Vol. 20 No. 3 (2022)

In Vietnam, black rice varieties are being used as functional food for the improvement of human health. Breeding and selection of black rice varieties with early maturity, high yield, good quality, high anthocyanin content and low susceptibility to pests are of necessity. The present experiments were conducted to evaluate agronomical characteristics, yield and quality of some newly developed black rice lines at Crop Research and Development Institute, Vietnam National University of Agriculture. The SSR molecular markers were used to identifyied genes controlling anthocyanin content in black rice lines. Out of 25 inbred lines, there are seven promising lines havwere been selected, viz.as C1, C12, C14, C18, C19, C21 and C25 with a desirable desiredgrowth duration of 109-117 days,yield of 6.15-8.05 tons ha-1in the summer season, head rice ratio in the range of 74-80%, and grain length of 6.4-6.7mm. Out of 7 promising lines, only one elite line C1 was been selected. The new black rice line C1 that carries markers of Kala1, Kala3, and Kala4genes has an amylose content of 3.88% and, anthocyanin content of 619 mg/100g on dry matter basis. This suggested that SSR markers of Kala1, Kala3and Kala4genescould be used for making decision for selection of black rice genotypes with high anthocyanin content.

This study aimed to find out the most suitable artificial diets for rearing predatory mite Amblyseius swirskii Athias-Henriot. The experiment was conducted according to individual rearing method in an incubator at 27℃with four artificial diets, viz. TA1 as basic diet (containing sucrose, yeast extract, egg yolk powder, vitamins mix); TA2, basic diet supplemented with 20% black soldier fly pupal powder; TA3 and TA4, basic diet supplemented with 20% decapsulated and non-decapsulated TA4 of dry cysts of Artemia franciscana, respectively. The results showed that females of A. swirskii fed on TA2 and TA3 had the shortest life cycle (7.68 and 7.88 days, respectively), followed by those fed on TA4 (8.11 days) and the longest was those fed on TA1 (8.68 days).The total number of eggs laid by the females rearing on TA2, TA3 or TA4 was significantly higher than that of TA1. The intrinsic rate of increase (rm) of the females fed on TA2 (0.182), TA3 (0.176) and TA4 (0.174) were significantly higher than those fed on TA1 (0.151). In conclusion, the artificial diets TA2, TA3 and TA4 can be used in mass rearing A.swirskii, and can also be used as supplemental diets for supporting the mite population on crops in the absence or lack of prey.

Canine parvovirus (CPV) is a highly contagious viral disease that commonly causes acute gastrointestinal illness in dog breeds in Vietnam. We isolated and determined genotype and biological characteristics of CPV in the CRFK cell line. Three strains of CPV, VNUA.CPV.HN01, VNUA.CPV.HN04 and VNUA.CPV.HY05 in the CRFK cell line were isolated from 30 clinicalsamples. The phylogenetic analysis revealed that all CPVisolates belonged to the genotype CPV2c. CPV did not cause disease in the first passage but caused cytopathogenic effect in the CRFK cells after 2 to 4 blind passages. Cytopathic effect (CPE) occurred within 24 hours post-infection and the cells were completely destroyed after 60 to 72 hours of infection. CPE viral titer was high, at 107,47TCID50/ml. The growth curve reached the peak at 60 to 72 hours after infection and then decreased gradually.

Canine parvovirus (CPV) is a highly contagious viral disease that commonly causes acute gastrointestinal illness in dog breeds in Vietnam. We isolated and determined genotype and biological characteristics of CPV in the CRFK cell line. Three strains of CPV, VNUA.CPV.HN01, VNUA.CPV.HN04 and VNUA.CPV.HY05 in the CRFK cell line were isolated from 30 clinicalsamples. The phylogenetic analysis revealed that all CPVisolates belonged to the genotype CPV2c. CPV did not cause disease in the first passage but caused cytopathogenic effect in the CRFK cells after 2 to 4 blind passages. Cytopathic effect (CPE) occurred within 24 hours post-infection and the cells were completely destroyed after 60 to 72 hours of infection. CPE viral titer was high, at 107,47TCID50/ml. The growth curve reached the peak at 60 to 72 hours after infection and then decreased gradually.

