• Title/Summary/Keyword: H23

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Effect of Temperature, Salinity and Density on the Egg Development of the Sunray Surf Clam, Mactra chinensis (개량조개, Mactra chinensis의 난발생에 미치는 수온, 염분 및 수용밀도의 영향)

  • Min, Byeong-Hee;Kim, Tae-Jin
    • The Korean Journal of Malacology
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    • v.26 no.4
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    • pp.297-302
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    • 2010

  • Water temperature, salinity and density on egg development of the sunray surf clam, Mactra chinensis were investigated for artificial seedling production. The required time from fertilization to D-shaped larvae were 33.8 hours in $18^{\circ}C$, 20.6 hours in $23^{\circ}C$, 18.2 hours in $28^{\circ}C$ and 15.0 hours in $33^{\circ}C$. The development duration was reduced with increasing temperature. The relationships between temperature and the required time from egg to each developmental stage were described as follows: 2-cell, 1/h = 0.1051WT - 1.4782; 8-cell, 1/h = 0.037WT - 0.3686; gastrula, 1/h = 0.008WT - 0.0521; trochophore, 1/h = 0.0041WT - 0.0235; D-shaped larva, 1/h = 0.0024WT - 0.0102. Biological minimum temperature for the egg development was estimated to be $8.0^{\circ}C$ in average. The possible range of temperature for the development of D-shaped larvae was $18-28^{\circ}C$ and optimum of water temperature for the development of egg was $23^{\circ}C$. The possible range of salinity for the development of D-shaped larvae was 20-35 psu and optimum of salinity for the development of egg was 30-35 psu over 25 psu at least. The density of fertilized egg was below 40 per 1 ml in rearing seawater for elevating the development rate from fertilized egg to D-shaped larva.

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Oviposition Activities of Larger Black Chafer (Holotrichia morosa Waterhouse) and Korean Black Chafer (H. diomphalia Bates) (큰검정풍뎅이와 참검정풍뎅이의 산란활동)

  • 김기황;손준수
    • Korean journal of applied entomology
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    • v.30 no.4
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    • pp.265-270
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    • 1991

  • Oviposition activities of the larger black chafer(HolotTichia mOTosa Waterhouse) and Korean black chafer(H. diomphalia Bates) were examined in the laboratory and field from 1985 to 1990. In H. mOTosa and H. diomphalia, total durations of oviposition were 31.70$\pm$17.33 days and 61.17$\pm$23.15 days, numbers of days of actual oviposition were 9.00$\pm$5.03 days and 22.33 $\pm$11.72 days, total numbers of eggs laid laid per female were 23.43$\pm$16.26 and 65.67$\pm$37.97, and numbers of eggs laid per female per day were 2.60$\pm$2.50 and 2.94$\pm$2.34, under laboratory conditions. Difference of total numbers of eggs per female between both species seemed to be due mainly to numbers of days of actual oviposition. Oviposition period under laboratory conditions was considerably delayed behind that in the field in H. morosa but the two oviposition periods were almost overlapped in H. diomphalia. In the field, rates of gravid females of H. diomphalia were obviously higher than those of H. mOTosa, but numbers of eggs per gravid female were almost same in the two species, H. diomphalia adults did not show marked oviposition and feeding preference among several species of weed plants in the insect net chamber.

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Effect of Applying Soil Amendments on Potato Scab Prevention in Volcanic Ash Soil with Continuous Cropping System (토양개량제시용에 따른 화산회토양 감자 연작지 더뎅이병 억제 효과)

  • Joa, Jae-Ho;Moon, Doo-Kyung;Koh, Sang-Wook;Son, Daniel
    • Korean Journal of Organic Agriculture
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    • v.22 no.4
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    • pp.719-730
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    • 2014

  • This study was conducted to select proper soil amendments in order to reduce the occurrence of potato scab and maintaining soil health by applications of dolomitic lime, sulfur, potassium sulfate, shell meal fertilizer, silicate fertilizer, lime nitrogen and ammonium sulfate fertilizer in different pH levels of volcanic ash soil with continuous cultivation of potato. In potassium sulfate-applied plot with a low soil pH, the incidence rate and disease severity of scab were lowest at 84.4% and 28.4%, respectively. Those were lowest among the treatments. Value of potato scab control was 12.3% and marketable yield of potato was highest at 93.2%. In lime nitrogen-applied plot (60 kg/10a), the incidence rate was low at 38.3%, and control value was 23.8% and marketable yield of potato was high at 66.3%. In relatively higher pH soils, the incidence rate of scab was lowest at 38.3% in the lime nitrogen-applied plot (60 kg/10a). Value of potato scab control was 23.8%, which was four times higher than that in sulfur-applied plot. Marketable yield of potato was highest at 66.3% in the lime nitrogen-applied plot. In the lime nitrogen plot infected with potato scab pathogen such as S. acidiscabies and S. scabiei were remarkably lower than other soil amendments at 2.5, 5, and 10 g/L concentrations of lime nitrogen using Glucose Yeast Malt (GYM) medium. In conclusion, this study suggests that potassium sulfate application in low pH soil (less than pH 5) and lime nitrogen application in relatively higher pH soil (more than pH 6) before potato seeding might be helpful to reduce the occurrence of potato scab.

  • https://doi.org/10.11625/KJOA.2014.22.4.719 인용 PDF KSCI