• ALGAE
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• 제34권3호
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• pp.237-251
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• 2019

The dinoflagellate genus Alexandrium is known to often form harmful algal blooms causing human illness and large-scale mortality of marine organisms. Therefore, the population dynamics of Alexandrium species are of primary concern to scientists and aquaculture farmers. The growth rate of the Alexandrium species is the most important parameter in prediction models and nutrient conditions are critical parameters affecting the growth of phototrophic species. In Korean coastal waters, Alexandrium affine and Alexandrium fraterculus, of similar sizes, often form red-tide patches together. Thus, to understand bloom dynamics of A. affine and A. fraterculus, growth rates and nitrate uptake of each species as a function of nitrate ($NO_3$) concentration at $100{\mu}mol\;photons\;m^{-2}s^{-1}$ under 14-h light : 10-h dark and continuous light conditions were determined using a nutrient repletion method. With increasing $NO_3$ concentration, growth rates and $NO_3$ uptake of A. affine or A. fraterculus increased, but became saturated. Under light : dark conditions, the maximum growth rates of A. affine and A. fraterculus were 0.45 and $0.42d^{-1}$, respectively. However, under continuous light conditions, the maximum growth rate of A. affine slightly increased to $0.46d^{-1}$, but that of A. fraterculus largely decreased. Furthermore, the maximum nitrate uptake of A. affine and A. fraterculus under light : dark conditions were 12.9 and $30.1pM\;cell^{-1}d^{-1}$, respectively. The maximum nitrate uptake of A. affine under continuous light conditions was $16.4pM\;cell^{-1}d^{-1}$. Thus, A. affine and A. fraterculus have similar maximum growth rates at the given $NO_3$ concentration ranges, but they have different maximum nitrate uptake rates. A. affine may have a higher conversion rate of $NO_3$ to body nitrogen than A. fraterculus. Moreover, a longer exposure time to the light may confer an advantage to A. affine over A. fraterculus.

• 한국토양비료학회지
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• 제44권4호
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• pp.551-558
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• 2011

The aim of this study was to know whether leaf nitrate can be a substitute of total leaf N to justify plant N status and how nitrate influences macro elements uptake and physiological parameters of tomato plants under different nitrogen levels. Leaf nitrate content decreased in low N, while showed similar value with the control in high N, ranging from 55 to $70mg\;g^{-1}$. Differences in nitrate supply led to nitrate-dependent increases in macro elements, particularly cations, while gradual decrease in P. Physiological parameters, photosynthesis rates and antioxidants, greatly responded in N deficient conditions rather than high N, which didn't show any significant differences compared the control. Considering nitrogen forms and physiological parameters, total-N in tomato plants represented positive relation with growth (shoot dry weight), nitrate and $CO_2$ assimilation, whereas negative relation with lipid peroxidation.

• 한국물환경학회지
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• 제20권6호
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• pp.571-576
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• 2004

Since anaerobic/anoxic/oxic process, which is a typical mainstream biological nitrogen and phosphorus removal process, utilizes influent organic matter as an external carbon source for phosphorus release in anaerobic or anoxic stage, influent COD/T-P ratio gives a strong influence on performance of phosphorus removal process. In this study, a bench scale experiment was carried out for SBR process to investigate nitrogen and phosphorus removal at various influent COD/T-P ratio and nitrate loadings of 23~73 and 1.6~14.3g $NO_3{^-}-N/kg$ MLSS, respectively. The phosphorus release and excess uptake in anoxic condition were very active at influent COD/T-P ratios of 44 and 73. However, its release and uptake was not obviously observed at COD/T-P ratio of 23. Consequently, phosphorus removal efficiency was decreased. In addition, the phosphorus release and uptake rate in anoxic condition increased as the nitrate loading decreased. Specific denitrification rate had significantly high correlation with organic materials and nitrate loadings of the anoxic phase too. The rate of phosphorus release and uptake in the anoxic condition were $0.08{\sim}0.94kg\;S-P/kg\;MLSS{\cdot}d$ and $0.012{\sim}0.1kg\;S-P/kg\;MLSS{\cdot}d$, respectively.

• Molecules and Cells
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• 제40권3호
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• pp.178-185
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• 2017

Nitrogen is one of the most important mineral elements for plant growth. We studied the functional roles of Oryza sativa DNA BINDING WITH ONE FINGER 18 (OsDOF18) in controlling ammonium uptake. The growth of null mutants of OsDOF18 was retarded in a medium containing ammonium as the sole nitrogen source. In contrast, those mutants grew normally in a medium with nitrate as the sole nitrogen source. The gene expression was induced by ammonium but not by nitrate. Uptake of ammonium was lower in osdof18 mutants than in the wild type, while that of nitrate was not affected by the mutation. This indicated that OsDOF18 is involved in regulating ammonium transport. Among the 10 ammonium transporter genes examined here, expression of OsAMT1;1, OsAMT1;3, OsAMT2;1, and OsAMT4;1 was reduced in osdof18 mutants, demonstrating that the ammonium transporter genes function downstream of OsDOF18. Genes for nitrogen assimilation were also affected in the mutants. These results provide evidence that OsDOF18 mediates ammonium transport and nitrogen distribution, which then affects nitrogen use efficiency.

