CTU Journal of Innovation and Sustainable Development
Journal of Can Tho University
Attitudes towards cycling in Long Xuyen, Viet Nam: An exploratory study
The promotion of cycling has recently received strong support from the Vietnamese government, and there has been a call for changes in planning to create suitable environment for cycling. However, knowledge in this field is limited since the travel behavior literature in Viet Nam focused on other travel modes, and the context of small cities was largely ignored. The aim of this research is to understand people’s attitudes towards cycling in a small city like Long Xuyen. This serves as an exploratory study to inform and develop future research on this issue. A qualitative approach was used to identify the main influences affecting people’s cycling decisions. The results showed that people’s cycling choice was affected by attitudinal factors, subjective norms, and perceived behavioral control. Interestingly, habit was also found to impact people’s choice of cycling.
Impact of temperature and relative humidity on physicochemical properties of the spray dried red flesh pitaya powder during storage
This study was carried out to evaluate the changes in physicochemical properties of pitaya powder produced by spray-drying under the different temperature storage at 5-7 , room temperature, and 50 for 40 days, The results showed that delta E of color increased but the content of betacyanin and total phenolic decreased following temperature increase. The degradation of betacyanin and total phenolic content in all samples during storage fitted the first-order reaction. Moreover, the behavior of moisture content in pitaya powder under different relative humidity was investigated. The isotherm curve of pitaya powder was built (y = 3,2655e0,0106x). The result also showed the GAB equation can be used to calculate the M0 of the sample better than the BET equation.
Build coconut counting system using image technology
In our country today, the counting of dried coconuts at the production facilities is done manually, takes a lot of time and is not accurate. The goal of this study is to build an automatic, fast and accurate coconut counting system. The study was conducted on the peeled dried coconut fruit with a diameter of 15 cm to 20 cm using image processing technology and open-source computer vision library - OpenCV library. The algorithm includes four main steps. First, determine the object and the background using the Otsu segmentation method. Next, estimate the distance between the background and the object to determine the closest area to the center of the object. Then, find the contour, determine the center and area of the object to reduce the noise. The watershed segmentation algorithm is used to separate overlapping and stacking objects. Finally, count the number of objects contained in the image. In the initial experimental results, the counting system has had an accuracy of over 95% with processing time per image about 75 ms and the counting capacity of the system is over 2000 fruits/hour has confirmed the efficiency of the proposed method.
Effects of pre-sowing seed treatments on rice yield, grain quality and soil chemical properties in salt-affected soils
This study aimed to evaluate the effects of sowing density and iron (Fe) coated seeds on rice grain yield, grain quality, and soil properties in saline soils in Phuoc Long district, Bac Lieu province, Vietnam. Experimental treatments include: (T1) Intact dry seed (50 kg seed/ha); (T2) Hydro-primed seed (120 kg seed/ha); (T3) Hydro-primed seed (50 kg seed/ha); (T4) Hydro-primed then sprouted seed (50 kg seed/ha); (T5) Fe-coated dry seed (50 kg seed/ha); (T6) Fe-coated hydro-primed seed (120 kg seed/ha); (T7) Fe-coated hydro-primed seed (50 kg seed/ha); (T8) Fe-coated hydro-primed seed which was sprouted before sowing (50 kg seed/ha); (T9) Hydro-primed then sprouted seed (120 kg seed/ha); (T10) Transplanting (50 kg seed/ha). The results indicated that applying Fe-coated seeds significantly increased tiller number at 45 and 60 DAS compared to free-Fe-coated seeds and transplanting treatments. There was no significant difference in tiller number among treatments at harvest stage. The plant height, yield, amylose, protein contents, gel consistency, soil pH, Eh, and Fe content in soil solution among the treatments did not differ significantly. This study demonstrated that reducing seed rate, broadcasting dry seeds, and coating seeds with Fe could reduce production cost while plant growth, yield and grain quality are maintained.
