Published: 2019-04-29

Effects of water pH on susceptibility of whiteleg shrimp (Litopenaeus vannamei) to acute hepatopancreatic necrosis disease Vibrio parahaemolyticus

Tuan V. Vu, Khuyen T. T. Phan, Huyen M. Huynh, Kieu T. N. Nguyen, & Dung T. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.11.02.2019
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Abstract

Effect of water pH on susceptibility of white leg shrimp Litopenaeus vannamei to acute hepatopancreatic necrosis disease caused by Vibrio parahaemolyticus was carried out in laboratory condition. White leg shrimp (2 - 3 g) were challenged by immersion for 2 h with tryptic soy broth (TSB)-grown Vibrio parahaemolyticus at 10 times lower dose of LD50. The results showed that the cumulative mortality of V. parahaemolyticus-immersed shrimp after 240 h was increased from low to high pH water levels (23.3 ± 5.8% in pH 6.3; 30.0 ± 20.0% in pH 7.3; 86.7 ± 15.3 in pH 9.3, respectively). The cumulative mortality of shrimp that held in pH = 8.3 was the lowest (20.0 ± 0.0%). In another experiment, immune parameters such as total haemocytes count and respiratory burst of Litopenaeus vannamei held at different pH levels were examined at 0, 24, 48, 72 and 96 h. The results indicated that no significant difference of total haemocytes count was observed at different pH water levels (pH 6.3, 7.3, 8.3, 9.3) at 0 - 72 hpc (hour post challenge). At 96 hpc, total haemocytes count at high pH water level (9.3) was increased and significant difference in comparison with the total haemocytes count recorded in low pH water levels (6.3, 7.3, 8.3). Respiratory burst was also not diferent at different pH water levels at 0 hpc. However, respiratory busrt of shrimp that held at low pH water levels (pH 6.3 and 7.3) was rapidly reduced and significant difference in compared with the shrimp that held in high pH water levels (pH 8.3 and 9.3). It was therefore concluded that low and high pH stress decrease the resistance of Litopenaeus vannamei against V. parahaemolyticus and decrease several parameters of the immune response.

Effects of water pH on physiological parameters and color changes of Asian Bumblebee Catfish (Pseudomystus siamensis Regan, 1913)

Tuan V. Vu, Truc T. T. Nguyen, Binh T. T. Vu, & Duyen T. H. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.10.02.2019
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Abstract

Effects of water pH on blood physiological parameters and color change of Asian bumblebee catfish (Pseudomystus siamensis) (4 - 6 g/fish) were carried out in laboratory condition. The experiment was set up in 8 weeks at different pH water levels (pH = 3, 4, 5, 6, 7, 8, 9, 10, 11). The results have shown that the cumulative mortality ratio of Asian bumblebee catfish at the end of 24 h challenge was 100% at pH = 11, 70.83% at pH = 10, and 62.5% at pH = 3. No mortality of fish was observed at pH = 4, 5, 6, 7, 8, 9 after 24 h of the challenge. The lowest and highest pH threshold that killed 50% of fish after 24 h of the challenge were 3.04 and 9.95, respectively. After 24 h of the challenge, total number of red and white blood cells of fish increased at pH = 3, 9, 10, and get the highest level at pH = 3 (1.87 × 106 cells/mm3và 1.59 × 105 cells/mm3, respectively. At the end of the challenge, highest number of red and white blood cells were observed at pH = 8 (2 ± 0.23 × 106 cells/mm3 và 1.27 ± 0.26 × 105 cells/mm3, respectively). Fish were in bright and beautiful color when cultured in high pH water levels.

Antibiotic resistance of E. coli isolated from whiteleg shrimp (Litopenaeus vannamei) collected from wet markets and supermarkets in Ho Chi Minh city and their transferability

Kha H. N. Nguyen, & Hue N. D. Truyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.12.02.2019
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Abstract

n this study, a collection of 130 E. coli isolated from white-leg shrimp collected from three wet markets and two supermarkets in Ho Chi Minh City was analysed to examine their antibiotic resistance characteristics and the transferability of resistance markers. High levels of resistance to ampicillin, tetracyclines, trimethoprim/sulfamethoxazole, nalidixic acid and chlorampheni-col were observed. The percentage of multiple drug resistance (4 to 10 tested antibiotics) was 73.8%. The multiple antibiotic resistance (MAR) index values of 0.4 to 0.73 (of each sample collection site) indicated that these isolates were exposed to high risk sources of contamination where antibiotics were commonly used. Conjugation experiments demonstrated the successful transfer of all or part of the resistance phenotypes of shrimp isolates to the human recipient strains.

