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Long Xuyên, Vietnam

Loc V.T.T.,Can Tho University | Bush S.R.,Wageningen University | Sinh L.X.,Can Tho University | Khiem N.T.,An Giang University
Environment, Development and Sustainability

This paper investigates the structure, function and wealth distribution within the Pangasius hypophthalmus and Henicorhynchus spp./Labiobarbus spp. value chains in the Mekong Delta of Vietnam. The analysis is driven by key questions relating to the form and function of value chains, their contribution to the livelihoods of farmers and fishers, the effectiveness of government policy and the potential for value chain governance mechanisms, such as contracts and certification, to steer towards sustainable production. The results indicate that actors in the high value Pangasius hypopthalmus export chain have a higher potential income, but face considerably higher economic vulnerability from global markets. Alternatively, Henichorhychus/Labiobarbus spp. fishers are severely constrained in their ability to negotiate higher prices for their fish but appear to be less vulnerable to economic and environmental change. The paper concludes that for value chain governance to improve the livelihoods of fishers and farmers in both high and low value chains, new arrangements are needed that better accommodate customary institutions and informal market relations. © The Author(s) 2010. Source

Dick Zambrano A.,University of Queensland | Bhandari B.,University of Queensland | Ho B.,An Giang University | Prakash S.,University of Queensland
International Journal of Food Properties

This study examined the retrogradation and digestibility relationship of fresh and stale cooked rice of three rice varieties: glutinous (TDK11) and non-glutinous (Doongara and floating rice). The effect of rice variety, degree of milling and retrogradation (staling) of cooked rice on the estimated glycaemic index was determined. Although high-glycaemic index values were obtained for fresh cooked rice of all varieties, staling rice at 4oC for 24 h showed positive effect on floating rice only, yielding intermediate-glycaemic index. The effect of staling on retrogradation rates was corroborated by changes in x-ray diffraction peaks. The thermal and textural properties of rice samples showed higher pasting temperature, final viscosity, and hardness, and lower peak viscosity and adhesiveness for fresh cooked non-glutinous varieties, which were also significantly affected by degree of milling, in terms of hardness, after retrogradation. © 2016, Taylor & Francis. All rights reserved. Source

An experiment was carried out in the research farm of An Giang University from January to April 2011.to compare integrated culture of Tilapia (Oreochomis niloticus) and Common carp (Ciprinus carpio) in an intensive indoor system with earthworms as feed, with an outdoor natural pond system, using biodigester effluent as fertilizer and duckweed as feed supplement. There were four treatments with three replicates in a completely randomized design with mixed stocking of Common carp and Tilapia (50: 50) at low and high densities (3 or 5 fish//m2 in the natural ponds and 60 or 100 fish/m3 in the intensive indoor system. In the outdoor system the fish were raised in natural ponds (4m2), seeded with duckweed and fertilized with biodigester effluent. In the indoor system, the fish were raised in PVC tanks (0.5m3) in an enclosed building and fed with earthworms. Growth rates at the higher stocking rate were lower for the Common carp in the pond system and tended to be lower for the Tilapia as compared with the low stocking rate. In the indoor system where the fish were fed ad libitum, the growth rates were less affected by stocking density. In the outdoor pond system growth rates were much higher for the Tilapia than for the Çommon carp. In contrast, in the intensive indoor system, there were no differences between the two species. The Tilapia gained from 0.95 to 1.32 g/day at high and low densities in the natural pond system but only 0.26 and 0.33 g/day in the intensive system. In the natural pond system the net fish yields were equivalent to 9 and 10 tonnes/ha/year for the low and high densities, respectively. Environmental pollution, as measured by concentrations of total ammonia-N and nitrite in the water, was some 50% greater in the intensive system. An economic analysis, on the basis of gross returns from the fish less the variable costs (fingerlings and feed), showed positive margins for all species/density combinations in the natural pond system compared with the negative margins for the intensive indoor system. Source

Son N.-T.,National Central University | Chen C.-F.,National Central University | Chen C.-R.,National Central University | Duc H.-N.,An Giang University | Chang L.-Y.,National Central University
Remote Sensing

Rice crop monitoring is an important activity for crop management. This study aimed to develop a phenology-based classification approach for the assessment of rice cropping systems in Mekong Delta, Vietnam, using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The data were processed from December 2000, to December 2012, using empirical mode decomposition (EMD) in three main steps: (1) data pre-processing to construct the smooth MODIS enhanced vegetation index (EVI) time-series data; (2) rice crop classification; and (3) accuracy assessment. The comparisons between the classification maps and the ground reference data indicated overall accuracies and Kappa coefficients, respectively, of 81.4% and 0.75 for 2002, 80.6% and 0.74 for 2006 and 85.5% and 0.81 for 2012. The results by comparisons between MODIS-derived rice area and rice area statistics were slightly overestimated, with a relative error in area (REA) from 0.9-15.9%. There was, however, a close correlation between the two datasets (R2 ≥ 0.89). From 2001 to 2012, the areas of triple-cropped rice increased approximately 31.6%, while those of the single-cropped rain-fed rice, double-cropped irrigated rice and double-cropped rain-fed rice decreased roughly -5.0%, -19.2% and -7.4%, respectively. This study demonstrates the validity of such an approach for rice-crop monitoring with MODIS data and could be transferable to other regions. © 2013 by the authors. Source

Son N.T.,National Central University | Chen C.F.,National Central University | Chen C.R.,National Central University | Chang L.Y.,National Central University | And 2 more authors.
International Journal of Remote Sensing

Predicting rice crop yield at the regional scale is important for production estimates that ensure food security for a country. This study aimed to develop an approach for rice crop yield prediction in the Vietnamese Mekong Delta using the Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) and leaf area index (LAI). Data processing consisted of four main steps: (1) constructing time-series vegetation indices, (2) noise filtering of time-series data using the empirical mode decomposition (EMD), (3) establishment of crop yield models, and (4) model validation. The results indicated that the quadratic model using two variables (EVI and LAI) produced more accurate results than other models (i.e. linear, interaction, pure quadratic, and quadratic with a single variable). The highest correlation coefficients obtained at the ripening period for the spring-winter and autumn-summer crops were 0.70 and 0.74, respectively. The robustness of the established models was evaluated by comparisons between the predicted yields and crop yield statistics for 10 sampling districts in 2006 and 2007. The comparisons revealed satisfactory results for both years, especially for the spring-winter crop. In 2006, the root mean squared error (RMSE), mean absolute error (MAE), and mean bias error (MBE) for the spring-winter crop were 10.18%, 8.44% and 0.9%, respectively, while the values for the autumn-summer crop were 17.65%, 14.06%, and 3.52%, respectively. In 2007, the spring-winter crop also yielded better results (RMSE = 10.56%, MAE = 9.14%, MBE = 3.68%) compared with the autumn-summer crop (RMSE = 17%, MAE = 12.69%, MBE = 2.31%). This study demonstrates the merit of using MODIS data for regional rice crop yield prediction in the Mekong Delta before the harvest period. The methods used in this study could be transferable to other regions around the world. © 2013 Copyright Taylor and Francis Group, LLC. Source

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