Vol. 15 No. 2 (2017)

The study was carried to evaluate the effectsof transplanting date and plant density on growth and grain yield of photoperiod sensitive rice varietyBao thai lun in summer season in the Red River Delta. Seeds were sown in nursery on 02/7/2016 but seedlingsweretransplanted on different transplanting dates. The 3x2 factorial experiment was laid out in a randomized complete block design (RCB) withthree transplanting dates: T1 (22/07/2016 - seedlingsat 20 days old), T2 (05/08/2016 - seedlingsat 35 days old), and T3 (05/08/2016 - seedlingsat 50 days old) and two plantingdensity: M1 (35 hills m-2), and M2 (45 hills m-2). Results indicated thatthe transplanting dates had a significantinfluenceonplant height, number of tillers, leaf area index (LAI) and dry matter of the photoperiod sensitive rice. With delayed transplanting date, the growth duration slightly increased. Higher plant density led tohigher number of tillers m-2and a greater dry matter whereas the growth duration, plant height and LAI were less affected. Delaying in transplanting reduced the panicles number m-2, percentageof filled grains, 1000 grains weight and grain yield. The number of panicles m-2increased with increasing plant density,while no significant effectonpercentage of filled grains and 1000 grains weightwas recorded.

Solanum procumbensLour., a Vietnamese valuable herbal medicine, has an effect on liver detoxification. Our study provided basic botanical information of S. procumbensinto the list of Vietnam plants data base for identification purpose, and some methods of S. procumbensgrowing protocol in Gia Lam,Hanoi. This study indicated that spring - summer crop in Gia Lam,Hanoi were appropriate to S. procumbensplanting with media of alluvial soil:acacia bark (1:1), and distance of 0,25 x 0,25 meter. This species also could be propagated by stem cutting in order to rapidly supply with large quantity of plants during the year.

Pot - experiments were laid out in a randomized completely block (RCB) with five replications at the green house of Vietnam National University of Agriculture in autumn cropping season 2016 to investigatephotosynthesis and translocation of non - structural carbonhydratesin an early maturing rice line DCG72 under three levels of potassium application (no potassium application - K0: 0 g K2O/pot; low potassium application level - K1: 0.5g K2O/pot and high potassium application level K2: 1.0 g K2O/pot). The control variety was KD18. The results showed that photosynthetic intensity of two genotypescorrelated with individual productivity and increased withincreasing K level from K0 to K1. Increased K level,K2, reduced leaf area and chlorophyll in DCG72.. Translocation of non-structuralcarbonhydratesof two genotypes was significantly higher at K1 than K0 and K2 within DCG72, higher than KD18 at K1. Individual plant productivity in two rice genotypes increased withincreased K level from K0 to K1only. Individual plant yield of DCG72 was similar to that ofKD18 at K0, but higher than that in KD18 at K1 due to high spikelets per panicle, filled grain rateand 1000 grain weight.At K2, howeverindividual plant yield of DCG72 was lower than in KD18due to low spikelets per panicle and filled grain rate.

Sesame (Sesamum indicum L.) is an important oilseed crop with high-quality seed oil and richness inantioxidant substances. The genetic relationship analysis of sesame is inportant for genetic conservation and exploration. In this research, we reportedthe results on analysis of genetic diversity of 56 sesame accessions by using DNA markers. Among 15 markers (10 SSR and 5 SRAP markers)used,3 were monomorphic and 12 were polymorphic with a total of 34 allelesand an average of 2.3 alleles per locus. The proportion of polymorphic bandsranged from 66.7 to 100% and reached 80.9% on average. Genetic similarity coefficient of 56 sesame accessionsranged from 0.52 to 0.97. At 0.70 similarity, 56 accessionswere divided into 7 groups, the largest group with 35 accessions, followed by group 2 with 17 accessions.

Reverse transcription - polymerase chain reaction (RT-PCR) and sequencing methods were used to identify porcine deltacoronavirus (PDCoV) in eighteen fecal and intestine samples of diarrhae piglets in four farms in Thai Binh and Hanoi in 2015. The diagnostic results showed that 15/18 (83.33%) samples were possitive with PDCoV. The nucleotide and deduced amino acid analysis based on the nucleocapsid (N) gene sequence indicated that nucleotide and aa sequences of PDCoV/VN/TB1/2015 were homologous to Dong Nai isolate (VN-1215, isolated in 2015) at 99% and 99.5%, respectively. The phylogenetic analysis indicated that PDCoV/VN/TB1/2015 and VN-1215 strain were closely related to PDCoV isolates found in 2012 in Hongkong and in 2014 in China.

