Vol. 4 No. 4 (2021): Vietnam Journal of Agricultural Sciences

The study was conducted to evaluate the effects of a medicinal plant mixture (MP) (60% Bindens pilosa L., 15% Urena lobata L., 15% Pseuderanthemum palatiferum, 5% Ramulus Cinnamomi, and 5% Illicium verum Hook. f.) as a feed additive to promote the growth performance and meat quality of grower-finisher pigs. Forty-eight crossbred pigs (Duroc × (Landrace × Yorkshire)), with initial live body weights of 30.3 ± 1.42kg, were randomly allocated to four dietary groups, with three replicates of each group and four animals per replicate. The experimental pigs were fed a basal diet supplemented with MP powder at 0, 20, 40, or 60 g kg-1 of feed (T0, T20, T40, and T60) for 15 weeks. The growth performance, carcass quality parameters, chemical composition, fatty acids, and cholesterol contents of the pig meat were measured. There were no statistical differences (P> 0.05) in the final live body weight, overall average daily gain, average daily feed intake, and feed conversion ratio among the control and MP treatments. MP supplementation significantly increased the protein content (P = 0.02) and decreased the cholesterol content (P = 0.04) of raw longissimus dorsi muscle. The obtained results indicate that the dietary MP supplementation tested could have the potential to improve meat quality and decrease the cholesterol content in pork with no adverse effects on the growth performance.

Bighead catfish, Clarias macrocephalus, is an important species for aquaculture. Nevertheless, information on population variation in their reproductive characteristics and larval growth is limited. This research aimed to evaluate the reproductive performance and larval growth of three bighead catfish broodstock strains collected in Ca Mau (CM) and Hau Giang (HG) provinces (wild strains), and Can Tho (CT, domesticated strain) in the Mekong Delta, Vietnam. The three groups of fish were cultured under optimal maturation conditions in a recirculating system for three months. Then, 16-18 pairs from each broodstock source were artificially propagated. Relative fecundity differed among the sources, from 48,600 (CM) to 69,300 (CT) eggs/kg female (P< 0.05). The three broodstock sources also differed in fertilization and hatching rates. In addition, wild breeders (CM and HG) had slightly larger eggs, and their offspring had larger sizes at hatching and larger yolk sac volumes than those of cultured (CT) breeders (P< 0.05 for all tests, except for egg sizes). In the larval rearing experiment, 2 day-old larvae were stocked in 40 L-rectangle tanks (1,000 individuals/tank) in a recirculating water system. Larvae were fed with Moina combined with commercial feed. After 40 days, survival rates of the three fish groups ranged from 46.7% (CT) to 54.7% (HG). The final weights varied from 177 mg (CM) to 201 mg (HG) and 202 mg (CT). However, the effects of broodstock sources on the growth and survival rates of the offspring were not statistically significant (P> 0.05).

The trophic levels in urban lakes are typically based on the forms of nutrition and phytoplankton communities in the lakes. In this study, comparisons between eutrophication indices and the water quality index (VN-WQI) were used to classify the water quality of 20 lakes in Hanoi, Vietnam. The results showed that the water quality ranged from very bad to poor. High levels of the eutrophication phenomenon in terms of total N and P were observed in all sampling sites. Cyanobacteria was the dominate algae phylum making up 65.78% of the total population, whereas Chlorophyta (including 19 genera) was the most diverse phylum. The density of the algae was 5,000-14,000 cells mL-1 and the chlorophyll-a level was 10-40 µg L-1. Based on this information, the water quality levels in the lakes were classified from eutrophic to polytrophic. The Trophic Status Index (TSI) and Trophic Level Index (TLI) values ​​were 66.9-86.0 and 54.4-76.0 points, respectively, corresponding from eutrophic to extreme-trophic. Classifications based on algae community structure indices were from oligotrophic to eutrophic, similar and consistent with the TLI classifications. According to the results in this study, the TLI was found to be more accurate and precise than the other indices. It is recommended that the TLI is an applicable tool to classify eutrophication in urban lakes.

Environmental problems have become one of the top concerns in Vietnam since 2016. This study aimed to investigate what groups of people were most concerned about the environment and to what extent their concerns differed from each other. Logistic regression models were used to perform the analyses. The analysis on the gender - environmental concern relationship indicated that males were more likely to be concerned about the environment than females. The age - environmental concern relationship suggested higher concern levels of younger people as compared to older people. In the examination of the social class - environmental concern relationship, people who were wealthier, well-educated, and had greater occupational prestige tended to have more concerns. People with higher education levels also expressed higher levels of concern toward the environment. People with postgraduate degrees reported the highest level of concern, while people with no formal education showed the least concern. From the perspective of the political involvement - environmental concern relationship, it was shown that while people who were not a member of any organization were the least environmentally concerned, the members of university alumni associations were the most concerned. Finally, the exploration of the residence - environmental concern relationship pointed out that Kinh people were more environmentally concerned than Vietnamese ethnic minority groups, and people in the North Central Coast paid the highest attention to the environment in Vietnam.

