• 방사선산업학회지
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• 제6권2호
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• pp.189-197
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• 2012

This study was carried out to develop the improved useful mutants for yield or composition of stevia plants using the gamma ray or chemical mutagens treatments. The seeds of stevia 'Suwon No. 11' were irradiated up to 400 Gy of gamma ray. Chemical mutagens were treated on the seeds of the 'Suwon No. 11' using 0.07% colchicine, 10 mM sodium azide, or 10 mM NMU for various durations. The germination rate, and shoot and root growth of seedling were estimated at 30 days after gamma ray irradiation or chemical mutagen treatment, and the plant height, the number of branches, and leaf length and width were examined at 3 months after mutagenesis treatments. In the case of gamma ray treatments, the germination rate and early-stage growth were decreased as the increase of radiation dose, and the 50% lethal dose was found to be 200 Gy. the plant height was decreased as the increase of radiation dose, while the number of branches per plant and leaf length were increased. Leaf shape was modified to the relatively longer one compared to the control, which was identified more apparently at the treatments of higher than 150 Gy. In the treatment of chemical mutagens, the rate of germination and survival were decreased as the increase of incubation time. The 50% lethal dose for germination rate were identified as the conditions of the 15 hours incubation in 0.07% colchicine, the 4 hrs in 10 mM sodium azide, and the 2 hrs in 10 mM NMU, in the three chemical mutagens treatments. Chemical mutagens had no influence on shoot growth, while root growth was increased, especially as the incubation time was extended. The highest root growth occurred in the NMU treatment at 6 hrs incubation time. The plant height was decreased as the increase of incubation time in the chemical mutagens treatments. Among the chemical mutagens, NMU was the most effective to induce the mutants with long-shaped or the least lobed leaves.

• 한국양식학회지
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• 제7권4호
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• pp.225-237
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• 1994

해산 어류나 갑각류의 유생 사육시 초기 동물 먹이 생물인 rotifer, Brachionus plicatilis를 oil의 종류와 함량을 서로 다르게 첨가한 유지효모로 배양한 결과와, 이 rotifer와 Artemia nauplius에 위에 각 유지효모와 다른 여러 영양강화제로 영양강화한 후 넙치 자어에 공급하여 자어의 성장과 생존을 비교해 본 결과, 다음과 같이 요약할 수 있다. 1. 12종의 유지효모로 rotifer를 배양했을 때 오징어 간유 $15\%$가 첨가된 유지효모의 경우가 가장 좋았다. 2. 오징어 간유 $15\%$의 유지효모로 rotifer를 배양했을 때, rotifer.의 최대성장이 Chlorella ellipsoidea의 경우와 비슷하였고 (140 inds./ml) 나머지 유지효모는 현저히 낮았다. 3. 그러나 오징어 간유 $15\%$의 유지효모로 배양된 rotifer를 넙치 자어에 공급했을 때 자어의 성장과 생존율은 Chlorella의 경우보다 좋았다. 4. 또 영양강화제로 영양강화된 rotifer와 오징어 간유 $15\%$ 유지효모로 배양된 것을 넙치 자어에 공급하여 자어의 성장과 생존율을 비교했을 때도 오징어 간유 $15\%$의 유지효모가 가장 좋았다. 5. 오징어 간유$5\%,\;15\%,\;25\%$ 첨가된 유지효모로 영양강화된 Artemia nauplius를 넙치 자어에 공급했을 때 intact nauplius의 경우보다 자어의 높은 성장과 생존율을 나타냈고, 그 중에서 $25\%$ 함량의 유지효모가 가장 좋았다. 6. Artemia nauplius에 대한 유지효모의 적정 영양강화 시간과 농도는 각각 6시간과, 1.5g/g cyst였으며, 유지효모(오징어 간유 $5\%,\;15\%,\;25\%$)와 여러 영양강화제를 비교했을 때도 오징어 간유 $25\%$의 경우가 자어의 가장 높은 성장과 생존율을 나타냈다.

