Vol. 22 No. 9 (2024)

The rice lines that have high number of grains per panicle often have low filled-grain rate, probably attributable to an imbalance between source and sink in plants. Thus, studies on technical management such as fertilization to enhance photosynthetic rate and to improve proper sources for high sinks. Soil pot experiments were conducted in 2023 spring and autumn cropping seasons to assess the effects of three N levels, viz. 0, 1, and 2g N pot-1 on photosynthesis at heading and ripening stages of DCG31 (carrying GN1a gene) and Khang dan 18. The obtained results showed that high applied N fertilizer enhanced photosynthetic rate and its related parameters. It helped maintain high photosynthesis, chlorophyll content, leaf area, and dry matter during the heading-ripening stages. The good maintenance of functional green leaves during the seed-setting period led to an increase in grain yield, especially in the spring season. Compared to the normal N dose, the high N application improved 26.4% of the grain yield in DCG31 (57.3g plant-1), whereas that was 6.7% in the KD18 (43g plant-1). Increasing applied N also led to an improved number of panicles per plant and number of filled grains per panicle and did not reduce nitrogen use efficiency, especially in the spring season.

The aim of this study was to evaluate the combining ability of 10 purple waxy corn inbred lines according to the Griffing IV model and to select elite parental lines and hybrids for national testing and commercialization of new purple waxy corn varieties in Vietnam. The cross combination were generated in 2022 spring cropping season and the resultant 45 crosses were evaluated for agronomic characteristics in copmarison with two checks in 2022 winter crop season using a randomized complete block design with 3 replicates. The results showed that 5 lines viz., D2, D4, D5, D7, D9 had significantly high positive GCA on marketable yield, and 5 lines viz., D1, D2, D7, D8, D10 had significance high positive GCA on total soluble solids. A total of 20 crosses with high significantly positive SCA on marketable yield and 21 crosses had high significantly positive SCA value on sweetness index. Based on the MGIDI with 20% selection pressure, 08 elite purple waxy corn hybrids were identified having breeding potential were selected (THL8, THL12, THL16, THL21, THL6, THL2, THL36 and THL1).

The study was conducted to assess the status of shrimp larvae, and juvenile in the coastal and inshore waters of Nghe An province. Data used for analysis was collected from four seasonal surveys including the Southwest Monsoon (SM) trip (May - June 2022) and the Northeast Monsoon (NM) trip (November - December, 2022) with 24 fixed stations. Overall, 19 species belonging to 15 families were identified. Of-which, 4 commercial families (Squillidae, Sergestidae, Penaeidae, Palaemonidae) contributed a high proportion in both SW and NE monsoons, 55% and 88% respectively. The average density of shrimp larvae and juveniles reached 8,309 individuals/1.000m3 of seawater with a higher density in coastal waters than in inshore areas (P = 0.008). The high-density area of shrimp larvae and juveniles covers the coastal waters of Dien Chau Bay with mantis shrimp (Squillidae), paste shrimp (Sergestidae), and penaeid shrimps (Penaeidae), showing that this is a breeding and nursing area for shrimp. These results are the base for Nghe An's fisheries management to establish the resources protected areas

This study was carried out to evaluate the effect of different stocking densities on growth and survival rate of the black apple snail (Pila polita) in intensive tank culture. Each treatment had 3 replicates and with densities of 250, 500, 750 ind./m2. The initial weight and height of the seed snails were 0.08g and 6.77mm, respectively. After 90 days, the survival rate of snails (> 80%) was not significantly different among treatments (P >0.05). Snail weight reached the highest value at the density of 250 ind./m2 (8.62g), which was significantly different (P <0.05) compared to the density of 500 ind./m2 (4.99g) and 750 ind./m2 (4.68g). Snail biomass achieved the highest result at the density of 750 ind./m2 (2.95 kg/m2). However, the weight differentiation rate was very high in this treatment (37.8%), and the snails with small sizes accounted for a large proportion. Research results show that the stocking density from 250 to 750 ind./m2 did not affect the survival rate of black apple snails after 90 days of culture; however, the higher the stocking density, the slower the snail's growth rate and the lower percentage of snails reaching commercial size.