Analyzing the factors affecting the high school dropout in Ca Mau
The yearly dropout rate of high school students of Ca Mau was relatively high (as of 5.61% in the school year 2019–2020). The problems and consequences of dropping out of school might raise numerous social problems. Therefore, this study is to examine the factors affecting the students’ dropout of high school in Ca Mau province and propose several solutions to reduce the dropout rate. Data were collected from 06 districts in Ca Mau in 2019–2020 by interviewing 268 parents and 16 educational managers and surveying 168 homeroom teachers in high schools. The analysis results demonstrate that the main reasons for students’ dropout were poor academic performance (57.46%), economic difficulties (26.87%), living in an unhappy family (9.33%), and improper learning motivation (6.34%). The findings provided crucial information for practically efficient solutions in reducing the high school dropout rate in Ca Mau.
Physicochemical, antioxidant and microbiological behavior of soursop purees during thermal treatment
In this study, the influence of thermal treatment at temperatures 70, 80, and 90°C for 0 to 45 minutes on the quality of soursop puree was investigated in terms of physicochemical properties and antioxidant activity. Total phenolic content and antioxidant activity of the sample were evaluated using spectrophotometric methods, ascorbic acid was tested using the titration method. The result showed that high temperature and prolonged heat treatment accelerated the degradation of physicochemical properties in soursop puree. The kinetic degradation of polyphenol, ascorbic acid, and antioxidant activity belonging to temperature was performed by Arrhenius equation with the Ea values were 54.42 kJ/mol, 48.83 kJ/mol, and 20.07 kJ/mol, respectively. Total aerobic counts and ∆E values of all samples were less than 1 x 102 CFU/g and 2.51, respectively. The soursop puree reached a good quality for all the tested attributes at 80°C for 15 minutes.
Evaluating the optimal working parameters of the color sensor TCS3200 in the fresh chili destemming system
In a previous study, a fresh chili destemming system has been proposed, and the TCS3200 color sensor was used as low-cost equipment in the arrangement section of the system. However, the working and installing parameters have not yet been investigated in detail. This study focused on investigating the optimal working conditions of TCS3200 on the fresh chili destemming system. The study included three experiments including the effect of the red and green color channels, the effect of the height between the sensor and fruits, and the effect of the running velocity on the received signal level of the sensor. A total of 260 ripen fruits were chosen to test. The results showed that the red channel generated a stronger signal than the green one. The optimal height from the sensor to the fruits was obtained at 25 mm, and the maximum conveyor velocity is limited to 100 mm/s. This study helps to determine the optimal operating parameters and enhance the working ability of a low-cost sensor. However, the high-speed pushing actuating mechanism should be developed in further works.
Application of different control algorithms on a ‘home-made’ temperature control lab kit
Providing enough facilities for students to do laboratory activities is important. An existing useful kit was proposed for students learning a variety of control engineering topics. A temperature control lab kit is made from scratch using common electronics components as a replacement for the original TCLab introduced by Hedengren (Hedengren et al., 2019). Mathematical models of the system derived from theoretical and experimental methods are simulated in Matlab/Simulink to verify their accuracy to the physical kit. Different control algorithms such as: On/Off, PID, Fuzzy are then applied on the Kit as well as its mathematical models to illustrate their control feasibility. Human machine interface (HMI) is also designed using Matlab GUI allowing an operator to select a control algorithm, tune control parameters and monitor parameters of the process. Experimental results show that the derived models can reflect quite well dynamics of the physical kit with temperature deviation among them in the range of ±3°C. This confirms that the kit is well-suited for teaching different control topics such as system modelling, system identification, classical control and advanced control algorithms.