Making polymer membranes immobilized with phosphate solubilizing bacteria to produce controlled release fertilizer in combination with microorganisms

LINH D. P. BUI, Hung T. Huynh, Ha N. Nguyen, & Luan Q. Le
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.13.02.2019
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Abstract

The combination of slow-release nutrients with microbial activities in a fer-tilizer product could increase the fertilizer’s efficiency, and limit the impact of chemical hazard of fertilizer on the environment. The aim of this research was to determine the optimal parameters for adequate size of immobilized bacterial particles, mechanical properties of polyvinyl alcohol (PVA) and chitosan membranes with or without intergrating of immobilized bacterial particles to produce slow release fertilizer. The result showed that the com-bination of 1% sodium alginate concentration (molecular weight of 100 kDa) and 1% calcium chloride concentration was optimal for the preparation of immobilized microbial calcium alginate particles. The activity of phosphate solubilizing bacteria Burkholderia silvatlantica immobilized in micro calcium alginate particles, in PVA membrane, and in chitosan membrane after 72 h was about 84.2%, 82.2%, and 52.9%, respectively in comparison with free bacteria. Mechanical properties of PVA membrane with and without bac-terial immobilized particles with modulus, elongation, and toughness were 0.122 GPa, 115.1%, 17.65 MPa and 0.022 GPa, 220.8%, 18.70 MPa, respec-tively. Mechanical properties of chitosan membrane with and without bac-terial immobilized particles with modulus, elongation, and toughness were 0.6 GPa, 7.6%, 0.66 MPa and 0.842 GPa, 32.4%, 3.52 MPa, respectively.

Effects of soaking and germination conditions on gamma - aminobutyric acid and total phenolic content in geminated mung bean

Anh T. Vu, Huan T. Phan, & Tuyen C. Kha
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.14.02.2019
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Abstract

Germinated mung bean is a well-known food due to its high content of gamma aminobutyric acid (GABA). This study was designed to test the effectiveness of soaking and germination conditions on GABA and total phenolic contents in germinated mung bean. The results showed that reasonable conditions for soaking mung bean was at 300C within 8 h, which created the highest content of GABA (4,51 mg/g). Meanwhile, the highest content of polyphenol (1,25 mg GAE/g) was reached at 350C within 8 h. The optimized conditions for germinating mung bean were at 350C for 24 h giving the most highest content for both GABA and TPC, 4,46 mg/g and 1,30 mg GAE/g, respectively.

Production of protein powder from salted duck eggs white

Trinh A. Nguyen, Thuy T. P. Nguyen, & Thao T. T. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.15.02.2019
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Abstract

The objective of the research was to determine process conditions to pro-duce protein powder from salted duck egg whites based on the two main steps including precipitation of the protein from egg white and drying the protein. Optimization for process parameters of protein’s precipitation and drying were carried out by Response Surface Design method with the results obtained from the experiment. Basing on the determination of the limits of studied factors, defining the regression and choosing the optimal parameters for precipitation and drying processes. The result of optimal protein precipitation was the ratio of water/salted duck egg white: 3.5/1, the temperature of 800C and precipitation time of 60 minutes with the process yield was 9.63% and the salt separation was 19.61%. The result of optimal drying process was the drying temperature at 750C, material density: 0.35 g/cm2(wind speed of 0.64 m/s and drying time of 4 h) with the product solubility of 11.05%, the water content of 8.19% and aw of 0,476. Verifying the defined regression equation and experiment showed the different level is less than 5%, the defined regression equation is valid and has the potential to apply in production.

Assessment of the cooperation activity in seed-corn production by contract farming: A case study at Phuoc Tan commune, Xuyen Moc district, Ba Ria Vung Tau province

Luan D. Tran, Tho N. Vu, & Giang T. Tran
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.1.02.2019
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Abstract

This paper used the qualitative research, based on the analysis of multi-dimensional information from stakeholders to investigate the seed-corn production activity by the contracted farming at Phuoc Tan commune, Xuyen Moc district, Ba Ria Vung Tau province. The results showed that Thailand CP Company supported the farmers by sponsoring the seeding cost, providing technical support in production and buying the products. Farmers who participated in seed-corn production had a significantly higher income compared to those of other crops. In the collaboration contract, the company had terms and conditions to reserve its monopoly seed-corn product. Therefore, most of the farmers complied with the agreement of not selling the products to outsiders. The descriptive statistic data, using Likert scale, also showed that the farmers had a fairly high levels of satisfaction. This study also found that the better the market capacity of a company was, the higher the scale and sustainability of cooperative activities from farmers in Phuoc Tan commune was.

