Vol. 14 No. 10 (2016)

The effects of drying temperature on the profile of volatile compounds produced by black tea were evaluated at 80, 90, 100, 110, 120, 130,and 140oC. Aroma concentrate was prepared bytheBrewed Extraction Method (BEM) method and analyzedbyGC/MS. The volatile compoundscontent increased as the drying temperature increasedfrom lowto high temperatures. However, the relative content of group II volatile compounds, which are the degradation products of carotenoids and amino acids, rapidly increased more than the group I volatile compounds which are mainly the products of lipid breakdown, but when the drying temperature was higher than 120oC, the relative content of some volatile compounds belonging to group II rapidly decreased more than the volatile compounds belonging to group I. The highest flavour indice, which is defined as the ratio between desirable to undesirable volatile compounds, was obtained in samples dried at 120, followed by 110oC. Given the above results, in the present study, the optimal temperature condition to dry black tea was 120oC or 110oC.

An efficient regeneration protocol of large scale micropropagation for clonal establishment ofsweet potato from seedlings is an essential step for clonal selection. The objective of thisstudywas to evaluate the potentials of young coconut water and simple aerated culture conditionin glass bottles with Milliseal®forin vitro propagation of sweet potato using nodal explants.Shoot regeneration of sweet potato nodes bearing dormant buds was effectively promoted by aerated culture condition in full strength MS salt solidified by 8g.L-1agar supplemented with 3% sucrose,BAP 1.0 mg.L-1,0.5 mg.L-1IAA and 20% coconut waterand subsequentroot induction was effective on full strength MS salt solidified by 8g.L-1agar supplemented with 3% sucroseand 0.3 mg.L-1α- NAA. The plantlets derived from aerated culture condition were more vigorous compared to conventional non-aerated culture condition, leading to high survival rate (~ 100%) and enhanced growth during acclimatiztion. Sand -smoked rice husk potting mixwas suitable for hardening of in vitro -derived plantlets.

Water demand for agricultural production has become a crucial factor for sustainable development. With regard to reducing the risk posed by water suppliedfrom irrigation or natural water sources, water reuse and recyclinghave been initiated in many parts of the world, especially where water scarcity is becomingserious due totheimpact of climate change. One of the challenges in water reuse is how to eliminate toxic compounds from agricultural wastewater. This paper demonstrates a method to remove estradiol (E2), an environmental hormone excreted mainly from animal husbandry farms and 2,4 dichlorophenol (DCP), a weed control chemical. The operating conditions for electro-chemical oxidation of estrogens (estrone (E1), E2 and ethynylestradiol (EE2) and 2,4 dichlorophenol (2,4D) were evaluated using synthetic wastewater. The results showedthat although estrogens and DCP oxidized in the range of 0.5-0.8V, the optimal condition for electropolimerization was achieved in alkaline conditions. In addition, the continuous treatments show that more than 80% of removal efficiency was achieved with energy consumption around 1-10 Wh.m-3. It is recommended that further studies using available materialsat local sitesshould be conducted to make this process possible in practice.

The aim of this study to evaluate the effects of mycoroot bio-product to the Pb accumulation capability of ferns. This pot experiment was carried out in agreenhouse with 4 treatments arranged inarandomized complete block. Soil of the Dong Mai village, Chi Dao commune, Van Lam district, Hung Yen province,Vietnam was analyzed and its Pb contamination was 37 times higher than the permissible standard (QCVN 03: 2008 / BTNMT). After 40 daysofexperimentation, mycoroot treated fernshadincreasedbiomass and Pb content of plant parts. The increase of plant biomass depended on the dose of the inoculant applied to the soil. The Pb content accumulated up to 834.63 mg.kg-1in theroots and 121.19 mg.kg-1in thestalk-leaves when thefernsweretreated with 40g mycoroot bio-product/plant. Fernshad loweraPb content ineach fresh biomass unit and a higher biomass weight whenmycoroot bio-productwas appliedat a rate of 80 gper plantcompared to 40 gper plant. Thus, the total amount of Pb removed from the soil was higherafter the fernswere treated with 80 gper plant mycoroot bio-product (7.27 mg Pbper pot). The total amount of Pb accumulatedin theroots was always higher than in the stalk- leaves. The flexibility of Pb could be increased when soil was mixed with mycoroot bio-product beforeferns weretransplanted.

The research aim was to analyse the main aspects of water use management and stakeholder conflicts within Nam Rom irrigation system, Dien Bien valley, Dien Bien province in the northwest region of Vietnam. The study identified the key stakeholder groups relating to water distribution, viz. Dien Bien provincial People’s Committee (DBPC), Dien Bien Irrigation Management Co. Ltd.(DBIMC),Dien Bien Phu city People’s Committee, and Dien Bien district People’s Committee. The results of this study indicated that the conflicts over water use for irrigation relate to quantity and quality of water supply, decentralized management and water fee exemption policies. The outputs of the study are important for improving water allocation and management in irrigation sector in Dien Bien province.