An object detection method for aerial hazy images
Image processing and object detection in aerial images have to deal with a lot of trouble due to the existence of haze, smoke, dust in the atmosphere. These factors can blur objects and severely decline image quality which might lead to incorrect or missing object detection. To solve this problem, this study shows a method that can reduce the bad effect of haze on object detection in aerial images. A combination of a dehazing method called Feature Fusion Attention Network (FFA-Net) and an object detection method named Probabilistic Anchor Assignment (PAA) was conducted to evaluate two hypotheses: (1) haze was a noisy factor and (2) haze was treated as part of objects. Through extensive experiments, the selective dehazing hypothesis, which was used for truck objects, improved the detection result of car and bus from 19.6% to 21.9% and 0.7% to 4.4%, respectively, on the UAVDT-Benchmark-M dataset. This result showed that our approach was effective.
Fabrication of PZT Thick Film by Electrophoretic Deposition on the Platinum Substrate
PbZrxTi1-xO3 compositions near morphotropic phase boundary have been reported to have high piezoelectric properties. In this study, Pb(Zr0.5Ti0.5)O3 (PZT 50/50) powder was produced by the solid-state reaction from the relevant oxides at 950oC. Phase analysis using X-ray diffraction revealed the single phase of the tetragonal perovskite structure. PZT thick film was fabricated by electrophoretic deposition of the resulted PZT powder onto the Pt substrate. The electrophoretic deposition process was conducted in an ethanol medium, and the effects of deposition parameters such as pH, applied voltage and deposition time on the film thickness were investigated. A green film with a maximum thickness of ~95 μm and sintered film with a maximum thickness of 80±2 μm were prepared. The effects of sintering atmosphere and temperatures on phase transformation and microstructures of PZT film were evaluated using X-ray diffraction and scanning electron microscopy. At room temperature, a PZT film of 68 ± 2 μm thickness has a relative permittivity of 477 ± 13 and ~ 9,500 at TC = 405oC, showing typical dielectric properties.
The influences of oral communication strategies on students’ English speaking proficiency
This study aims to examine the spoken communication techniques of non-English major students at University of Economics – Technology for Industries (UNETI) to get a better knowledge of language acquisition techniques, namely oral strategies used in communicative activities. Data were collected through questionnaire adapted from the Oral Communication Strategy Inventory (OCSI) by Nakatani (2005) and analyzed using OCSI. Participants were 50 EFL students from the Faculty of Accounting, UNETI. The results show that students utilized certain communication strategies (CSs) when they encountered oral communication difficulties. It was additionally anticipated that UNETI students would think more deeply about their oral communication abilities. Consequently, teachers will develop more effective methods of teaching them how to communicate successfully with others throughout the process. Moreover, students will acquire additional CSs that they may use more effectively in real-world conversations with native and non-native speakers. Thus, speaking strategy training should not be overlooked throughout students’ learning process.
The effects of extraction conditions on the yield of crude pectin extract from passion fruit (Passiflora edulis Sims.) and the application of the extract on jam forming ability
The peel of purple passion fruit (Passiflora edulis Sims.) can account for up to 60% of the total weight and contains usable organic compounds such as polymeric sugars, including pectin. The influences of ripeness stages and the extraction conditions (solvents, peel to solvent ratio, temperature, time) on the extract of crude pectin yield were investigated. The results indicated that pectin yield was independent of fruit maturation. The extraction efficiency reached its peak when extracted with citric acid and demonstrated optimal pectin production yield with the ratio of 1:5 (w/v) and at 95°C for 80 minutes. The extracted crude pectin was then applied to mango jam production. Jam made from extracted pectin had a good structure, moderate hardness, nice color, and harmonious taste. The ability to form coagulation on mango jam of crude pectin was weaker than commercial pectin. This study found that the topic's practical applicability to the processing of food products was significant.
