Time filter

Source Type

Poolkhet C.,Kasetsart University | Chairatanayuth P.,Kasetsart University | Thongratsakul S.,Kasetsart University | Thanapongthum W.,Ministry of Agriculture and Co operative | Rakkwamsuk T.,Kasetsart University
Kasetsart Journal - Natural Science | Year: 2012

Highly pathogenic avian influenza (HPAI) H5N1 is an infectious disease that can be transmitted from animals to humans. The disease is widely spread throughout the world, including Thailand. Many researchers have studied the risk factors associated with the presence of H5N1 and spatial techniques are commonly used for evaluation. The present study investigated outbreaks of HPAI H5N1 in Thailand between January 2004 and November 2005 using kernel smoothing and Kulldorff's scan statistics. A total of 1,493 HPAI H5N1 outbreak points from 288 districts in 60 provinces around Thailand were recorded using national outbreak data. For the kernel smoothing, the provinces with the highest risk were Phitsanulok, Phichit, Suphan Buri, Ang Thong, Samut Prakan, Bangkok, Chon Buri, Kamphaeng Phet and Saraburi. Kulldorff's spatial scan statistics showed that the high-risk districts were in the central and lower northern parts of Thailand. The findings confirmed that central Thailand had the highest risk for HPAI H5N1 outbreaks. The appropriate authorities should focus on this area for disease control and prevention, and should pay special attention to this area when outbreaks occur in neighboring countries. This may help authorities to prevent outbreaks or decrease the magnitude of outbreaks when they occur.

Clermont-Dauphin C.,IRD Montpellier | Clermont-Dauphin C.,Ministry of Agriculture and Co Operative | Suvannang N.,Ministry of Agriculture and Co Operative | Pongwichian P.,Ministry of Agriculture and Co Operative | And 6 more authors.
Agriculture, Ecosystems and Environment | Year: 2016

Rubber tree plantations (Hevea brasiliensis) are expanding into marginal areas with low soil fertility and long dry seasons with a high risk of soil erosion and drought damage to trees. Introducing an N2-fixing legume cover crop in rubber plantations may reduce runoff and soil erosion as well as increasing the availability of nutrients but may also increase competition for water. This study quantified the effect of the legume cover crop Pueraria phaseoloides on N, P and K nutrition, water status and growth of young rubber trees (three years old in 2007) over a four year period (2007-2010). The plantation was located on a toposequence with a range of soil depths and water storage capacities in northeast Thailand.The legume aboveground biomass production and its nutrient content and decomposition rate were measured and the N2 fixation was estimated using the abundance of 15N (δ15N) in the legume. Measurements were taken of the tree stem girth and height and tree leaf predawn water potential, nutrient content and greenness. The transfer of N2 fixed by the cover crop to the trees was estimated using δ15N in the tree leaves.The annual biomass production of the legume was 8Mgha-1 year-1 and the N accumulation by the legume was 250kg N ha-1 year-1. The natural abundance method applied to the aboveground components of the legume gave N2 fixation rates varying from 85 to 93% depending on the year. The leaf δ15N was similar in the three non-legumes (H. brasiliensis, Vetiveria zizanioides and Praxelis clematidea) used as reference plants for estimating the N2 fixation. The higher level of N and the much lower leaf δ15N values for the rubber trees intercropped with P. phaseoloides, compared to rubber trees growing without a legume cover crop, showed that there was a relatively high transfer of fixed N from the legume to the trees, varying from 39% to 46% of tree leaf N depending on the year. Neither N2 fixation nor N transfer varied significantly along the toposequence. At the bottom of the toposequence, both the nutrient (N, P and K) and water status of trees was significantly improved with the legume cover crop, doubling the tree girth at seven years of age (tree girth: 28cm, tree height: 700cm). However, at the top of the toposequence with low water storage capacity, the legume cover crop improved tree nutrition and growth but reduced the trees' ability to survive intense drought.These results raise concern about the resilience to drought of the rubber tree/. P. phaseoloides system, since the positive effect of the legume on rubber tree nutrition and growth may increase the risk of water stress and tree mortality. With future changes in climate, an increasing number of areas will be concerned by the question of optimizing the tradeoff between N inputs and water availability. © 2015.

