The apple snail Pomacea canaliculata becomes a much more serious pest in direct-sown rice fields than in transplanted fields. In south Japan, it represents an important constraint on the implementation of direct seeding. Described here are possible measures to control the snails and suggestions for its management in Japanese direct-sown rice fields. Crop rotation with upland crops is a practical way with the lowest extra cost. The apple snails were often not eradicated by growing an upland crop in the previous summer. However, snail densities always decreased below the control threshold in direct-sown fields (0.5 snails/m²). Longer drainage period after sowing greatly reduced snail damage. Thus,draining fields for 10 to 20 days after sowing is a basic practice to control snails in direct seeding. Tillage and puddling have a function to crush snails and, thus, reduce snail densities. “Intensive tillage”, in which a field with compacted hard soil is tilled shallow with faster cultivator rotation, achieved higher snail mortality. It is recommended to lower the risk of snail damage after unexpected heavy rain. An application of bait type metaldehyde showed enough control effects to avoid rice damage by snails even in heavy rain conditions. The stable effects seemed to be due to the active ingredient in the bait type which is dissolved slowly. Improving techniques for weeding and for draining fields effectively are necessary for better snail management in direct seeding.

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The objective of this study was, using the data of field experiment and visualization of internal airflow,to clearly understand forced ventilation of a piglet house with perforated ceiling which was very popular in Korea. This study was conducted at a commercial piglet house to investigate the performance of the forced ventilation and determine the effect of the ventilation system on internal airflow, air temperature, humidity, dust, and gas in the piglet house. The internal airflow patterns were studied with the help of computational fluid dynamics (CFD). Comparing the recommended maximum ventilation rate and measured ventilation rate, the ventilation system of the piglet house was 16% overestimated. The air temperature measured at 0.8 m from the floor in a compartment of the piglet house was always higher than the setting temperature while relative humidity, dust, and ammonia gas were controlled pretty well during data collection. Compared to the measured air velocities at piglet location in the compartment, the CFD computed results showed 10-18% error. The CFD computed results without piglets showed that the maximum air velocities at piglet location were 0.06, 0.55, and 0.95 m/s, respectively for 5, 50, and 100% of ventilation settings. Observing the dilution of internal relative humidity of the time-dependent CFD model, very poor environmental conditions were found at both end wall areas compared to the other areas of the compartment.

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A PCR-RFLP-based method of species identification was considered for 5 Japanese species of Orius Wolff flower bugs, Orius strigicollis (Poppius), O. minutus (Linnaeus), O. sauteri (Poppius), O. nagaii Yasunaga, and O. tantillus (Motschulsky). Nucleotide sequences of the internal transcribed spacer 1 of the nuclear ribosomal gene and a portion of mitochondrial cytochrome oxidase subunit I gene were compared among species and recognition sites of diagnostically useful restriction enzymes were examined. The PCR-RFLP analysis using 108 individuals of 26 laboratory strains confirmed that the 5 species could be correctly identified by banding patterns generated using these DNA regions. Because our PCR primers can amplify DNA fragments from DNA template extracted from both freshly killed insects and dried specimens stored at room conditions, the PCR-RFLP-based method was considered useful for analyses of field populations in which researchers store and accumulate field-collected samples before they perform laboratory examinations.

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In establishing a technology system for labor saving in cabbage production, the most important issues are streamlining harvesting, reducing the work load, and reducing the amount of time required. We developed a mechanized trailer-supported harvesting system for cabbage growers in upland field areas. The system will benefit family-managed farms. The system, which requires only three people to operate, consists of a harvester, remote-controlled tractor, and a trailer, where the cabbage can be processed, boxed and palletized. We investigated the suitability of this system from the point of work efficiency, ergonomics, and farm management through trials on a commercial farm. This article presents the results of the field tests of the system.

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It has been stated that the quality of the aromatic rice variety, Khao Dawk Mali 105 is influenced by the environment of the production area or cultivation method. In this study, 2-acetyl-1-pyrroline content of various rice samples in Thailand was investigated. The results showed that the samples from the Northeastern region, where Khao Dawk Mali 105 was cropped in rain-fed paddy fields, were higher in 2-acetyl-1-pyrroline content. The “Tungkularonghai” area, stated as being the highest quality rice production area, had the highest content among the areas in Northeastern Thailand. Samples collected from non-drought condition areas showed lower content even in the Tungkularonghai area. However, differences in seeding method did not affect 2-acetyl-1-pyrroline content in the Tungkularonghai area. These results showed that dry climate might be a factor for 2-acetyl-1-pyrroline content in Khao Dawk Mali 105. Since Khao Dawk Mali 105 is a photosensitive variety, it was expected that the ripening stage becomes uniform at a certain period which should be suitable for 2-acetyl-1-pyrroline formation in paddy fields.