Synthesis of silver nanoparticles using extract of Citrus maxima peel
In this work, silver nanoparticles (AgNPs) were synthesized by the extract of Citrus maxima (C. maxima) peel with the presence of pectin as a principal reductant and stabilizer. Parameters such as concentration of C. maxima powder, extraction temperature, and extraction time for AgNPs synthesis have been studied. The synthesized AgNPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and transmission electron microscopy instrument (TEM). The synthesized AgNPs were quasi-spheres with an average particle size of 17 nm and high purity of silver phases. In addition, synthesized AgNPs exhibited good antibacterial activity against Gram-positive bacteria: Salmonella enterica (S. enterica) and Pseudomonas aeruginosa (P. aeruginosa) while no activity inhibited against Gram-negative bacteria: Staphylococcus aureus (S. aureus) and Lactobacillus fermentum (L. fermentum).
Preparation of Fe3O4/HAp nanoparticles from eggshells with highly adsorption capacity for methylene blue
Multifunctional materials have become one of the most interesting research subjects in recent years. Hydroxylapatite (HAp) coating on the surface of iron oxide (Fe3O4) nanoparticles allow to obtain material with adsorbable and magnetic properties. This study aims to salvage recycled eggshell to successfully produce adsorbent nanoparticles and evaluate treatment ability of methylene blue (MB) dyes in water. The magnetic nanomaterial was synthesized by a simple and inexpensive method. The X-ray diffraction technique was employed to characterize the structure of nanoparticles. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique to determine the presence of functional groups and bonds in the molecule. The surface morphology of as-synthesized Fe3O4/HAp nanoparticles was studied by transmission electron microscopy. The magnetic properties of Fe3O4 nanoparticles and Fe3O4/HAp nanoparticles were evaluated by vibrating sample magnetometer technique. The typical synthesized-HAp were dispersed rod-like particles with about 10 nm in width and 50 nm in length, the other part of final material was dispersed in spherical shape and their magnetism was 16.2 emu.g-1. The adsorption of MB was conducted with 89.6% yield at pH 8.
Effects of dietary protein and lipid levels on growth, feed utilization and meat quality of clown knifefish (Chitala chitala)
Effects of dietary protein and lipid levels on growth, feed utilization and fillet quality of clown knifefish (Chitala chitala) were implemented to determine the protein and energy requirements of this species at 400 g stage. A 4 x 3 factorial design with four dietary protein levels (25%, 30%, 35% and 40%) and three dietary lipid levels (6, 9, and 12%) corresponded to 3 energies levels 18, 19 and 20 MJ/kg. Clown knifefish (407 ± 5.0 g) was stocked at a density of 10 fish/m2. The experiment was arranged in a completely randomized design in triplicate tanks for 8 weeks. There was a significant interaction effect (P<0.05) between protein and lipid levels on weight gain and specific growth rate with the fish growth being highest in the 35 CP-9% lipid treatment. The survival rate of fish was not affected (P>0.05) by dietary protein and lipid levels and ranged from 93.3 to 100%. The feed efficiency of fish was influenced by dietary protein or lipid content as well as the interaction between these two factors. Protein utilization efficiency increased as protein content increased, and diet contained t 35% protein and 9% lipid, enhanced chewiness and hardness of fish paste. These results showed that clown knifefish fed 32.8% dietary protein and 19 MJ energy with a P/E ratio of 18.6 had the optimal growth and the best quality of fish meat.
Characteristics of lightweight foamed concrete with various contents of polypropylene fiber
This study investigates the influence of polypropylene (PP) fiber content on the mechanical properties of lightweight foamed concrete (LFC). Four LFC mixtures with a target dry density of 1000 kg/m3 were designed with different PP fiber volumes of 0%, 0.25%, 0.5%, and 0.8%. The fresh unit weight (UW), dry density, compressive and flexural strengths, water absorption, thermal conductivity, ultrasonic pulse velocity (UPV), and scanning electron microscopy (SEM) of the LFC were examined. The results indicate that the fresh UW, dry density, UPV, and thermal conductivity decreased when the PP content varied from 0% to 0.8%. At 28 days, the compressive and flexural strengths of the LFC increased approximately 11.85% and 41.8% when the PP fiber amount varied from 0% to 0.8%, respectively. The result implies that the PP fiber content had a higher influence on the flexural strength content than the compressive strength. Furthermore, the results of SEM could explain well the obtained mechanical properties. The findings of this study indicate that PP fiber could be used up to 0.8% by volume to reduce the self-weight of the LFC and enhance the mechanical strength as well as thermal isolation characteristics of the LFC.
