• 한국축산시설환경학회지
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• 제1권1호
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• pp.65-75
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• 1995

This experiment was carried out to the effects of population density and C/N ratios of feed on the growth, reproductive effciency and cast producation of the earthworm(Eisenia foetida). The population densities of 50, 100, 150, 200 and 250 individuals of the earthworm fed with different C/N ratios of 25, 35, 45 and 55 cow manures were studied in rearing box($6,400cm^3$), and at the fertility stage during a period of 60 days. The results were summarized as follows; The survial rate(SR), increasing rate(IR), reproductive efficiency(RE) and cast production of the earthworms showed highest values in C/N ratio of 25. These results may indicate that C/N ratio of 25 is a very favourable feed for the growth of the earthworms. The survial rate(SR) indicated significant positive correlation with reproductive efficiency(RE) in different C/N ratios of feeds. The survial rate(SR) showed highest values in population densities of $50{\sim}100$ worms/$6,400cm^3(64.0{\sim}128.0cm^3/worm$). On the contrary, increasing rate(IR) tended to decreased with the increased population densities. The survival rate(SR) indicated significant negative correlation with reproductive efficiency(RE) in different population densities of the earthworms. The cast production estimated were $31.6mg{\sim}67.4mg/day/worm$ grown in optimum population densities($50{\sim}100\;worms/6,400cm^3$). The earthworm casting are an excellent soil conditioning material or organic fertilizer sources with a high chemical composition and their physical properties.

• Asian-Australasian Journal of Animal Sciences
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• 제13권7호
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• pp.929-934
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• 2000

Optimum stand density of alfalfa (Medicago sativa L.) varies with locations and climates. Stand density is one of the factors that determines herbage yield, forage quality and persistence of alfalfa. As establishment costs increase, the question arises whether present population densities are optimum for obtaining maximum herbage yield and forage quality. The objectives of this study were: 1) to determine the optimum plant density for highest herbage yield and forage quality for the dehydrated alfalfa industry under Edmontons climatic conditions in Alberta, Canada; 2) to compare herbage yield and forage quality of the cultivars 'Algonquin' and 'Vernal' grown at a range of stand densities. Alfalfa seedlings of both cultivars were either transplanted at spacings of 6, 10, 15 and 25 cm or direct seeded at the 4.5 cm plant spacings, providing population densities of 494, 278, 100, 45 and $16plants/m^2$. The experimental design was a randomized complete block with a split-plot arrangement having three replicates; the main plots consisted of two alfalfa cultivars Algonquin and Vernal, and the sub-plots were the five population densities. The cultivar Vernal had significantly higher annual yield than did the cultivar Algonquin. There was no significant effect of plant density on herbage yield. There was no difference in crude protein (CP) between the two cultivars. At the first cut, there was a significant quadratic effect of plant density on CP content and the greatest CP occurred at the 100 plants/m2 density. Crude protein was not affected by plant density at the second cut. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) were not affected by plant density. The cultivar Algonquin usually had a lower ADF and NDF than cultivar Vernal. In conclusion, high population densities ($278plants/m^2$ or more) of alfalfa did not improve herbage yield and forage quality compared with low plant population densities ($100plants/m^2$ or less) of alfalfa.

• The Plant Pathology Journal
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• 제18권5호
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• pp.271-278
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• 2002

The effect of five plant population densities [5 (D$_1$), 10 (D$_2$), 20 (D$_3$), 30 (D$_4$), and 40 (D$_{5}$) plants/m$^2$] of four groundnut cultivars [ICGV 86699, ICG (FDRS) 10, ICGS 11 and TMV 2] and fungicide application (Kavach, chlorothalonil) to manage late leaf spot (LLS) and rust were studied in a field experiment during the 1995 and 1996 rainy seasons. LLS and rust severities were low in fungicide sprayed plots in all the cultivars irrespective of plant densities. Severities of LLS and rust, and percentage defoliation caused by LLS were significantly more in higher plant densities (D$_4$, D$_{5}$) than in lower plant densities (D$_1$, D$_2$, D$_3$) in fungicide sprayed and unsprayed plots in all the cultivars. All the cultivars gave significantly higher haulm and pod yields in fungicide sprayed plots than in unsprayed plots. Haulm and pod yields were significantly higher in higher plant densities than in lower plant densities. A combination of higher plant densities (D$_4$, D$_{5}$) and fungicide protection against LLS and rust gave maximum yield.yield.

