Tập 15 Số 9 (2017)

A pot experiment was conducted in a net house to evaluate the effects of three different irrigation frequencies (irrigation at a 7-day interval (T1), a 14-day interval (T2) and a 21-day interval (T3)) on the growth of three mugwort accessions. Results from the experiment revealed that different irrigation frequencies significantly affected the agronomical, anatomical, and physiological characteristics of mugwort. Decreasing the irrigation frequency from a 7-day interval (T1) to a 21-day (T3) led to significant decreases in plant height, leaf number, leaf area, and dry matter accumulation of each mugword accession. The highest value of plant dry weight was recorded in T1G1 (5.98g plant-1) and the lowest was observed in T3G1 (2.53g plant-1). Among the three mugwort accessions used in the study, G6 was seen to have the highest drought tolerance performance, followed by G1 and G7, respectively.

Supplementation of immuno-stimulant can act as a potent immune modulator and have the effect on inducion of immune- related genes which involved in host defense. In order to clarify the anti-lipopolysaccharide factors (ALF) expression of Kuruma shrimp (Marsupenaeus japonicus) after feeding immuno-stimulant, the supplement containing microalgae and Euglena (Ex400) was selected for the trials. Total RNA was extracted by RNA Iso Plus from the lymphoid organ, intestine and blood of shrimp that was fed with Ex400 diet. Tissues were collected at 0, 3, 7, and 10 days after feeding. ALF transcripts were significantly increased by Ex400 compared to control-diet-fed shrimp (with P<0.01) at 3 days post-feeding in the intestine and lymphoid organ. This suggested Ex test diet might stimulate ALF of Kuruma shrimp immune defence in the intestine and lymphoid organ.

The study was performed to evaluate the use of gut weed (Enteromorpha sp.) as a protein source to substitute soybean meal protein in the diets of post-larval tiger shrimp (Penaeus monodon). A diet without gut weed meal, considered as a control, was compared with four experimental diets in which soybean meal protein was replaced by different gut weed protein levels, namely 15, 30, 45 and 60%. All diets were formulated to be equivalent in crude protein (40%) and lipids (7%). The feeding trial was conducted in 100 L plastic tanks filled with water at a salinity of 10 ppt, and provided with continuous aeration. Thirty shrimp post-larvae with a mean initial weight of 0.033g were stocked in each tank and fed the test diets for 45 days. Results showed that survival of the shrimp was not affected by the feeding treatments, and ranged from 84.4 to 88.9%. Overall, the growth rate and feed efficiency of the shrimp fed the gut weed-based diets were comparable to or better than animals fed the control diet. Moreover, the shrimp fed diets containing gut weed meal also showed a better formalin resistance than the ones fed the control diet, although a significant difference was only observed between the 30% replacement treatment and the control group indicating the optimal replacement level for tiger shrimp PL diets.

The development of histomorphology structures of small intestine in pigs is affected by food consumptions. In the present study, twelve Muong indigenous pigs and nine Vietnamese wild boars were investigated to compare the morphology of small intestine. The tunica muscularis in duodenum of Muong indigenous pigs was significantly thicker than that in wild boars. In jejunum, the difference was observed in submucosa layer and the crypt depth. In the segment of ileum, the thickness of submucosa and inner mucosa layers of Muong indigenous pigs was significantly greater than that of the wild counterparts. Conversely, the villous height and the cript depth in the wild boars showed higher value. The ratio of villous height/crypt depth in duodenum and jejunum of Muong pigs was higher than that in wild boars but the contrary result was found in the ileum. The distribution of Goblet cells in duodenum of Muong indigenous pigs was 2.8 times more than that of Vietnamese wild boars. The results suggested that the difference in nutrient sources might be a factor to decipher the histomorphology structures of small intestine of pigs.

