Published: 2019-02-28

Evaluation of probability of linkages between enterprises and farmer’s potatoes in Lam Dong province

Nam H. Tran, Lap D. Tran, & Vu Le
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.1.01.2019
Abstract | PDF (260.1K)

Abstract

In this study, the collaboration between buyer and the famers in potato production was evaluated by using a multinomial Logistic regression model with MLE estimating. The data were collected by directly interviewing of 245 farmers at the Xuan Tho commune, Da Lat city and Don Duong district, Lam Dong province. Results of the research showed that a tight collaboration between the companies and farmers would increase in a higher productivity. The estimation showed that the probability of farmer which would and would not collaborate with buyer were 14.6% (Y2/Y1) and 63.0%(Y3/Y1). The factors affecting the proability of linkages between enterprises and farmers were enterprises and farmers were experience, farm, size, profit, policy supports and gender. The results also revealed that when price of potatoes increase, farmers would not comply with argreement.

Participation of community in the implementation of new rural development program in Tra Vinh province: Status and solutions

Minh T. N. Doan, & De N. Nguyen
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.2.01.2019
Abstract | PDF (260.1K)

Abstract

The study aimed to evaluate the current status and pro-posed solutions for improving the engagement of commu-nities in development of New rural village in Tra Vinh province. The study was conducted in 3 districts of Tra Vinh province namely Tra Cu, Tieu Can and Cang Long districts by interviewing of 405 households. Statistical de-scriptive analysis, factor analysis, problem tree and solution tree were used. Results showed that the levels of partici-pation depended on the wealth of household groups (rich, medium, poor and near poor). Rich household group con-tributed more than other groups. Three factors were found as influencing factors to the parcipation of communitues such as (1) Culture, social situation and public services, (2) Planning, infrastructure and production organization, (3) Household status and local government, with human, social, financial and physical capital figures. Based on the analy-sis, two overall solution groups (internal and external driv-ing forces) from 2 main problems (subjective and objective factors) were proposed (1) Upgrading individual household capacity and (2) Improving attractive factors of community participation.

Research and design of a robot for pruning street trees

Vinh D. Dao, Khoa D. Nguyen, Phuc T. Nguyen, & Nga T. K. Tran
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.3.01.2019
Abstract | PDF (260.1K)

Abstract

Trees are planted on street to improve the general landscapes. The landscape’s original design is manually maiternaned by the workers. Thus, a robot that can assit workers in trimming the trees is necessary. A self-propelled robot has been developed in order to reduce the risk to humans. The new developed robot would trim uo to 1180 m2 of tree contour when the speed is set at 1 km/h. This robot can follow the road contour and trim tree automatically.

Effects of different dosages and frequencies of fertigation on growth and yield of cucumber (Cucumis sativus L.) grown in soilless culture

Nguyen H. Pham, Hung T. Huynh, & Vy T. T. Nguyen
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.6.01.2019
Abstract | PDF (260.1K)

Abstract

Crop yield of cucumber cultivated by soilless culture technique is most likely affected by growing media and fertigation-frequency. Growing media and fertigation-frequency have become important factors affecting crop yields in the technique of soilless culture in general and cucumber in particular. The objective of this study was to determine the appropriate dosages and frequencies of fertigation for growth, development and yield of cucumber grown in the soilless culture under plastic house conditions in Ho Chi Minh City. The expriment was conducted in strip-plot design with three replicates; the vertical factor (A) including three different dosages of nutrient solution was applied variously based on plant growth stages (A1: combination of 226, 280 and 236 mL/plant/ day applied in three different periods from 0 to 3, 3 to 5 and after 5 weeks of planting, respectively; A2: 339, 420 and 359 mL/plant/day; and A3: 452, 560 and 472 mL/plant/day). The horizontal factor (B) was four different fertigation frequencies of 2, 3, 4 and 5 times/day. The results showed that cucumber fertigated with the nutrient solution having concentration of 452 mL/plant/day (from 0 to 3 weeks), 560 mL/plant (from 3 to 5 weeks) and 472 mL/plant (after 5 weeks) in combination with the fertigation frequency of 5 times/day had the best plant height (333.5 cm), number of leaves per plant (40.9 leaves/plant), the highest absolute yield (12.65 kg/m2), and commercial yield 12.52 kg/m2, and this fertigation regime also resulted in the highest profit (64,275,400 VND/1000 m2) and return on investment (1.07).

