• 생물환경조절학회지
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• 제13권4호
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• pp.209-216
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• 2004

본 연구에서는 폐쇄형 식물 생산시스템 내에서 생체정보에 의한 최적 환경제어와 식물의 환경스트레스 판단을 위하여 엽록소형광 분석법으로 광합성효율 모델을 만들었으며, 광합성효율 모델에 유전알고리즘을 적용하여 재배환경 최적화 프로그램의 응용성을 평가하였다. 6가지 미기상 요인 중 5가지는 고정하고 1가지씩만 변화시켜 가며 측정한 Fv'/Fm'이 최대가 되는 환경조건은 기온 $21^{\circ}C,\;CO_2$농도 $1,200\~1,400ppm$, 상대습도 $68\%$, 기류속도 $1.4m{\cdot}s^{-1}$, 배양액온도 $20^{\circ}C$이었으며 PPF가 $140{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ 보다 증가할수록 광합성 효율은 감소하였다. 광합성효율모델의 오차는 평균 $2.5\%$였다. 재배환경 최적화 프로그램으로부터 계산된 밀폐형식물 생산시스템내에서 상추의 최적재배환경조건은 기온 $22^{\circ}C$, 배양액온도 $19^{\circ}C,\;CO_2$농도 1,400ppm, 기류속도 $1.0m{\cdot}s^{-1}$, PPF $430{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 상대습도 $65\%$이다. 이상의 연구 결과로부터 광합성 효율 모델을 이용하여 식물 생산시설의 환경모니터링 시스템과 식물 생체정보에 의한 최적제어시스템의 개발이 가능함을 확인하였다.

• 한국환경과학회지
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• 제22권6호
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• pp.705-715
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• 2013

The response of the freshwater microalga Chlorella vulgaris to mercuric ion ($Hg^{2+}$) stress was examined using chlorophyll a fluorescence image analysis and O-J-I-P analysis as a way to monitor the toxic effects of mercury on water ecosystems. The levels of photosynthetic pigments, such as chlorophyll a and b and carotenoids, decreased with increasing $Hg^{2+}$ concentration. The maximum photochemical efficiency of photosystem II(Fv/Fm) changed remarkably with increasing $Hg^{2+}$ concentration and treatment time. In particular, above $200{\mu}M\;Hg^{2+}$, considerable mercury toxicity was seen within 2 h. The chlorophyll a fluorescence transient O-J-I-P was also remarkably affected by $Hg^{2+}$; the fluorescence emission decreased considerably in steps J, I, and P with an increase in $Hg^{2+}$ concentration when treated for 4 h. Subsequently, the JIP-test parameters (Fm, Fv/Fo, RC/CS, TRo/CS, ETo/CS, ${\Phi}_{PO}$, ${\Psi}_O$ and ${\Phi}_{EO}$) decreased with increasing $Hg^{2+}$ concentration, while N, Sm, ABS/RC, DIo/RC and DIo/CS increased. Therefore, a useful biomarker for investigating mercury stress in water ecosystems, and the parameters Fm, ${\Phi}_{PO}$, ${\Psi}_O$, and RC/CS can be used to monitor the environmental stress in water ecosystems quantitatively.

• ALGAE
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• 제20권2호
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• pp.121-125
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• 2005

The modern integrated fish-seaweed mariculture has been tested to reduce the environmental impacts of an intensive fed culture. To obtain the best seaweed bioremediation performance, the effects of therapeutants used for fish disease control on the selected seaweed species should be considered. As a selected seaweed, Porphyra yezoensis was tested with six commercial antibiotics including erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, doxycycline, pefloxacin, and amoxicillin trihydrate under the batch incubation at a photon flux density of 10 $\mu$mol ${\cdot}m^{-2}\;{\cdot}\;s^{-1}$ at 15$^{\circ}C$. Among the tested commercial antibiotics, erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, and doxycycline showed decreases in Fv/Fm, the photochemical efficiency of photosystem II, with a dose-dependant and time-dependant manner. From the quenching analysis of chlorophyll fluorescence, three differential patterns were observed in the antibiotics-treated Porphyra: (1) high nonphotochemical quenching (NPQ) and low photochemical quenching (qP) in the cases of Erythromycin thiocyanate_B and amoxicillin trihydrate, (2) high NPQ and high qP in the case of pefloxacin and (3) low NPQ and low qP in the case of oxytetracycline. These results indicated that antibiotics affected in various ways on the photosynthetic apparatus, reflecting differential lesion sites of antibiotics. In addition, the rates of ammonium uptake also decreased with a decrease of Fv/Fm in P. yezoensis thalli treated with erythromycin thiocyanate_B and oxytetracycline. Therefore, the four antibiotics mentioned could affect the bioremediation capacity of the selected seaweed species in the integrated fish-seaweed mariculture system due to the decrease of photosynthetic activity and the simultaneous decrease of ammonium uptake.

