Locations In Taiwan Research Articles

Radioactivity concentrations of 137Cs and 40K in basidiomycetes collected in Taiwan

Radioactivity concentrations of 137Cs and 40K in 64 mushroom samples belonging to 16 species of basidiomycetes collected at various locations in Taiwan have been measured in 1994. All of the samples were mushrooms cultivated indoors. The concentrations of 137Cs in many samples were below the limit of detection (< 1.0 Bq kg −1 dry weight), and 134Cs was not detected in any of the samples. The radioactivity concentration ranges of 137Cs and 40K in basidiomycetes were < 1.0–7.3 Bq kg −1 dry weight and <50–1230 Bq kg −1 dry weight, respectively. The transfer factors of F. velutipes, G. lucidum and L. edodes from sawdust (growing substrate) to mushroom were ∼ 10, 10.2, <3.8 for 137Cs, and 7.2, 1.6, 1.8 for 40K, respectively. The effective dose equivalent due to the dietary intake of radiocesium through mushrooms for the Taiwanese people was estimated to be only 4.4 × 10 −10 Sv y −1.

Effects of intercropping and soil amendment with urea and calcium oxide on the incidence of bacterial wilt of tomato and survival of soil‐borne Pseudomonas solanacearum in Taiwan

Intercropping and soil amendment experiments were conducted to determine if they reduced populations of Pseudomonas solanacearum and bacterial wilt of tomato at the Asian Vegetable Research and Development Center (AVRDC) and at three other locations in Taiwan. At AVRDC, intercropping tomato with cowpea planted within the row significantly reduced bacterial wilt (P &lt; 0.05) compared to when tomato was cropped alone. The P. solanacearum population in soil was not affected by intercropping with cowpea, soybean, or Welsh onion.At the same site, however, a preplanting soil amendment consisting of urea (200 kg ha−1 N) and CaO (5000 kg ha−1) significantly reduced the pathogen population and tomato bacterial wilt (P &lt; 0.001). The effect of the soil amendment was not consistent when applied to soil from three other sites in Taiwan; in soil from two sites no reduction of the pathogen population occurred. At these sites, tomato bacterial wilt in the field was not reduced significantly after amending. In comparison with a non‐amended control, the addition of only CaO reduced the P. solanacearum population in AVRDC soil significantly (P &lt; 0.05), but the reduction was significantly greater when the complete soil amendment was added. In contrast, urea alone did not affect the survival of P. solanacearum in the soil. In a greenhouse experiment with AVRDC soil, P. solanacearum was undetectable 2 weeks after soil amendment, but in the same treatment tomato yield was significantly reduced by 48% (P &lt; 0.05) compared with non‐amended treatments. The suppressive effect of the soil amendment on the P. solanacearum population was probably due to the generation of one or several toxic substances during the transformation of urea in the presence of CaO.

Variable Reaction of Tomato Lines to Bacterial Wilt Evaluated at Several Locations in Southeast Asia

Bacterial wilt (BW), caused by Pseudomonas solanacearum E.F. Smith, is one of the most destructive disease of tomato (Lycopersicon esculentum Mill.) in the tropics. Twenty tomato lines/accessions previously identified as BW-resistant were evaluated for BW reaction in fields providing high disease pressure at Subang, Indonesia; Los Baños, Philippines; Malaysian Agricultural Research and Development Institute (MARDI), Kuala Lumpur; Asian Vegetable Research and Development Center (AVRDC), Taiwan; and Taiwan Seed Improvement and Propagation Service (TSIPS). Entries also were tested in the greenhouse at the AVRDC with a P. solanacearum strain from Taiwan (Pss4) using a drench inoculation method. Objectives of the study were to identify stable sources of BW resistance for southeast Asian tomato breeding programs, and to determine the correlation between field and greenhouse reactions. Mean entry survival was 21.6% at Subang, 31.9% at Los Baños, 76.7% at the AVRDC, 93.6% at Malaysia, and 93.3% at TSIPS, indicating that most entries were resistant at MARDI and the Taiwan locations but susceptible at Subang and Los Baños. L285 (mean survival = 83.8%) and CRA 84-58-1 (mean survival = 79.4%) were the most resistant entries in the field trials. Mean survival (70.1%) of CRA 66-derived entries was significantly better than the mean of entries with resistance derived from UPCA 1169 or UPCA 1169 plus `Venus' or `Saturn'. Mean survival of AVRDC entries bred in the 1980s (59.4%) was significantly greater than mean survival of AVRDC lines bred in the 1970s (45.7%). The correlation between entry BW percent survival averaged over the five field trials and entry means from drench inoculation in the greenhouse was highly significant (r = 0.70), suggesting that the drench inoculation method is effective in selection for BW resistance.

Microflora and tetrodotoxin-producing bacteria in a gastropod, Niotha clathrata

Shellfish ( Niotha clathrata) were collected in both July and November from three locations in Taiwan (Pingtung, Kaohsiung and Chiai Prefecture) and assayed for anatomical distribution of tetrodotoxin (TTX) and aerobic heterotrophic bacteria. Pingtung specimens showed higher toxicity than those from Kaohsiung and Chiai, and did not show much seasonal variation. At each site, the total aerobic bacterial counts in November samples were higher than in July. The predominant genera were Vibrio, Pseudomonas, Pasteurella, Aeromonas and Plesiomonas. Vibrio comprised more than 35% of the genera, with V. alginolyticus as the major species. The viable counts of Vibrio species were higher in November than in July. However, the results did not suggest any relationship between the total count or viable count and the toxicity of the shellfish. HPLC, UV and gas chromatographic-mass spectrometric analyses demonstrated that some of the bacteria isolated, such as V. alginolyticus, V. parahaemolyticus, Pseudomonas spp., Plesiomonas sp. and Aeromonas sp., produced TTX and/or related substances.