Antibacterial resistance of Vibrio parahaemolyticus isolated from shrimp farms located in east coastal region of the Mekong Delta, Vietnam
The study was conducted to evaluate the susceptibility of 58 Vibrio parahaemolyticus bacterial isolates to 16 antibiotics. These bacterial isolates were recovered from diseased shrimp which displayed typical pathology of AHPND such as hepatopancreatic atrophy, empty gut, and hepatopancreatic changes including hemocytic infiltration and bacterial infection. Results of antibiotic susceptibility testing by the disk diffusion method showed that single resistance to tested antibiotics was relatively rare. The bacterial strains were resistant to amoxicillin (100%), cephalexin (100%), Sulfadiazine Sodium (94.7%), and Erythromycin (87.7%). Sensitivity of tested strains was recorded with doxycycline (84.2%) and oxytetacylin (49%). The minimum inhibitory concentrations (MICs) were determined for the sensitive isolates using a broth macro dilution method. The majority of tested isolates had an MIC value of 2μg/mL with doxycycline. The current study suggests caution in the use of antibiotics for the prevention and treatment of AHPND in shrimp farming.
Disease incidence in shrimp farms located in east coastal region of the Mekong Delta, Vietnam
A field study on the water quality parameters and prevalence of diseases was carried out in four locations in the Mekong Delta, Vietnam. A total number of 960 samples (816 with disease signs and 144 without disease sign) of farmed shrimp were collected over 8 sampling months (2 production cycles). Samples were collected every two weeks and when abnormal behavior from cultured shrimp was observed. Five major groups of gross clinical signs were recorded among diseased shrimp samples. Diseases that appeared through the sampling months were: (1) atrophy and pale-colored hepatopancreas (HP) with the empty or little food in the mid gut; (2) empty/little/discontinued food in the midgut and (3) slow growth, HP atrophy and gut with discontinued food. White feces disease was not found in April but appeared for the rest of sampling months with the highest prevalence in July (39,2%) and the lowest prevalence in September (4,9%). White spot disease appeared from October to December (at the end of when the monsoon season and low temperature).
Quinazolinone based hydroxamates as anti-inflammatory agents
Five thioether-linked hydroxamate/quinazolinone hybrid structures were synthesized and tested for their anti-inflammatory activities. The obtained results indicated that compounds 7a-c and 7e showed the inhibition on LPS-stimulated NO production with the IC50 values ranging from 58.03 to 66.19 mM. Molecular docking results showed that all synthesized compounds displayed affinity towards the 5-LOX, MK2, P2Y12, 15-PGDH, and DNA polymerase receptors based on the observed low binding energies and interactions with the key amino acids in the binding sites of the enzymes. Noticeably, compound 7e exhibited as a potential compound targeting six receptors including 5-LOX, MK2, mPGES-1, P2Y12, 15-PGDH, and DNA polymerase receptors.
Docking-Based Virtual Screening for the Discovery of 1,3,4-Oxadiazoles as Aminoacyl-tRNA Synthetase Inhibitors
Aminoacyl-tRNA synthetases (aaRSs) are one of the leading targets for the development of antibiotic agents. In this paper, we reported the discovery of aaRS inhibitors using a structure-based virtual screening method. The interactions of 52 designed structures with the methionyl-tRNA synthetase (MetRS) target were performed by docking the ligands into the active zone of the MetRS using Autodock Vina. The data revealed 14 compounds displaying interactions with key amino acids (Asp287, Tyr250, Val473, Trp474, Phe522, Ile519, Ala477, Leu478, and His523) at the binding pocket of the enzyme, indicating their potential as MetRS inhibitors. These results could be served as the references for further synthetic work and bioassays experiments for discovering MetRS inhibitors and other pharmaceutical agents that may assist in the generation of new antibiotics.