• 한국초지조사료학회지
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• 제42권3호
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• pp.208-214
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• 2022

Drought stress is a condition that occurs frequently in the field, it reduces of the agricultural yield of field crops. The aim of the study was to screen drought-adapted genotype of Italian rye grass. The experiments were conducted between the two Italian ryegrass (Lolium multiflorum L.) cultivars viz. Hwasan (H) and Kowinearly (KE). The plants were exposed to drought for 14 days. The results suggest that the morphological traits and biomass yield of KE significantly affected by drought stress-induced oxidative stress as the hydrogen peroxide (H₂O₂) level was induced, while these parameters were unchanged or less affected in H. Furthermore, the cultivar H showed better adaptation by maintaining several physiological parameter including photosystem-II (Fv/Fm), water use efficiency (WUE) and relative water content (RWC%) level in response to drought stress. These results indicate that the cultivar H shows improved drought tolerance by generic variation, improving photosynthetic efficiency and reducing oxidative stress damages under drought stress. These findings can be useful to the breeder and farmer for improving drought tolerance in Italian rye grass through breeding programs.

• 한국환경과학회지
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• 제6권4호
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• pp.369-378
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• 1997

The effects of various intensity of W-B on barley seeding were investigated by PS I and II activities and chlorophyll fluorescence. The Inhibitory effect of UV-B radiation on electron transport activity was Increased as the intensity of UV-B Irradiation was increased. Especially, PS I is more sensitive to UV-B radiation than PS I is. By the addition of uncle electron donor, DPC, to the chloroplasts of the barley seedlings treated with UV-B, the photoreduction of DCPIP was recovered by only 1 IBI on electron transport activity. However, the activity of PS II was Inhibited by 45% by the treatment with UV-B, but recovered it only 11% by the addition of DPC. These suggest that other sites besides the oxidation site of PS II may be affected more by UV-B Irradiation. As the intensify of UV-B was Increased, Fo was Increased while Fv was decreased, and thus Fv/Fm was decreased. This means that photochemical efficiency was reduced. With this parameters, it might be that UV-B radiation affected adversely to around PS II.

• 한국초지조사료학회지
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• 제38권3호
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• pp.170-174
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• 2018

Environmental stresses caused by climate change, such as high temperature, drought and salinity severely impact plant growth and productivity. Among these factors, high temperature stress will become more severe during summer. In this study, we examined physiological and molecular responses of maize plants to high temperature stress during summer. Highest level of $H_2O_2$ was observed in maize leaves collected July 26 compared with June 25 and July 12. Results indicated that high temperature stress triggers production of reactive oxygen species (ROS) in maize leaves. In addition, photosynthetic efficiency (Fv/Fm) sharply decreased in leaves with increasing air temperatures during the day in the field. RT-PCR analysis of maize plants exposed to high temperatures of during the day in field revealed increased accumulation of mitochondrial and chloroplastic small heat shock protein (HSP) transcripts. Results demonstrate that Fv/Fm values and organelle-localized small HSP gene could be used as physiological and molecular indicators of plants impacted by environmental stresses.

• 한국약용작물학회지
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• 제26권2호
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• pp.181-187
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• 2018

Background: This study aimed to investigate out the influence of drought stress on the physiological responses of Dendropanax morbifera seedlings. Methods and Results: Drought stress was induced by discontinuing water supply for 30 days. Under drought stress, photosynthetic activity was significantly reduced with decreasing soil water content (SWC), as revealed by the parameters such as Fv/Fm, maximum photosynthetic rate ($P_{N\;max}$), stomatal conductance ($g_s$), stomatal transpiration rate (E), and intercellular $CO_2$ concentration (Ci). However, water use efficiency (WUE) was increased by 2.5 times because of the decrease in $g_s$ to reduce transpiration. Particularly, E and $g_s$ were remarkably decreased when water was withheld for 21 days at 6.2% of SWC. Dendropanax morbifera leaves showed osmotic adjustment of -0.30 MPa at full turgor and -0.13 MPa at zero turgor. In contrast, the maximum bulk modulus of elasticity ($E_{max}$) did not change significantly. Thus, Dendropanax morbifera seedlings could tolerate drought stress via osmotic adjustment. Conclusions: Drought avoidance mechanisms of D. morbifera involve reduction in water loss from plants, through the control of stomatal transpiration, and reduction in cellular osmotic potential. Notably photosynthetic activity was remarkably reduced, to approximately 6% of the SWC.

