Rubber Research Institute of Vietnam

Ho Chi Minh City, Vietnam

Rubber Research Institute of Vietnam

Ho Chi Minh City, Vietnam
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Duong T.T.T.,University of Adelaide | Duong T.T.T.,Rubber Research Institute of Vietnam | Verma S.L.,University of Adelaide | Penfold C.,University of Adelaide | Marschner P.,University of Adelaide
Geoderma | Year: 2013

Improved understanding of the effect of compost application on soil properties is critical for optimizing the desired effects of compost application. However there are no studies on the effect of composts on soil properties within the first centimetres of the compost layer. In this microcosm study three composts from different feedstocks, namely C1 (from animal manures) and C2 and C3 (from the organic fraction and municipal solid waste) were applied as a layer which was separated from the soil by a mesh. Microcosms without compost served as controls. Microbial and chemical properties of the soil were determined at 0-5 and 5-10. mm distance from the mesh after 30 and 63. days. During the 63 day incubation, the total C, N and P and available N concentrations in the composts decreased whereas the available P concentration increased. The composts induced higher microbial biomass and activity, total organic C and available N and P concentrations up to 10. mm into the surrounding soil with greater effects after 30 than after 63. days. The increase in nutrient concentrations was generally greater in soil adjacent to the two finer-textured composts with the higher nutrient concentration (C1 and C3) than in the coarser-textured compost (C2) which had lower nutrient concentrations, however the differences in nutrient concentrations in the soil were small compared to those among the composts. The 0-5 and 5-10. mm layers did not differ in most of the measured properties except for greater soil respiration and N and P availability in the 0-5. mm layer. It is concluded that composts release nutrients into the surrounding soil over a period of 2. months which increase nutrient availability and microbial activity, with the zone of influence extending at least 10. mm from the compost-soil interface. © 2012 Elsevier B.V.

Duong T.T.T.,University of Adelaide | Duong T.T.T.,Rubber Research Institute of Vietnam | Penfold C.,University of Adelaide | Marschner P.,University of Adelaide
Biology and Fertility of Soils | Year: 2012

Although the beneficial effects of compost on soil properties are well known, there are few systematic studies comparing the effects of composts on soils of different textures. The aim of this pot study was to assess the effects of a single application as mulch of two types of composts derived from different feedstocks, namely C1 (from garden waste) and C2 (from agricultural residues and manures) on three soils with different clay contents (46%, 22% and 13%, hereafter referred to as S46, S22 and S13) in terms of their physical, chemical and biological properties as well as on plant growth and nutrient uptake. The composts were placed as 2.5-cm-thick mulch layer on the soil surface, and wheat plants were grown for 35 days and to grain filling (70 days). The composts reduced the soil pH by 0.3-0.7 units, slightly increased total organic C, but increased soil electrical conductivity compared to unamended soil. Soil respiration was significantly higher in S13 than S46 in all treatments after 5 weeks. At grain filling, soil respiration was higher in S13 than in the other two soils and higher with C2 than with C1 and in the non-amended soil. The addition of compost significantly increased soil cation exchange capacity (CEC) in S22 and S46, but not in S13 which also had the lowest CEC among the soils. C2 increased the available P concentration and macro-aggregate stability in all soils compared to C1 and the unamended soil. Compost addition increased available N in S46 and S22 compared to the unamended soil with a stronger effect by C1. Both composts increased wheat growth and shoot P concentrations with the effect of C2 being greater than that of C1. It is concluded that the effect of composts varies with soil type as well as compost type and that this interaction needs to be taken into account when composts are applied to improve specific soil properties. © 2012 Springer-Verlag.

Duong T.T.T.,University of Adelaide | Duong T.T.T.,Rubber Research Institute of Vietnam | Penfold C.,University of Adelaide | Marschner P.,University of Adelaide
Plant and Soil | Year: 2012

Background: Composts with different feedstocks may have differential effects on soil properties and plant growth which, may be further modulated by soil texture. Materials and methods: In a 77-day pot experiment in the glasshouse, we investigated the effect of a single application as mulch of six types of composts derived from different starting feedstocks in two soils (13% and 46% clay, referred to as S13 and S46) on soil physical, chemical and biological properties, plant growth and nutrient uptake. Composts were placed as 2.5 cm thick mulch layer on the soil surface and wheat plants were grown and harvested at 42 days and at 77 days (grain filling). Results: Composts differed in total and available N and P and particle size with C1, C3, C4 and C5 being fine-textured, whereas C2 and C6 were coarse-textured. Compost addition as mulch increased soil total organic C and EC, but had no effect on pH. In all treatments, cumulative soil respiration was higher in S13 than in S46 and was increased by compost addition with the greatest increase with C2 and C6. Compared to the unamended soil, most compost mulches (except C2) increased macroaggregate stability. Compost mulches significantly increased available P and N in both soils, except for C2. Compost mulches increased available N up to 6-fold in both soils with the strongest increase by C5. Most composts also increased wheat growth and shoot P and N concentrations with the greatest effect on plant N concentration by C5 and on plant P concentration by C4. However, C2 decreased shoot N and P concentrations compared to the unamended soil. Most compost mulches (except C2) increased mycorrhizal colonization by up to 50% compared to the unamended soil. Conclusions: Fine-textured compost mulches generally had a greater effect on soil properties and plant growth than coarse-textured composts. Despite distinct differences between the soils with respect to clay content, TOC and available P, the effect of the compost mulches on soil and plant properties was quite similar. © 2011 Springer Science+Business Media B.V.

