Search

Search Results

• The Impacts of Financial Development, Trade Openness, Natural Resources Rent, and Government Expenditure on Economic Growth: Evidence in Northeast Asia

  Nguyen Anh Tru

  Received: May 02, 2023 / Published: Dec 30, 2023

   Abstract PDF

  The association among financial development, trade openness, natural resources rent, government expenditure, and economic growth has been investigated by scholars, but the results have been controversial. This study attempts to examine the relationship among financial development, trade openness, natural resources rent, government expenditure, and economic growth in three Northeast Asian countries, namely China, Japan, and the Republic of Korea, between 1981 and 2020 using the fixed effect and random effect models. The results of the feasible generalized least squares model stated that economic growth of these countries can be fostered by financial development and trade openness.  However, surprisingly, natural resources rent had a negative effect on the economic growth of the three countries in the region, while the relationship between government expenditure and economic growth was not statistically significant. Finally, policies are recommended to accelerate economic growth and achieve sustainable development for the region. First, financial development should be encouraged by improving domestic credit to the private sector. Second, trade openness should be facilitated to exploit competitive advantages in export-led growth, and science and technology. Finally, the countries should implement sustainable growth models to their reduce dependence on natural resources and achieve sustainable development for the region.

• Responses to Water Deficit of Mung Bean Cultivars at the Vegetative and Flowering Stages under Greenhouse Conditions

  Vu Thi Thuy Hang, Le Thi Tuyet Cham, Phan Thi Thu Hien, Pham Thi Ly

  Received: Aug 22, 2023 / Published: Dec 29, 2023

   Abstract PDF

  Mung bean (Vigna radiata L. Wilczek) is grown mainly under rainfed conditions, facing water deficits in different growth stages. This study was conducted to evaluate the responses of a local cultivar, Dau tam Thanh Hoa, and three introduced mung bean cultivars (DX14, Mongo Labo, and TV06425) to water stress at the different growth stages. The experiment was carried out in a greenhouse following a completely randomized arrangement with two replications. Drought was induced by withholding water at either the vegetative or flowering growth stages for 20 consecutive days. The control consisted of well-watered plants. After 8, 12, 15, and 20 days of drought, plant available water, growth characteristics, and the weights of fresh stems and roots were measured. After 20 days of drought, plants were watered to assess their recovery after 7 days and the growth characteristics, weights of fresh stems and roots, and yield components at the harvest stage were evaluated. The results showed that drought affected the growth, resilience, and yield-related factors more severely at the vegetative stage than at the flowering stage. The longer drought was imposed, the greater decline in plant growth was observed. Despite the recovery, fresh root mass and root length were still 40-50% and 10-30% worse than the control, respectively. Based on the growth responses and individual yields, Dau tam Thanh Hoa and DX14 were more tolerant to water deficit and can be used as materials for improving the drought tolerance of mung bean.

• Effects of Nitrogen Application on the Growth and Yield of Quinoa under Saline Conditions in Northern Vietnam

  Dinh Thai Hoang, Dang Thi Phuong Anh, Luu Hue Nhan, Nguyen Viet Long

  Received: Sep 06, 2020 / Published: Jun 18, 2021

   Abstract PDF

  This study aimed to determine the optimum nitrogen application rate for quinoa in saline soils. Two experiments were conducted: (i) the first experiment was under artificial saline conditions with the two factors of saline regime (stressed and non-stressed) and nitrogen application level (0, 30, 60, 90 and 150 kg N ha-1) in net-houses located in Gia Lam, Hanoi; and (ii) the second experiment was under natural field saline conditions with the two factors of quinoa cultivar (Atlas and Moradas) and nitrogen application level (0, 30, 60, 90, and 150 kg N ha-1) in the coastal areas of Hai Hau, Nam Dinh province. Data were collected for growth duration, insect and disease infestations during the growth period, and various growth parameters and yield components at harvest. The results showed that saline stress reduced the growth and yield parameters, but did not affect the quinoa growth duration of the investigated quinoa cultivars. In both experiments, the growth parameters and yield components increased according to the increase of the nitrogen application rates from 0 to 90 kg N ha-1, then decreased when the nitrogen rates were higher. The results suggested that 90 kg N ha-1 was the optimum nitrogen application dose for quinoa growth and development under saline soil conditions.