• 한국환경농학회지
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• 제26권3호
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• pp.239-245
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• 2007

The effect of ultraviolet-B (UV-B) radiation on photosynthesis was studied by the simultaneous measurements of $O_2$ evolution and chlorophyll (Chl) fluorescence in tobacco leaves. When the tobacco leaves were teated with UV-B (1 $W{\cdot}m^{-2}$), the maximal photosynthetic $O_2$, evolution (Pmax; 4.60 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) at 200 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) was decreased with increasing time of UV-B treatment showing 80% decline after 4 h treatment. Chl fluorescence parameters were also affected by ultraviolet-B. Fo was increased while both Fm and Fv were decreased, resulted in the decreased of photochemical efficiency of PSII (Fv/Fm). Non-radiative dissipation of absorbed light as heat as estimated as NPQ (Fm/Fm' - 1) was also decreased with increasing time of UV-B treatment while the extent of photochemical quenching (qP) was not changed. Thus, the ratio of (1-qP)/NPQ parameter was also increased with increasing time of UV-B treatment indicating PSII is under the threat of photoinhibition. The result indicate that UV-B primarily decreases the capacity to dissipate excitation energy by trans-thylakoid pH, which in turn inhibits PSII activity.

• 한국작물학회지
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• 제64권1호
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• pp.48-54
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• 2019

본 연구는 염 농도 별 나문재의 생장과 식물체 내의 무기 이온과 아미노산 함량, 광합성 효율 등을 조사하여 염농도에 따른 나문재의 생리적 특성을 구명하고자 실시하였다. 나문재의 초장, 분지수, 건물중을 조사하였을 때, 50 mM에서 최적의 생육 상태를 보였고 50~100 mM의 염농도 범위에서 생육이 양호하였다. 식물체 내 무기이온의 함량은 염농도가 높을수록 Na 이온의 함량은 증가하였고, K, Ca, Mg 이온의 함량은 감소하였다. 식물체 부위별 무기이온의 함량은 Na 이온의 함량은 지하부보다 지상부에서 더 높게 나타났다. 염농도에 따른 식물체의 유리아미노산 함량을 보면, proline을 제외한 glycine 등의 16종의 아미노산은 공통적으로 생육에 최적 염농도인 50 mM에서 함량이 가장 낮게 나타났으며, proline은 정반대로 50 mM에서 현저히 높은 함량을 보였다. 염농도에 따른 광합성 효율은 50 mM에서 가장 높았으나 400 mM의 높은 염농도에서도 광합성효율의 저하는 크지 않았다. 결론적으로, 나문재의 생육에 최적 염농도는 50 mM이었지만, 염농도 변화에 따른 식물체 내의 무기이온, proline 등의 아미노산 함량의 변화, 그리고 고염조건에서도 광합성 효율을 유지할 수 있는 생리적 특성으로 0~400 mM의 넓은 범위의 염농도에서도 생육이 가능하여, 염농도의 변이가 큰 신간척지에 적합한 염생식물로 판단된다.

• Journal of Photoscience
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• 제1권2호
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• pp.95-105
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• 1994

Experiments were carried out to investigate whether P, deficiency in detached 25 mM mannose-feeding led to a decline of the photosynthetic electron transport rates through acidification of the thylakoid lumen. With increasing mannose-feeding time, the maximal CO2 exchange rates and the maximal quantum yields of photosynthesis decreased rapidly up to 6 h by 73% then with little decrease up to 12 h. The ATP/ADP ratio declined by 54% 6 h after the treatment and then recovered to the control level at 12 h. However, the NADPH/NADP~ ratio was not significantly altered by mannose treatment. Electron transport rates of thylakoid membranes isolated from 6 h treated leaves did not change, but they decreased by 30% in 12 h treated leaves. The quenching analysis of Chl fluorescence in mannose-treated leaves revealed that both the fraction of reduced plastoquinone and the degree of acidification of thylakoid lumen remained higher than those of the control. The reduction of PSI in mannose fed leaves was inhibited due to acidification of thylakoid lumen (high qE). The reduction of primary quinone acceptor of PSII was inhibited by mannose feeding. Mannose treatment decreased the efficiency of excitation energy capture by PSII. Fo quenching was induced when treated with mannose more than 6 h, and had a reverse linear correlation with (Fv)m/Fm ratio. These results suggest that Pi deficiency in Chinese cabbage leaves reduce photosynthetic electron transport rates by diminishing both PSII function and electron transfer from PSII to PSI through acidification ofthylakoid lumen, which in turn induce the modification of photosynthetic apparatus probably through protein (de)phosphorylation.