• 환경생물
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• 제24권3호
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• pp.258-267
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• 2006

본 연구는 경상남도 사천시 삼천포 항을 중심으로 인근의 40개의 조사정점을 선정하여 해수와 저질토에서 해양종속영양세균, E. coli, 그리고 Salmonella와 Shigella의 분포를 2003년 7월부터 12월가지 3차에 걸쳐 실시하였다. 본 연구의 조사기간(2003년 $7{\sim}12$월)중 삼천포만 인근해역의 조사정점에서 해양 종속영양세균의 분포는 $1.7{\pm}0.9{\times}10^3{\sim}2.4{\pm}0.9{\times}10^5CFUmL^{-1}$의 범주에서 변화하였으며, 정점 34에서 9월에 가장 높은 값을 나타냈다. 전반적으로 9월이 7월과 12월에 비해 모든 정점에서 다소 높은 값을 보였다. 저질토에서 혐기성 세균의 분포는 $2.2{\pm}0.2{\times}10^3{\sim}2.0{\pm}0.2{\times}10^5CFUg^{-1}dry$ wt.의 범주에서 변화하였다. 혐기성 세균의 경우 외해 정점에서는 내만에 위치한 정점들보다 년 중 낮은 균체수를 유지하고 있어 물리, 화학적인 환경요인들에 의해 별 영향인 없음을 알 수 있다. E. coli의 분포는 해수의 경우, 7월중에만 사천만 인근(St. 1, 2, 3, 4),진주만과 창선도 인근 (St. 15, 23, 31), 삼천포항 인근(St. 14)에서 검출되고 9월과 12월에는 전 정점에서 전혀 검출되지 않았다. 저질토의 경우, 7월에 사천만 인근(St. 1, 2)과 창선도 인근(St. 16, 31)에서만 검출 되었다. Salmonella와 Shigella의 분포는 해수와 퇴적토에서 7월과 9월에 일부 해역에서만 검출되었다.

• 유기물자원화
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• 제1권2호
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• pp.259-266
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• 1993

사육밀도를 달리한 지렁이 개체군에 우분을 먹이로 공급하였을 때 지렁이 생육과 분립의 생산량 및 분립의 화학적 조성을 조사하였다. 지렁이의 생존율과 증식속도사이에의 유의한 정상관이, 생존율과 증식속도간에는 역상관이 존재하였다. 최적사육밀도는 $42.7-128cm^3$/마리의 범위로 추정되었으며, 최적사육밀도에서 분립의 생산량은 36.5-80.9 mg/마리의범위로 추정되었다. 분립은 그화학적 조성과 물리적 성상으로 볼 때 토양개량제로서 이용가치가 높다고 판단되었다.

• 미생물학회지
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• 제13권4호
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• pp.157-164
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• 1975

The distribution and population densities of yeasts including their epiflora on seaweeds were estimated over two months in inshore waters of Mok-po, Korea. Nine species of 48 isolates were obtained from this area. Rhodotorula, Torulopsis and Debaryomyces that are widespread in estuaries were of common occurrence in this water body. The highest counts belonged to Torulopsis candida which was predominated in temperate estuarine zone. The distribution of sea weeds seems to be correlated with the population densities of yeasts. Two species of marine algae harbored yeasts during May and July, 1975. Among seaweeds isolates, the highest numbers werre of the species Rhodotorula glutinis var. glutinis. A dominant colonization of this strain on Chlorophyceae and Phaeophyta and a role of water temperature for the growth of yeasts are discussed.

• 한국응용곤충학회지
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• 제32권2호
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• pp.168-175
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• 1993

This study investigated the composition and distribution of the soil microarthropods community in plantations of the Korean pine(Pinus Koraiensis SIEB. et ZUCC, the sudong area, Namyangju-gun, Korea) , which had been planted in different years. The soil samples intended to collect soil animals were taken monthly from June 1988 to July 1989. The composition of soil microarthropods community included Arachnida, Chilopoda, Insecta, Collembola, Diplopoda, Crustacea, and Symphyla. The Acarina were composed of 82.4% of Cryptostigmata, 8.0% of Mesostigmata, 7.9% of nymphs, and 1.7% of others. The Insecta included six orders including Hymenoptera(65.8%) and Diptera(13.9%). Population densities increased from when the plantations were first established until the planting were 25 years old, after which they declined. Population densities of the soil microarthropods were highest in July and lowest in January. The Collembola/Acarina ratio is 0.16 overall, and was highest in January and lowest in August.

