Can Tho University Journal of Science
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Published By Can Tho University

2615-9422

2021 ◽  
Vol 13 (3) ◽  
pp. 9-16
Author(s):  
Thanh Phuong Nguyen ◽  
Tinh Em Nguyen ◽  
Thi Kim Ha Nguyen ◽  
Quoc Viet Le ◽  
Thi Thanh Huong Do

This study aimed to evaluate the effects of temperature on the growth and survival of mud crab (Scylla paramamosain) larvae in two stages including zoea-1 to megalopa (the first experiment) and megalopa to crablet-1 (the second experiment). Each experiment was conducted in a completely randomized design with four temperature levels (27, 30, 33, and 36℃) in triplicate. Stocking density of 200 ind./L for the first experiment and 4 ind./L for the second experiment. Fiberglass tanks of 500-L (containing 300-L and 250-L of 25‰ water for the first and second experiment, respectively) were used in the experiments. The results showed that S. paramamosain larvae at zoea-3 and zoea-4 died at 33℃ or above, while the highest survival rate of this stage was found at 27℃ (11.5%). The growth and larval stage index during the zoea to megalopa stage were significantly higher in 30℃ (p<0.05) compared to those in the 27℃ treatment. In the second experiment, the survival rates of crablet-1 were highest (72.9%) at 27℃ and lowest (34,7%) at 36℃. The growth rate of crablets at this stage increased with increased temperature. The highest carapace width and weight (3.41 mm and 0.030 g, respectively) were recorded at 36℃. The findings of this study suggested that mud crab larvae should be reared at the temperature range of 27-30℃ to maximize their production.


2021 ◽  
Vol 13 (3) ◽  
pp. 17-22
Author(s):  
Tien Doan Thi Kieu ◽  
Tai Ngo Ngoc ◽  
Kaeko Kamei ◽  
Thi Thu Thuy Tran ◽  
Thi Thu Nga Nguyen

The study on the procedure of applicating bacteriophage (or phage) to prevent rice bacterial grain rot caused by Burkholderia glumae was conducted in the greenhouse conditions. The first experiment investigated the effect of different phage titers (i.e. 105 PFU/mL, 106 PFU/mL, 107 PFU/mL, 108 PFU/mL) in controlling bacterial grain rot of rice. The results showed that all four titers gave disease reduction with different levels, among these were the titer of 108PFU/mL expressed highest efficacy in disease reduction with the lowest percentage of infected grains compared to the rest treatments. The second experiment examined the effect of phage application times (i.e. spraying phage at 2 hours before pathogen inoculation, 2 hours before and 5 days after pathogen inoculation, and 5 days after pathogen inoculation) in suppressing bacterial grain rot disease. The results found that two treatments (i.e. one time spraying at 2 hours before pathogen inoculation, and two times spraying at 2 hours before and 5 days after pathogen inoculation) expressed high efficacy in reduction of grain rot disease through percentage of infected grains and improved yield parameter regarding rate of filled grains.


2021 ◽  
Vol 13 (3) ◽  
pp. 39-47
Author(s):  
Diem Nguyen Thi Kieu ◽  
Van Loi Nguyen

Web 2.0 applications with multimedia affordances provide a creative way to expose students to a non-threatening environment for practising English. Motivated by the potentials of this type of application for English speaking instruction, this study aimed to examine the effects of high school learners’ self-practice using an app called Voki on their speaking performance. A quasi-experimental control group design was employed, in which the effect was measured by means of two speaking tests before and after the treatment, and further explored with a semi-structured interview. The results showed the increase in the students’speaking skills and the satisfaction with this Web 2.0 tool for its effectiveness and engagement. Their shyness and nervousness about uttering the target language diminished as their confidence increased. Accordingly, more evidence of the efficacy of Voki on EFL learners’ speaking performance was offered in the study. Future research can investigate learners’ improvement in language proficiency in different skills and contexts and involve larger sample sizes.


