Vol. 10 No. 3 (2012)

Research was carried out to produce virus-free plants via meristem culture of Allium wakegi. The explants were apical meristems (0.3 - 0.5mm) derived from virus infected plants. The results indicated that MS medium supplemented with 0.75 mg/l BA and 0.5 mg/l IAA was the most suitable medium for in vitro shoot regeneration from meristem, the rate of regenerated shoots was 73.33%. The highest rate of shoot propagation was 2.0 times with type I shoot and 4.07 times with type II shoot after 4 weeks, on MS medium containing 1.5 mg/l BA. The shoots were transferred to rooting media by addition of 0.5 mg/l IAA and the rate of root formation was 100%, the average number of root was 4.33. RT-PCR method with primers CIfor/ CIRev showed that the regeneration plants from meristem were virus-free.

Chromatomyia horticola (Diptera; Agromyzidae) were reared from the collected leaves. This leafminer was found infesting 11 vegetable species at Gia Lam, Ha Noi. C. horticola commonly infests tomato, cumcuber and garland chrysanthemum,being most abundant in spring and winter cropping season. The density of and the rate of damage by C. horticola were lowest in late winter season, but there was no significant difference between main and early season. Previous crops affect the density of C. horticola on curcumber. The density C. horticola was also lowest in the field that plants were not found hosts as wax gourd. The density of the leafminer in crossed curcumber higher than in local curcumber.

A study of burrying rice straws combined with two microbial product treatments (Bio-plant and Trichoderma) was conducted in spring rice and summer rice seasons on Red River alluvial soils of Ha Noi University of Agriculture. The experiments were arranged in randomized complete block design. Research results pointed out that rice straw burrying with and without microbial product treatment led to differences in growth and development of rice plants. Observations indicate statistically significant differences in leaf area index (LAI) and dry matter accumulation, yield components and grain yield. The use of Bio-plant product combined with rice straw burrying brought higher rice yield than Trichoderma product and control (without microbial treatment, with the summer crop yield of 40.5; 38.0 and 36.5 quintal ha-1, respectively. The treatment of rice straws with Bio-plant product gave higher income by VND 5.2 to 6.5 millions per crop hecta-1.

Four isoenergic feed pellets of different protein and lipid levels, namely D1 (35% Pr, 10% L), D2 (42% Pr, 10% L), D3 (42% Pr, 5% L) and D4 (35% Pr, 5% L), were used to investigate the growth of bagrid catfish Mystus nemurus in cages breed in water reservoir in Yen Thanh, Nghe An. Experimental fish of initial size of 47.0 ± 1.2 g were fed twice a day to satiation in 85 days. Fish fed on diet D2 which contained the highest protein and lipid levels showed the best growth rate and the lowest feed conversion ratio (P <0.05). Fish fed on D4 diet with the lowest in protein and lipid content yielded the lowest growth rate and protein efficiency ratio and the highest feed conversion ratio (P <0.05). Fish fed on diet D3 gave similar growth rate, protein efficiency ratio to those fed on diet D1 but had a lower feed conversion ratio (P <0.05). Survival rates of fish from all feed treatments were high (93.0-96.0%) and no significant difference was found among treatments. Based on these results, diet D2 (42 % protein and 10 % lipid) was recomended for maximizing growth rate and feed utilization of Mystus nemurus.

Study was conducted by gathering natural ocurring snails, Bithynia spp., in Ha Noi, Hai Duong and Nam Dinh provinces. It was determined that Bithynia snail is the intermediate host of Clonorchis sinensis. Bithynia mainly occurs in calm water with the rate of 58.27%; The prevalence of Cercaria infection Clonorchis sinensis varied from 0.32 to 4.78%. Laboratory study showed that 100% snails float on the water surface in summer, 93.34% snails settle to mud; 100% snail lay eggs in summer and fall with hatching interval between 9 to 12 days. The study on micro-lesions of liver and bile ducts of cat infected by natural Clonorchis sinensis has shown that bile duct wall was thickened and fibrized, some ducts were obstructed with the hyperplasia. Inflamative cells of eosinophil, plasmocyte, lymphocyte and macrophage appeared around. Other symptoms include hepatic congestion, radial capillary expansion with infiltration of erythrocyte; central vein area of small lobe and interlobular vein expanded widely with infiltration of erythrocytes. Hepatocytes were found with fatty degeneration and vacuolar degeneration