• 한국패류학회지
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• 제29권2호
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• pp.91-96
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• 2013

북방전복 초기 유생의 사육에 적합한 부착 규조류를 파악하기 위하여 C. californica, Rhaphoneis sp. C. schroederi를 대상으로 veliger 유생의 부착률, 변태율, 생존율 및 성장을 조사하였다. 각 규조류의 단독 먹이 실험구, 3종의 혼합 먹이 실험구 및 먹이를 공급하지 않은 대조구로 구분하여 사육하였다. 유생의 부착률은 C. californica와 Rhaphoneis sp.에서 48시간째에 80-82%로 가장 높았고, C. schroederi의 최고 부착률은 96시간째에 67%로 상대적으로 늦고 낮은 경향을 보였다. 변태율도 C. schroederi는 6일째 37%로 C. californica와 Rhaphoneis sp.의 45-49%에 비하여 낮고 느린 결과를 보였다. 혼합 먹이 실험구는 단독 먹이 실험구에 비하여 낮은 부착률과 변태율을 보였다. 변태 후 10일째 C. californica와 Rhaphoneis sp.는 각각 69%와 61%의 높은 유생 생존율을 보였고, 일간 각장 성장은 각각 33.7 ${\mu}m$과 32.5 ${\mu}m$로 C. schroederi의 29.0 ${\mu}m$, 혼합 먹이 실험구의 21.8 ${\mu}m$에 비하여 유의하게 높았다. 따라서 북방전복 초기 유생 사육을 위한 최적 규조류는 C. californica, Rhaphoneis sp., C. schroederi의 순으로, 이들 규조를 단독으로 공급하는 것이 혼합하여 공급하는 것보다 효과적일 것으로 판단된다. 그러나 본 실험은 북방전복 초기 유생단계의 결과이므로 차후 치패를 대상으로 한 장기간의 먹이효율 조사가 필요하다.

• 한국양식학회지
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• 제18권3호
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• pp.142-146
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• 2005

이 연구에서는 홍합과 지중해담치 치패의 크기별 재 부착 과정을 관찰하고 재 부착시간, 부착률 및 생존율을 조사 비교하였다. 또한 주사전자현미경(SEM)을 이용한 홍합과 지중해담치 족사의 외부형태를 관찰하였다. 홍합 소형 치패(각고 $3{\sim}7mm$)의 새로운 족사 생성에 의한 재 부착은 족사 분리 7분 내에 100%의 재부착률 및 생존율을 보였으며 크기별로 재 부착 시간과 생존율에는 차이가 없었다. 중형치패(각고 25 mm)는 5시간 내에 85%의 재 부착률을 보인 이후 24시간동안 나머지 개체는 부착하지 않았으나 생존율은 24시간 동안 100%를 나타내어 소형치패가 중형치패에 비해 족사 분리 후 재 부착에 소요되는 시간이 빠르고 재 부착률도 높았다. 홍합(각고 28 mm)과 지중해 담치(각고 30 mm) 중형치패의 시간경과에 따른 재부착률 및 생존율은 5시간내에 각각 73%, 73%의 재 부착률을 보인 이후 24시간 동안 나머지 개체는 부착하지 않았고 생존율은 모두 100% 를 보였으며 지중해담치가 홍합보다 빠르게 재부착한 치패가 많았다. 주사전자현미경을 이용하여 관찰된 담치류 부착 족사의 외부 형태는 고착반, 부착줄기, 부착근으로 구분할 수 있었으며, 각고 $20{\sim}30mm$ 범위의 홍합과 지중해담치의 치패에서 부착 족사의 크기를 비교한 결과 고착반은 각각 장축 $2,392{\times}934{\mu}m$, 장축 $1,056{\times}614{\mu}m$, 부착줄기 $39{\mu}m,\;28{\mu}m$, 부착근 $58{\mu}m,\;83{\mu}m$로 나타나 홍합이 지중해담치에 비해 고착반의 면적이 넓고 부착줄기의 두께가 두터웠다. 고착반과 부착줄기를 잇는 부착근의 두께는 지중해담치가 홍합보다 다소 두텁지만 단조로운 형태인 반면, 홍합은 물결모방의 가지를 뻗어 고착반에 부착한 미세구조를 확인할 수 있어 참담치의 족사 부착력이 지중해담치 보다 강한 것으로 판단되었다.