• 한국초지조사료학회지
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• 제20권3호
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• pp.199-206
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• 2000

사료용 옥수수에 대한 동계호밀 재배 및 헤어 리베치 녹비의 영향을 규명하기 위하여 동계호밀, 헤어리베치 녹비, 동계휴한의 세 작부체계에 질소 수준을 100, 200kgN/ha를 각각 두어 토양의 질산 태 질소와 옥수수의 수량 및 질소 흡수량의 차이 를 살펴 본 결과는 다음과 같다. 옥수수 파종직전 호멸을 재배한 구는 토양의 질산태 질소량은 동 계 휴한구보다 다소 감소하였으나 헤어리베치 재 배구는 동계 휴한구와 큰 차이가 없었다. 베치녹 비구는 옥수수 질소추비기 및 수확기에 토양 질 산태 질소가 증가하여 동계 휴한구나 호밀잔사구 보다 평균 60~70 kgN/ha의 질산태 질소가 많았으며 베치를 녹비로 환원하고 질소비료를 200 k kgN/ha 시용하였을 때 100 kgN/ha 내외의 질산태 질소가 옥수수에 흡수되지 못하고 수확기 에 토양 에 잔류하였다. 옥수수 수량 및 종실의 질소 함량은 세 작부체계 모두 질소비료 100 kgN/ha 이상 에서는 증가하지 않았지만 간엽의 질소 함량과 질소 흡수량이 베치녹비시 현저히 증가하여 동계 휴한 및 동계 호밀구보다 50 - 60 kgN/ha의 질소 를 옥수수가 더 흡수하였다. 따라서 옥수수 수확 시 토양에 잔류하는 질산태 질소량 및 옥수수의 질소흡수량의 증가를 고려할 때 동계에 헤어리베 치를 재배하여 녹비의 환원시 독비에 의한 무기 태 질소 공급효과가 100 kgN/ha 이상일 것으로 추측되며 질소기비의 100 kgN/ha는 필요 없는 것으로 판단되었다.

• 한국토양비료학회지
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• 제30권1호
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• pp.29-34
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• 1997

본 연구(硏究)는 수경재배토마토에 있어서, 음(陰)이온이 무기양분흡수(無機養分吸收) 및 식물체의 원소조성(元素組成)에 미치는 영향을 구명하고자 수경재배의 주요 질소원으로 사용하고있는 $NO_3-N$의 영향에 관해 검토하였다. 토마토(TVR-2)는 파종후 24일에 정식하고 정식후 126일에 재배를 종료하였다. 배양액은 일본원시(園試)표준액을 기본조성(基本組成)으로하여 $NO_3-N$농도 8, 16, 24, 32cmol/l 처리구를 설정하고, 정식후 33일에 양액탱크용량 150l, 베드크기 $90{\times}90{\times}5cm$에 8주를 정식하여 재배하고, 재배종료기의 식물체를 화방별(花房別) 기관별(器官別)로 분획채취(分劃採取)하여 건물중을 평량한 후 무기성분(無機成分)을 분석 검토 하였다. 엽신(葉身)과 엽병(葉柄)의 건물중은 $NO_3-N$농도가 높을수록 증가 하였으나, 과실의 건물중은 $NO_3-N$농도 16cmol/l 처리구가 가장 높았다. 생식기관(生殖器官)에 대한 영양기관(營養器官)의 건물중비율(乾物重比率)은 $NO_3-N$농도 16cmol/l 처리구가 가장 낮았고, $NO_3-N$처리농도가 증가함에 따라 높아졌으며, 과실수량은 $NO_3-N$농도 16cmol/l 처리구가 가장 많았다. $NO_3-N$처리농도가 증가함에 따라, 엽신(葉身)과 엽병중(葉柄中)의 전질소, $NO_3-N$, Ca 및 Na농도가 증가하였으며, $NO_3-N$ 농도 24 및 32cmol/l 처리구에서 K, P, S 및 Cl농도가 감소하는 경향을 나타냈다. 이상의 결과로부터 수경재배토마토에 있어서 $NO_3-N$의 적정농도는 생육시기에따라 다르며 영양생장기(營養生長期)에는 8cmol/l가, 생식생장기(生殖生長期)에는 16cmol/l가 적절한 것으로 나타났다. 식물의 무기음(無機陰)이온흡수에 미치는 양액중의 $NO_3-N$의 영향은 그 농도에 따라 다르며, $NO_3-N$농도가 낮을때는 주로 $Cl^-$과 그리고 $NO_3-N$농도가 높을때는 $SO_4{^{2-}}$ 및 $H_2PO_4{^-}$과 흡수길항관계(吸收拮抗關係)가 있었다.