Adding enzyme in feed in order to increase food digestibility, reducing pollution and increasing economical efficiency are being focused in fish nutrition research in recently. The rainbow trout at the size from 150 g to 450 g were cultured to evaluate the effect of the addition of enzymes to the feed for rainbow trout. This study used 3 different feed formulations: feed without enzyme supplement (CT1), feed was added with mixed of 6000 IU amylase, 2000 IU protease and 2000 IU phytase/1 kilogram (CT2) and a feed control RAISIO - Finland (CT3). The results shown that the survival rates are more than 97%. The Average Daily Growth rate (g/fish/day) of CT1 was 3.18, CT2 was 3.48, CT3 was 3.65 and significant difference (P < 0.05). The Food Comsumption ranged from 343 to 360 g of feed/fish and there was no significant difference between the three feed formulars (P > 0.05). The Food Conversion Ratio ranged from 1.12 to 1.31 and there was no significant different between CT2 and CT3  (P > 0.05). The initial research results show that food added enzyme is better than it did not added enzyme and can replace for imported feed to culture rainbow trout at the size of 150-450 g.

This study was to evaluate some characteristics of semen of Ri chicken breed. Semen from 4 Ri cockerels was collected by massage method 3 times/week on Monday, Wednesday and Friday from August to October, 2011, and assessed under light-microscope. Motility, concentration and volume of semen were 57.91±16.79%; 2.09±0.87 tỷ spermatozoa/ml; 0.056±0.030 ml, respectively. One way repeated measures ANOVA test showed that there was no significant variation of the quality of Ri cockerels’ semen during the study period. These findings suggested that a collection frequency of 3 times/week during 2 months did not have significant effects on the quality of semen of the Ri cockerels. This is the first report about some charateristics of semen of Ri chicken beed in Vietnam. Future researches are required to evaluate other criteria of Ri cockerel’s semen and in a larger scale.

Studying on relationship among pH, driploss and colour of pork post-mortem revealed signicant difference for pH value, colour and driploss of ham and loin at time points 45min, 6h, 12h, 24h, 36h, 48h, 60h and 72h post-mortem (p=0,00). Along storage time at 4oC, reduction of pH and increment of driploss level leading to decrease of pork colour were recorded. Drip loss was significantly correlated with pH and colour of loin at 24h (R2 = 0,61) and 36h (R2 = 0,69) post-mortem (P<0,01). Results implied that loin and ham should be consumed within 24h after slaughtering.

The experiment was implemented to identify the effectiveness of aerobic composting of chickrn manure and dead chicken over 40 day period through two experimental groups. The main difference of these groups was that the layers of chicken manure were separated by using rice husk in second group and the ratio between chicken waste and rice husk (3.42 : 1 and 2.5:1 respectively). The results demonstrated that the optimal temperature was obtained from first experimental group, where temperature reached a peak of 74.50C after 4 days during process of experiment. This group was also advantgeous that rice husk quantity could be saved. After 40 day period of experiment, Salmonella was negative, the quantity of Coliform and E.coli declined significantly. Coliform decreased from approximately 4.05.107 to less than 102. Similarly, E.coli also declined to less than 3 per MPN. The first application of aerobic composting to treat dead chicken demonstrated the potential and effectiveness of this method. Dead chickens were completely decomposed after 20 day. NH3 and H2S were not detected at 1 m, 5m, 10m and 20 m distances from experimental site.