The objective of this research wasto analyze the correlation between land use change and the social-natural factors in Tien Yen district using logistic regression model. The target variable was land use changeand the dependent variables wereelevation, slope, distance to the main road, distance to the secondary road, distance to riverandstream, distance to village, ethnology, policies, population density, population growth rate, and average food per capita. The model was run in SPSS (Statistical Package for the Social Science) software version 20. The results showed different relationship between land use change and social-natural factors in different periods. From 2000 to 2005, the land use change of Tien Yen increased with the increase of elevation, distance to the secondary road and Dao ethnic minority, whereas slope, distance to stream and Kinh, Tay, San Chi ethnic minorities decreased. In the period of 2005 - 2010, the land use change in Tien Yen have positive correlation with slope, ethnology and Government policies while elevation and distance to the main roads showed reverse correlation.

Thisexperiment was conducted duringthewinterof2014 on the alluvial soils of the Red River delta to evaluate the effect of irrigation method onthegrowth, yield and water use efficiency of tomato. Soils used for experiments are alluvial, neutral, less acidic, not silted annually. Experimental results have shown that drip irrigation positively affected growing period, plant height, fruiting rate, yield and water use efficiency. Drip irrigation prolonged tomato growing periodfrom 6-11 days compared to furrowirrigation; plant height in the treatments with drip irrigation was also higher compared withfurrowirrigation. The fruiting rate in the treatments with drip irrigation was higher than in furrowirrigation, the highest fruiting rate was obtained in drip treatment T4 with (70-100)% βdr (βdr is field capacity) of 71.3%. Drip irrigation has increased individual yieldof tomato plants from 8.9 - 36.3%, while reduced the amount of irrigation water from 22 - 39.1% and water use efficiency increased from 30 - 57% compared to furrowirrigation. The drip irrigation treatmentwith (70-100)% βdr (T4) achieved highest individual yieldand water use efficiency(2788.2 gplant-1; 16 kgm-3).

Maize has become the second most important crop after rice in Vietnam, particularlyit is main cash crop for farmers intheNorthwest region. To seek a solutionforadapting to climate change, the impact of climate change onmaize production needs to be analyzed. The AquaCrop model was usedhereto predict maize yield inresponse toclimate change. The model was calibrated and validated for maize production at field scale in Muong Lum commune, Yen Chau district, Son La province duringtheperiod of 2008 - 2012.The AquaCrop model application under climate change scenario B2 shows that maize yield hasapositive response to climate change with apredicted increase of 2.2% in 2100 compared totheperiod of 2008 - 2012. It recommends that maize production can be continued in the study area.

Lodging is one of the important factors that limitsrice yield and reducesgrain quality. Lodging obstructs the process of transporting carbohydrates fromtheleaves and stem to grains, and causes the panicles to sink into water and decompose, which causes many difficulties for harvesting. This study was conducted with the aimof determining the optimal paclobutrazol concentration with respect to the growth and hardness of rice to help limit lodging and increase the yield. The experiment was conducted in the field on the autumn-winter crop inVi Thuy District, Hau Giang province. The experiment was carried out in a randomized complete block design (RCBD) with five paclobutrazol treatments (control (spraying water without paclobutrazol), 25 mg.l-1, 50 mg.l-1, 75 mg.l-1, 100 mg.l-1) and four replications per treatment. The results showed that the treatment of paclobutrazolat a concentration of 50 mg.l-1induced the rice to increase the number of tillers, the stems’ hardness index (the lodging index was reduced),the filled grain ratio,andthe yield (6.98 tons/ha, increasing 12.1% compared to the control).

In this study,we performed experiments to screen and identify actinomycetestrains that are antagonisticto Xanthomonas oryzae pv. oryzaecausing rice bacterial blight disease. Among of 98 strainsisolated, we obtained two strains capable of antagonizing X.oryzae pv. oryzaeusingagar diffusion plate method. The strain numbered43 hada strong activity with a diameter of 22 mm clear zone of bacteria. The strain 43showedwhite colonies after threedays of incubation.Sevendays of incubation the white colonies hadgrey borders, produced soluble pigmentsonthe medium, grew well at 30°Candneutral pH, and adapted wellto high salt concentration medium. The strain 43was able toutilize different sources of carbon and nitrogen. Sequence analysis of 16S rRNA showed that strain 43 hada similarity of 100% comparedto Streptomyces diastaticus subsp.ardesiacus. Based on morphology, culture, physiologicalandbiochemical characteristics and molecular biological analyses the strain 43 was identified asS.diastaticus subsp.ardesiacus.

Fuzzy set theory and rough set theory have many applications in the fields of data mining, knowledge representation. Nowadays, there are many extensions which are mentioned along with the properties and applications of them. Concept T-rough set which allows us to discover knowledge is expressed as a map. In this paper, we introduce the concept of T-rough fuzzy set on crisp approximation spaces; their properties and fuzzy topology spaces which based on definable sets are studied. Then, by the same way, we also introduced the concept of collective T - rough fuzzy fuzzy approximation space, it is seen as a more general concept ofT-rough fuzzy set on crisp approximation spaces.