1500 swab pools were collected from poultry and birds in 15 live-bird markets in 5 provinces in the north of Vietnam from July 2015 to July 2016 to determine the prevalence of avian influenza A virus (H5N6, H5N1 and H7N9) in these provinces. We identified 343 positive samples in 1500 samples with the prevalence of 22.86 percent for influenza type A viruses. 69/1500 samples (4.60%) from 4 provinces (Lang Son, Quang Ninh, Cao Bang and Lao Cai) were positive with H5 subtype virus. For avian influenza A/N6 subtype virus, we detected 49/1500 (3.27%) positive samples with prevalence in Lang Son, Quang Ninh, Cao Bang and Lao cai (6.0%; 5.0%; 2.33% and 3.0%, respectively). The results showed 7/1500 (0.47%) positive samples with avian influenza A/H5N1 virus in Cao Bang, Lang Son and Quang Ninh.

The study was carried out on the KTY-PRRS-01 virus strain isolated in Vietnam. The PRRSV strains were cultured for 5thconsecutive generations on the Marc145 cell and in each passage the virus was tested for biology and molecular biology characteristics. The results of the study showed that through 5th passages, the ability to multiply and destroy the cells of the original virus over time had no significant difference in the generations. The virus began to multiply and had cytopathogenic effect after 48 hours post - infection, cytopathogenic effect reached 80% at 72 hours post - infection, and the cells were completely destroyed after 84 hours post - infection. TCID50 of virus was stable through 5th passages with a titre from 3,03x106/ml to 7,12x106/ml. The ORF5 and ORF7 gene sequences of the virus strain through 5th passages were sequenced. Sequences of these genes showed no difference in nucleotide sequences as well as amino acids through 5th passages. Thus the KTY-PRRS-01 virus strain is stable in biological and molecular biology characteristics over 5th passages.

White spot syndrome virus (WSSV), the causative agent of white spot syndrome in shrimp, has a wide host range includingcrabs, zooplankton (Copepods), molluscs, poultry and polychaete.Ucasp.isa common fiddler living in intertidal land, estuary and sourcewaterused for settling pond of shrimp farmsin Nam Đinh, Nghe An and Quang Ninh. WSSV, an important viral pathogen of the shrimp, can replicate in crustacean species,therefore, it is a potential vector for virus transmission. The major aim of this study was to determine whether WSSV can be replicate on Ucasp and transmitted from Ucasp. to shrimp (Litopenaeus vannamei) through water environment. Uca sp. wasinfected withWSSV by injecting suspension containing WSSV in dilution 10-2on the second leg. Results showed that, WSSV was detected in infected fiddler in experimentby PCR method after 107 hours of infection. WSSV was transmitted from Ucasp. to shrimp through water environment horizontally after 83 hours of exposure to Ucasp. carrying WSSV. Our findings support the contention that Ucasp. was a potential vector for virus transmissionandcan be a source of WSSV infection of culture shrimp.

In this study, the technological parameters for extraction of polyphenols from tea have been examined. The results indicated that the suitable parameters of this process were determined as follows: water content of the material of 5%, material size of 0.5 - 1.0 mm, 50% (v/v) acetone solvent, ration of material/solvent of 1:12, extraction time of 2 h, extraction temperature of 450C and three times of extraction. In addition, with these parameters, the polyphenols extraction yield was 84.55%.

Cacao tree (Theobroma cacao L.) is widely grown in the Central Highlands of Vietnam. During the harvest period, the leaves are not used for any purpose. The present study was conducted to determine the suitable extraction conditions to obtain a rich polyphenol and antioxidative extract from the cacao leaf. The dried cacao leaf extract was applied to prevent lipid peroxidation in the cobia muscles. The suibtale extraction conditions were determined as follows: the extraction solvent was 50% ethanol, the extraction temperature was 75°C, the extraction time was 90 min and the extraction method was ultrasound-assisted extraction. The extract obtained under the suitable conditions had the total polyphenol level, DPPH radical scavenging activity (EC50) and total reducing power (EC50) of 21.33 mg GAE/g dry matter, 0.05 mg/ml and 0.39 mg/ml, respectively. The dried cacao leaf extract was effective in retarding lipid oxidation of minced cobia muscles during cold storage of 9 days. Thus, the cacao leaf extract had a potential to be used as a natural antioxidant to control lipid oxidation during the cold storage of aquatic products.