It has been demonstrated that in human, isoflavone aglycones (daizein, genistein and glycitein) are absorbed faster and in greater amounts than their glycosides. However, most of isoflavones in soybean seed exitsted in glycosylated form. In this study, we investigated conversion of isoflavone from glycoside form to aglycone form during water soaking at different temperatures (20oC to 60oC) in 8 hours. Besides, water absorption rate and changes in the turbidity of the water, which the soybean were soaked in were also observed. Isoflavone glycosides and isoflavone aglycones were determined by HPLC. The results showed that the conversion of isoflavone from glycoside form to aglycone form was highest during soaking in 50oC water and it takes 4h to increase isoflavone aglycones from 6.1 mg/100 g (2.1% of total isoflavone) to 15.4 mg/100 g (5.6% of total isoflavone). In this condition, the water absorption rate of soybean reached 126.5%. Soaked soybeans are potential materials for functional food production.

This investigation on the possible role of mould in production of traditional rice wine was carried out with the 4 candidate mould strains which were selected from 21 mould strains isolated from traditional rice wine starters and traditional soysauce starters. The 4 mould strains were preliminarily identified and named as M3 (Rhizopus spp.), M10 (Rhizopus spp.), M16 (Aspergillus oryzae), and M18 (Endomycopsisfibuliger). M10, M16 and M18 strains expressed very strong extracellular enzyme activities (amylase, protease, cellulase), while M3 strain had weak extracellular protease and cellulase activity and no extracellular amylase. Noteably, the yield of rice wine of the traditional alcoholic fermentation was not increased when large amounts of the biomass of the 4 isolated mould strains were added. There was a strong correlation between the pH of fermention liquid and the final yield of wine. The lower the pH of fermentation liquid was, the lower the yield of wine. Moreover, all 4 mould strains were determined to have no role in the formation of aldehyde, methanol and higher alcohol in rice wine products.

Equipment system SV-1.0 for drying litchi by combining convection and radiation method has been designed and manufactured at Department of Agricultural products Processing and Storage, Faculty of Engineering, Hanoi University of Agriculture. This drying system has simple structure and the heat are supplied by combining thermal convection and radiation method. As a result, heat transfer effect was improved. The effect of temperature, drying air velocity, density of material in drying chamber on drying material heterogeneity of dried product and specific fuel consumption was identified. In comparison with common drying systems being used, the drying system SV-1.0 has several advantages: drying time was reduced (70.5 hours), equal to 55.7% of manual drying ovens and 94% of improved drying equipmen. The heterogeneity of dried product is 2.1%, reduced by 2.2% in comparison with manual drying oven and by 1.6% with the improved drying equipment. Specific fuel consumption is 0.45 kg of coal for 1kg of dried product, equal to 46.1% of manual drying oven and 74% of the improved drying equipment. The dried litchi product has good quality with nice shape and colour.

The popular use of additives in food may adversely affect community health. This study aimed at improving management of the use of additives in food processing in Quang Binh province. The intervention model front-end evaluation was conducted from April 2009 to December 2011. The interventions included training, direct communication with leaflets and propaganda on TV, increased inspection, testing, point of use modeling, free supply of and consultancy on use of food additives. The samples were taken from 164 of food processing and business units for the welding tests, coloring, acid benzoic and sorbic acid both before and after intervention. It was found that after intervention, the sample rate of foof with toxic color additive dropped from 25.8% to 9.9% and borax food samples decreased from 37.1% to 19,7%. The proportion of unsatisfactory food samples decreased from 46.3% to 8.1% for benzoic acid and from 50.0% to 18% for sorbic acid.

An investigation on chilling injury sensitivity and quality changes of banana fruits (Musa AAA) stored at two different temperatures (7 and 10oC) was carried out in the laboratory conditions. Bananas were harvested at 85% maturity, cleaned by fresh water to remove latex, then treated with 0.5% Benomyl and dried at room temperature. Then banana fruits were placed in carton boxes and transfered to low temperature for storage. The results showed that bananas were susceptible to chilling injury at both 7 and 10oC. Chilling injury resulted in several physical and biochemical changes such as discolouration of peel (reduction of L value), abnormal changes of pulp texture. Cool-stored bananas riped abnormally with low content of total sugars. However, bananas stored at 10oCwere affected less than those stored at 7oC.