• Identification of Optimal Culture Conditions for Mycelial Growth and Cultivation of Monkey Head Mushrooms (Hericium erinaceus (Bull.: fr.) Pers)

  Bich Thuy Thi Nguyen, Nghien Xuan Ngo, Ve Van Le, Luyen Thi Nguyen, Anh Dong Tran, Lam Hai Thi Nguyen

  Received: Oct 17, 2018 / Accepted: Oct 19, 2018 / Published: Oct 19, 2018

   Abstract PDF

  Monkey head mushrooms (Hericium erinaceus (Bull.: Fr.) Pers) have been broadly cultivated and widely consumed as traditional medicinal herbs as well as functional food in the Orient for several hundred years of history. The identification of optimal culture conditions for mycelium growth and fruiting body formation is one of the most important steps in cultivation of mushroom. The aim of this study was to investigate the optimal culture conditions including pH level, temperature, media and substrate mixtures for the mycelium growth  and cultivation of Hericium erinaceus strain He-2. Results of the study revealed that the optimal conditions for mycelial growth were observed at 25 ± 1oC and pH 8.0. H. erinaceus was cultured on five different types of culture media: Czapek, Raper, PGA (potato, glucose, agar), PGA supplemented with rice bran, and PGA supplemented with fresh mushrooms. PGA supplemented with fresh mushrooms was found to be the best medium for the growth of mycelia. A media containing 99% grain of rice + 1% CaCO3 was considered as the best mother spawn media for mycelial growth. Among various culture media, the highest mycelium growth rate and biological efficiency of H. erinaceus were obtained when grown on a treatment of 87% sawdust + 4% corn bran + 8% rice bran + 1% CaCO3.

• Effects of Fertilization Ratios on the Growth of Pinto Peanut (Arachis Pintoi) under Drought Stress Conditions

  Vu Duy Hoang, Nguyen Thi Loan, Bui Thi Tam, Tran Thi Thiem

  Received: Jan 23, 2019 / Published: Feb 16, 2019

   Abstract PDF

  The objectives of this study were to evaluate the effects of different fertilization ratios on the growth of pinto peanut (Arachis pintoi) propagated vegetatively under varying water regimes. The experiment was carried out in a net-house in a completely randomized design with three replicates. The N:P2O5:K2O ratios were applied at six levels: F1 (1:1:1), F2 (1:3:1), F3 (1:1:3), F4 (3:1:1), F5 (3:3:1), and F6 (3:3:3) while soil moisture included three different levels: 30% (W1), 60% (W2), and 100% (W3) field capacity. Water stress conditions were treated from 30-65 days after planting, and then the pots were irrigated to 100% field capacity. The results indicate that drought conditions significantly reduced (P<0.05) the growth of stolons, leaf appearance, number of secondary stolons, and dry matter, while the root/shoot ratio was higher compared to plants under well-watered conditions. There was no significant effect of the fertilization ratios on the number of secondary stolons. Higher-NP and NPK application ratios showed significant influences on the growth of A. pintoi under drought conditions by stimulating stolon lengths and the number of leaves, while the root/shoot ratio was decreased. Higher ratios of single fertilizers (N, P, or K) did not show a consistent effect on the growth of A. pintoi under drought conditions. The results suggest that a higher-NP fertilization ratio stimulates the growth of A. pintoi under both drought and well-irrigated conditions.

• Effects of Nitrogen Applications on Transpiration, Physiological, and Growth Characteristics of Sugarcane (Saccharum spp.)

  Dinh Thai Hoang

  Received: May 21, 2023 / Published: Jun 30, 2023

   Abstract PDF

  Improving fertilizer and water use efficiencies is an important strategy in agricultural production. This study aimed to evaluate the effect of nitrogen fertilization on the daily whole-plant transpiration, growth, and physiological activities of sugarcane. The pot experiment was conducted under glass-house conditions. Five treatments of various nitrogen application rates (0, 4, 8, 12, and 16mM) were assigned in a randomized complete block design with three replications. The result showed that higher nitrogen applications led to higher growth, physiological, and biomass parameters. Nevertheless, biomass nitrogen use efficiency and photosynthetic water use efficiency declined because of applying nitrogen at higher rates. During the first weeks of plant growth, no significant differences in plant height, leaf number, SPAD, and whole-plant transpiration among nitrogen treatments indicated that higher nitrogen added was not necessary during this time. Nitrogen and water use efficiencies could be improved if the remaining soil nitrogen and crop growth stage nitrogen requirements are estimated in cultivation practice.   