2021 ◽  
Vol 13 (3) ◽  
pp. 23-29
Author(s):  
Ngoc Bich Tran ◽  
Quang Trung Le ◽  
Thi Ngoc Truc Dang ◽  
Van Hieu Truong ◽  
Thi Kim Quyen Nguyen ◽  
...  

The aim of this study was to evaluate the influence of vitamin and β-glucan supplementations on growth performance of growing-finishing pigs in Ben Tre province. A total of 36 post-weaned piglets (Duroc x Yorkshire-Landrace) with the initial live weight of 17.42 kg±0.26, was allotted into 3 treatments and 4 replications in a completely randomized design. There were three diets, including basal diet (BD) without any addition of β-glucan or vitamin (diet CT), the BD supplemented with vitamin (diet Vit) and the BD supplemented with β-glucan (diet Glu). The results on growth parameters indicated that final live weight (kg), weight gain (kg), and average daily gain (g/head/day) of pigs in the experimental diets were significantly higher (P<0.01) than those in the control treatment. FCR was lowest in Glu and highest in the control (P<0.01). Financial benefit based on feed and veterinary expenses was higher in the vitamin and β-glucan supplement diets than that of the control from 15.74% to 18.98%, respectively.


2021 ◽  
Vol 13 (3) ◽  
pp. 30-38
Author(s):  
Anh Thi Nguyen ◽  
Thi Ngoc Lien Nguyen

The present study aims to investigate perceptions of pre-service teachers of English on the quality of a training course on English Language Teacher Education. Thirty-nine pre-service teachers who had just completed their training program at a university participated in the study. Data were collected through semi-structured interviews. The results show that the pre-service teachers on the whole showed a high level of satisfaction with the quality of the training course. However, the results indicate certain variances in the way the pre-service teachers responded to the issue of quality. The study also indicates suggestions proposed by pre-service teachers regarding how to help the university improve the quality of education and training as well as the services it offers. Accordingly, this study brings significant insights for related stakeholders in achieving a better quality for education.


2021 ◽  
Vol 13 (3) ◽  
pp. 58-65
Author(s):  
Thi Ngoc Diep Duong ◽  
Quang Binh Hoang ◽  
Le Hanh Trang Do

In this study, the optimal conditions for spray drying of the extract made from flesh and peel of red pitaya were tested using the central composite design (CCD). The response surface methodology was used to evaluate the effect of inlet air drying temperature (145 – 155°C) and concentration of maltodextrin (13-17% w/w) on the physicochemical properties of the powder. The regression models accurately predicted the retention of betacyanin (R2=0.94) and total phenolic (R2=0.95). The optimal conditions for spray drying were determined as inlet air drying temperature at 148  and 14.62% maltodextrin. Under these conditions, the spray-dried powder achieved retention of betacyanin of 68.04% and retention of total phenolic of 84.17%. The optimized sample achieved a moisture content of 4.41%, the water activity of 0.39, and the water solubility index of 97.41%.


2021 ◽  
Vol 13 (3) ◽  
pp. 66-70
Author(s):  
Thi Bach Le ◽  
Tien Dung Le ◽  
Trong Tuan Nguyen ◽  
Xuan Canh Do ◽  
Chan Du Lam ◽  
...  

Guava, Psidium guajava L., is well-known tropic tree which is abundantly grown for fruit. It belongs to phylum Magnoliophyta, class Magnoliopsida and Myrtaceae family and has been found a lot in the Mekong Delta of Viet Nam. Antioxidant activity of different extracts from Psidium guajava L. leaves revealed that ethyl acetate and n-butanol extracts have the good activities. Processing of these fractions using repeated column and thin layer chromatographic techniques resulted in the isolation of four compounds, which have identified their chemical structures by spectroscopic techniques including avicularin (1), kaempferol (2), gallic acid (3), and protocatechuic acid (4). All the isolated compounds showed antioxidant activity using DPPH and ABTS scavenging assays. These results suggest that the leaves of guava  would be useful natural sources of antioxidants.