The paper describes some typical clustering algorithms for categorical attributes. Specifucally, we focus on research clustering algorithm called MMR which is based on the rough set theory. The algorithm has the ability to control uncertainty in processing cluster. It has been successfully installed and four standard data sets were tested. The results indicate that MMR generates better quality clusters than some traditional algorithms.

Single nucleotide polymorphism (SNP), one of the most popular variant of the DNA of the organism. The SNP studies have important roles in biological research, gene mapping, selected animals and plants. The contents of the article presents an overview of SNP detection methods are now widely used around the world.

Since 1990s the bloom of industrialization and urbanization brings about the changes in social and economic issues of Vietnam, especially in rural areas. Along with those changes, how rural family has changed? By surveying 48 families outside urbanization area and 54 families within urbanization area, the research found that urbanization process has not exerted impact on the traditional structure of the families in both areasd. However, the income generation activities of family have changed towards dependence on the family member and the family consumption activities have shifted from self-sufficience to market dependence. Moreover, ubanization seems to make family educational function blurry due to more concentration efforts on economic function.

Pig production industry in Vietnam current risks faced by pig producers are one of the main barriers to overall industry's development. Based on the survey results of current risk exposure in 1400 pig producing households in 7 provinces representing 7 ecological regions, the research shows that epidemic risks and market risks are the most serious risks faced by pig producers across all production scales. In addition, analysis of risk management policy in the industry also shows that of 62 legal documents, 53 documents are categorized as risk - prevention purpose, 04 documents categorized as risk - sharing purpose and 06 documents categorized as risk - coping purpose. However, this legal framework still exposes two major shortcomings: legal promulgation is slow and the framework is incomplete and not synchronized. Based on the analysis of risks exposure and current risk management policy, the research proposes recommendations towards improving risk management policy in pig production in two dimensions: i) In long term, the risk management system should aim at satisfying international standard (Codex); ii) In short term, legal documents need to focus on better risk management in epidemic prevention and treatment.

Sam Son beach in Thanh Hoa province is one of the most beautiful beaches in Vietnam attracting millions of tourists each year. However, the beach is facing several problems such as the average number of days that tourists spent at the beach is decreasing, service quality is not good, etc. A questionnaire of 57 evaluation criteria using Likert scale is used to interview 83 tourists to measure tourists' satisfaction in five main groups of services at Sam Son beach and propose some measures to improve the tourists' satisfaction. Analysis results show that quality of the main groups of services at Sam Son beach is acceptable. Only 27.69% of the inteviewed tourists satisfied with services at the beach with the average satisfaction index of 3.05. The beach did not really satisfy high-income tourists. The availability of the current services is only sufficient to meet the needs of low income tourists and local customers. It is necessary to take measures to improve the tourists' satisfaction such as promoting investment in infrastructure and facilities for tourism development, timely correcting defects in service delivery, enhancing professional qualifications for service staff, etc.

Litchi is a major agricultural crop in Thanh Ha district, Hai Duong province. However, the lichi farm households have faced many difficulties in their livelihood stability in recent years due to the decrease in the litchi market price. This study aims to investigate the response of litchi farm households to the lichi price volatility and to propose several measures to help lichi farm households overcome the difficulties in their litchi industry in the coming time. The study results reveal that the responses of lichi farm households were very diverse such as the replacement of lichi crop by better efficient crops, the intercroping of annual crops, the application of selective harvests for better price, enhancement of drying lichi fruits, changes in sale mode, participation in litchi production and marketing association. The measures to help lichi farm households overcome the difficulties in their litchi industry included the replanning of the litchi production areas, the enhancment of applying techniques for lengthening the harvest time and post-harvest processing technologies, the improvement of linkages in product marketing, etc.,.