• Supplemental Effects of Self-extracted Organic Nutrient Solution on the Growth and Yied of Water Spinach (Ipomoea Aquatic F.) in an Aquaponic System

  Nguyen Thi Ai Nghia, Nguyen Thi Ngoc Dinh, Nguyen Hong Hanh, Do Thi Huong

  Received: Dec 06, 2021 / Accepted: Sep 22, 2022 / Published: Sep 30, 2022

   Abstract PDF

  Aquaponics combines two technologies, recirculating aquaculture systems and hydroponics in a closed system. The nutrients recycled from fish tanks supply nutrients for vegetables grown in hydroponics, however in some cases, the nutrient levels may not be sufficient for the optimal growth and yield of plants. In this study, two experiments were conducted to understand the effects of supplemental organic nutrient solutions on plant growth and yield in climbing perch-water spinach aquaponics. Experiment 1 (Exp.1) was conducted to evaluate the effects of three types of leaf-based organic fertilizers on the growth and yield of water spinach, namely self-extracted organic nutrient solution (OE), and two popular commercial foliar organic fertilizers, Hydro Fulvic (OF1) and TCN HUME (OF2), with the dose of 1%. Exp.1 showed that supplementation with the self-extracted solution significantly increased the growth and yield of water spinach but did not change the quality of water spinach in terms of the Brix values and nitrate residue content compared to the control. However, the self-extracted solution showed less effectiveness than the two commercial fertilizers in this experiment. Therefore, we conducted experiment 2 (Exp.2) to determine the suitable concentration and potential use of this extract for water spinach in aquaponics. The results of Exp.2 indicated that the concentration of 2% was the most economical and effective to provide supplemental nutrients for water spinach in the climbing perch-water spinach system. The study suggests that self-extracted organic nutrient solutions can be effectively used for growing water spinach in aquaponic systems.

• Growth Characterization of Sugarcane (Saccharum spp.) under Salinity and Drought Stresses at the Seedling Stage

  Le Thi Tuyet Cham, Vu Khanh Linh, Vu Thi Thuy Hang

  Received: Dec 19, 2023 / Accepted: Aug 26, 2024 / Published: Sep 30, 2024

   Abstract PDF

  This study aimed to assess the combined effects of salinity and drought stresses on the growth and physiology of sugarcane. The pot experiment was carried out in the Autumn cropping season of 2021 under the polyhouse conditions at the Vietnam National University of Agriculture. The experiment consisted of four treatments: non-stress treatment (control), drought stress, salt stress, and salt and drought stress (combined stress). Five weeks after transplanting, salt stress was applied first for four weeks and followed by drought stress for another two weeks. The results showed that under the impact of stresses, sugarcane growth was inhibited with decreases in plant height, number of leaves, Fv/Fm, SPAD, and the fresh and dry weights of roots and stems. The growth and physiology indicators were the lowest under the combined effects of salinity and drought stress.

• A Review on Potential Application of CRISPR/Cas Systems in the Improvement of the Growth Habits and Fruit Quality of Tomato (Solanum lycopersicum) in Vietnam

  Van Hai Tong, Trinh Thi Thu Thuy, Phan Thi Hien, Chu Duc Ha, La Viet Hong, Tran Van Tien, Nguyen Quoc Trung

  Received: Aug 16, 2021 / Published: Mar 30, 2022

   Abstract PDF

  Tomato (Solanum lycopersicum) is known as the most important vegetable crop that is widely cultivated throughout the world. Improvements of the growth, development, and productivity have become core strategies for the sustainable development of tomato in many countries. Here, we performed an intensive summary of recent applications of genome editing in customizing the growth habits and fruit quality in tomato plants. First, the advantages of genome editing, particularly CRISPR/Cas systems, were introduced. We then summarized all up-to-date studies related to the genome editing-based functional characterization of genes of interest in tomato with the aim of designing the growth habits and enhancing the fruit quality. Finally, we discussed the potential applications of this promising tool in tomato breeding programs in Vietnam. Taken together, our review has provided a wide view for further studies towards improving the growth, development, and productivity of tomato in Vietnam.