Clermont-Dauphin C.,IRD Montpellier | Clermont-Dauphin C.,Ministry of Agriculture and Co operative | Suvannang N.,Ministry of Agriculture and Co operative | Hammecker C.,IRD Montpellier | And 6 more authors.
Agronomy for Sustainable Development | Year: 2013

Rubber tree cultivation is presently expanding rapidly into dry subhumid areas. As a consequence, trees face a long dry season. Low growth rates are delaying the start of tapping. The relationship between the growth rate and the soil water availability is not clear. Therefore, we studied the origin of low growth rates. For that we analyzed the relationships between growth, plant water stress, and soil water availability along a toposequence with a soil depth gradient. The plantation of 3-year-old Hevea brasiliensis trees was located in northeast Thailand. Tree circumference, predawn leaf water potential (p), soil water potential (s), and micrometeorological parameters were monitored from 2007 to 2010. Results show spatial and temporal variability of growth with a threshold value of leaf water potential of -0.4 MPa for growth. This leaf water potential threshold was not associated with very dry soils as soil water potentials were higher than -0.05 Mpa. But the leaf water potential threshold was associated with a high air vapor pressure deficit higher than 3-4 kPa. Leaf water potential decreased when the soil at the bottom of the slope was saturated in the rainy season. These results provide, for the first time, evidence that soil water shortage is unexpectedly not the main cause of low growth rates. Dry air in the dry season and waterlogging in rainy season are major constraints. © 2013 INRA and Springer-Verlag France.

Thavong P.,Chiang Mai University | Archbold D.D.,University of Kentucky | Pankasemsuk T.,Chiang Mai University | Koslanund R.,Ministry of Agriculture and Co operative
International Journal of Food Science and Technology | Year: 2010

The effects of postharvest treatment with hexanal vapour on longan fruit decay, quality, hexanal residue, phenolic compound content, and polyphenoloxidase (PPO) and peroxidase (POD) activities were studied during storage at 5 °C for 30 days. Hexanal exposure for 2 h at 900 μL L-1 before cold storage reduced the percentage of fruit with decay and was deemed the optimum treatment. Hexanal exposure resulted in a pericarp that was more reddish brown and less intense in colour. Hexanal residue in the pericarp and aril of fumigated fruit was several fold higher than that of nonfumigated fruit, although levels were low at the end of cold storage. Electrolyte leakage of pericarp increased during 5 °C storage and was further increased by hexanal exposure. Hexanal reduced pericarp phenolic content, and increased PPO and POD activities. Overall, use of hexanal vapour reduced postharvest disease of longan fruit but increased the likelihood of pericarp browning. © 2010 The Authors. International Journal of Food Science and Technology © 2010 Institute of Food Science and Technology.

Thavong P.,Chiang Mai University | Archbold D.D.,University of Kentucky | Pankasemsuk T.,Chiang Mai University | Koslanund R.,Ministry of Agriculture and Co operative
Chiang Mai Journal of Science | Year: 2011

Longan (Dimocarpus longan Lour.) fruit have a very short postharvest shelf life due to microbial decay and exocarp browning. The most common commercial means for prevention of longan fruit rot and browning is SO2 fumigation, but it is facing food safety regulations and alternatives are needed. The aims of this study were to determine if the natural volatile hexanal could inhibit mycelial growth and spore germination of common longan decaycausing fungi, and if hexanal could affect fungal-derived cell-wall degrading enzymes that are involved in pathogenicity. Four common longan fruit decay fungi, Lasiodiplodia theobromae; Pestalotiopsis sp.; Phomopsis sp.; and Curvularia sp., were exposed to hexanal vapour, and mycelial growth in vitro was measured. Also, hexanal vapour effects on spore germination, mycelial morphology, and activity of extracellular enzymes of L. theobromae were studied. L. theobromae growth was completely suppressed at a lower hexanal volume than the other fungi. Fumigation for 1 h with 15 μL hexanal per Petri dish was enough to completely suppress L. theobromae, with lower volumes for 1 to 48 h resulting in variable levels of suppression but not fungicidal effects. Spore germination was inhibited at 5 μL per dish for only 1 h, and the effect was fungicidal at greater than 15 μL. Hexanal vapour appeared to induce cell swelling with greater vacuolation and more mycelial branching of L. theobromae. Extracellular cellulase activity was reduced more than 80% by hexanal, but pectin methylesterase, polygalacturonase, and cutinase activities were not affected.

Loading Ministry of Agriculture and Co operative collaborators
Loading Ministry of Agriculture and Co operative collaborators