The study was conducted to assess the status of seaweed resources distributing around Nam Du archipelago, Kien Hai district, Kien Giang province. In four trips in three years from 2017 to 2019, using the field survey method of deep diving with SCUBA, combined with sampling, the research team identified 96 seaweed species belonging to 51 genera, 35 families, 20 orders of 4 seaweed phyla. Our results also recorded 1 seaweed species (Tubinaria decurrens) belonging to the list of endangered, precious and rare species that needs priority protection in the Vietnam Red Book (2007). The average coverage at the survey stations was 17.0 ± 3.8% and average biomass weas 1,946 ± 217 g/m2. The fresh seaweed resources were estimated at 1,751 ± 195 tons on 90 hectares around the archipelago. Some seaweed genera were predominant on the island, such as Turbinaria, Sargassum, Padina, Palisada etc. The results provide an essential scientific basis for the development orientation and management of seaweed resources in the coastal region around Nam Du archipelago, Kien Giang province.

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The study aimed to indentify the proper substitution ratio of chemical fertilizers with microbial organic fertilizer pellets obtained from composted chicken manure for improving fruit yield and fruit quality of 5-6 years - Suu pomelo in Doan Hung, Phu Tho province. The treatments consisted of the following: control treatment (the chemical fertilizer dose conventionally used by farmers’) (1.5kg NPK (5:10:3) + 1.75kg NPK(12:5:7) + 0.5kg K2SO4/plant/year) and the substitution of 25%, 50%,70% and 100% chemical fertilizer with microbial organic fertilizer pellets in such a way to ensure equal N supply in each treatment. The results showed that the substitutions of 25% and 50% chemical fertilizers with microbial organic fertilizer pellets stabilized soil pH, increased the contents of soil nitrogen, phosphorus and potassium and significantly increased fruit yield as compared to chemical fertilizer application. Substitution with 50% microbial organic fertilizer pellets gave the highest fruit yield with 25.61 tons/ha and economic profit with VND568.95 milion per ha, increased by 148.49 million VND/ha compared to the control. Application of microbial organic fertilizer pellets along with chemical fertilizer led to the increase of fruit quality. The substitution of chemical fertilizer with 50% and 100% microbial organic fertilizer pellets statistically increased total sugar, vitamin C and dry matter in fruits as compared to application of chemical fertilizer.

This study was conducted to assessthe actual status of forestry production of the households in the Central Highlands of Vietnam. Results fromface-to-face interviews with 175 households using semi-structured questionnaires and in-depth interviews with 28 officials indicated that the systems mixed forest trees + industrial plants +/and fruit trees weremost commonly applied in the Central Highlands. Components of timber trees planted in their land use patterns were fairly diverse (23 main species), in which Litsea glutinosa, Cassiasiamea, Ceiba pentandra, and Macadamia integrifolia were the dominant forest trees. However, a lack of arablelandand finance to maintain the area of tree planting and lower economic efficiency from forest trees compared with different plantswere considered as the limitations for the expansion of tree planting area of ethnic minority households in the Central Highlands. The households tended to prioritize the selection of the multifunctional trees in their land use patterns.

This study aimed to determine the suitable culture conditions for the production of pigments and monacolin K from mold Monascus purpureus NBRC 4485. The growth and production of pigments and monacolin K of M. purpureusNBRC 4485 were tested in various substrates including red rice, purple rice, wholegrain white rice, white rice, Japanese rice, corn, and soybean. The appropriate conditions of solid-state fermentation for pigments and monacolin K production from M. purpureusNBRC 4485 were investigated through determination of the following solid-state fermentaion factors: initial moisture content of cultural medium (30, 40, 50, 60, 70% w/v), the density of inoculum mold (104, 105, 106spores/g), and incubation time (8 to 24 days). The results show that the wholegrain white rice was considered as the most appropriate substrate among tested substrates. The highest contents of yellow pigment, red pigment, and monacolin K were obtained at 3,057.8 AU/g, 1,781.0 AU/g, and 1,329.3µg/g, respectively. The most suitable conditions to produce pigments and monacolin K from M. purpureusNBRC 4485 on wholegrain white rice were the moisture content of 40% w/w, mold density of 106spores/g, and incubation time of 22 days. The contents of yellow pigment, red pigment, and monacolin K were 6.750,2 AU/g, 4.960,9 AU/g, and 2.089,3 µg/g, respectively.

Treatment of aquaculture wastewater by biological method is being more attractive to the scientists. This study aimed to screen the salt-tolerant and ammonia-oxidizing Bacillusendophytic bacteria having potential to reduce ammonium levels in shrimp aquaculture wastewater. In this study, eight Bacillusstrains were screened from endophytic bacteria isolated from gooose grass. Among these strains, two strains, MT50 and MT51 showed the highest efficiency for ammonium removal (80.36 and 82.24%, respectively). They optimally grew at pH of 7 and in highly salty condition (4% NaCl). Investigation in laboratory conditions for their ability in improving shrimp aquaculture wastewater showed that both Bacillusstrains had ammonium removal from 72.25 and 78.85% at day 7th. Notably, strain MT50 in combination with unsterilized shrimp-wastewater presented the highest ammonium removal efficiency (79.91%) with 1% cell suspension at day 4th. The results also showed the nitrite and nitrate production in all experiments and these compounds were removed by the selected Bacillusspecies. Results suggested that tưo Bacillussp. isolated might be used as heterotrophic nitrification-aerobic denitrification species.