Crop management practices in intensive vegetable production can influence nitrous oxide (N2O) emissions from soils. This study quantified seasonal N2O emissions and N2O emission intensities, and investigated the factors driving emissions in different vegetable management practices. Emissions from four typical vegetable crops (two choy sums, a mustard, and a cabbage) were intensively measured over the 2016 autumn season on farms in Van Noi and Dang Xa communes in the Hanoi peri-urban area. Different N2O emissions were observed in the four leafy vegetable crops. The average daily emissions varied from 12.15 g to 40.08 g N2O-N ha-1 and the autumn season N2O emissions varied from 1.13 kg to 8.45 kg N2O-N ha-1 across the four crops. The greatest daily and season emissions were from cabbage, and the lowest were from mustard. Emission intensities varied among the types of vegetables and was the lowest at the mustard farm (37 kg CO2-e t-1), indicating that the crop management practices increased the mustard yield but retained a low N2O emission rate. Practices responsible for high N2O emissions were overuse of nitrogen fertilisers and furrow irrigation. An improvement in the farmers’ adoption of best practices in fertiliser application and irrigation could reduce N2O emissions without affecting crop productivity.

The Afforestation and Perennial Tree Plantation Project were implemented in several mountainous areas in Dien Bien province, Vietnam, for many purposes such as providing agricultural products, increasing incomes for the people in the projected areas, and reducing shifting cultivation. Based on these reasons, the central and local governments implemented several policies and subsidies for the growers, including rice subsidies for ethnic minorities who planted forests to replace shifting cultivation; investment support for planting protective forests and special-use forests; and providing seedlings. This article aimed to provide a clear view of the supporting policies in the Afforestation and Perennial Crops Project and its effects on the local people’s livelihoods in Dien Bien province of Vietnam. By analyzing the types of the capital of the livelihood assets (human capital, natural capital, financial capital, physical capital, and social capital), indicators of each capital type were chosen and scored in the context of achieving sustainable livelihoods. The results identified that the government has issued several policies to help the investors and farmers involved in this project. However, there were some concerns about the policies in practice, for example, the low percentage of dividend sharing for farmers, unclear land use rights, and inadequate applications of the policies in reality. In evaluating the livelihood assets, significant differences were found in the sustainable livelihood index gained between the rubber-based and non-rubber-based groups.

In order to select an appropriate heat treatment process for an industrial application of S45C medium carbon steel, it is necessary to investigate the influence of technological parameters during the heat treatment process such as heating temperature, holding time and cooling medium on the microstructure and mechanical properties. In this study, the experiments were conducted in various heating temperatures, holding times and cooling mediums for specimens made of S45C steel. Then, the relationship between the microstructure and the hardness of the steel was examined. The obtained results show that the heating temperature and cooling medium strongly affect the microstructure of this steel, leading to considerable changes in the hardness. The hardness of S45C steel was markedly improved when heated above 800oC and cooled in water. Moreover, the holding time needs to be carefully calculated to obtain finer grain structure to prevent an increase in the brittleness.

Anthracnose is the most prevalent and devastating fungal disease both before and after harvesting of mango worldwide. The anthracnose pathogen infects fruit in the field and remains quiescent until the fruit is harvested and starts to ripen. This is the major constraint in the commercialization of fresh mango. Currently, this is the first study that has evaluated the impact of a chitosan-based coating with Aloe vera gel and papaya leaf extracts on the postharvest quality of mango fruit infected with anthracnose under ambient storage conditions. After coating and drying, mangoes were artificially inoculated with Colletotrichum gloeosporioides (105 conidia per mL) and then air-dry, placed in perforated open-top plastic baskets, and stored at room conditions (average temperature 34.3 ± 2°C and relative humidity 71.8 ± 10%). The respiration rate, weight loss, color, firmness, vitamin C content, and spoilage rate were measured during storage. The results showed that the coating formula made with 0.5% chitosan combined with 0.3 % Aloe vera gel and 0.2% papaya leaf extracts was the most effective formula for maintaining postharvest quality and minimizing the spoilage of mango fruit infected with anthracnose under ambient conditions. Further in-depth studies are needed to determine both the mode of action in the successful commercialization of this new edible coating in the fresh mango fruit industry. 

The aim of this study was to show the level of lecturers’ subjective well-being at Vietnam National University of Agriculture and the differences in their subjective well-being levels according to the variables of gender, education, income, and teaching experience. The study used the Oxford Happiness Questionnaire (OHQ) designed by Hills and Argyle (2002). The questionnaire included 29 items and has been widely used as a scale for the assessment of personal subjective well-being. The results showed that most lecturers at Vietnam National University of Agriculture were quite happy. There were significant differences in the level of subjective well-being according to some variables investigated.