• 한국작물학회지
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• 제21권2호
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• pp.250-257
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• 1976

재식밀도를 달리한 조건에서 적엽처리가 대두품종의 수량 및 수량구성요소에 미치는 영향을 알고저 6월1일과 6월20일에 $\textrm{m}^2$당 80본, 40본, 27본 및 20본이 되도록 재식밀도를 조절 파종하고 개화시기에 잔여엽수가 상부로부터 각각 1,2,3,5,7엽이 되도록 하위엽을 적엽처리하고 무적엽의 표준구를 포함하는 6처이로 하여 시험을 실시하였는데 그 결과를 요약하면 다음과 같다. 1. 표준구에서의 최적엽면적지수는 파종기에 따라 다르며 광교에 있어서는 개화시에 LAI가 4~5이고 개화후 30일에는 5~6이었으며 SRF-300에 있어서는 개화시에 2.5~6.0이고 개화 30일후에는 6~7이었다. 2. 종실수량은 재식밀도가 낮은 경우에는 적엽처리에 의하여 직선적으로 감소되었으나 재식밀도가 $\textrm{m}^2$당 40본이상으로 높은 경우에는 수량과 착엽수사이에 유의적인 곡선효과가 인정되어 하위부의 경미한 적엽처리를 하므로서 표준에 비하여 광교에서는 25~35%, SRF-300에서는 13~32%의 증수를 보였다. 3. 적엽처리시에 수량에 가장 크게 영향하는 수량구성요소는 전체적으로 볼때 식물체당 협수이며 다음으로 6월1일 파종구에서 재식밀도가 감소됨에 따라서 광교에서는 립중의 효과가 증대되었고 SRF-300에서는 수량에 영향하는 임실율의 비중이 현저히 증대되었다.

• 유기물자원화
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• 제14권4호
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• pp.104-112
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• 2006

지렁이 사육상을 조성하는데 있어서 적정한 초기 지렁이 입식 밀도를 추정하기 위해서 단위 면적당 서로 다른 밀도의 지렁이($1m^2$의 사육상 면적당 지렁이 1, 2, 3, 5kg)를 입식하여 12kg의 먹이를 반복 급이하면서 그의 개체군 밀도 변화를 조사하였고, 효율적인 먹이급이량을 추정하기 위하여 최고 한계에 근접한 지렁이 밀도($5kg/m^2$)에서 먹이급이량을 달리하였을 때($1m^2$의 사육상 면적당 먹이 16, 24, 32, 40kg) 먹이섭식속도를 조사하였다. 지렁이 구입비용, 노동비용 등을 고려하였을 때, 지렁이 사육상을 조성하기 위한 초기 입식밀도는 사육상 면적 $1m^2$당 2kg 이하로 하는 것이 합리적인 것으로 판단된다. 지렁이 사육상에 지렁이 밀도가 최고밀도에 근접한 이후에는 단위 사육 면적당 1회에 투입되는 먹이량은 $40kg/m^2$정도인 것이 그 보다 적은 경우보다 지렁이 증식과 먹이급이를 위한 작업효율 측면에서 유리하였다.

• Animal cells and systems
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• 제7권2호
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• pp.127-132
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• 2003

Effects of genotype, settlement density and irradiane on the growth, mortality and population structure of Fucus serratus germlings were examined in the laboratory. The growth of F. serratus germlings was influenced by genotype of parent plants, which is likely to occur by microclimatic differentiation of substrata. The growth of germlings were greater at lower densities than higher densities indicating that intraspecific competition between germlings occurred within three weeks. Also, the growth of F. serratus germlings was better at $120\mumol\;m^-2/s^-1$ than at $60\mumol\;m^-2/s^-1$. However, mortality of germlings was determined by settlement density rather than irradiance. In population structure, skewness was increased at low irradiance and high density indicating that population structure could be changed by intraspecific competition. Thus, it is concluded that genotypic differentiation of F. serratus germlings occurred in a microgeographic scale, and the experimental density and irradiance level affected the growth of germlings.