Vol. 19 No. 2 (2021)

Thepurposeofthisstudywastodeterminethepropercombinationofchemicalandorganicfertilizersforimprovingtheyieldandqualityoforange.ThesubstitutionsofchemicalfertilizerbyorganicfertilizerwereappliedforSanhorange7-8yearsoldinBacQuang-HaGiangandCS1orange5-6yearsoldinCaoPhong-HoaBinh.Theexperimentsincluded4treatments,inwhichthecontrolapplied100%chemicalfertilizerasthelocalfarmerused.Intheotherthreetreatments,thechemicalfertilizerwassubstituted25%,50%and75%withorganicfertilizers.TotalN,P2O5andK2O/haofalltreatmentswereequal.Indetail,thecontrolofSanhorangeinBacQuang-HaGiangwasapplied390kgN+ 350kgP2O5+ 440kgK2O/ha;thecontrolofCS1orangeinCaoPhong-HoaBinhwasapplied300kgN+ 300kgP2O5+ 356kgK2O/ha.Theresultsindicatedthatthesubstitutionof25%ofchemicalfertilizerbyacommercialorganicfertilizerincreasedtheyield.Theaverageyieldoftwoyearswas34.2ton/haofSanhorangeand15.8ton/haofCS1orange.Thereplacementofchemicalfertilizerbyorganicfertilizerhasimprovedcarotenoid,totalsugarcontentbutitreducedvitaminC.Inaddition,soilpHrose0.2-0.3whileapplying25-75%oforganicfertilizer;OMandNmineralcontentsoftreatmentwith75%organicfertilizerincreased0.4-0.5%and3.7mg/100grespectively,inBacQuang-HaGiang.pHofsoilincreased0.1-0.7inCaoPhong-HoaBinhcomparedtocontrol.

Acollectionof102VietnameseIndicatraditionalricevarietieswere screenedfordroughttoleranceduringthevegetativestagetoselectgenotypeswithhighdroughttoleranceforricebreedingprogram.Underthegreenhouseconditions,six-week-oldplantsweredroughttreatedbystoppingirrigationfor4weeks.Aftereachweekofdroughtstress,leafrelativewatercontent,slopeofleafrelativewatercontentanddroughttolerancescoreweremeasured.Theleafrelativewatercontentremainedhighafteroneweekofdroughtstress,significantlydroppedafter2weeks,slightlydecreasedafter3weeksanddisplayedavaluelessthan23.5%after4weeks.Theslopeofleafrelativewatercontentwasstronglyreducedatthesecondandfourthweeksofdroughttreatment.Afteroneweekofdroughtstress,mostofthegenotypesweretoleranttohighlytolerant.Thelevelofdroughttolerancedippedafter2and3weeksofstress,andnogenotypewithtolerancewasobservedafter4weeksofstress.After2weeksofplantrewatering,therecoveryabilityrangedfrom0-85.2%.Basedontheresultsobtained,13highlypromisingricegenotypeswereselectedforplantwaterstatus,droughttoleranceandrecoveryability,amongthem,G42,G115andG163wereconsideredasthemostpromisingtoleranttodrought.

Dysosmatonkinense(Gagnep.)M.Hiroe- Berberidaceaeisapreciousmedicinalplantspecies.Duetolowregenerationabilityandover-exploitation,ithasbeenclassifiedas“Endangered(EN)species”ontheVietnamRedListandrequiredfurtherstudyfortheconservation,suitableexploitationanddevelopmentofthisgeneticresource.Thisstudyaimstoidentifythemorphologicalandanatomicalcharacteristics,especiallythoseofflowersandroots;andevaluatedthesexualandasexualpropagationofD.tonkinense.Theresultsshowedthatflowerswerehermaphroditewith6-7(8)calyxs,6-7(8)corollas,6stamens,andapistil.Seedshadathickcoatandshorttimedormancy.Thehighestgerminationpercentage(84.4%)andrateofstandardseedlingswereobtainedintheBQ0treatment(sowingseedsafterharvesting).TheanatomyofD.tonkinenseroottransversesectionincludedtheepidermis,cortex(parenchyma),endodermis,pericycle,vascularbundlesandpith.Adventitiousshootsoriginatedfromacelllayerofrootpericycle.ThesuitabletimetocuttingrootswasMay15thwith81.3%ofcuttingswereestablishedafter200days.ApplicationofGA3attheconcentrationbetween100ppmto175ppmreducedtimingforcuttingto150-190daysandimprovedcuttingqualitywith86.9%to89.5%reachedoutplantingstandards.