Acute hepatopancreatic necrosis disease (AHPND) is considered to be a new emerging shrimp disease currently affecting brackish water shrimp aquaculture in Southeast Asia including Viet Nam. It was first recorded in shrimp farms in China in 2009 and then in Vietnam in 2010, Malaysia in 2011, Thailand in 2012, and Mexico in 2013. It has been found that AHPND is caused by unique bacterial strains belonging to the Vibrio group. AHPND-causing strains have been found to be carried in a plasmid harboring virulent Pir A/B genes that code for the two toxin proteins inducing AHPND in shrimp. This paper will update all research progress on AHPND, including epidemiology and risk factors, etiology, disease diagnosis, disease prevention, and management. This review will serve as a useful introduction for researchers who are currently unfamiliar with AHPND and will hopefully encourage readers to participate in the research efforts to reduce AHPND’s impact on shrimp aquaculture.

Environmental concerns and limitations in water sources for aquaculture production are critical factors in the pursuit of wastewater treatment systems for sustainable aquaculture development. In the study, the accumulation of nitrogen components in the effluent from shrimp ponds was examined and the removal efficiency of a wastewater treatment system were evaluated for a commercial production scale. The wastewater treatment system consisted of three steps: (1) sedimentation, (2) sand-filtration, and (3) bioremediation of a high rate algal pond (HRAP), which cultivated Ulva ohnoi seaweed as a monoculture. The study showed that the discharged water from intensive shrimp ponds at the end of the production cycle contained high levels of nitrogen components. Compared to the inlet water (from reservoirs), the total nitrogen (TN) concentration in the effluent increased from 0.26 mg/l to 6.23 mg/l and was composed of 25% total particle nitrogen (TPN), 42% total ammonia nitrogen (TAN), 30% dissolved organic nitrogen (DON), and a very low proportion (approximately 3%) of oxidised nitrogen compounds (NOx). The combined treatment system effectively removed 78% of TN in the wastewater, reducing TN from 6.23 to 1.33 mgN/l. The removal efficiencies of the sedimentation pond, sand-filtration, and HRAP were 47%, 15%, and 16% TN, respectively. While the sedimentation pond mainly cleared the TPN components; the sand-filtration effectively reduced TAN and converted this compound into NOx due to its function as a habitat for nitrifying bacterial growth, and the treatment step with HRAP significantly removed both TAN and NOx in the effluent. Therefore, the treatment system integrating seaweed cultivation presented a high efficiency in removing the nitrogen components in the wastewater from intensive shrimp farms.

Gialam district is one of the gateways into Hanoi capital, where urbanization is actively progressing. As a result of urbanization, in recent years, land market in Gialam has been booming. Therefore, in order to avoid possible financial losses on land use, it is necessary to improve the cadastral management system. A cadastral database has been developed for Ninhhiep commune, Gialam district based on  GIS technology, which includes spatial data (landuse maps) and their attributes (detailed information of land owner, land category, land price and legal status of 3494 land parcels). This properly and carefully developed cadastral database allows users to get all necessary information (referring map and its attributes) for every land parcel  in the area. Therefore, while using this cadastral database, users can get recorded land use status, land use ID and its area, and land use owner's financial responsibility. This cadastral database also allows users to get necessary information for preparing  financial reports on land use and to develop a land price map. It can also support land use owners to clarify their financial responsibility. In order to enable timely update land use information, WebGIS technology was integrated in the database to allow users to get necessary land use information through internet (with limited access to secure this cadastral database) using smart phones. The result of the present study is practically significant in the era of the development of information technology for management activities in general and for cadastral management in particular.

The purpose of this study was to apply multivariate linear regression model to determine the factors that affect residential land price in Dien Bien Phu city, Dien Bien province. The obtained results showed that there were four groups of factors affecting the residential land price in Dien Bien Phu city, including: social factors, economic factors, regional factors and  individual factors. Collected data were processed using the statistical software SPSS; the consistency coefficient was measured with Cronbach's Alpha for scaling test and Exploring Factor Analysis (EFA) was used. The analysis of Multivariate Linear Regression Model indicated that 61.1% of the variation of residential land price could be explained by the variation of the 4 groups of independent variables, while the rest (38.9%) was explained by other factors outside the model. The model that showed factors affecting the residential land price of Dien Bien Phu city as follow: Y = 0.644 + 0.185X1 + 0.261X2 + 0.493X3 + 0.327X4. The regional factor had the highest effect on residential land price with 23.9%  contribution, followd by individual factor with contribution of 15.78%,  economic factor with contribution of 12.6%, and  social factor with contribution of 8.93%.