Creation of Variation through In-vitro Mutagenesis using Gamma radiation in Rose (Rosa hybrida L.) Variety ‘Lửa’
Rosa hybrida L. var. Lửa has been one of the most important roses for a long time and is most often used for ornamental purposes in Sadec city, Dong Thap province. The study aimed to induce variation through in-vitro gamma-ray irradiation in the rose variety ‘Lửa’ for further improvement in rose breeding. In-vitro single node cuttings (25 in-vitro cuttings per treatment with four replications) were irradiated with different doses of γ-rays (0, 5, 10, 15, 20, 25, or 30 Gy) using a 60Co source (India) at Da Lat Nuclear Research Institute. The γ-irradiated explants were then cultured aseptically on Murashige and Skoog’s basal medium supplemented with 1.0 mg/L BAP to induce multiple shoots, shoot proliferation, and acclimatization at Division of Vegetables, Flowers and Landscaping of Southern Horticultural Research Institute (SOFRI). The LD50 dose was determined at 20 - 25 Gy treatments and these doses affected the multiplication rate, growth in-vitro, and ex-vitro survival rate. Three types of mutants with altered or novel flower color in comparison to the original flower color were isolated, such as Type 1 with orange-pink (Red 52C), Type 2 with pink (Red 54B), and Type 3 with Red 45AB with Red 54B bicolor.
Diversity of medicinal plant resources in Lai Son island, Kien Giang province
This study was conducted with the aim of assessing the diversity of medicinal plants in Lai Son Island, Kien Giang province, which is a scientific basis for more effectively using, managing, and preserving this medicinal plant resource in this province. In this study, the PRA (Participatory Rural Appraisal), field investigation, morphological comparison, and classification, with the aid of specialized medicinal plant books were used. The results showed a total of 353 species of medicinal plants belonging to 264 genera of 112 families in 4 divisions. Among them, Magnoliophyta was the most diverse division with 94.90% % species, 95.08% genera, and 90.18% families. Seven species were listed in “Red List of Vietnamese medicinal plants” (2006), “Vietnam Red Book” (2007), and the Decree 06/2019/ND-CP. The medicinal plant species were divided into ten life forms and distributed in six biotopes. The most species diversity was recorded in the natural forest on rocky mountain biotope. Ten parts of plants were used to medicate 36 disease types. Twenty-four species were commonly used by local people.
Effect of heavy metals on duckweed growth
In this study, three clones of the duckweed genus Lemna, collected from three different regions of Vietnam Binh Thuan Bac Giang and Ben Tre were used to evaluate the growth and development in a culture medium containing different concentrations of As3+, Cd2+, or Pb2+. During 14 days of incubation, the growth rate was determined daily by measuring the surface area of all plants of each sample. Experimental results show that the three Lemna clones could grow in nutrient medium contaminated by heavy metal at a concentration of 0.3-0.5 mg/L for As3+, 0.15-0.3 mg/L for Cd2+, and 0.15 mg/L for Pb2+. At these concentrations, the division rate of the treated clones was several times higher than that of the controls. The highest increase in the surface area was recorded for Lemna BTN (68.47 times higher when cultured in medium supplemented in 0.3 mg/L Pb2+ than under control conditions). The surface area of Lemna BTR cultured in a medium supplemented with 0.3 mg/L As3+ was 54.65 times higher than in medium without arsenic. The obtained results showed that Lemna BGG and Lemna BTR can tolerate arsenic and cadmium pollution while Lemna BTN tolerates lead pollution.
