Vol. 20 No. 12 (2022)

The study aimed to evaluate the growth, yield, and seed quality of introduced sunflower cultivars in 2021 spring cropping seasonat Gia Lam, Hanoi. Six sunflower cultivars, Yuyoo (G1), Harutin 20 (G2), Roshia (G3), Kizzu Sumairu (G4), Yuyoo 3 (G5), and a hybrid(G6) were evaluated in a randomized complete block design with three replications. The results showed that the growth duration of the cultivars ranged from 89 to 111 days, classifying into two groups, early maturing (G1, G2, and G3) and medium maturing (G4, G5, and G6). There were significant differences among accessions on growth, physiological parameters, yield components, yields, and nutrient content in seeds. Among the cultivars evaluated, G3 had the highest yield (3.42 tonnes/ha) with low oil content (19.0%) suitable for snack consumption. G5 with a high yield (2.57 tonnes/ha) and high oil content (40.6%) is appropriate for oilseed production.

The fall armyworm Spodoptera frugiperda(J. E. Smith) (Lepidoptera: Noctuidae) is a serious polyphagous insect pest native to the Americas. The objective of the present study was to determine the effect of temperature on developmental time and oviposition of fall armyworm in Vietnam. Fall armyworm was reared individually in incubators at different temperatures (20, 25, 27.5, 30, and 33C), 75-85% RH, and12L:12D photoperiod with maize leaves (variety HN88) at 3-5 leaf stage as food. The life cycle of the fall armyworm at temperatures of 20, 25, 27.5, 30 and 33C was 50.56, 36.92, 31.91, 24.28 and 22.28 days, respectively. The total number of eggs laid by a female at temperatures 20, 25, 27.5, 30 and 33C was 1,119;1,020;1,152;1,168 and 778 eggs, respectively. The lower threshold temperature for development of egg, larvae, and pupae was 11.14C, 12.47C, and 13.59C, respectively. The thermal constant (K) for egg, larvae and pupae development was 42.7, 200.71 and 129.65 degree day, respectively. The degree-day required for egg-to-adult development of fall armyworm was 383.67.

Lactic acid bacteria play an important role in the production of fermentedfoods. This study aimed to isolate and select lactic acid bacteria strains from fermented products for application in the production of ginger-based probiotic drinks. Fourty sixstrains of bacteria were isolated. The isolates producedcolonies with 1.0 to 1.5mm in diameter, mainly round, glossy, milky white, and floating pellicle in liquid culture. Six gram-positive, catalase-negativestrains withrod orspherical shaped cellswere pre-selected. Identification by MALDI-TOF revealedthat theybelongto 4 speciesof Enterococcus faecium, Enterococcus casseliflavus, Lactobacillus fermentumand Lactobacillus plantarum. Furtherstudy was conducted for the strain L.plantarumSM1.3. Itwas tolerantto acid(pH 1.0-3.0)and 0.3%bile salts,and ableto produce amylase, protease, and cellulase. This strain inhibited two tested bacteria,E. coliand Salmonellasp.Gene alignment results indicated that the strain SM1.2 belongedto Limosilactobacillus fermentumspecies and strain SM1.3 namedLactiplantibacillus plantarum.Ginger-based probiotic drink usingL. plantarumSM1.3 has good sensory quality andbacterial density and can be stored up to 5 days at 4C.

Anthracnose caused by Collectotrichumspp is one of the most common postharvest diseases of dragon fruit. In this study, 56 strains of Streptomycesspp. were used to evaluate the antifungal ability agaisnt C. acutatumC1. Preliminary screening results using streak culture method showed that 33 strains had no antifungal activity, 17 strains showed weak effect, and 6 strain had strong resistance. Notably, the strain NARZ showed the strongest inhibition and was identified based on its 16S rRNA gene as Streptomyces murinus. Cell-free supernatant of Strep. murinus prevented the growth of C. acutatumC1 on PDA medium. Concentration of 28.89% had the ability to inhibit at least 50% of the growth of C. acutatumC1. Thus, Strep. murinusNARZ could have potential application in anthracnose control for postharvest dragon fruit.

