• 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.

• ALGAE
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• 제28권3호
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• pp.281-288
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• 2013

Photosynthetic carbon fixation regulates air-sea $CO_2$ fluxes in the waters of coral reefs. However, little has been documented on the effects of solar UV radiation (UVR, 280-400 nm) upon photosynthetic behaviors of phytoplankton dwelling in these ecosystems. In order to evaluate the aforesaid, surface dwelling tropical coral reef phytoplankton assemblages collected from the South China Sea were exposed to solar radiation (i.e., photosynthetically active radiation [PAR] + UV radiation A [UVA] + UV radiation B [UVB], 280-700 nm; PAR + UVA, 320-700 nm; and PAR, 400-700 nm) under static or simulated-mixing conditions. Under the static condition, UVA and UVB significantly reduced the carbon fixation with the maximum of 22.4 and 15.3%, respectively; while lower UVR-related photosynthetic inhibition was observed in case of phytoplankton samples being subjected to mixing. At a moderate level of mixing (i.e., circulation time 80 min), the UVA and UVB caused inhibition were lowered by 52.1 and 79.6%, respectively. Based on this it could be stated that vertical mixing induced by winds and/or tides in the natural environments could reduce the inhibitory effect of solar UVR on phytoplankton productivity in the coral reefs water.

• 한국대기환경학회지
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• 제14권6호
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• pp.537-544
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• 1998

We selected Spathiyhyllum patinii and Pachira aqkatica, since the former has high O3 absorption while the latter low absorption, and analyzed physiological factors such as diffusive coefficient, transpiration rate, photosynthetic rate, and CO2 absorption rate, which affected O3 absorption capacity There was significant relationship between gas absorption capacity and the other factors; photosynthetic rate, diffusive resistance, stomatal resistance and CO2 absorption rate. Therefore model formula for estimation of O3 absorption rate in plant was formulated by making use of these factors. There was difference for the estimation of O3 absorption rate according to plant species. In case of Spathiphyllum patinii, photosynthetic rate is an optimal factor for estimation of O3 absorption capacity. On the other hand, stomatal resistance and diffusive resistance are optimal factors of Pachira aquatica among various physiological ones. And we knew that CO2 absorption rate is a potential factor to evaluate gas absorption capacity regardless of plant species. But considering efficiency and practicality, diffusive resistance was the most effective factor for the estimation of O3 gas absorption.

• 미생물학회지
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• 제32권1호
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• pp.1-6
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• 1994

광합성 세균과 비광합성 세균에 속하는 종들 사이의 유연관계를 파악하기 위해 DNA 혼성화 방법을 실시하였다. 혼성화도는 종내 균주들 사이와 Rhodobacter capsulatus와 Rhodopseudomonas blastica 사이를(72-88%) 제외하고는 전체적으로 낮게 나타났다(2-35%). 광합성 세균 Rhodopseudommonas Palustris와 비광합성 세균 Pseudomonas aeruginosa ATCC 27853, Bradyrhizobium japonicu, 사이의 D%는 광합성 세균 사이의 D%보다 약간 높게 나타났다(26-33%). Rhodopseudomonas blastica와 Rhodobacter capsulatus 사이의 D%는 72%로 유전적 유연관계가 매우 높은 것으로 나타났다.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.1-7
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• 2007

A model was developed to predict the effects of rising air temperature on net photosynthetic rate of Quercus mongolica stands at Mt. Paekcheok-san, Kangwon-do in South Korea. The PFD (Photon flux density) and air temperature were determined from weather data from the research site and the Daegwallyeong meteorological station and gas exchange or release responses of each tree component were measured. Using these data, we simulated the effects of increases in mean annual air temperatures above current conditions on annual $CO_2$ budget of Q. mongolica stands. If mean annual air temperature is increased by 0.5, 1.0, 1.5, 2.0, 2.5 or $3.0^{\circ}C$, annual net photosynthetic rate will be increased by 8.8, 12.8, 14.5, 12.6, 9.2 and 1.0 ton $CO_2\;ha^{-1}yr^{-1}$ respectively. Simulations indicate that changes in air temperature will have a major impact on gas exchange and release in Q. mongolica stands, resulting in a net increase in the rate of carbon fixation by standing crops.