Morphological variation, chromosome number, and DNA barcoding of Giant Duckweed (Spirodela polyrhiza) in Vietnam
Our present study is the first systematic survey on duckweed biodiversity in Vietnam. More than 100 samples of Spirodela, Lemna, and Wolffia were collected throughout Vietnam and maintained under laboratory conditions. In this report, the morphological variation, chromosome number, and DNA barcoding on Spirodela samples were investigated. S. polyrhiza and S. intermedia are the only two species of Spirodela genus - the most ancient genus among the five duckweed genera. The obtained DNA sequences of atpF- atpH and psbK – psbI regions showed that all 29 Spirodela samples collected from different regions along Vietnam are S. polyrhiza. Specific SNPs of individual S. polyrhiza clones were identified in the psbK-psbI region. The differences in genome size (163 – 170 Mbp), frond size (0.80 – 1.25 cm2), frond shape (oval/circular symmetry/asymmetry), stomata (20.57 – 24.00 µm in length and 10.00 – 21.30 µm in width) and root number (4.75 – 6.69 roots) among six representatives S. polyrhiza clones were recorded. The chromosome number of these clones was uniformly 2n=40.
Isolation and identification of the antagonistic bacteria against Xanthomonas spp. causing the leaf spot from Rosa spp.
Three out of 203 bacterial isolates showed high antagonistic activity by in vitro screening against three strains of Xanthomonas spp. causing leaf spots from Rosa spp.. Antagonistic bacteria were collected from the rhizosphere substrate of potted rose in Sa Dec Flower Village of Dong Thap province, Viet Nam. While three pathogen strains of Xanthomonas spp. were stored at the Biochemistry Laboratory of Biotechnology Research and Development Institute of Can Tho university. Three effective isolates were identified by Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and analysis of 16S rRNA gene sequence. Using MALDI-TOF, these antagonistic bacteria belong to Bacillus genera. The amplification of 16S rDNA gene was performed using 27F and 1492R primers. The nucleotide sequences of this gene were aligned using the GenBank database and BLAST-N program from the NCBI site. The isolates identity of BR16, BR37, and BR88 shared the highest similarity values in turn with Bacillus velezensis MN160320 (99.11%), Bacillus subtilis MN493770 (99.11%), Bacillus amyloliquefaciens KX871898 (99.41%). These Bacillus isolates were designed Bacillus velezensis MW677565 (from BR16), B. subtilis MW828613 (from BR37), B. amyloliquefaciens MW828656 (from BR88). These isolates have shown the ability to fight phytopathogenic bacteria of rose plants in Dong Thap of Viet Nam.
Controlling efficiency of the potential rhizosphere bacterial antagonists against leaf spot disease from Rosa spp. caused by Xanthomonas spp. in vitro and under net-house condition
Bacterial leaf spots (Xanthomonas spp.) on roses cause great losses to farming. In vitro, the survey of antagonistic density was tested by using three antagonistic isolates (BR16, BR37, BR88) against Xanthomonas spp. (XR13, XR9, XR18 strains). These antagonists and pathogens were diluted separately at 10, 100, 1000 &10000 fold. Results showed that the inhibition abilities were increased with diminishing the population of the pathogen. In which, the antagonists with populations less than 106 CFU/mL are not sufficiently or low effective in forming the inhibitory zone against the pathogen. Therefore, a density of about 107 CFU/mL was selected in the trials on rose under net-house conditions. From that, with the foliar application, three isolates (BR16, BR37, BR88) were tested against the three mentioned pathogenic strains. Results showed that pretreating with antagonistic bacteria achieved high disease control efficiency. In which, BR88 has the highest disease reduction efficiency reaching 70.1%, 72.4%, and 73.3%, when infecting the XR13, XR9, or XR18, respectively. Furthermore, treatments from applying separately three antagonistic isolates all have AUDPC lower than the treatment with only disease inoculation from 2.4 to 4.7 times. In which, the AUDPC of treatment of BR88 was similar to BR16 when infecting XR13,...