• Effects of Nitrogen Application Doses on the Growth and Yield of Jiaogulan under Shading Conditions in the Spring-Summer Season

  Thieu Thi Phong Thu, Ninh Thi Phip, Nguyen Thi Thu Phuong

  Received: Mar 13, 2024 / Published: Jun 28, 2024

   Abstract PDF

  Jiaogulan (Gynostemma pentaphyllum (Thunb.) Makino) is distributed mostly in mountainous areas, in shaded and humid places at 300-3200 meters above sea level. This study was conducted to determine the appropriate application dose of nitrogen for the growth of Jiaogulan under different shading conditions. The experiment was arranged in a split-plot design with three replications in 2021. Nitrogen application dose was the main factor with three levels: N1, N2, N3 of 90, 120 and 150kg of N ha-1, respectively. The shading condition was the sub-factor with two regimes: S1 - no shading and S2 - 30% shading (30% reduction in solar radiation using black netting). The observation parameters included main stem length, number of leaves, and number of primary branches. The physiological indicators (LAI, SPAD, dry mass) were measured at 30, 60, 90, and 120 days after transplanting. Yield and total content of saponins and flavonoids were determined at harvesting time. The results showed that the application of the 30% shading condition combined with increasing nitrogen application doses had positive effects on the growth and yield of Jiaogulan. The highest yield was obtained in the treatment combining the 30% shading condition and N3 nitrogen application level. The total flavonoid and total saponin contents did not significantly differ among the treatments. Thus, in the spring-summer season, a combination of a 30% shading condition and nitrogen application of 150 kg N ha-1 should be applied to produce good growth and high yield as well as ensuring the quality of Jiaogulan.

• Effects of Mulching Materials on the Growth and Yield of Peanuts Cultivated in Coastal Areas of Thanh Hoa Province

  Vu Thi Thuy Hang, Nguyen Duy Bach, Le Thi Tuyet Cham

  Received: Sep 04, 2023 / Accepted: Mar 29, 2024 / Published: Mar 29, 2024

   Abstract PDF

  Mulches have been widely applied in crop production in order to minimize water requirements, preserve soil moisture, and curb weed growth for higher yield and water use efficiency. This research aimed to assess the impact of organic mulches on peanut productivity in the coastal areas of Thanh Hoa province. The experiment was carried out during the 2019 spring growing season. A split pot design was used with two peanut cultivars (L14 & L23) as the main plots and five types of mulching materials (clear plastic, rice straw, sugarcane bagasse, water hyacinth, and bare soil) as the subplots. It was  revealed that rice straw exhibited a positive influence on the growth attributes and yield of peanuts, comparable to clear plastic and other organic mulch materials. Notably, rice straw contributed to enhanced plant growth, dry matter production, pod filling, and yield. Additionally, the net return of rice straw application was also the highest. The results suggested that organic mulching materials (rice straw and plant residues) can be effectively used for peanuts because of their availability and biodegradability as an eco-friendly agricultural practice.

• Studies on the Biological Characteristics of the Bt116 Lingzhi Mushroom Strain (Tomophagus sp.) Collected in Hanoi

  Anh Dong Tran, Minh Nhat Ngo Nguyen, Nghien Xuan Ngo, Bich Thuy Thi Nguyen, Luyen Thi Nguyen, Canh Xuan Nguyen

  Received: Oct 19, 2018 / Accepted: Oct 22, 2018 / Published: Oct 22, 2018

   Abstract PDF

  In this study, an unknown mushroom species collected on rotting trunks of Ficus elastica in the Hanoi Botanical Garden was investigated. It was designated as Bt116. Based on the observed morphological characteristics, such as irregularly semi-circular, slightly yellow pileus; very soft, homogeneous, spongy, creamy white context; short and not clear stipes; and basidiospores typical of ganoderma mushrooms, etc., we hypothesized that Bt116 belongs to the Tomophagus Murr. mushroom genus. Some biological characteristics of the Bt116 strain were made. The results indicated that the temperature 35°C was optimal for Bt116 mycelial growth; an alkaline environment (pH 8.0) was conducive for the mycelial growth of Bt116 among a range of pH levels from 4.0 to 9.0; aerobic conditions were better than anaerobic conditions for the growth of Bt116 mycelium; and lighting time showed no significant effects on the growth of Bt116 mycelium.

