Vol. 15 No. 12 (2017)

Antagonistic fungi, Trichoderma spp., have been reported as potential bio-control agents to control soil borne plant pathogens more effectively than chemicals.Trichodermaspp.were widelyspread in soil and rhizospehre of plants. In this study, Trichoderma spp. were isolated from nine samples of soils cultivated with annual and perennial crops in five different provinces in the North of Vietnam. Trichoderma spp. were identified based on morphology and molecular characterizations. Based on the sequence analysis of ITS region, the results showed that eight isolates were identified as T. asperellum and one isolate was T. harzianum. The results indicated that T. asperellum exhibited a high growth rate and high sporulation on three different substrates and strong inhibitory effect against pathogens that cause root rot disease by Rhizoctinia solani and Sclerotinia stem rot by Sclerotinia sclerotiorum in vitro. Moreover, biosecurity assessment showed that T. asperellum was safe in rats at 20 g/kg. Our results revealed that T. asperellum is widely distributed in Northern provinces of Vietnam.

In current rice production, discoloration of grain is one of the most important diseases, leading to reduction in yield and deterioration in grain quality. The research was carried out to obtain current status of rice cultivation and seed-borne mycoflora of two rice varieties OM6976 and OM4218 at Chau Phu district, An Giang province. In addition, in vitro activity of plant extracts was tested against Fusarium sp. that are common seed-borne infection among rice seed mycoflora. Results of interview from 60 households showed that grain discoloration, blast and bacterial leaf blight were the important rice diseases. Examination on seed-borne mycoflora from 6,000 rice grains indicated that there were 12 kinds of fungi on both rice varieties, namely Fusarium sp., Curvularia sp., Pinatubo oryzae, Trichoconis padwickii, Tilletia barclayana, Nigrospora sp., Acremonium sp., Penicilium sp., Aspergillus sp., Chaetomium globosus, Bipolaris oryzae and Phoma sorghina. Among them, Fusarium sp. accounted for high percentage (29.5%) in variety OM6976. The rate of Curvularia sp. was high at approximately 24.6% in variety OM4218. Eupatorium leaf extracts at concentration of 2, 4 and 8% highly inhibited the growth of Fusarium sp.

This study was conducted to determine relationshipamong agronomic traitsand their contribution to plant grainyieldofsalt-tolerant rice cultivars in Central Vietnam. The experiment was arranged directly on saline soils at an average salinity level of 6.35 dS/m in 2017 winter-spring croppingseason in Thua Thien Hue with 10 popular salt-tolerant rice cultivars. Of all the agronomictraits studied, individual yields had a positive correlation coefficient with plant height (0.3624*), total panicles/plant (0.7019***), panicle weight (0.4530**) and total dry biomass (0.7837***). Total panicles/plant and panicle weight directly affect on the formation of rice yield. Total dry biomass and plant height do not directly affect yield, but are indirectly throughpanicle weights and total grains/panicle. Therefore, total number of paniclesper plant, panicle weight and total number of seedsper panicle would be effective selection criteriafor improvement of salt-tolerant rice cultivars in the central region.

To evaluate the pathological changes of chickens vaccinated against avian influenza (AI), then challenged with a virulent AI virus, experiments were conducted using a virulent A/H5N1 virus belonging to clade 2.3.2.1C (A/Ck/Vietnam(KienGiang)/NCVD15A7/2015(H5N1)). After virulent challenge, the dead chickens or chickens surviving until the end of the experiment were examined for macroscopic and microscopic lesions of the visceral organs. The examined specimens were visceral organs and macroscopic and microscopic lesions were examined by thorough necrosy and microscopical examination of HE stained specimens. The chickens were divided into 4 groups: Three experimental groups were vaccinated against AI and unvaccinated chickens as control. Chickens in all 4 groups were intranasally challenged with a virulent virus of 106TCID50/100 ul/animal and monitored for 10 days after challenge. The results showed that all control chickens died before the experiment ended, while 21/30 chickens of 3 experimental groups survived. Macroscopic lesions in chickens of chicken group vaccinated with Navet-vifluvac vaccine were pulmonary edema, congestion and hemorrhage. For chickens of chicken group vaccinated with Re-5 vaccine, in addition to pulmonary edema with swelling, congestion and hemorrhage, there were also hemorrhage in the thigh muscle, neck, intestines and liver. For chickens of chicken group vaccinated with Re-6 vaccine, pulmonary odema and spot haemorrhage were observed. Chickens of control group showed lesions typical for chickens infected with AI viruses. Microscopic lesions in the control chicken were severe and typical of AI. This indicated that unvaccinated chickens, after challenged with a virulent A/H5N1 virus exhibited more severe and typical lesions than vaccinated chickens, then challenged with the virulent virus.

Agricultural land use plays the vital role in production of agricultural products and agrciultural commodities.Recently, agricultural land use has changed significantly towards higher efficiency in the South of Vientiane Capital. The study objective was to point out effective land use patterns as a base for orientation of acgicultural land use in the future. In this study, we used field surveys, primary and secondary data collection, and statistical analyses to access land use situation and efficiency of agricultural land use. The results showed that there were 5 land use types (LUTs) with 15 sub-LUTs in Southern Vientiane. Some agricultural sub-LUTs were assessed as highly efficient, such as rice - vegetable and vegetable. Some agricultural sub-LUTs had high economic efficiency, however, they affected the environment due to the use of pesticides, crop monoculture and unbalanced useof organic and inorganic fertilizer, i.e. LUT of vegetable. The results might serve as a good basis for the orientation of agricultural land use towards efficiency in the future.