Efficacy of bacteriophages in controlling bacterial vascular wilt caused by Ralstonia solanacearum Smith on eggplants
The objective of the study was selection promising bacteriophages for lysis Ralstonia solanacearum in vitro and evaluation their ability to prevent bacterial vascular wilt on eggplants under greenhouse conditions. Primary selection of promising bacteriophages from four bacteriophages as Φ54, Φ60, Φ67, and ΦBT on Ralstonia solanacearum isolated from eggplant based on plaque diameter and phage multiplication in in vitro, the result found that three bacteriophages (Φ54, Φ67, and ΦBT) expressed plaque diameter over 7.00 mm at 48 hours, and phage titer with log (pfu/ml) reach over 7.00. Continuing the survey, the efficacy of these phages in controlling bacterial wilt on eggplants in greenhouse conditions through applying each bacteriophage or cocktail of three phages suspension two times (1010 pfu/ pot/ each time) before pathogen inoculation and 7 days after pathogen inoculation through soil drenching. As a result, all bacteriophages either single or mixture of three phages were effective in the prevention of bacterial wilt disease. Especially, phage Φ BT showed the highest disease reduction and was better than bacteriocide treatment applied with Starner 20 WP.
The chromosome numbers of Panax vietnamensis Ha et Grushv
The somatic chromosome number of Panax vietnamensis Ha et Grushv. was determined to be 2n = 24, based on the hypotonic shock method by potassium chloride solution. In this study, we investigated the effect of potassium chloride and colchicine solutions on chromosome dispersion of Panax vietnamensis at different concentrations. The treatment using 0.2% KCl solution in 45 minutes combined with 0.05% colchicine solution in 2 hours subsequently resulted in proper hypotonia. The result showed that chromosomes were evenly dispersed. The hypotonic shock method seemed to be effective in equally distributing chromosomes. The result can be applied in cell genetic studies and selective breeding programs for Panax vietnamensis.
Selection and characterization of a yeast strain for the suppression of brown spot on Tru Long pummelo (Citrus maxima)
Tru Long pummelo is an endemic plant of Quang Nam province with high economic value. However, many different diseases, especially brown spot disease caused by Alternaria fungus on pummelos, have affected the quality of pummelos. Pesticides are overused and misused for the environment and human health. Therefore, there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Eight yeast strains have been isolated from healthy leaves, pummelo fruits, and healthy mulberries. They were screened for biological activity against Alternaria sp. by the dual culture method. The inhibitory potency ranged from 10.46% to 59.86%. The strain with the highest percentage (59.86%) was identified as Candida tropicalis using sequence analysis of the ITS region.
Semi-chronic toxicity study of the extracts from different parts of burmese-grape Baccaurea ramiflora fruits of Ha Chau variety using mouse model
This study evaluated the semi-chronic toxicity of seed, peel, and pulp extracts from burmese-grape fruits of Ha Chau variety on Swiss albino mice. The ethanolic extract from peels and seeds as well as fruit juice from squeezing pulp were dried under a vacuum to obtain the crude extracts. The distilled water (control group) or these extracts at a daily dose of 400 mg/kg of body weight were directly inserted into the stomach of mice for 90 days. The mice were observed for toxicity signs, externally morphological features of organs, and histopathology after 45- and 90-days of treatment. The results revealed that there were no toxicity signs and statistically insignificant differences in body weight gain, the ratio of organ weight to body weight, and blood glucose level at 45 days of treatment. At 90 days of treatment, similar results were observed, except that the ratio of kidney weight to body weight significantly increased in peel extract mouse group as compared to the control. The semi-chronic toxicity assessment showed that Ha Chau fruit (HCF) seed and pulp extracts were safe at a daily dose of 400mg/kg for 90 days in mice and that HCF peel extract was safe when orally...