Vol. 1 No. 1 (2018): Vietnam Journal of Agricultural Sciences

The objectives of this study were to evaluate the effects of nitrogen forms on root system development (expressed as total root length, nodal root number, nodal root length, and lateral root length), water use, photosynthetic rate, and dry matter production under water deficit (WD) at 20% w/w and continuously waterlogged (CWL) conditions. Rice plants cv. Nipponbare were grown in plastic pots in a vinyl house. Six N forms were applied at the same rate of 360 mg N per pot, and were prepared as follows: N-NH4+ alone (A); N-NH4+ with nitrification inhibitor (A+DCD); N-NO3- alone (N); N-NO3- with nitrification inhibitor (N+DCD); combined N-NH4+ and N-NO3- (AN); and combined N-NH4+ and N-NO3- with nitrification inhibitor (AN+DCD). The nitrification inhibitor, dicyandiamide (DCD) (C2H4N4), was applied at the rate of 100 mg pot-1. The results of the experiment showed that under both WD and CWL conditions, significant increases were seen in the root system development as expressed through total root length, nodal root number, nodal root length, and lateral root length in the N-NO3- treatments with and without DCD compared to the application of N-NH4+ treatments with and without DCD. This led to an increase in water use, and eventually a significant increase in dry matter production. Similarly, the A treatments with and without DCD also significantly increased root system development as compared with the AN and AN+DCD treatments. Furthermore, under both CWL and WD conditions, the positive and notably significant correlations between the total root length and water use, as well as between the total root length and shoot dry weight, were found only in the A and A+DCD treatments. These results indicate that rice prefers sole ammonium over the mixed ammonium-nitrate treatment, and sole nitrate applications under both WD and CWL conditions.

The objective of this study was to determine the effects of 2,4-Dichlorophenoxyacetic acid (2,4-D) combined with 6-Benzylaminopurine (BAP) and sucrose on the shoot and root regeneration of Paph. micranthum var. North Vietnam. Young fresh leaves were cut into small explants and then cultured on media containing 2,4-D (0.5, 1.0, or 2.0 ppm). Within each of the 2,4-D concentration, BAP was added at three different concentrations (0.5, 1.0, or 2.0 ppm) for callus induction after 4 weeks. Shoot tips (2-3 mm in length) from the leaf-derived calluses were then transferred vertically on half-strength MS medium (2,4-D combined with BAP (0.5, 1.0, or 2.0 ppm) for shooting, and rootless shoots with 2 leaves were transferred to the same MS medium for rooting after 4 months of culture. Rootless shoots with 2 leaves were also transferred vertically on half-strength MS medium with different sucrose concentrations (0, 10, 20, 30, or 40 g L-1) to optimize the growth and development of the plantlets. The results indicated that the optimum degree of shoot and root regeneration occurred on half-strength MS medium containing 2.0 ppm 2,4-D combined with 2.0 ppm BAP. Approximately 86.6% of the cultures responded with 3.3 shoots and 3.0 leaves/explant. In addition, under the optimal concentrations, the number and length of roots per explant after 4 months of culture were 2.1 roots per explant and an average root length of 1.1 cm. MS medium supplemented with 30 g L-1 sucrose had the highest number of leaves and roots, and also the longest average length of roots, which gave 3.8 leaves, 3.3 roots/explant, and a root length of 1.8 cm after 4 months.

This study proposes the methodology and process to develop a Key Performance Indicators (KPIs) system in urban planning by utilizing the logic model. Firstly, the study introduces the role of KPIs in urban planning for measuring the performance of the whole planning process, and the logic model as a powerful tool for selecting KPIs, as well as the ability to apply it in urban planning issues. Secondly, methodologies are given, including: building a KPIs system from the logic model’s components, data collection for KPIs, and data analysis. Thirdly, the case of the Hanoi master plan is presented, to investigate how the logic model works for KPIs development. The process of the logic model application includes: identification of planning policies; zoning Hanoi for the simulation of the policies’ effects; utilizing the logic model for selecting KPIs; analysis of logical linkage between the logic model’s components; and Hanoi urban data availability for KPIs.

Zero valent iron (ZVI) nanoparticles have been considered as effective materials for environmental remediation because of their strong reducing ability, high reaction activity, and excellent absorption properties. In this study, we synthesized iron nanoparticles using an environmentally friendly method in order to treat Cr(VI) ions in an aqueous medium. Polyphenols from green tea leaf extracts were used as both the reducing agent and the stabilizer for ZVI nanoparticles. Modern techniques, including scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and infrared spectroscopy (FTIR), confirmed that ZVI nanoparticles were successfully prepared and surrounded by polyphenol molecules. Cr(VI) ion treatment of the nanoparticles was most favorable at pH 2.0, and 0.04 g ZVI nanoparticles for a 50 mg L-1 Cr(VI) solution. Under some treatment conditions, removal efficiency was 100%, suggesting that the synthesized ZVI nanoparticles can be used as materials for Cr(VI) ion removal.

Honeydew melon (Cucumis melo L.) is a highly nutritious fruit, but its climacteric respiration property leads to rapid quality degradation, a short shelf-life, and low marketability. The objective of this study was to evaluate the effects of Aloe vera gel coating on postharvest quality of honeydew melon cv. Ngan Huy under atmospheric conditions. The fresh fruits were completely immersed into Aloe vera gel solutions at different concentrations of 30%, 40%, 50%, 60%, and 70% at room temperature for 5 minutes. Tween 80 0.05%, CMC 1%, and glycerol 2% were added in the coating solutions. Thirty-six fruits were used in each treatment. The weight loss, firmness, respiration, and ethylene production rates, total soluble solids (TSS) and vitamin C content, and the rate of fruit spoilage were measured during storage to determine the efficacy of the Aloe vera gel in maintaining the postharvest quality of the honeydew melon fruits and protecting them from deterioration. Uncoated fruits exhibited significantly greater changes (P<0.05) in weight loss, firmness, respiration, ethylene production rates, TSS, and vitamin C content compared to coated fruits. Fruits coated with 60% or 70% Aloe vera gel exhibited the smallest changes (P<0.05) in all the tested parameters. Based on the changes of the overall quality characteristics, application of an edible coating with 60% or 70% of Aloe vera gel were considered to be the most suitable practice to maintain the quality of honeydew melon.