• 한국양식학회지
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• 제11권2호
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• pp.203-212
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• 1998

남해안 일원에서 다양한 어류의 종묘생산 및 양식이 시도되고 있는데, 자어기에 종묘의대량폐사가 발생하여 문제의 심각성이 야기되고 있다. 본 연구에서는 일본 킨키대학에소 높은 경과를 올리고 있는 참돔의 서발육종 및 잡종강세에 의한 품종개량된 일명 킨키돔의 수정란을 국내에 이식하여 종묘생산시 대량폐사와 관련되는 수질변화 등을 조사하였다. 부화직후 자어의 평균전장은 2.93 mm이었으며, 일령 40일째에는 19.83~20.12 mm로 성장하였다. 종묘생산과정중 자어의 1차 감모현상은 일령 25~30일째(7.98~9.37 mm)에 발생하였으며, 생존율은 59.8~60.3%에서 32.1~32.5%로 감소하였다. 그 이후에는 거의 폐사 없었으며, 40일째의 생존율은 20.5~25.4%였다. 일령 2-~3-일째 수질은 II등급 이하였으며, 조사기간중 COD, $PO_4$-P, $NO_2$-N, $NO_3$-N 및 $NH_$-N은 각각 3, 7, 34, 6 및 8배씨 증가하였다. 사육수 및 자어의 총세균수는 시간이 경과함에 따라 증가하였으며, 일령 25일째의 총 세균수는 각각 $6.3{\times}10^6$~$2.3{\times}10^7$ cfu/ml, 4.3~$7.4{\times}10^6$ cfu/g였다. 한편, 일령 25일째 참돔 자어는 수면위를 선회하고 복북가 팽만되는 특징을 보이는 질병에 의하여 다수가 폐사되었으며, 병어에서 Vibrio spp.를 분리.동정하였다. 분리된 Vibrio spp. PSV-1균주는 참돔자어에 병원성이 있으며, 참돔자어의 $LD_50$dms $10^6$ cfu/ml 이상이었다. 이상이 결과로부터 참돔자어의 1차 대량폐사는 수질의 급격한 변화, 총세균수 증가 그리고 병원 생물의 복합적인 상호작용에 의한 것으로 추정된다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.44-44
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• 2017

Recently, the occurrences of extreme flooding and drought, often in the same areas, have increased due to climate change. We tested the hypothesis that wetland species could help upland species under flood conditions; that is, the roots of wetland crops may supply $O_2$ to the roots of upland crops by a series of experiments conducted in both humid Japan and semi-arid Namibia (See Iijima et al, 2016 and Awala et al, 2016). Firstly, flooding tolerance of upland-adapted staple crops-pearl millet (Pennisetum glaucum) and sorghum (Sorghum bicolor) mix-cropped with rice (Oryza spp.) was investigated in glasshouse and laboratory experiments in Japan. We found a phenomenon that strengthens the flood tolerance of upland crops when two species-one wetland and one drought tolerant-were grown using the mixed cropping technique that results in close tangling of their root systems, hereinafter referred to "close mixed-planting". This technique improved the photosynthetic and transpiration rates of the upland crops subjected to flood stress ($O_2$-deficient nutrient culture). Oxygen transfer was suggested between the two plants mix-cultured in water, implying its contribution to the phenomenon that improved the physiological status of upland crops under the simulated flood stress. Secondly, we further tested whether this phenomenon would be expressed under field flood conditions. The effects of close mixed-planting of pearl millet and sorghum with rice on their survival, growth and grain yields were evaluated under controlled field flooding in semi-arid Namibia during 2014/2015-2015/2016. Single-stand and mixed plant treatments were subjected to 11-22 day flood stress at the vegetative growth stage. Close Mixed-planting increased seedling survival rates in both pearl millet and sorghum. Grain yields of pearl millet and sorghum were reduced by flooding, in both the single-stand and mixed plant treatments, relative to the non-flooded upland yields, but the reduction was lower in the mixed plant treatments. In contrast, flooding increased rice yields. Both pearl millet-rice and sorghum-rice mixtures demonstrated higher land equivalent ratios, indicating a mixed planting advantage under flood conditions. These results indicate that mix-planting pearl millet or sorghum with rice could alleviate flood stress on dryland cereals. The results also suggest that with this cropping technique, rice could compensate for the dryland cereal yield losses due to field flooding. Mixed cropping of wet and dryland crops is a new concept to overcome flood stress under variable environmental conditions.

