Vol. 19 No. 12 (2021)

This study described the plant morphology of seedless orange, Citrus sinensis(L.) cv. Soan discovered in Hau Giang provinceThe description of plant morphology was based on IPGRI (1999) descriptors for Citrus spp. by collecting 30 samples of leaves, flowers and fruits per tree of seedless and seedy trees.The results showed that, seedless Soan orange tree had some plant morphological characteristics that were different from those of the seedy tree such as the ratio of leaf length/leaf width (1.55 > 1.42), the ratio of petal length/petal width (2.49 > 2.21); the ratio of ovary height/ovary diameter (0.91 > 0.82), the ratio of fruit height/fruit diameter (0.93 > 0.90). This can be used to identify the seedless Soan orange tree. Fruits of seedless Soan orange collected in March and in September 2016) possessed a total of 2.25 seeds/fruit, 93.3% of fruits had total number of seeds less than 5 and 100% of fruits had the number of plump seeds less than 5. In addition, most of the plant morphological characteristics s of seedless Soan orange were not different from those of seedy Soan orange.

This study was carried out to effects of gamma ray irradiation of irradiation Co60 source forsome local and imported rice accessions. This experiment was designedwith 3 dose (200Gy, 300Gy and 400Gy) on the mutagenesisof three rice (12% seed humidity). At generation M1, the results showed that the seed germination and survival percentage of all rice accessions decreased with the increase of the irradiation doses. Mutated plants with shorter growth duration, lower plant height, more upright flat leaves appeared, greater tillering capacity with high mutation frequency at irradiation dose of 200Gy, 300Gy for imported rice varieties NN1, NN3 in the M2generation. The mutation appeared with very low frequency when irradiating the local rice variety Khau Mang. Selection on M3generation of 200Gy and 300Gy irradiation treated varieties NN1 and NN3 picked up some promising rice lines with short growth duration, short plant height, more upright flat leaves appeared and high tillering capacity. To sum up, gamma Co60irradiation at 200Gy and 300Gy dose on dried seeds could renovated some agronomic traits such as growth duration, plant height, flag leaf morphology and tillering capacity on two imported rice varieties NN1 and NN3.

The objective of this study was to determine the effect of nitrogen level and N-fixing rhizobacteria on growth and yield of sesame in undeposited alluvial soil. The experiment was arranged in a randomizedcompleteblock design with four replications. The first factor was nitrogen fertilizer levels (0, 50, 75 and 100%of recommendation rate);the second factor was application of bacteria: no rhizobacteria, a single strain AGVRB-07, single strain AGVRB-28,andthemixture of strains AGVRB-07 and AGVRB-28. The results showed that a reduction of nitrogen fertilizer application resulted in lower plant height, number of leaves per plant, leaf length, leaf width, number of flowers per plant, number of capsules per plant, capsule diameter, number of rows per capsule and grain yield. However, addition of N-fixing rhizobacteria as single strain AGVRB-07, AGVRB-28 or the mixture of AGVRB-07 and AGVRB-28 improvedplant height, number of capsules per plant and grain yield. The supplement of single strain or mixture of 2 strains also contributed to reducing approximately 25% of chemical nitrogen fertilizer as recommended, but sesame grain yield wasmaintained comparable to the full rate of nitrogen application.

Study was carried out to evaluate effect of probiotic cell wall (Lactobacilus rhamnosusand Saccharomyces cerevisiaecell walls - IV bio-product) supplement in growing-fattening pig diet on villus development, intestinal microbial change and economic efficiency. The rexperiment was conducted on 84 weaning pigs (PiDuxLY) (6.6±1.45kg), which were randomly assigned into 4 groups, viz. control group (ĐC), experimental groups IV0.01, IV0.03, IV0.06, with 3 replications (7 pigs/replication) to receive 4 dietary treatments with different levels of IV bioproduct at 0%, 0.01%, 0.03% and 0.06%. Results showed that the probiotic cell wall mixture did not affect the intake but improved growth rate and feed efficiency. The IVbioproduct supplement also increased villus height but reduced Crypt depth. Pigs fed 0.03%-0.06% IV mixture of supplement diets showed high population of Lactobacillusbut lower population of E.coliand Coliformin the jejunum and cecum. Using the Solver optimal analysis in order to obtain optimal live weight gain, FCR and profit, the optimal level of probiotic IV mixture supplement in pig diet should be 0.048%-0.051% (best at 0.05%).

