Vol. 16 No. 10 (2018)

Swollen siphon disease has been considered as a serious threat to otter clam farming in Vietnam. Virus-like particles (VLPs) were identified asthe main causative agent of the disease, however, the transmission pathway and the pathogenesis of the disease has not been clarified yet. In this study, by using electron microscopy analysis, some host species such as otter clam spat and venerid clam (Tapes dorsatus) were selected to screen for the presence of VLPs and VLPs were further analyzed and described their size, structure and location in the host cells. The studies showed that VLPs were found in otter clam spat that were sampled from the hatchery. This finding indicated that the otter clam spat is one of the causes of spead of the wollen siphon disease in otter clam. VLPs have rod-like shape with the size ranging from 70-90 nm x 600-1.000 nm. They consist of outer shell, outer membrance, inner membrance, coreand are located in the cytoplasm of the host cells. Thesestudiesare playsed as scientific basis for developing strategies for classification of VLPs and control, prevetion and treatment of swollen siphon disease in otter clam.

A survey was conducted to assess variation of marine fishery resources in the Gulf of Tonkin from 2000 to 2015. The swept area method for demersal and near demersal fish groups and hydroacoustics method for pelagic fish group were used. The survey data on fishery resources conducted annually in the Gulf of Tonkin during 2000-2015 period revealed about 568 marine fishery species/groups belonging to 321 genera, 145 families, including demersal fishes (197 species), pelagic fishes (70 species), crustaceans (47 species) and squids (30 species). In 2000-2005 period, the total standing biomass (TSB) was estimated at about 453,000 tones and the maximum sustainable fishing yield (MSY) about 225,000 tones. From 2010 to 2015, the TSB was estimated about 752,000 tones and 719,000 tones, respectively, for the NE and SW monsoon seasons, and the estimated MSY was about 350,000 tones. Noticeably, the pelagic fishes accounted for about 70-80% of the MSY values while the figure for the demersal fishes was only about 20% in both periods.

The objective of this study was to assess the current status and to find solutions for development of hard clam farming in Nam Thinh commune, Tien Hai district, Thai Binh province. Apart from secondary data, primary data were collected through survey of households involved in hard clam farming. Results showed that the total area of ​​hard clam farming in Nam Thinh had remained stable at 1,152 ha since 2014. However, the area and production of clam seeds increased (576 ha, 4,250 tons in 2017) while the area commercial clam production decreased (576 ha, 13,200 tons in 2017) in the last few years. The revenue from hard clam farming in Nam Thinh was over VND 220 billion in 2017, accounting for 42% of the total revenue from production and business activities of the commune. Based on SWOT analysis of hard clam farming in Nam Thinh the following measures were proposed for development of hard clam farming in Nam Thinh: improving planning and zoning for hard clam farming; improving infrastructure; implementing policies supporting farmers in access to investment capital; improving culture techniques and natural disasters response for farmers via trainings, workshops and sharing experience; managing seed sources, environment and diseases; and establishing production - processing - marketing chains for hard clam farming.

This research was conducted to assess the factors influencing the community-based management and use of forestland in Hoa Binh province. Exploratory Factor Analysis (EFA) method and Multiple Regression Analysis were employed to analyze data collected from 5 local communities and 219 households. It was identified that 29 factors significantly affected community-based management and use of forestland in the province. These factors consisted of four groups: the group of law related factors with greatest influence (b = 0.314), followed by the group of natural conditions and infrastructure (b = 0.303), then the group of economic factors (b = 0.236), and finally the and group of social factors (b = 0.086). Based on the research results, the following solutions for the improvement of community – based management and use of forestland were recommended: Improving the legal regulations related to community-based management and use of forestland; overcoming constraints in natural/physical conditions; enhancing the role of organizations in the community and accelertaing activities to change the economic conditions associated with the management and use of community - based forestland.

A study was conducted to determine the changes in tannin,vitamin Candpolyphenolscontentsand antioxidant activity of the cashew apple juiceat different maturity stages.The cashew apples were collected in Binh Phuoc province and classified into 4 different maturity stages including: green (X), color turning (VC), ripe (CV) and over-ripe (CM). Results showed that the tannin, vitamin C and polyphenol contents of cashew apple juice decreased from 470±0.02mg/100ml, 334±3.7 mg/100ml and 1873±5.2 mg/100ml at green (X) to 130±0.01mg/100ml, 176±3.1 mg/100mland280±3.5 mg/100ml at over-ripe (CM), respectively. The antioxidant activity of cashew apple juice was determined basedon the IC50value of DPPH free radical scavenging method and the optical density value(OD) of reducing power method. The IC50 value of DPPH free radical scavenging capacity were 32.3±2.3 gdry matter/ml for green group (X), followed by VC (IC50 = 172.4±2.5gdry matter/ml), CV (IC50= 239.6±2.1gdry matter/ml) and CM (IC50= 407.1±2.1gdry matter/ml). Reductingpower of the cashew apple juices decreased during ripening of cashew apple in the order: X > VC > CV > CM. Thus, the contentsof tannin, vitamin Csndpolyphenolsand antioxidant activity of the cashew apple juice decreased also in the order: X > VC > CV > CM. The results suggestedthat the cashew apple in ripe (CV) and over-ripe (CM) maturity stage aresuitable to produce cashew wineorcashew juice.

This paper introduces a rice germination dataset and retrieval tool for some popular rice varieties in Vietnam. Information and seed germination images from technicians and experts were collected and a dataset containing 7 seed types with 2800 germination images divided into 3 categories (normal seedlings, abormal seedlings, and dead seeds) was built. An image retrieval tool for seed germination was developed for users to get all needed information in a structured way with flexibility.

The purpose of this research was to determine the total phenolic content the and antioxidant capacity of the skin, pulp and seeds of Musa babisiana fruits harvested in Nam Dinh province at five maturity stages by using Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, respectively. Results showed that among the three parts of Musa babisiana, the seeds had the highest phenolic content and antioxidant capacity. Total phenolic content and antioxidant capacity of the three parts decreased with ripening. Furthermore, high Pearson’s correlation coefficients (r = 0.98-0.99) between phenolic content and antioxidant capacity of the skin, pulp and seeds indicated that phenolics were resposible for the antioxidant capacity. However, the low phenolic content and high antioxidant capacity of pulp suggested the presence of other types of antioxidant compounds rather than polyphenols in pulp and differences in phenolic profile in pulp, seeds and skin.

Thepaper investigatespig production towardsfood safety in Luong Tai district, Bac Ninh province. Descriptive statistics, classification, comaprison and F test and Chi-squaretest are methods utilized to implement the study. It has been found that there is an improvement in some farming practices to reduce pig diseases and increase food safety in pork. For example, pig houses are designed well to mitigate the disease spreading from outside. Pig manure is treated by biogas and composting. In addition, piglet and feed are also well managed. However, there are certain practices that affect the spread of diseases and food safety including the treatment of inorganic waste in pig production in combination with domestic waste, the direct dischange of livestock wastewater into dranage system,selling and slaughtering sick pigs for home consumption. Recommendations for improvement of pig health risk to mitigate food safety risk in pig production in Luong Tai district are drawn accordingly.