• 한국약용작물학회지
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• 제22권6호
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• pp.469-474
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• 2014

This study was performed to investigate the effects of sowing density and number of seeds sown on the emergence rate and growth characters of Panax ginseng C. A. Meyer under direct sowing cultivation in a blue plastic greenhouse. Ginseng seedlings, derived from seeds sown directly at different densities (90, 108, 135, and 162 seeds per $162m^2$), were cultivated in sandy loam soil within a blue plastic greenhouse. In contrast to the emergence rate, which decreased with an increase of sowing density, number of survival plant showed an increasing trend. Interestingly, the emergence and number of survival plant were significantly enhanced when 2 or 3 seeds were sown per hole compared with when one seed was sown per hole. Growth of the aerial parts of ginseng were not markedly influenced by sowing density or the number of seeds sown. However, chlorophyll content (SPAD values) increased with an increase in sowing density. Root parameters, such as root length, diameter, and weight, and the number of lateral roots decreased with an increase in sowing density, but were not noticeably influenced by the number of seeds sown. Total saponin content was the highest in the treatment plot containing 135 seeds. Similarly, the content of each ginsenoside was also tended to be higher in this treatment than in other treatment plots. On the basis of the results obtained in this study, it was possible to determine the optimal sowing density and seed number for the direct sowing cultivation of ginseng in blue plastic greenhouse.

• 한국환경복원기술학회지
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• 제18권3호
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• pp.1-11
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• 2015

This research was conducted to compare the effect of soil amendment and loess on physial and chemical properties of dredged soil and primary height growth of Ulmus davidiana var. japonica. Three types of research plots: control plot (Dredged soil only), DC treatment plot (Dredged soil + soil amendment) and DCL treatment plot (Dredged soil + soil amendment + Loess) were set at Okgu research site in Saemanguem. 32 trees of U. davidiana var. japonica were planted in each plots after 14 months from the construction. Soil texture, pH, electrical conductivity (EC), organic matter (OM), total nitrogen (TN), available P, exchangeable cation ($K^+$, $Na^+$, $Mg^{2+}$, $Ca^{2+}$) and sodium chloride were measured after 3 years from the construction. Also, survival rate and height of U. davidiana var. japonica were measured 22 months after planting, and the correlation between height of trees and the physico-chemical properties of soil were analyzed. Even though pH in both DC and DCL treatment plots are lower than control plot, they are still alkaline (> pH 8). OM, TN and available P in both DC and DCL treatment were higher than the control. Particularly, the content of available P in both DC and DCL treatment plots are 1.4~5.1 times and 2.0~3.1 times higher than the control respectively. The concentration of exchangeable Mg in DCL treatment plot was 1.1~5.5 times higher than the control (p < .05). The survival rate of the species was the highest in DCL treatment plot (98%) followed by DC treatment plot and the control. The average height of the trees in both DC and DCL treatment plots is 1.1m while the control is 0.8m. OM, TN, available P, K+ were significantly related to the height of U. davidiana var. japonica(p < .01). The results indicate that soil amendment affects on soil physial and chemical properties of dredged soil and height growth of U. davidiana var. japonica.