2021 ◽  
Vol 13 (3) ◽  
pp. 88-99
Author(s):  
Thuy Trang Nguyen ◽  
Hong Tu Vo

The study was conducted to analyze the competitiveness of OCOP standardized clown knife fish products in Hau Giang province. The data were collected from 73 observations involved in the clown knife fish value chain. The research results show that most farmers culture knife fish intensively and the feed cost shares the highest proportion of the total production cost. Processed products from knife fish are mainly boneless fish and fish balls. The OCOP knife fish value chain operated through four main distribution channels and included actors: fish farmers, traders, processors, and retailers. The farmers normally sell fresh knife fish to middleman, accounting for 80.15%. The processing factories create and share the highest proportion of added value. The distribution channel that farmers are linked directly with processors create higher added value than others. The study also analyzed the Porter’s five forces of the knife industry. The study found that there are many potential risks in the farming process, high competitive pressures from substitute products, and limited negotiation ability of both farmers and processors.


2021 ◽  
Vol 13 (3) ◽  
pp. 1-8
Author(s):  
Njihia Dedan Karanja ◽  
Thuy Yen Duong

The development of bighead catfish (Clarias macrocephalus) aquaculture in Viet Nam has been constrained by the slow growth performance in the domesticated strain. Crossbreeding can be a solution to improve fish production. This study was aimed to evaluate the growth and survival performance of the second generation (G2) fingerlings crossbreeds (CMCT and CTCM) from two bighead catfish strains (wild Ca Mau, CM, and domesticated Can Tho, CT) compared to offspring from their original strains (G0-CT and G0-CM) and G1 crossbreeds (♀CM × ♂CT and ♀CT × ♂CM). The larvae were reared in 50-L tanks (3 to 5 replications) with the density of 1,000 individuals/tank and fed with Moina and artificial feed (40% protein). After 40 days of rearing, the fish grew differently among crosses (P<0.05). In which, the two best-growth groups included CM×CT crossbreeds (body weight of 1,114 mg and length of 4.55 cm) and pure crossbred line CTCM (1,050 mg and 4.51cm, respectively). The CTCM group was recorded the highest survival rate (37.8%) while G0-CT was the lowest (27.2%); however, the difference in survival was not significant (P>0.05). The performance of these crossbreeds should be investigated further at the grow-out stage to see whether crossbreeding between wild and cultured strains of bighead catfish may be used in practice to increase bighead catfish production.


2021 ◽  
Vol 13 (3) ◽  
pp. 79-88
Author(s):  
Thi Dan Xuan Huynh ◽  
Tien Dung Khong ◽  
Viet Khai Huynh

This study is aimed at estimating economic value of municipal solid waste (MSW) reduction program in the Mekong Delta by employing the willingness-to-accept (WTA) approach. This research will address two important issues in current growing literature about MSW management. First, this is the first research to evaluate economic value of the MSW reduction program in Mekong Delta. The second major contribution is the approach employed - supply curve through the WTA. This program requires community participation and provision incentives to them, therefore the requirement of public acceptance through WTA is estimated. Findings reveal that people are willing to accept an average of 30,000 VND/month for the MSW reduction program. Assume that household's MSW management fee subsidy policy is canceled, and the household is facing a full fee for the MSW collection (about 150,000 VND/month), they are willing to classify MSW at source to get a reduction of 30,000 VND or they are willing to accept a fee of 120,000 VND/month. In addition, it is interesting that more than 70 percent of people are willing to participate in this program. The determinants of WTA identified include the type of MSW at the source, education level, type of urban areas. This research then proposes that MSW management implementation policy should be focused on motivating households and improving people's perception of MSW. In case of government budget deficit, community participation would be more appropriate to manage MSW.


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