This study was conducted to evaluate the hepatoprotective and antioxidant effects of the root extract (RE) of Moringa oleifera. BALB/c mice were induced for liver damage by carbon tetrachloride in and subsequently administered by RE as a protection. In the experiments, the RE and silymarin were used at the doses of 0,5 ml (2,0 gram root powder) and 50 mg per kg of body weight, respectively. The results showed that after 14 days of administration, a reduction of the level of liver enzymes AST, ALT, LDH and total bilirubin was observed similar to the case of silymarin. Micro and macro-analysis of liver showed positive effects of both RE and silymarin in liver protection. This study suggested the potential application of RE in liver protection.

Purpose of this research is estimating consumer satisfaction with the quality of electricity service; identifying and analyzing factors which have an influence on household satisfaction with services of Hung Yen Power Company in Hung Yen province. The information is collected by surveying 110 households using electricity (based on 27 standards in 6 groups of service quality, including service attitude; electricity price; receiving feedbacks; providing information to consumers; payment of electricity and time of delivering to consumers. Research methods are: Cronbach’s alpha, Exploratory factor analysis (EFA) with Likert - type scale and regression model to identify, select and analyze levels of satisfaction as well as factors which impact on customer satisfaction with the quality of electricity service of Hung Yen Power Company in Hung Yen province. The research findings are: the level of household satisfaction with the service quality of Hung Yen Power Company in Hung Yen province which bases on research indicators is normal; there is a positive correlation between household satisfaction and group of factors such as time of delivering to consumers, receiving feedbacks, service attitude and providing information to consumers.

Coffee production of farm households plays a vital role in socio - economic development process of Dak Lak provincebut coffee growers often face, among others, with drought, yield and price risks. To analyze coffee production risks, data were collected from 300 coffee-farming households in Buon Don district and Krong Nang districtof Daklak province. Descriptive statisticsand comparative method were used for data analysis. This study focused on analyzing the main risks relating to households’ coffee production including production risks, market risks and financial risks. The research results addressed and meassured the losses of different risks and proposed some recommendationsthat farm households can apply to reduce risks, of which buying production insurance and developing linkage in coffee productionwere highly recommended.

This study was conducted in Son La province to evaluate factors affecting thelinkage in the useofmaize as animal feed for pig keeping households. Data for the study were gathered from 690 pig farming households in Van Ho, Moc Chau and Mai Son districts (Son La province) by direct interviews. The chi-square test was used to test the difference in characteristics between groups of pig farming householdsengaging inlinkage and those that were notengaging in linkage. In addition, probit model was employed to measure factors affecting linkage in the use of maize as animal feed for pig farming households. It was found that therewas significant difference between income of households with linkage and income of households without linkages in the use of maize as animal feed. Moreover, research results also showedthat the education level, gender, ethnic group, social position of the household head, and livestock production scale hadsignificantly positive impact households’engagement in linkage whereas the age of the household head and number of household member significantly exhbited negative effects on households’to linkage engagement. To improve linkage, relevant policy implications were suggested.

For the development of the enterprises, the assessment of impact factors on production and business of enterprises are of great importance. In the present study, 103 small and medium-sizedenterprises (SMEs) in HaiDuong provincewereinvestigated to determine the impact of factors on their business.Themethod of Explanatory Factor Analysis (EFA) was used in the study.In addition, Kaiser-Meyer-Olkin (KMO) test and Cronbach's Alpha wereused for assessing factors on enterprise’s business. The internal capacity of the SMEshas the highest level of impact on the business of enterprises, followed by the capital and policy factors. Based on the findings, a set of policy implications was recommended for the research sites.

The research was carried out in the suburban area of NamDinh city to: (i) to analyze changes of livelihoods of farmhouseholds in the area, (ii) to suggest recommendations to help farmhouseholds select livelihood changes in coming time. The research focused on livelihood activity changes based on surveying 180 farmhouseholds in the area. The research showed that the livelihoods of the farmhouseholds mainly relied on four main activity groups (1) agriculture, (2) worker and hired labor, (3) trade and service and (4) other activity. Livelihood activity change caused structural change of farmhousehold. The households engaged in agricultural activities decreased from 52.11% in 2011 to 40.53% in 2015; the proportion of households engaged in groups 2 and 3 increased from 34.37 to 52.54%; the percentage of household engaging in other activities decreased from 13.18 to 7.13%. The number of jobs, income and living conditions of the households increased. The main factors affecting livelihood changes of the farmhouseholds included natural calamity, disease epidemics, urban development, support policy, livelihood capital change and household’’ attitude. Based on these results, the following recommendations were proposed: providing sufficient information to prevent risk for the households, changing livelihood activities to match changing in centre urban of the city, supporting farmhouseholds to improve livelihood capitals as basis for livelihood activity changes, promoting farmhousehold’ creativity for livelihood activity changes, and improving some policies and regulations related to farmhouseholds.