• Investigating the Influence of Inorganic and Organic Fertilizers on the Growth and Yield of Three Varieties of Okra (Abelmoschus esculentus)

  Esiosa F. Adewale, Andrew A. Efisue, Caleb I. Adewale

  Received: Jun 09, 2024 / Accepted: Sep 24, 2024 / Published: Sep 30, 2024

   Abstract PDF

  Fertilizers play an important role in enhancing crop yield, growth, and fertility of the soil. This research was conducted at the Faculty of Agriculture teaching and research farm, University of Port Harcourt, Nigeria to investigate the influence of inorganic fertilizer (urea) and organic manure (spent mushroom substrate and poultry manure) on the yield and growth parameters of three okra cultivars (Clemson Spineless, Perkin Long Pod and the Local Assertion). The urea was applied at the rate of 4g per 10kg of soil, while spent mushroom substrate and poultry manure were applied at the rates of 200g and 150g per 10kg of soil respectively at 4 weeks after planting. The treatments were laid in a completely randomized design (CRD) with 3 replications. The results revealed that the okra cultivars responded positively to both organic manures when compared with urea and the control group where no fertilizer was applied. Furthermore, varieties grown with poultry manure generally had the highest fresh fruit weight, plant height, fruit length, number of fruits, and fresh fruit yield. Spent mushroom substrate influenced the number of fruits and fruit yield while urea influenced the leaf area, number of leaves, and leaf area index. Poultry manure was recorded as the best organic manure for okra growth and yield and is recommended to be used to grow okra plants. Also, the Perkin Long Pod variety is recommended to be the best for cultivation.

• Effects of Osmotic Stress Induced by Peg and NaCl on the Germination and Early Growth of Mung Bean

  Thang Ngoc Vu, Khuynh The Bui, Gioi Huy Dong, Tuan Anh Tran, Tuyet Cham Thi Le, Chinh Dinh Vu

  Received: Oct 15, 2018 / Accepted: Oct 19, 2018 / Published: Oct 22, 2018

   Abstract PDF

  This study was performed to evaluate the effects of osmotic stress (measured by different water potentials) induced by Polyethylene Glycol 6000 (PEG) and NaCl solutions at the germination stage of five mung bean varieties (DX11, DX208, DX14, DX17, and DX22). Five water potentials: 0 (control), -0.15, -0.49, -1.03, and -1.76 Mpa were used as treatments in this study. The germination rates, root and shoot lengths, root and shoot fresh weights, and dry weights of the plants were measured. The results showed that the germination rate of the mung bean varieties decreased with increased NaCl or PEG concentrations. The germination rates of the mung bean varieties in the PEG treatments were higher than those in the NaCl treatments. In addition, low water potentials induced by NaCl (-1.76 Mpa and -1.03 Mpa) inhibited germination and seeding growth of all the mung bean varieties. The growth parameters of the mung bean seedlings, such as root and shoot lengths, fresh weights of roots and shoots, and plant dry weights, were reduced under low water potentials treated with either PEG or NaCl. However, more severe damage in seedling growth was observed in the NaCl induced treatments. Amongst five mung bean varieties used in this study, DX17 was more drought and salt tolerant than the other mung bean varieties.

• Growth and Physiological Responses of Sugarcane to Drought Stress at an Early Growth Stage

  Bui The Khuynh, Vu Ngoc Thang, Vu Dinh Chinh, Pham Thi Thom

  Received: May 14, 2020 / Published: May 15, 2020

   Abstract PDF

  A pot experiment was conducted in a net house to evaluate the effects of drought stress (a 20-day water withholding treatment from 100-120 days after planting) on the growth and physiology of five sugarcane cultivars. The results showed that water stress at an early stage significantly affected sugarcane growth and physiology. Water stress resulted in reductions in plant height, stalk diameter, and leaf number of sugarcane, in addition to reductions in the photosynthetic pigment content, Fv/Fm, and SPAD (Soil Plant Analysis Development) readings after the 20-day withholding water period (120 DAP), and in stem, root, and leaf fresh weights, and leaf area at 150 DAP. Besides, drought stress led to increases in stomata density and decreases in stomata length. Variation was also found among the cultivars in response to water stress. Significant genotypic differences in stem fresh weight and leaf area under water stress among the cultivars were observed. The highest value of stem fresh weight under stressed conditions was recorded in ROC22 (50.6 g), followed by QĐ159 (46.5g), ROC16 (46.2g), ROC10 (46.1g), and VL06 (44.4g). However, the highest DTI was recorded in ROC16, followed by VL06, ROC10, QĐ93-159, and ROC22, respectively.