Effects of thickness of substrate and spacing on growth and yield of Limnophila rugosa (Roth) Merr. under organic-oriented farming

Duong T. T. Pham, Thinh V. Tran, & Hung T. Huynh
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.5.01.2019
Abstract | PDF (260.1K)

Abstract

Limnophila rugosa (Roth) Merr. is an annual herb native to wetlands in Vietnam. It is widely cultivated and used as food flavoring, seasoning or culinary herb. While most studies examine the essential oil of Limnophila rugosa, reports of cultivation practices such as substrates and spacing that may enhance the growth and yield of Limnophila rugosais very limited. The objective of this study was to determine the appropriate thickness of the substrate and plant spacing for growth and yield of Limnophila rugosa under organic-oriented farming by using a completely randomized design (CRD) for the experiment. The results indicated that Limnophila rugosa performed the highest number of branches and plant fresh weight when it was grown at the substrate thickness of 20 cm in combination with spacing of 20 × 15 cm. However, the highest absolute yield (6414,6 kg/1000 m2) was obtained at a spacing of 20 × 10 cm combined with the substrate thickness of 20 cm.

Effects of Naphthaleneacetic acid (NAA) on culm cuttings of Thyrsostachys siamensis Gamble

Cham V. Mac, Ha V. H. La, & Thang V. Giang
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.7.01.2019
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Abstract

The objective of this study was to evaluated the effects of Naphthaleneacetic acid (NAA) on shooting rate, number of shoots per cut, rooting rate, number of roots per cut by culm cuttings of Thyrsostachys siamensis Gamble. In the study, the bamboo samples were treated with NAA at different concentrations and time intervals. The experiment was designed in a randomized complete block of 2 factors with 17 treatments and 3 replications, with 36 culm cuts per treatment. The results showed that the treated groups with NAA had very high shooting rate, while the shooting rate of the control was relatively low. The concentration of NAA and soaking time significantly affected the shooting rate,number of shoots per cut, rooting rate, number of roots percut. The interaction between NAA concentration and soaking time was significant. The result sugguest that soaking in NAA at the concentration of 200 ppm and 120 minutes is the most appropriate treatment.

Evaluation of tolerance to Phytophthora capsici-the causal agent of foot rot disease in black pepper

Anh T. Ton, Don D. Le, Phong V. Nguyen, Thanh T. L. Bien, & Tram T. N. To
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.4.01.2019
Abstract | PDF (260.1K)

Abstract

Vietnam is the leading black pepper export country in the world. However, the production of pepper may be affected by natural disasters, pests such as Phytophthora capsici. The Phytophthora capsici disease has caused a significant decline in pepper yields. The desease is characterized with a high mortality rate (up to 100%) and rapid outbreak and thus is very challenging to control. In the present study, eight strains of P. capsici were isolated from 100 samples of leaf, stem, root and soil that were collected from pepper-growing areas of Dong Nai, Binh Duong and Ba Ria – Vung Tau provinces. These isolates’ straits had capacity to cause foot rot on pepper leaf after two days of inoculation. Among them, the isolates with the highest pathogenicity are BR-L1, DN-D1 and DN-D2. In order to determine the resistance level to P. capsici of commonly grown pepper varieties (Vinh Linh, Se, Xanh, Trau and Kuching), the pepper leaves wewe in vitro infected with P. capsici BR-L1 spores in laboratory and greenhouse conditions. Trau variety showed the highest resistance level to P. capsici with the as indicated by (P < 0.01) disease ratio (74.1%) and disease index (73.7%) after 6 days in laboratory condition and the corresponding numbers of 17.3% and 15.8% after 12 days in greenhouse condition.

Effects of pH on physiological parameters of blood and growth performance of Asianbumblebee catfish (Pseudomystus siamensisRegan, 1913)

Tuan V. Vu, Truc T. T. Nguyen, Binh T. T. Vu, & Duyen T. H. Nguyen
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.11.01.2019
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Abstract

Effects of pH on blood physiological parameters and growth performance of Asian bumblebee catfish (Pseudomystus siamensis) were carried out in laboratory conditions. The experiment was set up in 8 weeks at different pH water levels. The results showed that the cumulative mortality of Asian bumblebee catfish (4 - 6 g/fish) in 24 hpi 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 at 24 hpi.The high content of glucose was recorded in fish cultured in water with low (4.02 mmol/L at pH = 3) and high (3.22 mmol/L at pH =10) pH levels. After 8 weeks of culture, the highest content of glucose was observed at pH = 8 (1.10 mmol/L). The daily weight gain and specific growth rate in weight of fish were 0.02 - 0.08 g/day and 0.35- 0.99%/day, respectively. The daily length gain and specific growth rate in length were 0.02 - 0.04 cm/day and 0.22 - 0.53%/day. The highest survival rate of fish was recorded at pH = 6 (95.96%) and the lowest survival rate of fish was recorded at pH = 8 (60%)