Tomato is a worldwide economic valuable and healthy crop with good nutritional properties. However, postharvest losses of tomato are relatively huge due to suboptimal harvest techniques and the maturity index. This issue could be solved if the biological variation of a tomato cultivar is quantified. In this study, a mathematical model was established to determine the biological age of tomato fruit cv 'Savior' grown during the winter. After which, the model was successfully validated using a single point estimation method. The model parameters estimated in this study could be used to predict the biological age of tomato grown in different locations and periods. The data play an important role for predicting the optimal harvest strategy in further research.

In Vietnam, root of Paramignya trimera has been known as a traditionally medicinal plant for treatment of various types cancers. For years, over-exploitation has led to the reduced diversity and availability of this plant resource. In nature, the multiplication rate of Paramignya trimera from seeds is very low. In order to increase the rate of multiplication for conservation purpose, in this study, in vitro micropropagation of Paramignya trimera was carried out. The results showed that woody plant medium (WPM) containing 20 g/l sucrose and 7.0 g/l agar was most suitable for in vitro propagation of Paramignya trimera. WPM supplemented with 3.0 mg/l BA, 0.2 mg/l TDZ was optimal medium for shoot formation while WPM supplemented with 1.5 mg/l IBA was suitable for the root induction.

Sesquiterpenes, a class of terpenes, consist of three isoprene units, constituting a highly diverse class of natural bioactive compounds that are found principally in plants but also in fungi and some invertebrates and myxobacteria as well. In this study, by using different approaches for isolation, analysis of morphology and bio-physio-chemical properties and comparison of the sequences of 16S ribosomal RNA genes, three strains belonging to the group of myxobacteria were isolated from soil samples collected from some areas in Vietnam. The sesquiterpene biosynthesis in the isolated strains was investigated. The data showed that the isolated strain DL1 was able to form fruiting body and sysnthesize an eremophilene-like sesquiterpene.

Porphyrins play vital roles in various biological processes. This study focused on porphyrin biosynthesis control under drought stress in rice plant. The results showed that in response to drought treatment by water withholding, the level of porphyrin intermediates greatly decreased after 36 h of treatment whereas final products (chlorophyll and heme) content just slightly reduced after 60 h of drought stress. The activity of some key enzymes in porphyrin pathway, including ALA-synthesizing capacity, PPO activity, Mg-chelatase activity, Fe-chelatase activity reduced together with the down-regulation of porphyrin biosynthetic genes and nuclear-encoded photosynthetic genes, especially at 48 and 60 h after treatment. It indicated a sensitivity of porphyrin pathway to drought stress. And it also demonstrated a tight control of porphyrin biosynthesis in order to prevent the accumulation of toxic metabolic intermediates by down-regulation of their biosynthesis under drought condition. Abbreviates: ALA: 5-aminolevulinic acid, ALAD: ALA dehydratase, CHLD: D-subunit of Mg-chelatase, CHLH: H-subunit of Mg-chelatase, CHLI: I-subunit of Mg-chelatase, FC: ferrochelatase, GSA: glutamate 1-semialdehyde aminotransferase, HEMA: glutamyl-tRNA reductase, MgProto: Mg-protoporphyrin IX; MgProto ME: Mg-protoporphyrin IX monomethylester; Pchlide: protochlorophyllide, PORB: protochlorophyllide oxidoreductase B, PPO: protoporphyrinogen oxidase, Proto IX: protoporphyrin IX, ROS: reactive oxygen species.