Measurement of the Taiwan Ambient Trace Gas Concentration by Kilometer-Pathlength Fourier-Transform Infrared Spectroscopy

A portable open long-path Fourier-transform infrared system (POPFT-IR) operable at pathlengths of up to 961m has been constructed for the detection and measurement of trace gases in ambient air and for photochemical smog formation studies. The long optical path is achieved by using a three-mirror multiple reflection cell with a 15.5m base path. The combination of a retro-reflection mirror with one of three mirrors eliminates any air-turbulence interference. The design, construction, advantage, and use of this novel folded open-path optical system and calibration spectrum for quantitative analysis are described in detail. Preliminary ambient air measurements were made at a variety of locations in Taiwan from urban, suburban and rural to remote areas. The existing trace gases in the background atmosphere were measured as nitrous oxide (N2O), methane (CH4), carbon monoxide (CO) and carbon dioxide (CO2). Major pollutants such as ethylene (C2H4), propylene (C3H6), ammonia (NH3), ozone (O3) and peroxyacetyl nitrate (PAN) were measured in the polluted urban atomosphere.

The distribution and influence of heavy metals in mangrove forests of the Tamshui Estuary in Taiwan

Abstract The Tamshui estuary area is one of the few locations in Taiwan where mangroves are still growing. Heavy metals are generally carried by the water of the Tamshui river and accumulate in the estuary soil. Their accumulation is closely related to the frequency and duration of tidal flood. The concentration of heavy metals in Kandelia candel showed a sequential decline from roots to stems, leaves, and seedlings. There was a correlation between the amount of extractable heavy metals in soils and that in the tissues in Phragmites communis, while in Kandelia candel the correlation varied largely with the habitats except for the roots. The availability of heavy metals in mangrove soil may decrease due to the flooding which subsequently reduces their uptake in plant tissues. Sequential extractions of mangrove soil Indicated that the labile fraction contained a relatively small proportion of the total amount under the mangrove estuary environment. The tolerance of Kandelia candel seedlings to copper and zinc was much higher than that of rice plants (Oryza sativa). The value of 50% inhibition concentration (IC50) of root development in Kandelia candel was estimated at 3.8 mg liter-1 for Cu and 46.33 mg liter-1 for Zn. For comparison, the correspecting values of the IC50 in rice was 0.39 mg liter-1 for Cu and 9.63 mg liter-1 for Zn. Field studies and greenhouse experiments have revealed that Kandelia candel can adapt to areas polluted with heavy metals partly because of its tolerance and partly because of the low availability of heavy metals in mangrove soil.

Distribution and survival of sclerotia of rice sheath blight fungus, Thanate phorus cucumeris, in Taiwan.

The number of sclerotia of rice sheath blight fungus, Thanatephorus cucumeris (Rhizoctonia solani AG 1, Sasakii type), from single sampling spot (50×50×20cm), varied from 561 to 13 with an average of 156.5 after harvest of the first rice crop from 13 sampling locations in Taiwan in 1979. Sclerotia were most densely distributed on the surface layer (0-1cm) which contained 36.1 per kg dry soil. As the soil depth increased, the numbers of sclerotia decreased to 3.2, 3.3, 2.6, and 0.9 per kg dry soil, respectively, from 1-5, 5-10, 10-15 and 15-20cm depth. Per cent germination of the recovered sclerotia on 2 per cent water agar, in average, was 45.4, 19, 14.8, 8.5, and 5.5, respectively, from the surface to 20cm soil depth. The buoyant sclerotia in the paddy showed 14-40 per cent germination with average of 36.4 during 120 days growing period of the first rice crop in 1979. Sclerotia collected from the rice plants began to decrease in germination after being buried in soil for 4-6 months without regard to the cover crops. However, one year after burial, the sclerotia still showed 50-80 per cent germination. The germination of sclerotia kept at room temperature in the laboratory for 6 months declined to half and ceased 8-12 months later. The number of smaller sclerotia (those captured on 40 mesh screens after passing through 20 mesh screens) was 78.2% in average of those captured in the 20 mesh screen from the same sample while per cent germination from 40 mesh ones was almost half of those in the 20 mesh ones.

Physiological races of Phakopsora pachyrhizi in Taiwan.

Soybean cvs. Ankur, TK 5, TN4, and P.I.'s 200492 and 230971 are suggested as differentials for race identification of Phakopsora pachyrhizi causing soybean rust in Taiwan. Three races of P. pachyrhizi, based on lesion type, were identified among 50 sngile uredial cultures from soybean leaves collected at five locations in Taiwan. Reaction was determined 14 days after inoculation on intact leaves on plants as well as on detached leaves. The distribution of the three races varied among locations. Common bean, cowpea, hyacinth bean, lima bean, pigeon pea and yam bean also were tested but because no difference in lesion type was observed they were not used as differentials.

Diamondback Moth Resistance to Diazinon and Methomyl in Taiwan12

Diazinon- and methomyl-resistant strains of Plutella xylostella (L.) with resistance ratios of 14.4 and 175, respectively, were developed in the laboratory by continuous selection for 14 and 19 generations. The susceptibility to these 2 chemicals of this insect pest at several locations in Taiwan from 1975–77 was determined. This survey confirms the development of resistance to these insecticides in some field populations of the diamondback moth. Electrophoretic studies revealed qualitative differences in esterase and phosphatase zymograms in susceptible and resistant strains.