This study was carried out to identify lactic bacteria producing bacteriocin potentially as supplement in the aquaculture feeds to replace the antibiotics. Combining methods of spreading and observing morphological characteristics of the colony on MRS medium, 16 strains of lactic acid bacteria were isolated from 18 fish gut samples collected at different locations. Among these, 8 strains were able to produce bacteriocin showing antibacterial activity against Salmonellasp. and Escherichia coli. The strain HN1 isolated from Tilapiagut samples collected in Hanoi had the most vital bacteriocin - producing ability and exhibited strong antibacterial activity simultaneously against Salmonellasp. and Escherichia coliwith antibacterial ring diameters of 16mm and 15mm, respectively. On MRS medium supplemented with 3% glucose as a carbon source and 3% yeast extract as a nitrogen source, the strain HN1 was able to grow and produce the highest amount of bacteriocin. The combination of morphological, physiological, biochemical characteristics and analysis of molecular biological sequences has identified the strain HN1 as Enterococcus faecium.

Research was performed to select soil bacteria showing degradation of chlorpyrifos and producing antifungal activities. Strain BPTC-316 had the highest biological activity among 32 potential isolates using selective medium, culture characteristics and 16S rRNA gene sequence analysis. The strain BPTC-316 showed the closest similarity of 99.78% to Rhodococcus tukisamuensisJCM 11308T(AB067734) based on analysis of 16S rRNA gene sequence. BPTC-316 was able to degrade 96.8% chlorpyrifos after 10 days of incubation. In addition, the crude bioactive compound extracted from strain BPTC-316 was able to inhibit growth of Fusarium oxysporumKACC 41083 and Phytophthora capsiciKACC 40483 with antifungal diameters of 17.6 and 16.8mm, respectively.

The purpose of the study was to determine the factors influencing the labours’ satisfaction when they participate in the labor export program and make decision to accept or not accept again a new labor export contract. Applying the JDI model and prior researches' results as background, the research identifed the factors relating to labour’s satisfaction with 20 criteria classified into 5 groups, i.e application procedures, training, working conditions, income and specific job position. The survey was conducted on 164 labors in Hai Duong province who had been or being participants of the labor export service to Japan. Results showed that income was the largest impact factor of satisfaction, followed by the job position and working condition.

The study uses a binary regression model, rational action (TRA) theory, and the theory of intentional behavior (TPB). The study's objectives are to determine the factors affecting the intention to choose the farming model of crab - shrimp - rice of farmers in Kien Giang province. The results of the analysis of 102 extensive crab-shrimp-rice farming households showed that male respondents accounted for 82.4%, the average age of the household head was 51 years old, the average education level of the household head was 7th grade. The average number of years of experience of the household head was 10 years, the average area of the household was 2.8 ha. The results of binary regression analysis showed that 9 variables (education, training, experience, area, salinity, increased profit, model fit, impact of people around, and model implementation ease) influenced the intention to choose the farming model of crab-shrimp-rice of farmers. From the research results, the following solutions were proposed: Farmers’ management of all kinds of risks during the productionand consumption of shrimp and rice,regular monitoring of weather/environmental studies or forecasts,selection of seed sources and inputs (feed, lime, antibiotics) from reputable establishments,participating in local trainingandsqueezing the shrimp back before putting them in the pond.

Dogs and cats are two types of domesticated animals that have been close to humans since ancient times. They are kept for house keeping, hunting, and entertainment (racing) purposes and are increasingly popular as pets. Viet Nam currently has more than 5 million families raising more than 7.5 million cats and dogs, equal to the number of largeruminants in the country. As pets, so their owners pay more attention to optimize nutrients to ensure good health (ideal body condition, neither obese nor rather thin) rather than maximize nutrients. The objective of this paper was to review the basic nutrient requirements of cats and dogs based on recommendations of NRC (2006), AAFCO (2014) and FEDIAF (2017) and some other studies.Dogs and cats are both carnivores, their energy requirements are higher than that of other livestock (4,000 kcal metabolizable energy/kg feed).The crudeprotein requirements of dogs are lower (18-23%) than those of cats (20-33%), but these are also higher than those of cattle and pigsor poultry, and the requirement for some nutrients is also very different from that of traditional livestock.