• Variations in Growth Performance and Nitrogen Uptake of Sugarcane Cultivars Under Rain-Fed Conditions

  Dinh Thai Hoang, Hiroo Takaragawa, Le Trong Lu, Eizo Taira, Yoshinobu Kawamitsu

  Received: Apr 03, 2020 / Published: Nov 27, 2020

   Abstract PDF

  The experiment was conducted to evaluate growth and nitrogen uptake of the twelve sugarcane varieties, viz. NiF3, NiF8, Ni9, Ni12, Ni15, Ni17, Ni21, Ni22, Ni25, Ni27, Ni28, and Ni29, under rain-fed conditions during the period from 70 to 160 days after transplanting (DAT) at the experimental field, Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan. The results showed that water shortage from a rain-fed condition caused reductions, but not significant in plant height and SPAD of sugarcane varieties. The genetic variation in leaf area, yield components, partial and total biomass, and cane yield was found among the investigated varieties. The positive associations between total nitrogen uptake with total biomass production and cane yield suggested that higher nitrogen uptake supports better growth performance of sugarcane under rain-fed conditions. From this study, NiF3 and Ni27 could be introduced as the promising sugarcane varieties for better growth performance and high nitrogen uptake under rain-fed conditions.

• Effects of Mineral Fertilizer Doses and Ratios on Tea Yield and Quality

  Tran Xuan Hoang, Vu Ngoc Thang, Dang Van Thu, Nguyen Ngoc Binh, Nguyen Van Toan, Dinh Thai Hoang

  Received: Oct 27, 2020 / Published: Aug 10, 2021

   Abstract PDF PDF

  Mineral nutrients are essential to plant growth and development. The present study aimed to evaluate the effects of mineral fertilizer doses and N:P:K ratio on growth, yield, and raw material quality of the tea variety PH10 to improve the production of high-quality tea products. The field experiment was conducted from 2015 to 2017. A two-factor experiment was designed by split-plot design with three replications. The mainplot treatments were three fertilizer doses of N  for one metric ton of fresh shoot products (30, 40, and 50 kg N ha-1). The subplot treatments were two NPK ratios (3:1:1 and 3:1:2). Plant height, leaf canopy, plant diameter, shoot yield parameters, shoot components, biochemical compounds, and sensory quality for Oolong and Sencha tea products were evaluated. The results showed that increasing fertilizer doses from 30 up to 40 kg N per ton of fresh product improved remarkably growth, yield, and tea quality of PH10 variety. Different fertilizer ratios resulted in variations in plant growth, the content of carbohydrate, sensory quality for taste and flavor as well as total sensory quality with higher values at NPK ratio of 3:1:2. Applying mineral fertilizer with an NPK ratio of 3:1:2 and 40kg N per ton of fresh shoot products was recommended to bring about the most benefits of tea yield and quality as well as economic profit.

• Impacts of Dietary Supplementation of Peptidoglycan Extracted from Lactobacillus sp. on the Growth Performance and Resistance to Streptococcus Agalactiae of Nile Tilapia

  Nguyen Thi Mai, Mai Van Tung, Do Hoanh Quan, Vu Thi Thanh Huong, Nguyen Thu Hang

  Received: Mar 14, 2023 / Published: Jun 30, 2023

   Abstract PDF

  The current experiment aimed to determine the effects of peptidoglycan, known as a prebiotic compound, on the growth, feed efficiency, and disease resistance in Nile tilapia. Fish at an initial body weight of 22.6 ± 0.3g were distributed into a 100 L-glass tank system. Peptidoglycans extracted from Lactobacillus sp. were added to commercial feed at ratios of 0, 5, and 10 g kg-1 diet corresponding to the PG0, PG5, and PG10 treatments, respectively. Fish were then fed at 4% their body weight for four weeks. After a 4-week trial, fish were infected with Streptococcus agalactiae at 50% the lethal dose (1.1×106 CFU mL-1), and monitored for 14 days. After 2 and 4 weeks of the feeding trial (T2 and T4) and on the second day of the bacterial challenge, fish blood samples were collected for hematological analysis. The results indicated that the dietary supplementation of peptidoglycan induced a positive effect on fish growth performance and the highest value was observed in the PG5 treatment. The lowest value of cumulative mortality was also observed in the PG5-fed fish indicating that the dietary supplementation at 5 g kg-1 diet supported the highest resistance to S. agalactiae. In conclusion, the beneficial effects of dietary supplementation of peptidoglycan extracted from Lactobacillus sp. were recorded on the growth performance and disease resistance in Nile tilapia.