PubMed | CIRAD, Rubber Research Institute of Vietnam, Societe Africaine de Plantations dHeveas, Societe des Caoutchoucs de Grand Bereby and 2 more.
Type: Journal Article | Journal: PloS one | Year: 2016

An indirect phenotyping method was developed in order to estimate the susceptibility of rubber tree clonal varieties to Corynespora Leaf Fall (CLF) disease caused by the ascomycete Corynespora cassiicola. This method consists in quantifying the impact of fungal exudates on detached leaves by measuring the induced electrolyte leakage (EL%). The tested exudates were either crude culture filtrates from diverse C. cassiicola isolates or the purified cassiicolin (Cas1), a small secreted effector protein produced by the aggressive isolate CCP. The test was found to be quantitative, with the EL% response proportional to toxin concentration. For eight clones tested with two aggressive isolates, the EL% response to the filtrates positively correlated to the response induced by conidial inoculation. The toxicity test applied to 18 clones using 13 toxinic treatments evidenced an important variability among clones and treatments, with a significant additional clone x treatment interaction effect. A genetic linkage map was built using 306 microsatellite markers, from the F1 population of the PB260 x RRIM600 family. Phenotyping of the population for sensitivity to the purified Cas1 effector and to culture filtrates from seven C. cassiicola isolates revealed a polygenic determinism, with six QTL detected on five chromosomes and percentages of explained phenotypic variance varying from 11 to 17%. Two common QTL were identified for the CCP filtrate and the purified cassiicolin, suggesting that Cas1 may be the main effector of CCP filtrate toxicity. The CCP filtrate clearly contrasted with all other filtrates. The toxicity test based on Electrolyte Leakage Measurement offers the opportunity to assess the sensitivity of rubber genotypes to C. cassiicola exudates or purified effectors for genetic investigations and early selection, without risk of spreading the fungus in plantations. However, the power of this test for predicting field susceptibility of rubber clones to CLF will have to be further investigated.

Nguyen B.T.,Cornell University | Nguyen B.T.,Rubber Research Institute of Vietnam | Lehmann J.,Cornell University | Hockaday W.C.,University of New South Wales | And 2 more authors.
Environmental Science and Technology | Year: 2010

Global warming accelerates decomposition of soil organic carbon (SOC) pools with varying rates and temperature sensitivities. Black carbon (BC) materials are among the slowest decomposing components of the SOC pool. Although BC is a large component of SOC in many systems, the influence of temperature on decomposition of BC bearing different chemical and physical structures remains poorly understood. Four BC materials, produced by carbonizing corn residue and oak wood at 350 and 600 °C (corn-350-BC, corn-600-BC, oak-350-BC, and oak-600-BC), were mixed with pure sand and incubated at 4, 10, 20, 30, 45, and 60 °C for 1 year. Corn-BC was more porous than oak-BC as determined by scanning electron microscopy (SEM). Increasing the charring temperature from 350 to 600 °C led to greater aromaticity with 5-15% more C in aromatic rings and a 39-57% increase in both nonprotonated aromatic C and aromatic bridgehead C quantified by nuclear magnetic resonance (NMR) spectroscopy and a greater degree of order and development of C layers as observed by transmission electron microscopy (TEM). With a temperature increase from 4 to 60 °C, C loss of corn-350-BC increased from 10 to 20%, corn-600-BC, from 4 to 20%, oak-350-BC, from 2.3 to 15%, and oak-600-BC from 1.5 to 14% of initial C content, respectively. Temperature sensitivity (Q10) decreased with increasing incubation temperature and was highest in oak-600-BC, followed by oak-350-BC, corn-600-BC, and corn-350-BC, indicating that decomposition of more stable BC was more sensitive to increased temperature than less stable materials. Carbon loss and potential cation exchange capacity (CECp) significantly (p < 0.05) correlated with O/C ratios and change in O/C ratios, suggesting that oxidative processes were the most important mechanism controlling BC decomposition in this study. © 2010 American Chemical Society.