Innate immune responses of whiteleg shrimp (Penaeus vannamei) experimentally infected with acute hepatopancreas necrosis disease-causing Vibbrio parahaemolyticus

Tuan V. Vo, Truc T. T. Nguyen, & Binh T. T. Vo
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.10.01.2019
Abstract | PDF (260.1K)

Abstract

The innate immune responses of the whiteleg shrimps (Penaeus vannamei) experimentally challenged with V. parahaemolyticus by immersion were investigated for a period of 120 h. The results showed that the lethal dose 50% (LD50) of shrimps (2 - 3 g) challenged with V. parahaemolyticus was 4.7×106 CFU/mL. No significant differences in immune parameters were observed between the control and challenged group right after challenge (0 hpi). However, the total haemocyte count, phenoloxidase activity and respiratory burstsactivity were decreased in the challenged shrimps after 24 and 48 hpi and significantly different from those in the control shrimps (P

The fisheries resources at sub-zones irrigation works of Omon - Xano and Quan Lo -Phung Hiep in the Ca Mau peninsula

Van V. Mai
Electronic version: 28 Feb 2019 | DOI: hcmuaf.jsi.2019.012
Abstract | PDF (260.1K)

Abstract

A study on the fisheries resources at sub-zones irrigation works of O Mon-Xa No and Quan Lo-Phung Hiep in the Ca Mau Peninsula was conducted from January to December 2016. The data on fish species compositions were collected from the field in six times a year in combination with using the prepared questionaire for interviews of 240 fishing households inside and outside the irrigation system (IS) area in two freshwater and brackish water ecosystems. The results showed that the composition of fish species in the study area was diverse. The size of major fish species recorded in the study area was relatively small. The production of fish and shrimp in 2016 decreased by 50 - 60% as compared to 2012 and the production inside the IS area was lower than that outside the IS area in both ecosystems. Some indigenous fish species, such as Channalucius, Notopterus notopterus, Clarias macrocephalus, Clarias batrachus, Morulius chrysophekadion and Toxotes chatareus were rarely found in fresh water ecosystems. Similarly, the indigenous fish species of Arius maculatus and Otolithoides biauri-tuswere rarely found in brackish water. Pterygoplichthys disjunctivus has established populations in many natural water bodies in this study area resulting in a threat to competition, diversity and abundance of indige-nous fish species. There were many reasons for the significant decline of fisheries resources; for example, the IS has blocked the migration of aquatic species. Many fishermen used electricity, poisoning, catching broodfish and fry during breeding season and water pollution by waste from aquaculture pond rehabilitation in the study area. Thus, it is necessary to deploy a community-based model of fishery resources management and preservation in the Ca Mau Peninsula.

Factors influencing yield loss due to diseases in black tiger shrimp (Penaeus Monodon Fabricius, 1798) culture in Soc Trang province

Nhan T. Trinh
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.9.01.2019
Abstract | PDF (260.1K)

Abstract

This study aimed to determine the influencing factors on the yield loss due to diseases in black tiger shrimp (Penaeus monodon Fabricius, 1798) cultured in Soc Trang province. Data for the study were collected by interviewing 334 households farming black tiger shrimp in Soc Trangprovince in 2017. Descriptive statistical analysis was employed to evaluate the current situation of yield, disease and yield loss due to diseases in black tiger shrimp culture of households. Multiple linear regression analysis was used to determine the factors in influencing the yield loss of black tiger shrimp due to diseases. The results showed that the average black tiger shrimp yield fluctuated from 0.54 to 3.28 tons/ha/crop. The household percentage affected by black tiger shrimp diseases was from 33.3% to 90.8%. The percentage of yield loss due to diseases was between 34.6 and 74.2%. The influencing factors (variables) on the yield loss due to diseases included: being a member of black tiger shrimp culturing cooperative; application of trained techniques for shrimp culture and employment of tested post larva (negative correlation with the yield loss in all culture models: reformed extensive culture, semi-intensive culture and intensiveculture). For semi-intensive culture and intensive culture, the yield loss due to diseases way negatively correlated with farmer’s education degree, employment of accumulation pond and the total pond area for shrimp culture of household whereas farmer’s age positively correlated with farmer’s age.