• Reproductive Parameters and Larval Growth of Bighead Catfish (Clarias microcephalus Günther, 1864) from Wild and Cultured Broodstock Strains

  Tran Quoc Cuong, Duong Thuy Yen

  Received: Jul 17, 2020 / Published: Dec 31, 2021

   Abstract PDF

  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).

• Effects of Dietary Supplementation with a Mixed Powder of Medicinal Plants on the Growth Performance, Carcass Characteristics, Chemical Composition, and Meat Quality of Pigs

  Nguyen Cong Oanh, Nguyen Thi Huyen, Nguyen Dinh Tien, Vu Dinh Ton

  Received: Jun 17, 2021 / Published: Dec 31, 2021

   Abstract PDF

  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.

• The Impacts of Social and Economic Determinants on Poverty: An Empirical Study on Southeast Asia

  Nguyen Anh Tru

  Received: Sep 02, 2021 / Accepted: Jun 27, 2022 / Published: Jun 27, 2022

   Abstract PDF

  The article attempted to examine the influences of social and economic determinants on poverty in seven Southeast Asian countries, namely Lao PDR, Malaysia, Myanmar, the Philippines, Thailand, Timor-Leste, and Vietnam, between 1996 and 2013 using a panel dataset. It was empirically found that the average GDP per capita and Gini index contributed to poverty reduction in Southeast Asian countries. The results also addressed that the population and poverty gap had positive impacts on the rate of the poverty headcount in the region. Policies were recommended to accelerate economic growth, reduce poverty, and achieve sustainable development in Southeast Asia. First, economic growth should be fostered since it assists in reducing poverty in Southeast Asian countries. Second, although the growth of population provides the labor forces to the economy, population growth in Southeast Asia should be carefully controlled since it increases poverty in the region. Third, an increase in the number of rich inhabitants in the society should be encouraged because it can mitigate poverty in the region. Finally, policies in redistributing income as well as in narrowing down income inequality in each society should be considered by the governments because these contribute to poverty reduction in the region.

• Optimal Culture Conditions for the Enhanced Mycelial Growth and Cultivation of Shiitake Mushroom (Lentinula edodes)

  Nguyen Thi Huyen Trang, Nguyen Thi Bich Thuy, Nguyen Thi Mo, Nguyen Thi Luyen, Ngo Xuan Nghien

  Received: May 24, 2023 / Published: Dec 29, 2023

   Abstract PDF

  Lentinula edodes (Berk.) Pegler, commonly known as shiitake mushroom, is one of the most popular edible mushrooms with valuable medicinal properties. Despite its global popularity, the cultivation of shiitake in Vietnam has been limited due to a lack of research on this macrofungus. This study aimed to optimize the culture conditions for the mycelial growth and fruiting body development of two shiitake strains, J1 and J2. The culture conditions were optimized by one-factor-at-a-time method. A temperature of 25°C was found to be optimal for the growth of both strains, while glucose was identified as the most effective carbon source. Yeast extract and ammonium chloride (NH4Cl) were found to be the optimal nitrogen sources for favorable mycelial growth of strains J1 and J2, respectively. The most suitable spawning material for upscaling the mycelium was a mixture of 74% grain rice, 25% sawdust, and 1% CaCO3. Additionally, the cultivation of strain J2 on a mixture of 69% corncobs, 20% sawdust, 10% wheat bran, and 1% CaCO3 led to a higher biological yield (36.5%) than that of strain J1 (23.5%). These findings provide useful information for improving the cultivation technology of shiitake and expanding its cultivation in Vietnam.