Aflatoxins are toxic carcinogenic secondary metabolites produced predominantly by two fungi: Aspergillus flavusand Aspergillus parasiticus. These fungi are a health risk and are responsible for losses and contamination of processed foods and feeds. It is very important to find methods to inhibit the growth of A. flavus andA. parasiticus,and degrade aflatoxin. In laboratory conditions, the Percentages of Inhibition of Radial Growth (PIRG %) of Trichodermasp. TC1 against A. flavusLA21 and A. parasiticusNG10 after 7 days’ dual culture were 63.51% and 60.22%, respectively. However, the use of Trichodermasp.TC1mycelium has restrictions in agricultural products due to the risks of consuming the substrate and degrading the products’ quality. Therefore, its extracts are more preferred in application. In the PD media, when up to 4% Trichodermasp. TC1 extract was added, the biomass rate for A. flavusLA21 and A. parasiticusNG10 reduced to 74.00% and 60.30%, respectively, after 5 days of incubation. The toxin levels of corn samples deliberately infected by aflatoxin producing fungi were negatively correlated with sprayed on Trichoderma sp. TC1 extract. Seven days after spraying the extract 4%, the aflatoxin in samples from more than 60 ppb at the initial time reduced down to 16 ppb for A. flavusLA21 and 21.33 ppb for A. parasiticus NG10.

The aims of this research were to identify the factors affecting consumption of importedapplesin Hanoi. A random sample of 80 respondentsin Hanoi was selected to collect data on their consumption of importedapples. Methodologically, a statistical analysis was used to identify the preferences of consumers in purchasing importedapplesand the two-step econometric technique was applied to measure the effects of the socio-economic and characteristics of the market on consumption of importedapples in Hanoi. The integrating results from the two models showed thattheincome of the consumerhasstrongly positive effects onthe consumer’s decisions to buy and consume imported apples in Hanoi.Atalighter level, the age of the consumerand information about importedapplesalso have positive effects on the probability of importedapple purchasing.In contrast, the price of appleshas anegative effect on the consumer’s decision to buy imported apples.Finally, several implications of this study highlighted the contribution of the research to theory by enriching the body of literature and marketing perspective by showing the worthy bases for the government to develop the market and for imported apple tradersin making their business behaviors more consistent.

From many perspectives, agricultural production is essential to the economic growth of the least developed countries (LDCs). While international trade is considered one of the main sources of growth, the fact that LDCs rely heavily on primary commodities export and may not benefit significantly from trade raises concerns about the impact of trade on the economic development of LDCs. In this paper, the instrumental variable method was employed to ensure consistency and unbiasedness of the estimates of the impact of trade on agricultural productivity. The resource rents was used as an instrumental variable in determining the export and import indexes, especially in the case of LDCs. The semi-elasticity showed that a one percentage point increase in the terms of trade reduced agricultural productivity growth by approximately 0.23% on average, holding other factors constant. This estimate was statistically significant, and implied that expansion in trade does not improve agricultural productivity in LDCs.

The study was conducted to survey one thousand households(HH)from 5 out of 62 villages in Bac Ninh provinceto estimate people’s willingness to pay(WTP)for water quality improvement, to identify the factors affecting people’s willingness to pay. Respondents are the heads of household. The Turnbull techniquewas usedto estimate expected willingness to payfor water quality improvement. Results of this research show thatthe average WTP is 485.273 VNDper per HHper per year. The potential fundsobtainedwould beapproximately 6 billion VNDper year (268,251USDper year) and the real fundswould havea value of 3.45 billion VNDper year (154,475 USDper year). For Bac Ninh province, the total fundingthat would really be achieved would be 100.2 billion VND per year (4.48 million USD). Potential fundinghas a value of 155.4 billion VND per year (6.9 million USD). Several factors positively impact the WTP of HH with HH type, trade-offbetween economic growth and environmental quality, using tap water, and income of HH beingsignificant statistic variables with positive coefficients. These coefficients indicate that the heads of handicraft households who have high incomes, agree to sacrifice environmental quality to get fast economic growth, andwho use tap water aremore likely to say “yes” to the given bid. The factors of village and bidhadnegative coefficients and high statistical significance.

This study focused on the factors that influence job satisfaction level of the workers working at Cam Binh Shoes Company. Theresearch usedthe primary data collected from thesurvey of 180 workers in 2015. The descriptive statistics, exploratory factor analysis (EFA) and multiple regression were employed. The study showed that about 64.4% of the surveyed workers felt satisfied with their current job. Their high evaluation wasinclinedtowardsthe training and promotion opportunities, working condition, co-worker relationship, and work nature. The average mark of bonus - welfare was the lowest. All of seven variables formulated after EFA had statistically significant effect on job satisfaction of the workers.