A multiplex real-time PCR method for differentiation of beef, buffalo meat and pork

Tan M. Tran, & Tuan N. Nguyen
Electronic version: 28 Feb 2019 | DOI: 10.52997/jad.8.01.2019
Abstract | PDF (260.1K)

Abstract

The objective of this study was to optimize a multiplex real-time PCR protocol for detection of DNA of beef, buffalo meat and pork, serving for food authenticity. The optimized concentrations were 200 nM primer and 100 nM specific probe for beef/buffalo meat, and 300 nM primer and 150 nM probe for pork. The amplification was performed using initial denaturation at 50oC for 2 min, 95oC for 2 min, followed by 45 cycles of denaturation at 95oC for 15 sec, and annealing and extension at 60oC for 40 sec. This protocol had high sensitivity and specificity. The detection limit of this method was found to be 0.1% in raw and heat-treated meat mix (80 - 121oC/15 min) or 0.005 ng DNA/reaction. The protocol of testing was applied for the commercial products both fresh and processed meats. The results demonstrated that 50% of raw beef sample (6/12) weren’t found beef DNA. Eight of twelve beef sausage samples (66.67%) contained buffalo DNA. Beef DNA were found in all 12 samples of beef meatballs, but eight out of the 12 meatball samples were confirmed to have buffalo DNA (66.67%) and two out of the 12 meatball samples (16.67%) also contained porcine DNA.

Determination of cry2A genes in Bacillus thuringiensis isolated from southern provinces of Vietnam

Hoang P. T. Truong, Don D. Lo, Linh B. Tun, Ha K. Duong, T. H. N. Tran, T. T. Dang, & N. C. L. Huynh
Electronic version: 28 Feb 2019 | DOI: hcmuaf.jsi.2019.013
Abstract | PDF (260.1K)

Abstract

In 27 isolates of Bacillus thuringiensis from southern provinces of Vietnam with ability to produce bipyramidal inclusions, 21 isolates were positive for cry2A-type genes via PCR methods. Analysis of DNA sequences revealed the amplified products belonged to cry2A-type genes of B. thuringiensis with identity above 90% compared with cry2A sequences published on GenBank sequence database. The identity values of the amplified products of the isolates BT5 and TN7.1 with cry2A group primers were 97% and 99%, respectively, while the identity of 99% were observed in the PCR products of TN7.1 with specific primers for partial sequences of cry2Aa and cry2Ab. These results may be useful for prediction of insecticidal activity of the B. thuringiensis isolates and development of new bioinsecticide produtcs.

Assessment of nutritional status of the dormitory students at Nong Lam University, Ho Chi Minh City

Phuong T. Nguyen, & An T. L. Vu
Electronic version: 28 Feb 2019 | DOI: hcmuaf.jsi.2019.015
Abstract | PDF (260.1K)

Abstract

The objective of this study was to assess the nutritional sta-tus of the dormitory students at Nong Lam University, Ho ChiMinh City. The nutritional status was assessed based on bodymass index (BMI), waist-hip ratio (WHR) and body fat per-centage. Food consumption data were obtained through theapplication of a 24-h food recall. Socioeconomic and behav-ioral variables were obtained by a structured questionnaire.Results from 240 dormitory students (136 females and 104males) showed means of BMI of 20.37±2.82 kg/m2, WHRmeans of male and female students of 0.85 and 0.80 respec-tively; and the average body fat percentage was 20.13±6.49%.Sixty-six percent of students were in normal health status.The proportion of students overweight-obesity was 3.75%, andgreater in males higher than in females. The overall malnutri-tion rate was 29.59%, and greater in female students thanin male students. Food consumption data obtained throughthe application of a 24-h food recall showed that dormitorystudents frequently consumed high-carbohydrates foods andlow-fiber foods (fruits, fresh vegetables). Therefore, there is aneed to implement health education interventions strategiesto improve the nutritional status of students.

Caculation of sterilization conditions using Ball method and shelf life for canned salmon fish bone extract

Tuyen C. Kha, & Anh T. Vu
Electronic version: 28 Feb 2019 | DOI: hcmuaf.jsi.2019.014
Abstract | PDF (260.1K)

Abstract

The objective of this study aimed to determine sterilization condi-tions (temperature and time) in order to maximize sensory quality and color of the canned salmon bone extract and minimize harm-ful organisms at the lowest level. The study was also designed to predict the shelf life of the canned extract. The sterilization condi-tions were calculated using the Ball method. The results showed that two sterilization conditions to achieve the F0 value of 2.8 min were determined at 1210C for 14 min and 1160C for 27 min. According to quality assessment, there were no significant differ-ences in color and pH of the product sterilized at such conditions. However, overall score of the product sterilized at 1210C for 14 min was found to be better than that of the lower temperature and longer time in terms of sensory evaluation. For the shelf life prediction, the acceleration testing method was used with differ-ent responses measured including color, pH and sensory quality. The product was stored at 300C for 60 days, and at 45 and 550C for 20 days. Several kinetic equations have been constructed to describe the changes of those responses during storage periods. According to kinetics equations, the shelf life of the product was predicted and confirmed as 19 months at 300C.