• Determinants of Liquidity Risk in Vietnamese Commercial Banks

  Nguyen Thi Huong, Dang Thi Hai Yen

  Received: Dec 12, 2022 / Published: Mar 29, 2024

   Abstract PDF

  Liquidity risk, which tends to compound other risks such as credit and market risks, has become one of the principal risks in banks. Thus, this study examined the determinants of liquidity risk measured by the loan deposit ratio (LDR). The sample included 30 commercial banks in Vietnam based on secondary data coverage from 2017-2021. Descriptive statistics were used to determine the general situation of the banks' assets, liabilities, and business performance. The random effects model (REM) was chosen to determine factors affecting liquidity risk. The results show the huge gap in the business performance of the four state-owned banks and the rest of the joint-stock commercial banks, and the state-owned banks always accounted for over 50% of the total credit, assets, and deposits of the whole banking system. The average banks’ credit and profit growth rates were around 17% and 30%, respectively, and the bad debt ratio was about 2%. Increasing a bank’s credit growth rate and profitability would push up its liquidity risk. On the other hand, holding several liquid securities that banks could sell immediately to meet solvency requirements and maintaining a high capital adequacy ratio (CAR) would reduce their liquidity risk. These findings are valuable to the banks in understanding how to minimize liquidity risk, such as controlling the credit growth rate and CAR, setting appropriate profit targets, and investing in liquid securities. Additionally, by conducting monetary policies, the State Bank should regulate market liquidity and bank liquidity for the safe operation of the financial system.

• Effects of Calcium Levels in Artificial Pellet Feed on the Growth and Survival Rate of Black Apple Snails (Pila polita)

  Le Van Binh, Ngo Thi Thu Thao

  Received: Feb 13, 2019 / Published: Aug 30, 2019

   Abstract PDF

  The present study was conducted to evaluate the effects of different dietary calcium levels on the growth and survival rate of black apple snails (Pila polita) in the grow-out period. There were 3 replicates for each treatment and the snails were fed with five calcium levels (% dry matter) in diet as follows: 1% (Ca1), 3% (Ca3), 5% (Ca5), 7% (Ca7), and 9% (Ca9). Two-month-old juveniles with an average initial body weight of 2.13g, shell height of 21.71mm, and shell width of 16.35mm were reared in tarpaulin tanks (1 × 1 × 1m; 40cm water depth) at the density of 100 individuals per tank. After 4 months of the rearing period, the average body weight, shell height, and shell width of the snails reached the highest values in the Ca5 treatment (28.43 g, 54.97 mm, and 40.09mm, respectively) and these values were significantly different compared to the remaining calcium contents (Ca1, Ca3, Ca7, and Ca9). The survival rate of the snails in Ca3 (75.7%) was higher than in Ca1 and Ca7 (74.7%), Ca5 (73.7%), and Ca9 (71.7%). However, the survival rate was not significantly different among the treatments. Snails in Ca5 obtained the highest productivity (2.88 kg m-2) and this value was significantly different from Ca1 (2.55 kg m-2) and Ca9 (2.35 kg m-2). The results of this study showed that the growth rate and productivity of black apple snails were highest when they consumed a diet containing 5% calcium. The optimum requirement of calcium for the black apple snails in the grow-out period was 4.51%.

• Effects of Temperature on Population Growth and Resting Egg Production of Freshwater Rotifer (Brachionus calyciflorus)

  Doan Thi Nhinh, Pham Thi Lam Hong, Truong Dinh Hoai, Kim Van Van

  Received: Jun 10, 2020 / Published: Dec 31, 2020

   Abstract PDF

  Resting egg production of rotifers provides critical advantages in larviculture of most fish species due to the reduction in the costs of labour and algae production. The study was conducted to investigate the effects of temperature on population growth and resting egg production of a freshwater rotifer, Brachionus calyciflorus, collected in Northern Vietnam. The rotifer was pre-cultured at 27ºC before being transferred to the cultures at 15 and 35ºC while the control was maintained at 27ºC. One-liter beakers filled with 500mL culture medium were used with three replicates for each temperature group. Stock rotifers were inoculated at an initial density of 200 ind ml-1 and fed with concentrated fresh algae. The results indicated that population growth rate (r) of rotifers cultured at 27 and 35ºC were significantly higher than that of rotifers at 15ºC while the highest density was attained from the treatment of 27ºC, at 608.3 ind mL-1, compared to 468.3 and 360.5 ind mL-1 at 35 and 15ºC, respectively. Transferring the cultures from 27 to 35ºC significantly increased the rate of resting egg carrying females with the maximum rate of 31.5% compared to 21.2 and 13.5% of the rotifers at 27 and 15ºC, respectively. The resting egg densities of the cultures at 35ºC were also significantly higher than those at 15 and 27ºC. The resting egg carrying females appeared and increased their rates in concurrence with increases in the population density. The present results are important information for resting egg induction and production of rotifer in larviculture.