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Probiotics are viable microorganisms that exhibit beneficial effects on the health of the host when they are ingested. In Asian areas including Japan, various fermented vegetable foods are produced and actively consumed in our meals. In the present study, we isolated lactococci from plant materials (fermented vegetables, silage and plants) and investigated their probiotic activities, such as tolerance to bile and the ability to remove cholesterol. A total of 411 lactic acid bacteria strains were isolated from plant materials. Out of the strains, 27 strains were identified as Lactococcus lactis subsp. lactis by phenotypic tests and a PCR-based method. Among them, 12 strains were subjected to further study. All lactococci tested could grow in broth containing 0.3% bile, and removed cholesterol from media during growth. These results showed that the lactococcal strains isolated from plant materials had probiotic activities.

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To evaluate the ability of lactic acid bacteria (LAB) strains for making good quality silage in tropical regions, a silage fermentation model system was constructed by modifying a pouch method. Enterobacter sp. SG 1-1T and Saccharomyces cerevisiae SG 2-1Y, both isolated from Guinea grass silage,were used together with the LAB strain in the modified pouch method as typical silage coliform bacterium and yeast, respectively. For the silage material, autoclaved Napiergrass (Pennisetum purpureum Schumach.) was used. Two strains, LG 2-1 and N-22, used as model LAB strains grew well in this model system (modified pouch method) and their growth properties were strongly influenced by the inoculum size of each microorganism. From these results, this modified pouch method seems to be useful for the screening of LAB strains to make good quality silage in Thailand.

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The effect of a commercial inoculant on the fermentation quality of silage made from agricultural byproducts (ABP silage) prepared in Thailand was examined. By adding an inoculant, the pH of silage became low and the counts of yeast and clostridia in silage decreased in comparison with the silage without inoculant. The effect of temperature against the inoculant was also examined by using a modified pouch method. The addition of inoculant provided good quality silage at 30°C. However at 45°C, the addition of the inoculant resulted in a remarkable decrease in the amount of lactic acid produced and an increase in pH about 0.6-0.8 with no good quality silage produced. From these results, it was suggested that the inoculant used in this study was effective for improving the fermentation quality of ABP silage in Thailand at temperatures less than 37°C, but was not effective at 45°C.

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A deep-sea video monitoring system on a towed sledge was used in Pacific coastal waters of northern Japan at depths ranging from 440 to 700 m to estimate the density and the spatial distribution of kichiji rockfish Sebastolobus macrochir. Thirty observations were completed at 24 survey sites in daytime during May and June in 2001. A seafloor area of 86,160 m² was surveyed, and 253 kichiji rockfish were observed. Most of the fish showed no behavioral response to this system. Densities ranged from 0 to 11 fish/1,000 m² (mean 2.94 fish/1,000 m²). Kichiji rockfish stayed on the seafloor as solitary individuals. Only 4.9% of kichiji rockfish was situated less than 5 m to other kichiji rockfish, 3.5% occurred between 5 and 10 m to other fish and the remaining 91.6% was more than 10 m away from other fish. Of the 253 kichiji rockfish, 209 were small (5-9.9 cm) and 44 were more than or equal to 10 cm. Most of the small fish were between one year and two years old. Kichiji rockfish would be distributed as solitary individuals at least from one year old. The method to estimate the density of the kichiji rockfish using this system is effective for stock assessment.

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The objective of the study is to evaluate the use of integration of spectral and textural features derived from IKONOS imagery to identify agricultural land cover types in a mountainous case study area in Pangalengan, West Java, Indonesia. The study includes image preprocessing, development of an image quantization method, calculation of textural measures, development of data sets and an accuracy assessment. Image preprocessing focuses on image registration and topographic normalization. Topographic normalization is conducted to minimize the effect of illumination differences on surface reflectance. In this study, two image quantization methods, i.e. image segmentation and averaging filtered were developed. The image segmentation method classifies the image into several segmentations based on a determination of the total number of pixels per class, while the averaging filtered method classifies the image based on the average of the digital number values within a window size. Four textural measures, inverse difference moment, contrast, entropy and energy, were calculated based on the gray level co-occurrence matrix (GLCM). The results indicate that a combination of spectral and textural aspects significantly improves the classification accuracy compared with classification with pure spectral features only. Image segmentation and averaging filtered methods can reveal more effectively spatial forms of agricultural land cover types than using a 256 gray-level scale. The overall accuracy increased 11.33% when using the integration of spectral and multiple textural features of inverse difference moment (5×5) and energy (9×9).

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