PubMed | Japan National Institute of Environmental Studies, Hanoi University of Science and Technology, Nagaoka University of Technology and Rubber Research Institute of Vietnam
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2017

Conventional aerated tank technology is widely applied for post treatment of natural rubber processing wastewater in Southeast Asia; however, a long hydraulic retention time (HRT) is required and the effluent standards are exceeded. In this study, a downflow hanging sponge (DHS) reactor was installed as post treatment of anaerobic tank effluent in a natural rubber factory in South Vietnam and the process performance was evaluated. The DHS reactor demonstrated removal efficiencies of 64.2 7.5% and 55.3 19.2% for total chemical oxygen demand (COD) and total nitrogen, respectively, with an organic loading rate of 0.97 0.03 kg-COD m

Ariff Z.M.,Universiti Sains Malaysia | Khang T.H.,Rubber Research Institute of Vietnam
Advanced Materials Research | Year: 2013

The possibility of using Cadmould software to simulate the filling behaviour of a natural rubber compound during an injection moulding process was investigated. For the simulation process, the determination of required material input data involving the rheological and cure kinetics data of the designed rubber compound were conducted. It was discovered that the acquired data were able to function as reliable material input data as they were comparable with related data available in the Cadmould software materials' database. Verification of the simulated filling profiles by experimental short shots specimens showed that the Cadmould Rubber Package was able to predict the realistic filling behaviour of the formulated natural rubber compound inside the mould cavity when the measured material data were utilized. Whereas, the usage of available material database from the software failed to model the mould filling progression of the intended natural rubber compound. © (2013) Trans Tech Publications, Switzerland.

Duy N.Q.,Universiti Sains Malaysia | Duy N.Q.,Rubber Research Institute of Vietnam | Rashid A.A.,Universiti Sains Malaysia | Ismail H.,Universiti Sains Malaysia
Polymer - Plastics Technology and Engineering | Year: 2012

Cassava starch-filled natural rubber (NR) composites were prepared by using direct blending and co-coagulation method. The effects of two different method and cassava starch loading on morphology, mechanical properties and thermal properties of cassava starch/NR composites were studied. X-ray diffraction results and scanning electron microscopy images proved that co-coagulation method promotes better dispersion of cassava starch than direct blending method. The composites prepared by co-coagulation method exhibited higher values of tensile strength, tear strength, hardness, and thermal stability. The optimum value of tensile strength and tear strength of cassava starch/NR composites were achieved at a 10 phr cassava starch loading. © 2012 Copyright Taylor and Francis Group, LLC.

Nguyen B.T.,Rubber Research Institute of Vietnam
Industrial Crops and Products | Year: 2013

Investigation of elevation dependence of latex productivity of natural rubber (NR, Hevea brasiliensis Mull. Arg.) plantations and determination of elevation thresholds for landuse management are an urgent need of study. The current study was, therefore, conducted, aiming to investigate attitudinal gradient of NR production in Vietnam. The study was based on 146,000ha of harvested NR plantations located from the southeast region to highland. There were 45 NR clones planted in the areas studied and GT1, the clone planted with a largest portion, was examined separately from the other 44 clones, combined in processing (the Rest). Three main variables, latex productivity, individual yield and tapping density were calculated for two tapping periods, from year 1 to 10 (1-10) and from year 11 to 20 (11-20). Over the investigated elevation range, 15-738m, the latex productivity declined at different rates, 109 for GT1 (1-10), 127 for GT1 (11-20), 110 for the Rest (1-10) and 117kgha -1year -1 for the Rest (11-20) for every 100-m increase in elevation. An S-like curve, obtained by fitting latex productivity along the altitudinal gradient using 3-order polynomial could be separated into three stages, of which the first and the last stages were characterized with a rapid drop of, and the middle was with a stability of, latex productivity. With a rise in elevation, tapping density (tapped treeha -1) and individual yield (kgtree -1year -1) significantly declined. As tapping density increased, individual yield declined whereas latex productivity rose. The results indicated that not all lands are suitable for a good NR production and that only areas with elevation under a certain magnitude depending on individual NR clones should be considered for NR cultivation. The altitudinal gradient of NR production could involve a number of soil and climatic variables, which need to be further investigated. © 2012 Elsevier B.V.

Khang T.H.,Universiti Sains Malaysia | Khang T.H.,Rubber Research Institute of Vietnam | Ariff Z.M.,Universiti Sains Malaysia
Journal of Thermal Analysis and Calorimetry | Year: 2012

Vulcanization kinetics of natural rubber (NR) compounds with efficient vulcanization system was studied through phenomenological approach using the experimentally cure data obtained from a moving die rheometer. The cure kinetic parameters were defined using the proposed models by Claxton-Liska and Deng-Isayev with the support of curve fitting software. The effects of the amount of accelerators, sulfur and silica in the formulations on the cure characteristics and cure kinetic parameters at high cure temperatures were investigated. Kinetic data results showed that the above two models were able to describe the curing behaviour of the studied compounds satisfactorily. It showed that the fitting of the experimental data with Claxton-Liska and Deng-Isayev could provide a good platform to investigate the cure kinetics of the prepared NR compounds. © Akadémiai Kiadó, Budapest, Hungary 2011.

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