• Fisheries and Aquatic Sciences
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• 제9권4호
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• pp.160-166
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• 2006

We explored the possibilities of using the freshwater rotifer Brachionus angularis as a live food for small fishes cultured in fresh- or brackish waters. Brachionus angularis were collected from a reservoir for isolation and laboratory culture. Length and width of the lorica were $102.3{\mu}m$ and $76.6{\mu}m$, respectively, and those of amictic eggs were $64.4{\mu}m\;and\;47.9{\mu}m$, respectively. When their growth rates were examined at six different temperatures, i.e., 15, 20, 25, 30, 35, and $40^{\circ}C$, the highest daily growth rate of 0.801 was observed at $35^{\circ}C$, and growth was lower with decreasing temperature. Adaptation to salinity change was evaluated with two different modes of salinity increase: step-wise elevation lasting for short durations of 5 to 30 min or a long duration of 24 h. With the short duration modes, no individuals survived salinity higher than 10 psu, and the number of live individuals did not increase throughout the experiment. However, in the 24-h elevation, the number of individuals increased when salinity was elevated by 1 to 2 psu per day for the first 2 or 3 days, while no increase in number occurred at salinity increments higher than 3 psu per day. In addition, to assess the effect of different diets, four single-component diets (Chlorella vulgaris, Nannochloris sp., baker's yeast, or dry yeast) and three combination diets (C. vulgaris + Nannochloris sp. + baker's yeast + dry yeast; C. vulgaris 70% + baker's yeast 30%; C. vulgaris 30% + baker's yeast 70%) were used. The specific growth rates of B. angularis fed combination diets were higher than those of rotifers fed any single-component diet, with the highest rate of 0.648 in B. angularis fed a mixture of C. vulgaris, Nannochloris sp., baker's yeast, and dry yeast, and the lowest rate of 0.200 in those fed dry yeast only. Our results indicate that the freshwater rotifer B. angularis can be used for seedling production of both freshwater and brackish-water fishes that require small (less than about $120{\mu}m$) live food during their early stages.

• 한국환경과학회지
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• 제29권3호
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• pp.209-218
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• 2020

This study was conducted to monitor the growth and development of Abies koreana seedlings in the Hallasan Mountain. Accordingly, the obtained results indicate that the number of A. koreana seedlings increased by 2.6 and 4.8 times in the Yeongsil and Jindallaebat areas, respectively, over the 10-year period. Most of these seedlings were found to be growing on moss-covered rocks. The average tree height over the last 10 years was obtained as 20.4 cm in the Yeongsil area and 3.6 cm in Jindallaebat with growths of 4.1 cm and 1.4 cm, respectively over the last 2 years. Of all the mature trees that were surviving in 2009, 6 died in Yeongsil in 2014 (with an additional 4 in 2018) and 13 in Jindallaebat in 2016. Over the 10-year period, the diameter at breast height of the trees in Yeongsil and Jindallaebat has increased by an average of 0.6 cm and 4.2 cm. Similarly, an average of 6.8 cones was found in the Yeongsil area in 2014 and 26.3 in Jindallaebat in 2016. However, in 2018, no additional cones were found in the former, although an average of 1.4 cones was observed in the latter. With respect to the average temperature and relative humidity, no significant difference could be observed between two monitored areas from 2016 to 2018. However, in July 2017 and February 2018, the average temperature was higher in the Jindallaebat area, while relative humidity was higher in Yeongsil, there by possibly affecting cone growth and flowering between areas. These results indicate the survival and growth of A. koreana seedlings in the Hallasan Mountain is sensitive to the environments of each area. Hence, continuous monitoring of the environment changes and in-depth studies on the flowering and fruiting of A. koreana seedlings needs to be carried out in order to analyze the relationship between their survival rates and changes in weather conditions.