Decision tree is a powerful and effective tool in classifying and forecasting. The decision tree method gives quantitative bases for land suitability classification. The analysis of survey data indicated several factor combinations according to plant average productivity and based on productivity, the adaptation level for each factor combination. Was assessed. Regression model of decision tree in this study included two kinds of variables: the target variable was the productivity (t/ha) and the predictor variables consisted of soil types, soil depth, slope and texture. This study was applied for rubber trees and conducted in Dau Tieng district, Binh Duong province. The study showed that the interpretation level of the predictive variables was 97.58%. The moderately suitable area was 60,850.65 hectares, and marginally suitableare was 6,332.97 ha.

Data classification is a common method used for mining the potentialknowledge from large databases. Several methods have been proposed such as AdaBoost, Support Vector Machine (sVM), Neural Network, random forest (RF), C45… Among all these classifiers, Random forest and SVM provided more accurate and efficient result for high-dimensional data. However, the performance of these algorithms may be affected/degraded when working on gene data with thousands of features. This is because gene data usually contain many redundant features which are uninformative to classification. Therefore, using the subsets of selected genes may give a better performance than using all the features. In this study, we summarizedthe data classification algorithms based on the random forest models, SVM, and evaluate the effectiveness of the algorithms for classifying high-dimensional data. Next, we evaluatedthe combination the features selection using GRF and other classifiers such as RF, WSRF, RUF, SVM. Sevengene data sets were used to evaluate the methods. Experimental results showedthat the combination not only increasedthe accuracy but also decreasedthe execution time of the algorithms

Golden camellia (Camellia sp.)is a medicinal plant containing a wide range of pharmacologically active compounds that can be used in anti-inflammatory, prevention and treatment of cancer. Golden camillia is also used as an ornamental plant because of its bright yellow flowers. This study successfully established in vitro multipropagation protocol of Camellia sp. collected at Ba Che district, Quang Ninh province, Vietnam. Unopened fruits were identified as the best initial material. Unopened fruits were surface sterilized with 7% NaOCl solution for 30 minutes. Seeds were then placed on MS medium supplemented with 1 mg/l BA and 3 mg/l GA3 for germination. Shoots were multiplied on MS media containing 5 mg/l BA + 1 mg/l GA3 + 300 ml/l coconut water + 30 g/l sucrose + 7 g/l agar. The rate of shoot multiplication was 4.7 shoots per explant. The shoots were then transferred onto medium of 1/4 MS + 0.5 mg/l α-NAA + 2 mg/l IBA + 30 g/l sucrose + 7 g/l agar for rooting. At the nursery stage, in vitro plants were grown in sand and reached the survival rate of 93.75%. The established protocol can be applied for multipropagation and conservation of the golden camellia.

Strawberry “SmiA” is a potential variety with outstanding features such as heart- shaped fruit, dainty little red berries with an ambrosial flavor of strawberry, rose, pineapple and honey. This study was carried out to establish in vitro micropropagationprotocol from in vitro germinated plants. The best shoot proliferation (7.8 shoots/explant) was obtained from explants grown on MS medium supplemented with 0.4 mg/l BA after 5 weeks. In vitro shoots were rooted on semi-solid MS medium with 0.25 mg/l α-NAA, maximum rooting rate (93.33%) with 12.36 roots/shoot and average length (1.49 cm) of roots was achieved after 4 weeks. The plantlets were successfully acclimated and well developed in soil substrate with a high survival rate. NPK fertilizer combined with Atonik solution was most appropriate for growth and development of in vitro SmiA plantlets with the average height of 19.13 cm after 1 month. Flowering was observed after 20 - 25 days of flower-bud formation, and masses of dainty, sweet tasting berries were produced after 30 - 35 days.

The effect of fertilizer doses on soybean was evaluated todetermine optimal fertilizer levelfor growth and yield of soybean grown in winter cropping season in Thanh Hoa province. Theexperiments were performed on two soybean varieties D140 and ĐVN5using two factor split - plotdesignwith 3 replications Research results of experiments showed thatfertilizer levelsaffectedthe leaf area, mass and number of nodules, dry matter accumulation, total podson plants and grain yield of winter grown soybean. Optimal dose of fertilizer to achieve high yieldandnet income for both soybean varieties D140 and ĐVN5 in Thanh Hoa provincewass 30 kg N + 90 kg P2O5+ 60 kg K2O/ha.

This study aimed to investigate the current status of aquaculture under VietGAP standard in the coastal area of Nam Dinh province. We conducted a survey of 240 households and 30 officials in the districts of Giao Thuy, Hai Hau and Nghia Hung and used secondary data bycomparison method, descriptive statistics, SWOT and Logistic Econometric model to assess the status of aquaculture following VietGAP standard. The results showed that, although VietGAP Standards in aquaculture has been deployed in Nam Dinh since 2014, the number of farmers who engaged in VietGap and granted with VietGAP standard certification still accounted for a rather low rate of aquaculture farmers in total. The expansion of VietGAP production scale was quite low and there were few types of economic organizations participating in aquaculture following VietGAP standard. Moreover, some participants have not implemented correctly the content of VietGAP standard. Price and productivity of aquaculture products of VietGAP were higher than ordinary practicesl, but the effect was still low due to higher initial investments. Furthermore, aquaculture under VietGAP standard has faced with a lot of difficulties and be affected by several factors. Thus, in order to develop aquaculture under VietGAP standard in the coastal area in Nam Dinh province, the study proposes solutions such as planning, technology adoption; market development and aquaculture services for VietGAP.