Assessment of the willingness of households to pay for clean water use in Cang Long district, Tra Vinh province

Dung C. Le, & Tri D. Pham
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.2.02.2019
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Abstract

This study aimed to estimate the willingness of households to pay for domestic clean water use against its price in rural areas of Cang Long district, Tra Vinh province. This research also identified the possibility and factors affecting the willingness to pay for a given price of 6,500 VND or above per m3 of clean water. A contingent valuation method with multiple prices (bidding game) ranging from VND 5,000 to VND 9,000 per m3  of clean water was applied to interview 120 households in Cang Long district. Results showed that the mean willingness to pay was VND 6,200 for each m3 of clean water used. The income positively affected the willingness to pay against the price of 6,500 VND or above whereas the household size had a negative impact on this parameter. It is suggested that the service provider should consider to extent the minimum volume of water used up to 10 m3/month instead of 4 m3/month in accordance with the minimum price of 5,700 VND per m3 of water used.

Factors influencing the change in purpose of land use of households at Lac Duong district, Lam Dong province

Anh T. N. Nguyen, & Hiep T. Ta
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.3.02.2019
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Abstract

The article aimed to investigate the effects of socio-economic and demographic characteristics of the households, the land area, and the occupation of household members in Lac Duong district, Lam Dong province, on the change in purpose of lan duse. The data for this analysis were collected in 2016 by sur-veying of 340 farm households in two administrative divisions (Dasar commune and Lac Duong town, Lac Duong district). The paper used the Probit regression method to measure the impact of independent variables on the probability of farm households changing land use purposes. The results showed that other production potentials on the land were maintained despite the limited use of land and income, which directly af-fected the decision to change the land use of farmers. The status of Lac Duong district affected the purpose of land use. The current context of the district suggested that this districtis in still a rural area, not strongly affected by urbanization, al-though the location is very close to Da Lat city and this dis-trict has large area of farmland. It is not necessary to change the land use purpose. Farmers can use advanced production methods such as hi-tech agriculture, urban agriculture, and agro-tourism. The further confirmation of results presented here from future studies is necessary.

Managing, exploiting and sharing cadastral databases in district 6, Ho Chi Minh City: Present status and solutions

Linh D. T. Truong, & Thy N. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.4.02.2019
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Abstract

As one of the first unit in Vietnam which got cadastral database, so the database of district 6, Ho Chi Minh City is quite limited in terms of building process, content and data structure. The database does not comply with the current reg-ulations of Ministry of Natural Resources and Environment, and not synchronized with cadastral database of other locali-ties. The Ho Chi Minh City Department of Natural Resources and Environment (2014) concluded that these limitations led to difficulties in managing, exploiting and sharing their cadas-tral database. The research aimed to the needs of society in reality and local characteristics in managing, exploiting and sharing cadastral database. As the study identified the advanatages and disadvantages of the current database and proposed appropriate solutions to complete this work for Dis-trict 6 in particular and Ho Chi Minh City in general. The new database improved the efficiency of cadastral database in land management and other related fields. The results of this study can be applied to completee and manage cadastral database in the citywide centralized model that is potential in contributing to the e-government and modern land admin-istration system in Ho Chi Minh City.

Effects of phytohormones and position on mother stem on culm cutting of Thyrsostachys siamensis gamble

Cham V. Mac, Ha V. H. La, & Thang V. Giang
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.9.02.2019
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Abstract

The effects of phytohormones and positions on mother stem on shooting rate, number of shoots per cut, foot diameter of shoots, height of shoots, rooting rate, average number and length of roots by culm cuttings of Thyrsostachys siamensisGamble Nam Bo were investigated. In this study, the phy-tohormones used were NAA, IBA and HVP. Cuttings were taken in three positions: near the root (V1), between the stem (V2) and near the tops (V3). The experiment was ar-ranged randomly with 3 replications, with 36 culm cuttings per treatment. The results showed that the groups treated with NAA had highest shooting rate (91.7%) and highest number of shoots per cut (3.39 shoots/cut). The phytohor-mones did not significantly affect the foot diameter of the shoots but the height of the shoots. The NAA gave high-est rooting rate (87.04%) and highest number of roots (8.5 roots/cuttings). The positions on mother stems did not sig-nificantly affect the shooting rate, but they significantly af-fected the number of shoots per cut. The foot diameter of the shoots, the height of the shoots, the rooting rate and the average root length of the cuttings taken between the stems were greater than those of near the root and near the top. In addition, the highest number of roots was observed when cuttings were taken at near the root.

