Vol. 20 No. 8 (2022)

A study was conducted to determine the appropriate rates of nitrogen fertilizer for two rice varieties, OM5451 and OM6976, by applying transplanter to combine transplanting with fertilization was done to encourage farmers to apply this practice and overcome the current shortage of labor. This study was carried out at the Cuu Long Rice Research Rice Institute with the aim to contribute to environmentally friendly rice production practices. Four slow-release fertilizer treatments were conducted in 2020 Summer-Autumn season. The results showed that application of high rate of fertilizer in the initial stage affected the survival rate of plants in the first stage, but it became better later for all varieties. The rate of nitrogen applied and fertilization methods did not affect the rice growth of two rice varieties, but the grain yield. Head rice percentage and amylose content were best in the treatment with 70N-40P2O5- 30K2Okg/ha.

The study was conducted to evaluate salinity tolerance of four rice varieties, OM5451, IR29, OM18 and MTL316 at germination and seedling stages in four NaCl salinity concentrations of 0, 2, 4 and 6‰. The experiment was arranged in a completely randomized design with three replications in the net house. Irrigation with 4-6‰ salinity solutions (EC = 7.4-10.1mS/cm) reduced germination rate and growth characteristics of four rice varieties at the germination and seedling stages, respectively. The shoot and root fresh weight of salt-treatment derived young seedlings and seedlings of OM5451 reduced less than the other three rice varieties as compared to the control (untreated seedlings). Na+content was accumulated mainly in the shoots. The results indicated that OM5451 had higher salt tolerance than other three rice varieties at both germination and seedling stages.

This study was conducted to investigate the water quality, growth, survival rates and feed conversion ratio (FCR) when rearing common carp (Cyprinus carpio) fingerlings by using biofloc technology (BFT) with carbohydrate source from molasses (RĐ)and corn starch (BN). Common carp fingerlings (33.5 ± 1.15 g/fish) were randomly stocked in 9 tanks (267 l/tank) at a density of 150 fish/m3(40 fish/tank) with three experiments: experiment 1 (BFT-RĐ) and experiment 2 (BFT-BN) were reared in biofloc system with molasses and corn starch, respectively, as a carbon source with C:N ratio of 20:1, whereas the control experiment (ĐC) was reared at similar intensity without biofloc technology and exchange 50% water/day. Fish was fed on demand with 35% protein diet. The result showed that after 60 days rearing water quality in BFT-RĐ was maintained better than that in BFT-BN and the control. The survival rate (98.33± 1.44%) and average daily weight gain (0.69 ± 0.05 g/fish/day)of common carp in BFT-RĐwere highest in BFT-RĐ (P <0.05)compared with the other treatments. Common carp in BFT-RĐ had the lowest FCR (1.53 ± 0.02) (P <0.05) comparedto BFT-BN (1.58 ± 0.02) and the control (1.73 ± 0.03).

To evaluate the reproductive biology of Puntioplites proctozystron at Bung Binh Thien, An Giang, females and males were captured to provide the detailed information on their reproductive biology in their natural habitat. The study was collected monthly by different fishing gear, starting from July 2018 to June 2019. At each sampling time, 60 samples were randomly selected with a length between 6.0-23.7cm to provide a continuous view of gonad development. The results showed that Puntioplites proctozystron can differentiate between male and female during spawning season. Fulton’s and Clark’s indices ranged from 2.00 to 3.97%, and from 1.77 to 3.60%, respectively. The highest indices were found in May and the lowest in January. Condition factor of the female was from 0.009 to 0.023, whereas those for the male ranged from 0.006 to 0.055. Female GSI ranged from 0.24 to 1.91%, that was highest in June 2019 and lowest in February 2019. Similarly, male GSI ranged from 0.19 to 0.51%, that was highest in June 2019 and lowest in March 2019. The average length of early-maturing fish was Lm50= 13.5cm. The absolute fecundity of Puntioplites proctozystron was 32,104 ± 17,501 eggs/female and its relative fecundity was 298,456 ± 140,909 eggs per kg of female with an average diameter of egg at stage IV of 0.97 ± 0.04 mm. The fish spawn annually, but reach maximum levels in June.

