legume strips, and 8) Cassava-based rotation with improved fallow element. Rainfall erosivity Drop size distribution measurements with a Joss-Waldvogel Distrometer showed that the USLE R factor is applicable for the research region as no significant differences were found between the measured kinetic energy of rainfall events and calculated values according to the USLE. The average annual r-factor values during the 12 year research period for Quilichao and Mondomo were 10,037 and 9,016 MJ ha-1 mm h-1 a-1 respectively. A highly significant relationship was found between a modified Fournier index based upon average monthly rainfall amounts and the equivalent monthly r-factor values. Soil losses K-factor values measured of 0.017 t h MJ-1 mm-1 at Quilichao and 0.011 t h MJ﷓1 mm-1 at Mondomo may be regarded as being between medium and low, although soil losses on the bare fallow plots were very high due to the extreme erosivity of the climate. Total soil losses in Quilichao on the bare fallow from 1986 to 1998 were 1,840 t ha-1. In Mondomo it was 2,380 t ha-1. From June 1994 to July 1997, the 7 cropped treatments in Quilichao showed susceptibility to erosion in the following order (from high to low): Sole continuous cassava, bush fallow >> farmer rotation, legume strips > improved fallow > minimum tillage, grass barriers. In Mondomo the susceptibility to erosion for the same period was: Sole continuous cassava >> legume strips >> bush fallow > improved fallow, farmer rotation > grass barriers, minimum tillage. When calculating soil loss for a representative plot only the minimum tillage and grass barrier treatments reached levels below the tolerable average annual soil losses under both the Quilichao and Mondomo conditions.The erosivity and erodibility values for the whole 12-year duration of this project showed that there is a highly significant relationship between annual soil loss amounts and the R-factor of the USLE. The continuous bare fallow plots showed strong declines of organic matter at both sites. Yield performance The two conservation treatments, minimum tillage and grass barriers, showed no significant differences regarding yield compared to the widely used continuous cassava system. The farmer rotation treatment showed the highest yield levels, but there were no significant differences between this treatment and the minimum tillage treatment at Mondomo and Quilichao. Conclusions The results confirm the high erosivity of the climate and support the necessity of maintaining permanent soil cover. The proven applicability of the R-Factor of the USLE for the region and the long-term soil erodibility values determined should enable the potential erosion risk to be estimated and appropriate soil conservation measures offered. Of the cropping systems evaluated, both the minimum tillage and the vetiver grass barrier treatments proved to be interesting alternatives to the local cropping systems as they reduced soil erosion to a sustainable level and at the same time reached or even surpassed the yields of the traditional cassava monocropping. All the other systems would lead to degradation if long-term permanent cropping was practised.