In this study, experiments were performed to identify and screen Streptomyces strains that are antagonistic to Aeromonas hydrophila, which causes hemorrhagic disease in fishes. Among 80 isolates, 3 strains capable of antagonizing Aeromonas hydrophila by the agar diffusion plate method were obtained. The strain numbered 1083 had a strong activity with a 25 mm diameter clear zone of bacteria. This strain showed grey colonies after 7 days of incubation. After 7 days of incubation, the grey colonies had white borders, produced soluble pigments on the medium, grew well at 30°C and neutral pH, and adapted well to medium containing a high salt concentration. Strain 1083 was able to utilize different sources of carbon and nitrogen. Sequence analysis of 16S rRNA showed that strain 1083 had a similarity of 99% compared to Streptomyces antibioticus. Based on morphological, physiological, and biochemical characteristics, as well as molecular biological analysis, strain 1083 was identified as Streptomyces antibioticus.

The paper presents an integrated wireless sensing system for monitoring environmental parameters, including temperature, relative humidity, and light intensity in mushroom houses. The developed system not only collects spatial environmental data but also enables end-users to remotely observe them via smart devices. Assembly of five sensornodes with a wireless sensor network was used to  gather data. The results have shown relatively accurate measurements in terms of environmental parameters. The system is low cost, simple and easy to operate by displaying the native language in interface monitoring software. Therefore, the generated system should be applied in monitoring air temperature, humidity, and light intensity in mushroom houses. Additionally, this study has provided good opportunities for Vietnamese farmers to approach the high technology application in agriculture.

Orange is one of the world’s most important economic fruit crops. Orange is the local fruit tree that has been cultivated for generations in Tuyen Quang province of Vietnam. Orange production has significantly improved the income of farm households and alleviated the rural poverty in Tuyen Quang in recent years. This paper aimed to investigate the actors involved in the orange supply chain in the province. The study used descriptive statistics and chain analysis methods to explore the problems in each stage of the orange supply chain. A total of 195 respondents including input suppliers, orange farmers, collectors, wholesalers, retailers, consumers, and public stakeholders were selected for direct interviews. The study revealed that the production and marketing of orange fruit in the province faces several constraints, such as spontaneous production, excessive supply, high seasonality, and difficulties in selling. There existed no preservation or processing facilities for oranges, resulting in high post-harvest losses. Oranges have been entirely consumed in domestic markets, not exported. In order to develop orange production and marketing in Tuyen Quang province towards concentrated commodity production, the study recommended feasible solutions for each stage as well as the whole of the orange supply chain.

Bac Kan is the mountainous province with the largest forest cover in Vietnam and forest dependence by rural households is of great significance. The objective of this study was to assess the situation of livelihood capitals, as well as their impacts on the poverty status of forest-dependent households in highland areas of Bac Kan province. Data were collected through direct interviews of 218 households living near forests in the districts of Ba Be and Na Ri. Descriptive statistics, comparison, logit model, student t-test, and chi-square test were used in this study. The results revealed that forest-dependence was high for poor households; the households’ livelihood capital was weak; and households with stronger livelihood capitals were primarily non-poor. The effect of livelihood capitals on household's poverty status was significant, and human and financial capitals had the strongest impact. The estimated logit model had high accuracy with 87.16% of observations correctly predicted. In poverty reduction programs, the state should improve the livelihood capitals, especially human and financial capitals, for the households in order to improve their welfare.

Barnyardgrass (Echinochloa crus-galli) is one of the most pernicious and problematic weeds in worldwide agriculture. The objective of this review is to highlight the morphology and habitats of this weed, and to present comprehensive information of the allelochemical constituents and pharmacological effects as well as its allelopathic interaction with rice (Oryza sativa L.) based on 115 worldwide literary resources reported over the last 40 years. In laboratory bioassays and root exudates experiments, barnyardgrass showed remarkable inhibition on the growth of the indicator plants. In greenhouse and field experiments, depending on the proportion density of barnyardgrass interference, rice yield is significantly reduced. Major isolated chemical constituents [including 59 compounds, belonging to phenolics, terpenes, steroids, lactones, long-fatty acids, and their derivatives] were identified and isolated from the different parts of this weed including root exudates and infested-soil, which are involved in allelopathic action. Among these, p-hydroxymandelic acids, diethyl phthalate, and two lactones [7,8-dihydro-5,6-dehydrokavain (DDK) and 7,8-dihydrokavain (DHK)], along with a gene cluster for the biosynthesis of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), may be responsible for the inhibitory effects of barnyardgrass in paddy fields. In attempts to elucidate the modes of action of these allelochemicals and allelopathic interactions between rice and barnyardgrass, it has been shown that the allelopathic actions of barnyardgrass and rice have similar responses in that they sense allelochemicals in the exudation of roots for enhancing allelopathic activity. However, the questions of which compounds play a main role in barnyardgrass allelopathy, and the actual modes of allelopathic interactions with rice remain unclear. This review may provide new insights into barnyardgrass’ adaptation and invasiveness as well as how the attributable interactions of all its present allelochemicals inhibit the growth of rice and the adjacent plants by allelochemical pathways.