Panama disease or banana Fusarium wiltcaused byFusarium oxyspoumf. sp. cubense (Foc)is one of the most destructive plant diseases. In particular, the strain Foc TR4can infect most banana varieties. Compared with traditional methods, biological measures using microorganisms in disease control are considered strategic measures. In this study, actinomycete strain VNUA27 was isolated and evaluated for its ability to antagonize FocTR4. The effect of culture filtrates of the VNUA27 strain on the growth of hyphae and germination ofFocTR4 fungal spores was evaluated. Based on the morphological, physiological, and biochemical characteristics and sequence analysis of 16S rRNA region, actinomycete strain VNUA27 was assigned as StreptomycesdiastatochromogenesVNUA27. The actinomycete strain VNUA27 exhibited high antifungal activity against Foc TR4 (54.78%). After treatment with the strain VNUA27 culture filtrates, the FocTR4 hyphae became shrunk and deformed. Spore samples of FocTR4 treated with culture filtrates of the strain VNUA27 showed a high percentage of non-germinated spores (82.42% inhibition). In particular, the results revealed the function of KSαgene clusters that contributed to the biosynthesis of active secondary metabolites of the strain VNUA27. This study showed that the actinomycete strain VNUA27 is a potential agent for biological control of Foc TR4 of Fusarium wilt withhigh efficiency.

This paper introduces a sensor network system based on wide area network technology to transmit signals over long distances, saving energy for concentrated agriculture. The system included 3 sensor nodes, 1 data collection station (gateway), and 1 online monitoring system. The system performed serial data transmission for the purpose of transmitting data over longer distances. Besides, the nodes transmitted data to the gateway to send data to the server, which helped users to monitor the system online. The maximum data transmission distance of the system was less than 900m at the test site with no obstructions. In places with many obstacles, the signals transmitted stably below 400m. This sensor network had a “sleep” state when not transmitting data, which saves system energy. The system parameters sent to the server for online monitoring on the Blynk application. These initial results suggest a solution for systems that need long distance transmission in agriculture.

The research aimed to identify potential biocontrol agents in controlling Phytophthora spp. that causes gummosis disease of citrus (C. sinensis). Out of 38 strains isolated from the soil samples collected from Hoa Binh and Tien Giang provinces, the strain LHB15 showed strong antagonistic activity against P. citrophthora 18PMS and P. palmivora 17PMS. Analysis of morphological characteristics and 16S rRNA sequence, the strain LHB15 was identified as B. siamensis. The optimal condition for the growth of B. siamensis LHB15 was determined in LB at 37C and pH 7. Testing the antagonistic activity against P. citrophthora18PMS in greenhouse conditions showed a strong reduction in the presence of fungi on soil and citrus roots after 45 days of treatment. The study indicated that the B. siamensisLHB15 is a potential strain for controlling gummosis in citrus.

The study investigated the effect of concentration and spray drying temperature on the quality of soluble green tea-lotus leaf powder. The extract was obtained from the mixture of old tea leaves (cv PH1) and lotus leaves in a ratio of 88:12 by dry matter weight. To obtain the extract mentioned above, the mixture was soaked with water at a ratio of 1/10 at 95C for 15 minutes and stirred 3 times (1 min/time) at 90rpm. The extract was concentrated at temperatures of 50 ± 2C; 60 ± 2C; 70 ± 2Cand 80 ± 2C, and spray-dried at temperatures of 110 ± 2C; 115 ± 2C; 120 ± 2C; 125 ± 2C; 130 ± 2C. The results showed that the concentration and spray drying temperatures of 60 ± 2C and 110 ± 2C, respectively, were appropriateto obtain good sensory quality of soluble green tea-lotus leaf powder, and the products meet customers’ satisfaction. In addition, there were no microorganisms and heavy metal, indicating that the product meets hygiene and food safety quality requirements.

In this article, we focus on software-defined networking(SDN) technology. SDN is a flexible, manageable, high-performance, and adaptable architecture. SDN has shownits potentials for application that require high bandwidth and flexibility. However, it also poses challenges in terms of datasecurity. To better understand SDN, we study the characteristics, advantages and disadvantages of SDN, compareit with traditional network. Next, we discuss the security threats in a SDN-based network. We also present some techniques that can be used to prevent and mitigate the risks to the network. Along with theory about SDN, we implement a demo SDN system using Mininet and Onos. This virtual system is simple but it showsall the advantage and disadvantage of a typical software-defined network.