This study aimed to identify effects of two housing systems and two crossbreeds on welfare quality of broiler chickens. A total of 132 (Ho ×Luong Phuong) chickens and 146 (Choi ×Luong Phuong) chickens were assigned into 4 treatments with 3 replicates by the completely randomized design method, including: Group 1 (Ho ×Luong Phuong chickens kept in outdoor access system with perches provision); Group 2 (Choi ×Luong Phuong chickens kept in the outdoor access system with perches provision); Group 3 (Ho ×Luong Phuong chicken housed indoor without perches); Goup 4 (Choi ×Luong Phuong chickens housed indoor without perches). Welfare parameters related to chickens’ health and behaviours were observed directly by naked eyes and scored according to Welfare Quality (2009) protocol. The outdoor access system with perches provision improved the welfare quality in term of food pad dematitis and plumage cleanness (P<0.05), and stimulated chickens to perform natural behaviours (30-45% ranging outdoor areas, 30-50% roosting on perches at night at 9-13 weeks of age), but no significant difference in the aggressive behaviour was detected. There was no significant effects of crossbreeds on welfare quality of chickens. Producers should adopt the outdoor access system if the ranging areas are available and provide broiler chickens with perches to improve their welfare quality.

Mango is a key crop and provides high economic efficiency in the Mekong Delta. However, its yield and quality are seriously affected by anthracnose disease. In order to select Trichoderma spp. with high antagonistic activity against disease fungi, 17 soil samples were collected from healthy plots in Hau Giang and other provinces in the Mekong Delta. A total of 56 strains of Trichodermaspp. were isolated and 14 strains were selected for high antagonistic activity against fungi causing anthracnose. Among those, strains Tr.X1, Tr.X2, Tr.X3, Tr.X4, T1, M2 and Tr.X2, Tr.X3 exhibited the most antagonistic activity from 77.76-86.25% inin vitro,and 75.3-72.01% in the net house. The strains were identified as Trichoderma harzianum(Tr.X2) and Trichoderma asperellum(Tr.X3) and they have potential of biological control to anthracnose in mango.

Our study aimed to determine the total contents, antioxidant and antibacterial activity of polyphenols of several medicinal plant species, including Chrysanthemum indicum, Astragalus membranaceusBge, Lonicera japonicaThumb, Andrographis paniculata, Aloe vera, Glycyrrhiza uralensis Fisch, Vetiveria zizanioidesL. Nash, Caesalpinia sappan, Coptis chinensisFranch. andWedelia chinensisOsb. Merr.Medicinal materials were extracted with solvents, including ethanol, methanol and hot water, then diluted with dimethyl sulfoxide. The results showed that the extracts of Caesalpinia sappan, Chrysanthemum indicumand Wedelia chinensisOsb. Merr exerted the strongest inhibitory effects against E. coliATCC25922(the diameters of inhibitory zones of ethanol extracts at 1000 mg/ ml were 25.15 ± 0.45, 23.25 ± 0.35 and 22.35 ± 0,65mm, respectively). They also had the highest polyphenol contents and antioxidant activities. Total polyphenol contents of Caesalpinia sappan, Chrysanthemum indicumand Wedelia chinensisOsb. Merr ethanol extracts were 5.817 ± 0.055, 5.034± 0.046 and 4.625 ± 0.069mg axit chlorogenic/100 mg plant material, respectively, while their antioxidant activities were 0.512 ± 0.012, 0.424 ± 0.006 and0.312 ± 0.009mg vitamine E/100mg plant material, respectively.

The paper introduces the method of designing optimal controllers for cascade control systems based on data obtained from an experiment, which is the Virtual Reference Feedback Tuning (VRFT) method. A special feature of this approach, a mathematical model of the actual plants is not required, only a data set achieved from the experiment is needed for acquiring the inner and outer controllers in cascade control systems. In this study, by using the VRFT method, we will achieve optimal inner and outer controllers of the cascade control system. Using these optimal controllers, the purpose of the control problem will be achieved such as the output of the cascade control system will be close to the desired output. The Matlab software is used for simulation, the simulation results show that with the achieved optimal controllers, the output of the cascade control system is asymptotic to the expected output. 