• Fisheries and Aquatic Sciences
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• 제3권2호
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• pp.151-155
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• 2000

Phaeodactylum tricornutum (Bacillariophyceae) is a marine diatom which has been supplied as a food of bivalves. In this study, growth responses of P. tricornutum to some nitrogen sources and sodium were investigated by measuring cell number and contents of chlorophyll a in culture. In medium with nitrogen and sodium, brisk cell division occurred and maximum growth rate was respectively found in the medium with 150 mg/l of nitrate and 10 mg/l of ammonium and urea. At 10-500 mg/l ammonium and urea and 200-500 mg/l nitrate, specific growth rate decreased slightly. However, no cell division observed in sodium-deficient medium, regardless of presence or absence of nitrogen. This suggests that sodium is required for the nitrogen uptake of P. tricornutum, resulting nitrogen uptake leading to cell division. Also the upper limits of ammonium and nitrate for the growth of P. tricornutum seem to be 10 mg/l and 500 mg/l, respectively.

• ALGAE
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• 제25권1호
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• pp.17-26
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• 2010

The effects of salinity on various ecophysiological parameters of Ulva pertusa such as growth, nutrient uptake, photosynthetic performance and internal nutrient composition were tested. U. pertusa was collected from an eelgrass bed in a semi-protected embayment on the southwest coast of Korea. Under salinity regimes from 5 to 40 psu, the specific growth rates $(\mu)$ of U. pertusa ranged from 0.019 to $0.032\;d^{-1}$. Maximum growth rate was observed at 20 psu, and minimum at 40 psu. This species showed various uptake rates for nitrate and phosphate. Nutrient uptake was noticeably higher at intermediate salinity levels, and lower at both extremes. Salinity significantly influenced chlorophyll-$\alpha$ content and effective quantum yield. Tissue nitrogen content ranged from 1.5 to 2.9% N (dry weight), whereas tissue phosphorus ranged from 0.1 to 0.14% P (dry weight). The N : P ratio in the tissue of U. pertusa was considerably higher, ranging from 30 to 50. Increased growth at lower salinity suggests that the initial growth rate of U. pertusa is greater during the rainy season (i.e., late spring and early summer) than any other season during the year. The appearance of an Ulva bloom in eelgrass beds may be triggered by salinity more than by other environmental factors such as light and temperature.

• 한국토양비료학회지
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• 제18권4호
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• pp.413-418
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• 1985

질소원(窒素源)을 달리한 배양액(培養液)으로 담배식물의 양분흡수와 생육반응을 조사한 결과 1. $NO_3-N$ 배양액에서 자란식물은 양분 흡수가 크게 촉진되었다. $NH_4-N$ 배양액에서 자란식물보다 $NO_3-N$의 흡수로 무기양(無機陽)이온의 흡수가 현저하게 증가되었고 그중 K의 흡수가 가장컷으며 처리직후부터 빠른 흡수속도로 총질소(總窒素)는 2배(倍), K, Ca, Mg는 모두 3배 이상 높았다. 그리고 $NO_3+NH_4$ 혼합배양액(混合培養液)에서는 $NO_3-N$ 선택흡수(選擇吸收)되는 경향을 보였다. 2. 담배식물이 자란 배양액의 산도(酸度)는 질소원별로 상이(相異)하여 $NO_3-N$ 배양액은 알카리쪽으로 미미하게 변하지만 $NH_4-N$ 배양액에서 산성(酸性)쪽으로 큰 변화를 나타냈고 $NO_3+NH_4$ 혼합액(混合液)도 산성(酸性)쪽으로 변하지만 $NH_4-N$단독배양액보다는 크지 않았다. 3. 담배식물의 생육반응은 $NO_3-N$ 배양액에서 가장 양호하게 나타났으나 $NH_4{^+}$을 함유한 배양액에서는 생육이 부진하였으며 특히 $NH_4-N$ 단독배양액에서는 생육이 거의 정지되었다.

• 한국작물학회지
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• 제51권1호
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• pp.107-111
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• 2006

This study was to verity that the uptake inhibition and accumulation of nitrogen in different potassium levels. Lettuce was used as model plant in this study and grown in pot of 10cm's in diameter and depth with mixture media of vermiculite and perlite under supply of different culture solution for three weeks. Nitrogen absorption at root was inhibited by increased potassium concentration in nutrient solution, and nitrate accumulation of plant was depended on absorption of nitrogen because nitrate content of 0 K level was 4-5 times higher than that of 2 K level, Concentration of ascorbic acid was decreased by increasing the nitrogen absorption, since ascorbic acid (AsA) content of 2K level was higher than those of OK level in both of old leaf and flesh leaf.