In this study, the mature gene encoding for the enzyme endochitinase from the Gram positive bacterium Bacillus licheniformis DSM13 (ATCC 14580) was cloned into the expression vector pET-21d, and then overexpressed in E. coli T7. A high expression level was indicated by SDS-PAGE and an enzyme activity assay using pNP-(GlcNAc)2 0.18 mM as the substrate. The activity of the enzyme expressed in E. coli T7 was approximately 8 times higher than that previously expressed in Lactobacillus plantarum. Recombinant chitinase was purified from cell extract and characterized using coloidal chitin 2% as the substrate. The enzyme showed good thermostability (half-lives of 15 days and 8 days at 37 and 50° C, respectively), and good stability in the pH range of 5 - 9. The main product of colloidal chitin hydrolysis as indicated by thin layer chromatography was diacetyl glucosamine. The results demonstrated that this enzyme was promising for chitin waste bioconversion into different chitin-oligosaccharides, such as functional diacetyl glucosamine.

This study aimed to isolate, select, and identify Aspergillus oryzae producing high salt tolerant neutral protease from traditional fermented foods which could potentially be used for food fermentation and other relevant applications under the high salt conditions. Twelve of 23 isolates were primarily assumed to be Aspergillus oryae by morphological observation. Of which, TB1 from soy sauce revealed the highest protease activity with 49.26 U/l, corresponding to a 17mm diameter clear zone on a BCG casein agar plate, and was identified using molecular biology methods and named Aspergillus oryzae TB1. Protease activity of this strain was highly active in the pH range of 5.0 - 8.0 and was optimal at pH 7.0. The enzyme activity remained 70% after 8 hours of incubation at pH 7.0 and 37oC.The protease activity of TB1 was reduced when the sodium chloride concentration increased from 0% to 16%, and relative activity was 51.8% at 16% NaCl. In the salt tolerance test, the results indicated that the protease tolerated 16% NaCl and residual activity was 49.2% after 9 hours of incubation at 37oC.

Cellulases are enzymes synthesized by diverse groups of microorganisms. These enzymes have demonstrated biotechnological potentials in various sectors, including food, animal feed, brewing and wine, and pulp and paper industries. In this study, 100 strains of Bacillus spp. were incubated in MT1 agar medium, and cellulolytic activity was qualitatively determined by measuring the diameters of the hydrolytic clear zones. The three most active strains (A1.2, A1.8, and B6.4) showing clear zone diameters above 24 mm were selected. Cellulase activity in a liquid medium was further quantitatively determined by the dinitrosalicylic acid (DNS) method. Cellulolytic bacteria were identified by 16S rRNA gene sequencing, and neighbor-joining phylogenetic analysis was conducted to determine the evolutionary relationships between the selected strains and reported strains from the GenBank database. The strains were identified as Bacillus cereus (A1.2 and A1.8), and Bacillus pumilus (B6.4). Cellulase produced by B. pumillus B6.4, a GRAS bacterium showing the highest cellulase production in a liquid medium, was partially purified and characterized. The enzyme was most active at 55°C and pH 6.5. Half-lives (conducted at pH 5.0) of the enzyme at 55, 65, 75, and 85°C were 180, 180, 30 and 20 min, respectively. Similarly, half-lives (conducted at 37°C) of the enzyme at pH 5.5, 6.5, 7.5, and 8.5 were 130, 135, 80 and 70 min, respectively. The broad range of working temperatures and the stability under mild acidic conditions suggest that the cellulase of B. pumilus B6.4 could be a good candidate for application in the lignocellulosic bioethanol industry.

The study focused on the impact of the village savings and loan (VSL) model on living conditions of rural women as well as on the extension of the model, thereby proposing model development in the local conditions. The study used data from 453 respondents including member and non-member of village savings and loan models in five districts of Quang Binh and Quang Tri provinces. Site observational methods combined with difference in difference (experiment methods) methods were the main methods used in the study. Research results show that the VSL model's unique impact on gender equity, in particular, is that women can move freely without a male companion (almost 90% respondent), the impact of the VSL model increased by 6%. In addition, members in the VSL model had a poverty rate of 27%, lower than the control group of 34%. The VSL model is able to replicate to other localities in the country. The Women's Union should enhance its role in communicating model replication through participatory study tours to model regions.