Thequalityofseedisoneoftheimportantfactorsaffectingthegerminationprocessandseedlingformationrate.Thisworkwas toinvestigatethevariationofseedsize-relatedparametersandthe relationshipbetweenseedweightandgerminationcapacityaswellasstudyingthestructure,developmentoftheembryoandseedgerminationinNgocLinhginseng.Atotalof2,000NgocLinhginsengseedsfrom6yearoldplantsgrowingunderforestcanopyinKonTumprovincewereincludedinthisstudy.Researchresultsdetermineddistributionforthefrequencyofseedweight,length,widthandthickness.A significantpositivelinearrelationshipwasobservedbetweenseedweightandlength,widthandweight.Theseedweightsignificantlyaffecteddehiscencespeedandgerminationratebutdidnotaffectthe dehiscencerate.Thehighestgermination(96.17±3.62%)wasdetectedinseedstreatedwitha weight≥50mg.Theembryointhe freshlyharvestedseedofNgocLinhginsengisnotfullydevelopedandhas anaveragelengthof0.81±0.08mm.During60daysofstratification,cotyledons,hypocotyls,radicles,andepicotylsbecomevisibleandtheembryoscontinuetodevelopandreachalengthof7.05±0.95mm.The seedofNgocLinhginsengishypogealgermination.

ThemajoraimofthisworkwastoproducepolyclonalantibodiesfordiagnosisofPassifloramottlevirus(PaMoV),aputativenovelpotyvirus(thegenusPotyvirus,thefamilyPotyviridae),whichwasfirstdiscoveredfrompassionfruit(Passifloraedulis)andnamedinVietnam.Theentiregeneencodingcoatprotein(CP)ofPaMoVwasclonedonpET28avectorandtheexpressionofthisproteinwasevaluatedintheEscherichiacoli(E.coli)strainRosetta(DE3).ThedenaturedrecombinantPaMoVCPproteinwasusedasan antigenforrabbitinjection.ThetiterandspecificityoftherabbitantiserumwereevaluatedbyDot-ImmunobindingAssay(DIBA)andPlateTrappedAntigenEnzyme-LinkedImmunosorbentAssay(PTA-ELISA).Theexperimental resultsshowed: (i) Rosetta(DE3)wasasuitablehoststrainforexpressionofthePaMoVCPprotein, (ii) thePaMoV CP antiserumdidnotreactwithhealthypassionfruitsapanddetected easily cognate inpassionfruitleaves, and (iii) the antiserumalsoreactedwithtwopotyviruses,Telosmamosaicvirus(TelMV)andEastAsianpassifloravirusstrainIB(EAPV-IB),bothareinfectingpassionfruitinVietnam.

ThisstudywasconductedtodeterminethetransmissionmannersofSriLankancassavamosaicvirus(SLCMV)causing cassavamosaicdisease(CMD).Thepupaofwhitefly (Bemisia tabaci) was collectedfromthefieldand and lettodeveloptoadultsonthedisease-freecassava plantsin the pots.Thedisease-freeadultwhiteflieswereisolatedinacagefortwo months toobtain anon-viruliferouscolonyofwhitefliesfor the inoculation experiment.Thenumberofwhitefliesintroducedindisease-freecassavawas 5,10and20andthefeedingperiod(inoculation)ondisease-freecassavawas2,6,12and24hrs.Thiswasreplicatedforthreetimesand 10 plant/replication.To identify the transmission manner via cuttings, cuttings from symptomatic and asymptomatic plants of KM94,HL-S11and KM419planted in Dong Nai province were grown in insect resistant cages and caculate the number of diseased plants. The results indicated that viruliferousB.tabaciadultstransmittedSLCMVwithvariousdegreesofefficiencydependingonthenumberofadultsusedtotransmitandfeeding duration. The disease incidence ranged from 25.0-90.0%. Symptoms started from the top leaves. The latent period ranged from 20 to 25 days.After20-30daysofplantingtheCMD-infectedKM94,HL-S11andKM419varieties,itbegantoshowtypicalsymptomsofCMDwithleafcurl,wrinkling,mosaicandinconsistentwithdiseaserateof100%;meanwhile,inthecontroltreatmentthatusinghealthycuttingsfromthesamevarietiesshowednosymptoms.AllthetestedplantsweresubjectedtoPCRanalysisusingprimerpairSLCMV-A-F1/SLCMV-A-R2,directsequencingandDNAanalysis.TheallsymptomaticplantswerepositivewithSLCMV.ThestudyhasprovidedessentialinformationonthetransmissionofSLCMVviaeitherplantingmaterialsorthewhiteflyvectorthatwillhelptounderstandthespreadofSLCMVinthefieldandfacilitatethepredictionofvirusepidemicsinVietNam.