Selection of drought-tolerant rice varieties from the rice variety bank of Can Tho university

Tin Q. Huynh, Loi H. Nguyen, Dien N. Huynh, & An V. Ngo
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.8.02.2019
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Abstract

Drought has been a big problem and damaged seriously to rice cultivation and production in Vietnam and the Mekong Delta region; evaluating drought tolerance of rice is a major objective for the rice improvement programmes in Can Tho University. Fifty-two collected rice varieties including resistant and susceptible control varieties were screened for water stress under the artificial drought condition. Marker RM223 was used to identify the drought tolerance genotypes for some selected varieties with good and moderate tolerant scores. After 30 days of water stress, the results were 6 varieties of good tolerant, 8 varieties of moderate tolerance, 36 varieties of moderately susceptible and 2 varieties of susceptible to drought. Analyse of PCR showed that 10 varieties expressed the similar bands with the resistant control variety. Four varieties (LH8, MTL812, Lua Canh and VB1) with good tolerant to drought were recommended to use for genetic materials of rice breeding program and applying in alternative wetting and drying irrigation technique for rice cultivation.

Effects of nitrogen fertilizer doses on growth and yield of Java lemongrass (Cymbopogon winterianus Jawitt) in Gia Lai province

Tam T. M. Pham, Nang D. Nguyen, Oanh T. T. Vu, Lan P. H. Nguyen, Cuong A. Pham, Hieu Q. Huynh, & Hiep D. Dao
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.7.02.2019
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Abstract

Java lemongrass is commonly cultivated in Vietnam for the food industry and traditional medicine. To achieve high productivity, the application of fertilizer is one of the most traditional farm practices and necessary. A single factorial experiment was carried out in a random-ized complete block design to investigate the effect of nitrogen fertilizer doses on growth, leaf and essential oil yields of Java lemongrass. Eight treatments were used in this experiment including 0, 15, 30, 45, 60, 75, 90 kg N/ha and applying only 2 tons Komic biofertilizer/ha as control. Fertilizer foundation for treatments 1 - 7 (for 1 ha) included 2 tonnes of Komix biofertilizer, 60 kg P2O5 and 60 kg K2O. The application of 90 kg N/ha significantly improved the growth of Java lemongrass and increased leaf yield (12.02 tons/ha/3 harvest times) as well as resulted in the highest oil yield (138.1 kg/ha/3 harvest times).

Identification of fgr gene and preliminary evaluation for agronomic traits of pandan sticky rice variety (Oryza sativa L.)

Toan D. Pham, & Thu T. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.5.02.2019
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Abstract

Rice (Oryza sativa L.) is the most important food crop in Vietnam particularly in the Mekong Delta. Screening of good quality and high yield rice varieties are needed for rice production in Vietnam. The purpose of this study was to use molecular techniques to identify fgr gene and to evaluate preliminarily agronomic traits of pandan sticky rice variety. The results showed that this variety contained fgr gene. The fragrant allele was amplified by ESP – IFAP primers with a product of 255 bp in size. Similarly, evaluation of agronomic traits showed that the pandan sticky rice variety displayed many desirable characteristics such as plant height of 108 cm, panicle length of 25.6 cm, seed/panicle 135, 100-grain weight 2.07 g, pandan smell, level 2 of alkali digestion, gel consistency 93 mm. These results were useful information and could be applied for improving and providing pandan sticky rice variety for rice production.

Effects of lime and coco peat on the uptake of Cadmium in peanut grown on alluvial soil without compensation in An Phu – An Giang

Loc T. V. Do, & Chuong V. Nguyen
Electronic version: 29 Apr 2019 | DOI: 10.52997/jad.6.02.2019
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Abstract

Cadmium (Cd) contamination in the soil has been identified as an issue for many districts in An Giang province. This study aimed to (i) assess the status of content Cd in soil using cultivation in An Phu district, An Giang province, (ii) investigate the influence of liming and cocopeat on reducing the absorption of Cd to peanut. The single-factor experiment was designed in a completely random block (4 treatments and 4 replicates). Treatments were based on the amount of lime and cocopeat fertilizers for peanut crops, specifically as follows: liming (5 tonnes/ha); cocopeat (5 tonnes/ha); combine lime (5 tonnes/ha) with cocopeat (5 tonnes/ha); control (no lime, cocopeat). The results showed that all soil samples used for peanut cultivation were highly Cd contaminated (from 235 to 240 μg/kg). The treatment combination of lime (5 tonnes/ha) with cocopeat (5 tonnes/ha) reduced the level of Cd in peanuts (from 34% to 19%). The combination treatments lime and cocopeat had the lowest Cd contaminations compared to other treatments. The average levels of Cd in the peanut body and nut were 81.0μg/kg and 27 μg/kg respectively. It can be concluded that liming combined with cocopeat can be the most suitable treatment for reducing Cd contamination in peanut cultivation.