The objective of this study was to select bacterial strains with strong nitrogen fixation and IAA biosynthesis ability. Five strains with both activities were selected from 32 tomato soil samples collected in Thai Nguyen province. The strain MN26 was selected for its strongest nitrogen fixation and IAA biosynthetic activity, corresponding to 20.82 µg/ml NH4+when grown on Ashby medium and 77.23 µg/ml IAA on Ashby medium supplemented with 0.1% L-Tryptophan. Based on 16S rRNA gene sequence analysis data and phylogenetic tree, the strain MN26 could be considered as a new species candidate belonging to the genus Flavobacteriumwith scientific name as Flavobacteriumsp. MN26. Results of culture characterization showed that Flavobacteriumsp. MN26 was capable of producing 8 enzymes (phosphatase alcaline, leucine arylamidase, valine arylamidase, trypsine, phosphatase acid, naphtol-AS-BI-phosphohydrolase, -galactosidase, and D-glucosidase) and capable of assimilation of various carbon sources including D-glucose, L-arabinose, D-mannose, D-mannitol, D-maltose, L-rhamnose, D-ribose, inositol, D-saccharose, N-acetyl-glucosamine, malic acid, phenylacetic acid, potassium gluconate, sodium acetate and trisodium citrate. The strain MN26 was capable of producing indole but incapable of converting nitrate to nitrite.

The purpose of this study is to create a variety of soy food products. This research supplemented Lactobacillusprobiotic to produce probiotic soymilk yoghurt. Using culture method to determine the density of cells, the soymilk fermentation capacity of 3 Lactobacillusprobiotic strains, Lactobacillus plantarumD4.3, Lactobacillus pentosusD4.10, and Lactobacillus fermentumD5.5 isolated from traditional fermented foods was investigated. The results showed that Lactobacillus plantarumD4.3 0.02% (v/v) with cell concentration 1010 CFU/ml after 6 hours of fermentation yielded the highest cell density 105 CFU/ml. This strainwas able to adapt to soy milk environment. Preliminary applicationofthis strain for soymilk fermentation and determination of pH, acidity, cells density and sensory evaluation indicated that Lactobacillus plantarumD4.3 with 0.5% (v/v) with cell concentration 1010 CFU/ml at fermented time 12h was suitable for soymilk yoghurt. The sensory qualityandconcentration of probiotic bacteria with 108CFU/ml of this product were kept after 15 days preserved at 4-6C.

The objective of this study was to immobilize Virgibacillus campisalisTT8.5 bacterial cells on a carrier in order to degrade histamine content in traditional fish sauce. Three immobilization techniques, adsorption, encapsulation and crosslinking with nine carriers were used. Factors affecting the immobilization process of bacteria on carrier such as cells/carrier (w/w) ratio, time and temperature of immobilization, salt concentration in buffer solution (%) and stirring speed (rpm) were investigated. The cell immobilization efficiency (%) and the ability to degrade histamine after 2 hours of reaction (%) of Virgibacillus campisalisTT8.5 were evaluated. Results indicate that, the adsorption technique with pig bone as carrier gave the highest immobilization efficiency and histamine degrading ability with 54.18% and 41.30% respectively. Suitable conditions for immobilization of Virgibacillus campisalisTT8.5 cells on pig bone were determined as follows: cell/carrier ratio 1/15 (w/w), stirring speed of 100 rpm, salt concentration of 15%, incubation time of 1 hour at 4C. The fixed bed bioreactor containing immobilized V. campisalisTT8.5 bacterial cells has potential application in histamine degradation in traditional fish sauce with efficiency of 37.1%.

This study evaluated the influence of some fermentation conditions on the biosynthesis of α-glucosidase inhibitors (AGIs) of AspergillusoryzaeT6 (A. oryzae T6) cultured on semi-solid medium from black beans in the production of health-protective foods for people with high blood glucose and overweight. By determining the inhibitory activity of α-glucosidas the results showed that the biosynthesis of AGIs on semi-solid medium from black beans (Vigna cylindrica Skeels) gave the best effect in terms of the thickness of the fermentation medium block (24cm). The periodic agitation of the semi-solid medium from black beans during fermentation was every 12 hours; humidity of semi-solid medium from black beans for fermentation was 55% and fermentation time was 56 hours. The resulting AGIs products with IC50of 0.202 ± 0.006 mg/ml were applied to food production to help stabilize blood glucose in people with high blood sugar and overweight.