The objective of this study was to assess the growth rate of some rotifer species and possibility to use them as live food for nursing of striped catfish (Pangasianodon hypophthalmus) fry. Three species of freshwater rotifers including Brachionus angularis, B. palaand B. calycifloruswas mass-reared and compared to brackish species B. plicatiscurrently used as live food for striped catfish fry in the Mekong delta. Then, these four rotifer species were used as feed for striped catfish fries within the first three days, followed by Moina used until the end of the experiment. The population of B. palaand B. calyciflorusattained its maximum density (increased 03 times) for day 03 and 04, respectively. Meanwhile, B. angularisandB. plicatilisreached its maximum density (increased 06 times) for day 07 and 09, respectively. The results on fish study showed that the highest survival was obtained (24.1%) in B. angularisfed fish, whereas the lowest survival was obtained in B. calyciflorusfed fish. The weight of B. angularis fed fish was significantly higher than B. calyciflorusfed fish, but the difference was not significant compared to B. plicatilisor B. palafed fish. The results of this study indicated that B. angularisis the optimal live food for striped catfish fry.

Porcine epidemic diarrhea (PED) is caused by the PED virus (PEDV), which is characterized by enteritis, vomiting, and watery diarrhea. The study was conducted a retrospective investigation of 63 small-scale farms, including 31 case farms and 32 control farms by a case-control study with a questionnaire including risk factors that could play a role in the spreading of PEDV. Thirteen risk factors as 13 independent variables included in the univariate analysis; there were 11 factors related to PEDV status at the P level less than 0.1. Only 3 of 11 risk factors remained in the multivariate regression model including a history of PED within 2 years; near residential areas and near to irrigation system were significantly associated with the spread of PEDV among small-scale pig farms (P

The purpose of this study was to detect anti-Toxocara spp. and Ascaris suum antibodies in freely raised chickens. Two hundred and fifty-one serum samples were collected at the fresh market (Trau Quy, Gia Lam, Ha Noi) and some small-scale free-range chicken farms (Bac Giang Province). Indirect ELISA was applied using As-SWAP crude antigen to screen and choose serum samples which showed positive reactions with anti-ascarid antibodies and using Tci-ES and Asm-ES antigens to discriminate infecting species. Next, Toxocara Western Blotting Kit was applied to confirm Toxocara infection, and pre-adsorbed ELISA was conducted to confirm A. suum infection. The results showed that: 38.65% of serum samples contained anti-ascarid antibodies. Additionally, the result of discrimination of infecting species assumed that 11.55% and 2.79% samples containing anti-Toxcocara spp. and anti-A. suum antibodies, respectively. This is the first study to detect Toxocara spp. and A. suum in naturally infected free-range chickens. The attained results of this study provides important information for chicken farmers in protecting themselves in order to avoid exposure to ascarid egg-contaminated soil. Besides, it gives evidence of the risk of getting A. suum infection in humans in Vietnam.

The study was conducted at animal farm of Faculty of Animal Science, Vietnam National University of Agriculture from October 2018 to November 2019 to evaluate growth performance, feed conversion ratio (FCR) and carcass characteristics. A total of 10 barrows and 8 gilts of crossbred F1 (Wild × Meishan) pigs were used for measurement of growth performance, feed conversion ratio (FCR) and carcass characteristics. The pig was individually notched by ear tag and kept separately by gender including 5 barrows per case and 4 gilts per case. The results showed that the average daily gain (ADG) and percentage of lean meat of crossbred F1 (Wild × Meishan) pigs were low (279.35 g/day and 50.79%, respectively). However, FCR was high (3.47kg). Gender did not affect growth performance, feed conversion ratio and carcass characteristics (P >0.05), feed intake of gilts was higher than barrows (P

This study was conducted on 720 semen samples of six Duroc boars to evaluate the effects of the different cooling methods on semen quality when stored at low temperatures in an extender without antibiotics. Semen was diluted in a modified BTS extender without antibiotics. Semen samples were cooled from 30°C to 5°C using five different cooling rates before stored at 5°C. Diluted semen was investigated after 24h, 48h, 72h and 120h of preservation. The results showed that: the lowest cooling rate sample (5-A4: 2h at room temperature, then stored at 10°C for 3 h) had sperm motility, abnormal acrosome, as well as morphology in different days of storage, which did not differ from semen samples stored at 17°C (P >0.05). Rapid cooling rate and direct storage at 5°C (5-A0 stored immediately at 5°C after dilution) were reduced sperm motility as well as increased abnormal spermatozoa (P