The livestock sector in general and pig production in particular is important in Vietnam not only for supplying food for its growing population but also for its significant contributions to the country’s economy. Smallholder pig producers which are predominant, supply at least 80% of pork in the market in the country. This paper aims to draw a picture of pig production performance of small farmers based on the survey data of ILRI-VNUA using a value chain approach. It is estimated that the income of pig smallholders was, on average, VND 765 thousand per 100 kg pig live pig weigh; regional differences in income were statistically significant. Pig diseases, feed use, and measures applied for disease protection had significant effects on farm income. However, different perceptions on food safety were not significantly associated with income levels of farmers. A long time is likely to be needed to change the perception and behaviors of farmers on food safety.

This study focused on analyzing corn value chains in Lao Cai province as well as proposing solutions to upgrade the corn value chains in order to improve the livelihoods of ethnic minorities in Lao Cai. The study used data from a survey of 120 corn ethnic minority households and corn value chain actors in Lao Cai in 2016. Descriptive statistics, comparative statistics, and the values chain analysis method ​​are the main methods used in the study. Research results showed that farmers used outdated cultivation techniques, especially ethnic minority households in upland communes, and often produced corn by extensive farming methods (no fertilizer or a small quantity of fertilizer) with unsecured technical procedures. The product distribution channel is long with many stakeholders. Nearly 75% of the corn producers sell their products to traders in their commune who then sell it to three other levels of agents (the district, province) before the products reach the consumer.

Coffee and pepper are key crops generating income and employment for farmers in the Central Highlands. The intercropping of the two crops has been practiced recently by farmers and this has initially shown to be a good production system. The study was designed to evaluate the economic performance of coffee and pepper intercropping in Quang Hiep commune, CuMgar district, Dak Lak province, and propose key recommendations to improve the economic performance of the system. In-depth interviews with 50 farm households were conducted, and evaluated using descriptive and comparative statistics. The results show that the average area of intercropping is estimated at about 1.5 ha/ farm household. On average, a hectare of intercropping produces 2.76 tons of coffee and 1.51 tons of pepper, generating an income of about 203 million VND/ha for households during the crop season 2014 - 2015. The system proved to be more economically efficient than the mono-system. Economic performance of the intercropping system was found to be different between households and depended on the production scale, irrigation status, seed quality, gender, ethnicity, and farmers’ technical know-how. The production system now faces other obstacles, such as crop diseases and pests, changing weather, input and output market, and market information. Key recommendations to improve economic performance of coffee-pepper intercropping in Quang Hiep commune are proposed accordingly.

The main objective of this study was to quantify food security at the household level in Tay Yen Tu Nature Reserve, Son Dong district, Bac Giang province. The Household Food Insecurity Access Scale (HFIAS) was used to obtain food insecurity statuses. Households in Tay Yen Tu Nature Reserve were classified into four categories including food security, mild food insecurity, moderate food insecurity, and severe food insecurity with prevalences of 25.28%, 20.8%, 32.5%, and 20.8%, respectively. The relationship between livelihood strategies and household food security (HFS) revealed that diversifying products and sales tended to improve the food security status. Furthermore, using Principal Component Analysis (PCA) and Cluster Analysis (CA), the research found that the livelihood strategies of the food security category were based on agricultural and natural forest activities, while those of the food insecurity categories related to commercial forest, off-farm, and other activities. Finally, this research suggested that policy makers should focus on promoting agricultural models in paddy rice, maize, peanut, and livestock production; provide support for poor households cultivating plants that consume less water such as soybean, maize, and peanut; shift traditional cultivation from “cereal-livestock mix” to a model of cash income diversification; and invest in and implement intensive horticultural production and infrastructure development including transportation development, irrigation systems, electricity, and market development.