The study was conducted to evaluate the effects of supplementing tannin in the diet on growth performance and feed conversion ratio of Ho x Luong Phuong hybrid chickens from the birth to 15 weeks of age. The experiment was carried out at experimental farm of Faculty of Animal Science, Vietnam National University of Agriculture from October 2022 to January 2023. A total of 120 chickens (60 males and 60 females) were randomly assigned to 4 treatments, including treatment 1 (CT1: 0.3g of tannin/kg feed), treatment 2 (CT2: 0.5g of tannin/kg feed), positive control (CT3: 1g Tylosin/kg feed), and negative control (CT4: 0g of tannin and 0g Tylosin). Experiments were carried out from one day old to 15 weeks of age of chickens. The results showed that in comparison with the negative and positive control, the supplementation of tannin in the diets (treatment 1 and 2) increased the body weights at 15 weeks of age by 20.47 to 24.14% and reduced FCR by 0.69 and 0.73kg, respectively. Adding tannin to the diet of crossbred chickens Ho x Luong Phuong could improve growth performance and feed utilization efficiency.

The study was conducted to investigate the effect of different dietary protein levels and stocking densities on growth, survival rate and feed conversion ratio of Armorhead catfish (Cranoglanis bouderius). Fish at the size of 24.8 ± 3.1 gr/fish and 21.7 ± 3.4 gr/fish were stocked respectively into two separated trials of three diets containing protein levels (30, 35, and 40% protein) and three stocking densities (20, 30 and 40 fish/m3). Experiments were carried out in a cage with the volume of 100m3 in three 3 replicates and the culture period was 12 months. Results showed that the growth rates of fish fed protein levels of 35% and 40% were similar and significantly higher than using the feed of 30% protein, while the survival rate over 80% were recorded in all treatments. The growth rate of fish in the stocking density of 20 fish/m3 and 30 fish/m3 treatments was equivalent and faster than that of 40 fish/m3. The average fish weight ranged from 580.2-648.6 gr/fish, the survival rate at all three stocking densities was higher 80% with no significant difference. It was recommended that the growth out Armorhead catfish in cage can be conducted at stocking densities (in 100m3 cage) of 30 fish/m3 and feed containing 35% protein was optimal for growth and food conversion ratio (FCR).

Nanosilver plasma, a new material created through the electrochemical silver plasma method, is believed for its higher potent antimicrobial activity against different types of bacteria. However, its application in aquaculture has yet to be extensively researched. This study evaluated the efficacy of nanosilver plasma in eliminating pathogenic bacteria Streptococcus agalactiae in tilapia, aiming to lay the groundwork for its practical use in disease prevention and treatment in aquaculture. Nanosilver plasma was examined for its capacity to inhibit bacterial growth under in vitro conditions, its safety on fish and its disinfection capability in experimental treatments. The research results demonstrate that nanosilver plasma at concentrations of 0.25, 0.5, and 1 ppm inhibited 97.8%, 99.9%, and 100% of S. agalactiae, respectively, under in vitro conditions and was entirely safe for tilapia when used for soaking and sterilization. Nanosilver plasma at 0.5ppm exhibits antiseptic capabilities comparable to BKC (0.5ppm) and Glutandehyl (0.05ppm) in treating diseases caused by S. agalactiae in tilapia, alongside the antibiotic amoxicillin(40 mg/kg fish) under experimental conditions.

Urbanization is an inevitable trend, a driving force for socio-economic development. Based on analyzing the urbanization indicators, the study was carried out to evaluate the progress of urbanization process in Binh Chanh district, HCMC. Methods used included documents and data collection, comparison, urbanization process assessment, and SWOT analysis. Calculation results show that the urbanization rate of Binh Chanh in the period of 2014-2023 was only 3.09%, much lower than Ho Chi Minh City (79.72%) and the whole country (35.3%); however, the urbanization speed was quite high at 31.38%, higher than the national average (26.19%) and much higher than Ho Chi Minh City (13.55%). During this period, the urban residential land at Binh Chanh showed an increasing trend (the area in 2023 increases by 271.50 hectares compared to 2014); the proportion of industry-construction and trade-services accounted for 98% of the district's economic structure, with 97.9% of the population operating in the non-agricultural sector. We also pointed out the strengths, weaknesses, opportunities, and challenges of urbanization process in Binh Chanh and proposed solutions to promote sustainable urbanization for the study area.