Endophytic bacteria living in the plant tissues support plant growth by synthesizing IAA and siderophore, inorganic soluble phosphate, and increasing disease resistance of the host plants. This study aimed to evaluate the effects of carbon and nitrogen sources, pH, temperature, and time of incubation on the concentration of IAA synthesized by two endophytic bacterial strains, HY9 and TT3, isolated from Lonicera japonica. Under various suitable culture conditions, maximum IAA of HY9 and TT3 strains was produced at pH=7 (42.9 µg/ml and 49.07 µg/ml, respectively), 35C (53.49 µg/ml and 56.73 µg/ml), and 4 days of incubation (51.47 µg/ml and 53.76 µg/ml). The suitable carbon and nitrogen sources were saccharose and NH4Cl. Comparing the nucleotide sequence of 16S rRNA of TT3 strain with nucleotide sequences of 16S rRNA of other bacterial strains on GenBank revealedthat TT3 strain had a very closed relationship with Klebsiella variicola strain 1, thus,strain TT3 was named Klebsiella variicola TT3.

The objective in this study was to determine the optimal nutrient environment and culture conditions for mycelial growth of mutated strain DTL1,25 of Lingzhi (Ganoderma lucidum). Each treatment was randommized complete block design andreplicated three times. The results of the experiment indicated that in the first stage of propagation, the optimal medium for mycelial growth was the background medium from the extract of 200g barley seeds supplemented with 2% glucose, 0.1% malt extract and 2% agar with medium pH of 6 and temperature at 26 ± 1C. In the second stage of propagation, mycelium growth of the mutant strain DTL1,25 was improved on environment consisting of 99% rice grain + 1% CaCO3with autoclaving mode at 121C for 120 minutes. At the third stage, the optimal composition included 99% rice grain + 1% CaCO3with autoclaving mode at 121C for 150 minutes.

Peanut production has been facing many difficulties due to the increasing incidence of Sclerotinia stem rot disease caused by Sclerotium rolfsiibut there is still no effective solution to deal with this disease. Therefore, this study was conducted to determine the biological characteristics of S. rolfsii, thereby orienting measures tocontrol the disease more effectively. From 10 peanut samples showing stem rot symptoms collected from Thai Binh and Nam Dinh provinces, by inoculating method on PDA medium combined with artificial infection method on peanut plant, 6 fungal strains were determined capable of causing disease, in which LT1 and LN1 expressed the strongest pathogenicity. They were identified as S. rolfsiiisolate LT1 and S. rolfsiistrain LN1, respectively. Two isolates were in the same mycelial compatibility group. Specifically, they grew and formed sclerotia well in PDA medium at 30oC and pH: 5,0-6,0. Simultaneously, on the PDA medium, the colonies of LT1 and LN1 showed maximum growth (>90 mm) after 3 days of culture. Their aerial mycelium was white and abundant. Their sclerotia were formed after 4-5 days of culture and turned brown after 6-7 days with 921 sclerotia (LT1) and 420 sclerotia (LN1). Both of them produced acid to reduce pH of the culture medium sharply and produced extracellular enzymes.

Today, most of the users of mobile devices are regularly bothered by a large number of scam messages, advertising messages in different fields such as entertainment, shopping, finance, and real estate. Among these, each SMS message can belong to one or more different message types at the same time. Therefore, using single-label classification methods to classify messages would be inappropriate. In this study, we have summarized multi-label classification techniques, collected a dataset of 2,000 Vietnamese SMS messages (SMSVN), and improved the accuracy of the methods for multi-label classification by using the preprocessing techniques to normalize and clean data. Moreover, we have also applied the well-known multiple classifiers to test classification on this dataset. The results show that, after applying the preprocessing techniques, most of the multi-label classification techniques had higher accuracy and lower classification error. The Classifier Chains technique using Naïve Bayes model was suitable for the Vietnamese SMS data classification issues.

The purpose of this research was to analyze the factors influencing the level of cooperation in the cold supply chain of lychee in Thanh Ha district, Hai Duong province. The research consisted of a combination of quantitative and qualitative analysis for a more in depth and detailed view. Thequantitative studywas conducted with 230 samples based on direct interview of the chain participants. The collected data were analyzed using regression to evaluate the factors influencing the degree of lychee cold chain cooperation. The qualitative research was conducted with in-depth interviews with 15 samples and analyzed using ATLAS.ti 9 software. The results show that six factors had positive influence, among these trust(0.309), price policy(0.231)and sharing information showed a great influence on the level of cooperation. The research proposed solutions to enhance cooperation and improve the efficiency in cold supply chain of Thanh Ha lychee