The objective of this study was to design and fabricate a handheld optical reflectance device on some common vegetables in Vietnam such as cabbage, lettuce, and bok choy. The handheld device was designed by AutoCAD 2019 software (Autodesk Inc, CA, USA). 3D modeling was performed by Sketchup 2019 (ver. 19.0.685, Trimble Inc, CA, USA). An interface designed by Matlab GUI was used to collect reflectance data from the handheld device. The collected data from the handheld device was compared with the data from a spectrometer of Ocean Optics. Results showed that the shape of the collected data from the handheld device and the spectrometer was similar. However, the collected spectral data of the handheld device were not jet adjusted and applied with pre-processing techniques such as smoothing, removing outliers and errors. Further studies on the effects of pre-processing and spectral calibration methods are needed for improving the accuracy of the handheld device. Additionally, assessments of the similarity and stability of reflectance over the wide range of vegetable leaves are required. The results of the present study provide meaningful design guidance for pesticide residue monitoring for leafy vegetables.

Enhancing people’s participation in community-based tourism (CBT) development process is a solution to develop a sustainable tourism, to preserve the indigenous culture andimprove the lives of ethnic minorities, particularly in region of cultural diversity of Moc Chau, Son La, especiallly in the context of Covid-19 pandemic. This study was carried out to assess people's change in tourism participation before and during the Covid-19 period. The people’s participation assessment was done by analyzing the information gathered from 198 households using descriptive statistics. The findings demonstrated that the participation level in CBT development activities was extremely poor or at induced level of Tosun's typology. The participation in the post-Covid-19pandemic was similar to the pre-Covid period. This was due to people’s dependency on the local government, low degree of linkages of the stakeholders in the CBT as well as low effect of the the Covid-19 pandemic on the household's income from tourism.

This article analyzed the current situation of accounting performance in the cooperatives in Nghe An province, indicated shortcomings in the accounting performance, and suggested some implications to improve the accounting performance of these cooperatives in the future. To achieve these objectives, this article used some research methods such as: Shapiro-Wilk normality test and T-test, descriptive statistics method, comparative analysis method, and Likert scale. The research results showed that (i) The number of permanent accountants in cooperatives was limited and the educational level of accounts was not high; (ii) applying the system of accounting vouchers, accounts, and ledger accounts were not complying with the guidelines of the accounting regime; (iii) reporting and providing the accounting information were still formal and accounting information was inaccurate, incomplete and untimely; (iv) the effectiveness of the internal control system in accounting was also limited. Therefore, this article suggested some implications to improve the accounting performance of these cooperatives: Improving capacity and creating accounting human resources for cooperatives; Applying some additional detailed accounting ledgers and management accounting reports to provide accounting information to the internal management of cooperatives; regulations on inspection and control on accounting.

The Covid-19 pandemic with its complicated and unpredictable occurrence negatively affects socio-economic aspects, including fisheries sector. The present paper reports the initial assessment about the impacts of Covid-19 on Vietnam’s fisheries management activities. The secondary data were collected through online survey and discusions with fisheries managerial staffs from Provincial Departments of Fisheries. Above 77.4% of respondents were unanimously in answering that the Covid-19 pandemic had a heavy effect on fisheries management activities. Fishermen supported services, seafood processing plants and exporting were affected seriously with 48.4%, 74.2% and 71%, respectively. The frequency of fishing vessels’ arrivals and departures in ports decreased by 10-30% compared with previous years. Several technical workshops and training courses for fishermen were postponed, cancelled or shifted to next year because of social distancing, lockdown and movement and gathering restrictions in order to cope with Covid-19 pandemic.

With nearly 5,000 publications in the world and more than 100 publications in Vietnam, the Soil and Water Assessment Tool (SWAT) is clearly one of the most extensively used ecological, hydrological models worldwide. Model capability assessment, land use/land cover change, and climate change assessment are the main SWAT applications that have been implemented in Vietnam since 1990s. The objectives ofthis paper are to: (1) introduce applications of SWAT model; (2) studies on SWAT model applications in Vietnam; and (3) challenges and potentials of SWAT model development in Vietnam. The results indicated that the challenges of the SWAT model’s applications in Vietnam including data unavailability and uncertainties which led to unreliable forecast results. Therefore, future studies should be paid attention to identifying and developing availability data and reliable input data for SWAT modeling. SWAT model modification based on the global climate model (GCM), geographical and land use conditions is another research direction to be considered in the future. In short, SWAT model is an effective tool for decision makers of land and water resources planning and management in the future.