The study was carried out to determine the level of application of adaptation measures and analyse the factors affecting farmers’choice fordifferent levels of adaptation measures to climate change in the Northwest region. The study site is one of the areas most vulnerable to climate change because most people have the main sourceof income from agricultural production. Primary data werecollected by direct interviewon 438 farmer households through questionnaires. The multivariable logit regression model was used to estimate the influence of the household's socio-economic factors on the level of application of 3 mainsolutionsthat are most frequently applied by surveyed households. The results show that the education level, number of members, agricultural land area and total income from agriculture of the household were the main factors affecting the household's application of adaptation measures. Therefore, the study recommends solutions to raise people's awareness and diversify incomes to minimise impacts of climate change.

The study seeks to identify the factors influencing Khmer household income in order to propose solutions to help increase income and improve the living conditions of Khmer people in Kien Giang province. The study used descriptive statistics and least squares regression analysis to determine the factors affecting the income of Khmer ethnic households in Kien Giang province. There were three factors that positively affected the income of Khmer households in Kien Giang province, namely education, arable land, and means of production. Therefore, in order to increase income, solutions such as increasing qualified resources for Khmer households, developing diverse income-generating activities, and providing support for production means must be implemented. In addition, natural disasters and epidemics also exerted a negative impact on the income of Khmer households. Thus solutions to minimize the impact of natural disasters on agriculture are necessary.

The aims of the present paper were to evaluate the results of the policy implementation in supporting the development of agricultural cooperatives, point out the shortcomings in policy implementation, and, finally,to propose some solutions to improve supporting policies for agricultural cooperatives in Hanoi city. Secondary data were collected from reports of Cooperative Alliance and Department of Agriculture and Rural Development. In addition, information collected from 90 agricultural cooperatives has been used to show the beneficiaries' assessment of the supporting policies. The research showed that while the preferential policies for credit, technology transfer, trade promotion and support for the establishment of new cooperatives played significant supporting roles, the other policies such as land allocation/land lease, infrastructure construction and product processing have not shown positive impacts on agricultural cooperative development. The crucial solutions that should be implemented include completing support mechanisms and policies, propagating for raising awareness about the role of agricultural cooperatives and supporting cooperatives in digital transformation.

Small-scale pig holders in Vietnam arefacing variousdifficulties because ofincreasing input costs and fierce competition withlarge-scale livestock farming. Therefore, finding ways to improve technical efficiency in pig production can help the farmers deal with this problem. To measure technical efficiency and analyze the factors affecting the technical efficiency in fattening pigsat household levelin Hanoi, the presentstudy useddata envelope analysis (DEA) approach and Tobit regression. The research results showedthat the technical efficiency of the households was 67.3% on averge, indicatingthat the households can reduce 32.7% of the inputs without affecting the output. To improve technical efficiency, in the short term, the households should use a combination of industrial feed and agricultural by-products, speed up the raising time, and adjust the density of pigs in the barn. In the long term, the households should adjust the production scale to improve technical efficiency.

So far, agricultural technicians believe a maxium yield while economists consider profits as the most important indicator for selecting the optimal input use level in agriculture. Based on reviewing theoretical and practical issues on selectionof an input use level in agriculture, this paper shows thatthe highest profit is the most important criteria for selecting the optimal input use level in agriculture. Selecting an inputuse level that produces the maximum yieldwhich is higher than level of technical efficiency would not only bring about low profit but encourage excessive input use and lead to lowering product quality and negative environmental consequences. A market-oriented agricultural development requires agricultural researchersto take into accountthe cost incurred and output value received as well as related environmental protection issues. There is a need to upgrade agricultural technical researchers’ knowledge on and perception of economic and technical efficiencies.Aside from collecting biological data, agriculturalresearchers should also collect priceinformation on input usedand outputproducedfor selecting anoptimalinput use level to attainhighestprofit, which shouldbe considered to be the most important indicator for evaluation of agricultural research projects at different management levels.