Thestudywasconductedtoassesswaterqualityinsnakeheadfishfarms inTraOndistrict,VinhLongprovinceusingwastewaterqualityparameterssuchaspH,temperature,dissolvedoxygen(DO),biochemicaloxygendemand(BOD),chemicaloxygendemand(COD),totalnitrogen(TN),andtotalphosphorus(TP).Watersampleswerecollectedinsnakeheadfishpondswiththreestockingdensitiesof60fish/m2,80fish/m2,and100fish/m2,fromthestartoftheculturetimetoharvest.Theresultsshowedthattemperaturewasstable,pHinthepondwaterwasslightlyacidic.Thedissolvedoxygenwasverylow.Themeanconcentrations​​ofBOD(12.9-32.7mg/l),COD(35.9-70.34mg/l),totalnitrogen(7.0-15.05mg/l),totalphosphorus(0.59-2.46mg/l)increasedduringthecultureperiodandwasenhancedathigherstockingdensities.Inapondwithadensityof100fish/m2,concentrationsofBODandCODinthefourthmonthexceededQCVN08-MT:2015/BTNMT.ThecalculationresultsshowedthattheloadsofBOD,COD,TNandTPwere2.16-3.86;5.13-6.93;1.21-1.66;0.213-0,296kg/m2/season,respectively.Thestudyresultsshowedthattheconcentrationsoforganicmatterandnutrientswererelativelyhighinsnakeheadfishpondwastewater,soitneedstobetreatedbeforebeingdischargedintotheenvironment.

Drought and moisture deficiency in crop cultivation on the coastal sandy soil in Nghe An province have occurred frequently in the late spring crop. Mono-culture is a factor that influences increasing soil temperature and water evaporation and nutrient losses than intercropping. Therefore, the objective of this study was to assess the impact of intercropping maize on the temperature, humidity, nutrition, yield of maize on sandy soil in Nghe An province. The experiments were conducted in two seasons of 2015 and 2016 in a randomized complete block design (RCBD) with 5 formulas: KX (No intercropping), NL (Maize-Peanut), NĐ (Maize- Black Bean), NX (Maize-Green Bean), NK (Maize-Sweet Potato). The results showed that intercropping between maize and other crops significantly influenced temperature, humidity, soil nutrient and yield. Soil moisture content in intercropping plots was constantly higher, whereas soil temperature was lower than those in a single maize plot. Soil nutrient indicators tended to increase after the experiment and gave the highest value in the NĐ plot. The highest yield of maize in the formula NĐ was 4.962 ton/ha in spring crop 2015 and was 4.831 ton/ha in spring crop 2016, the remained intercropping plots were perpetually higher than the single maize plot (P0.05).

Nghiên cứu ứng dụng công nghệ hàn tự động dưới lớp thuốc cho vật liệu cụ thể có ý nghĩa thực tiễn và khoa học. Thực hiện thí nghiệm cho quá trình hàn thép hợp kim thấp độ bền cao Q345B với mối hàn giáp mối không vát mép và có khe hở đã đưa ra được những thông số hàn phục vụ cho những nghiên cứu tiếp theo. Trong nghiên cứu này, qua nghiên cứu tài liệu và thực nghiệm sơ bộ đã xác định được một số thông số cho quá trình hàn. Qua quá trình khảo sát bước đầu, cố định một vài thông số và thực hiện quá trình hàn với thông số đầu vào và đánh giá thông số đầu ra để nhận được thông số cần thiết cho quá trình hàn với giá trị của cường độ dòng điện là 419,5 A và tốc độ hàn là 16 m/h. Dựa trên các thông số từ thí nghiệm và tính toán, thực hiện quá trình hàn với những mẫu cụ thể. Một số phương pháp cần thiết để đánh giá chất lượng của mối hàn đã được sử dụng như thử kéo, kiểm tra cấu trúc thô đại và cấu trúc tế vi. Ngoài ra, ứng dụng công nghệ hàn tự động dưới lớp thuốc cho các mẫu có hình dạng giống chi tiết máy đã thu được một số kết quả.

High tech-agriculture is a term officially used in Laws and Policies of the Vietnamese government. However, with the impacts of the Fourth Industrial Revolution, the concept of “smart agriculture” is used more widely than that of “high tech-agriculture”. Based on reviews of agricultural evolutions with development of social production modes and technological innovations and the emergence of smart, this paper discusses and derives meanings of high tech-agriculture term based on a view of “smart agriculture”. Finally, the paper points out nature, main features and tendencies of technological innovations in the high-tech agriculture with a new point of view.