The research aimed to identify potential antifungal bacteria against phytopathogenic fungi. From rhizosphere soil samples, 43 bacterial isolates were collected and screened. The results indicated that there were three strains with strong antifungal activity against fungal phytopathogens, including Fusarium solani, Fusarium oxysporum, and Alternaria alternata. In addition, the biological characteristics of three potential bacterial strains were evaluated. Based on analysis of 16S rRNA sequence and specific genes, all three bacterial strains were identified and named as Bacillus sp. TV1.1, B. amyloliquefaciens TV2.5, and B. subtilis TV2.12. The results indicate that all three antagonistic bacterial strains could be potential biocontrol agents to control fungal diseases in plants.

In this work, liquid chromatography in combination with tandem mass spectrometry (LC-MS/MS) was developed and applied to analyze biogenic amines in wine. Histamine, tyramine, tryptamine, phenylethylamine, putrescine, cadaverine, ethanolamine, and 5-hydroxyltryptamine were directly analyzed by LC-MS/MS using a HILIC column without a pre-column chemical derivatization step. Some critical parameters affecting the selectivity and sensitivity of method such as selection of precursor and product ions, collision energy, component of mobile phase… were investigated and optimized. Linearity range was established from 5 to 7.000 µg/l association with regression coefficient R2 > 0.995; The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.4-31.0 µg/l and 1.3-103.3 µg/l, respectively. Relative standard deviation of repeatability and reproducibility were in the range of 1.3-4.8% and 2.8-5.0%, respectively. The recovery of 8 biogenic amines was from 80.2% to 100.6%. The validated LC-MS/MS method was then applied to analyze 8 biogenic amines in 5 wine samples collected on the local market. Experimental results indicated that total biogenic amines range from 1,088-3,394 µg/l in analyzed samples. Histamine, considered as the most toxic and food safety relevant, was presents in all analyzed samples. However, the concentration of this compound in all analyzed samples was below the safe level according to EFSA.

Developing agricultural cooperatives associated with tourism is a way to meet the principles of sustainable development, it not only brings social benefits but also environmental and economic benefits to both the members and community. This study aimed to summarize experiences from three agricultural cooperatives models associated with tourism in three provinces in the Northern mountainous region of Vietnam. The information were collected from in-depth interviews with cooperative managers and group discussions with cooperative members. The results show that, besides the advantages in resources and “double” benefits for the community and members, the model of agricultural cooperatives associated with tourism still faced various obstacles not only in business size and running capital but also tourism knowledge and agricultural product promotional skills of members . Therefore, to promote this model, it is necessary to focus on improving either the capacity of managers and cooperative members, especially in tourism knowledge and selling skills or perfecting legal policies of land scale and equity.

The fourth industrial revolution and the Internet are increasingly being applied in managing and sharing information about agricultural development in a country or locality. WebGIS is a popular trend of disseminating information on the internet, including pure information and useful spatial information for managers and users. The article aims to overview some theoretical issues about WebGIS technology and WebGIS application process for agricultural development information management and then overview the practical application of WebGIS for agricultural information management and agricultural development in Vietnam today; From there, we propose research directions for the appropriate application of WebGIS in management of agricultural development information in the future.

The article used secondary information and data to summarize theory and empirical evidence about the Environmental Kuznets Curve. Some limitations of the Environmental Kuznets Curve hypothesis include the assumption of a one-way relationship between economic growth and environmental quality while considering economic growth as a solution to environmental problems; increased environmental quality of developed countries may be traded off for increased pollution and environmental degradation of developing countries, focusing on economic growth while ignoring several other important factors affecting environmental quality. Empirical research showed that the Environmental Kuznets Curve is correct for only some types of pollution and environmental degradation; suitable for some countries or regions; can be observed for a certain period but do not persist into the future; Environmental Kuznets Curve test results were sensitive to the input data, to the choice of variables, and to the model used in the study. In the case of Vietnam, there was no consensus on affirming the existence of the Environmental Kuznets Curve about the relationship between economic growth and environmental quality.

Coastal residents' livelihoods are currently encountering numerous challenges and risks. Climate change, environmental pollution, and unsustainable exploitation have led to a decline in marine resources and have adversely affected the biodiversity of coastal regions. The article employed a narrative literature review method to synthesize information from the published studies on coastal community livelihoods. Through this method, insights, concepts, and debates from scientists and international organizations were amalgamated from 39 studies sourced from reputable outlets like Google Scholar and Web of Science. The article's objective was to raise understanding by furnishing information on livelihood activities, resources, and proposed solutions, thereby aiming to chart a sustainable livelihood strategy for coastal residents.