• Journal of Ecology and Environment
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• 제31권4호
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• pp.261-267
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• 2008

Growth and photosynthetic responses of one $C_3$ and two $C_4$ plants in the family Chenopodiaceae in three $CO_2$ concentration $([CO_2])$ conditions-low (about $243{\mu}mol\;mol^{-1}$, LC), present (about 378, PC), and high (about 465, HC)-were investigated in open top chambers. The relative growth rate (RGR) and net assimilation rate in the $C_3$ plant, Chenopodium album, increased with increasing $[CO_2]$, though the RGR was not enhanced significantly in the HC condition. The leaf area ratio and leaf weight ratio of the $C_3$ plant drastically decreased with increasing $[CO_2]$, suggesting that the $C_3$ plant invests more biomass to leaves in lower $[CO_2]$ conditions. The two $C_4$ plants, Atriplex glauca and A. lentiformis, showed relatively small changes in those growth parameters. These photosynthetic-pathway-dependent responses suggest that growth patterns of $C_3$ and $C_4$ plants have been altered by past increases in atmospheric $[CO_2]$ but that there will be relatively little further alteration in the future high-$CO_2$ world.

• ALGAE
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• 제30권2호
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• pp.103-119
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• 2015

Photosynthetic rates of the large centric diatom Coscinodiscus granii were measured by means of multicolor variable chlorophyll fluorescence imaging, single cell $^{14}C$ assimilation, and optical $O_2$ sensor measurements during light acclimatization of cultures grown at five different irradiances: 50, 150, 235, 332, and $450{\mu}mol$ photons $m^{-2}\;s^{-1}$. Photo-acclimatization was evident from changes of cellular chlorophyll a content, growth rates, and light response curves. Each of the applied methods evaluates different parts and reactions in the photosynthetic apparatus, which makes a direct quantitative comparison of rates difficult, although a different degree of correlation were found between all three methods. However, when used in combination, they provide information about the internal relationship of photosynthetic pathways as well as the variation in photosynthetic capacity between individual cells within a single algal culture.

• 식물병연구
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• 제8권4호
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• pp.245-249
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• 2002

검은점뿌리썩음병의 병원균에 감염된 참외의 광합성 및 생육 반응을 측정한 결과, 수확기 참외의 광합성 속도는 이병주가 건전주에 비해 현저하게 낮았고, 기공저항은 이병주에서 큰 것으로 나타났다. 목부일비액은 이병주에서 전혀 분비되지 않았다. 수확기 참외의 잎과 줄기에서 무기양분함량은 이병주와 건전주 간에 차이를 보여주지 않았다. 참외의 생육특성은 이병주가 건전주에 비해 엽면적이나 생체중및 건물중에서 건전주에 비해 낮았으며, 평균 과중도 같은 경향을 보였다.

• 한국식품영양학회지
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• 제13권6호
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• pp.558-562
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• 2000

Ubiquinone-10생성 광합성 세균을 선정하기 위하여 경상북도 대구 근교의 강, 논, 호수 등의 수계혐기층에서 토양시료를 채취하거나 유기 폐수 중에서 시료를 채취하였으며. 총 50점의 시료에서 130주의 광합성 세균을 분리하였으며 이 중에서 ubiquinone-10의 생성이 가장 많은 균주번호 N-2를 최종 선정하였다. 선정된 균주의 미생물학적 특성을 규명한 결과 Rhodobacter sp.와 거의 일치하였으며 이 균주는 이와 동일한 균주이거나 유사한 근연의 균으로 판단하여 본 분리균주 N-2를 Rhodobacter sp. N-2로 명명하였다. 본 균주는 anaerobic light로 배양할 때가 aerobic dark일 때보다 훨신 생육이 양호하였다. 분리균 N-2의 growth factor는 biotin, thiamin, niacin중 하나이며, 3가지를 동시에 첨가하였을 때 완전한 생육을 나타낸다. 유황화합물 H$_2$S를 첨가하였을 때 매우 적은 농도에서 본 균주의 성장이 저해되었다.

• 미생물학회지
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• 제5권1호
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• pp.15-19
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• 1967

Chlorella ellipsoidea cells were cultured in an iron, copper, zinc, manganese, molybdenum or boron-free medium. Physiological activities such as growth rate, reproduction, endogenous and glucose respiration, photosynthetic activity and biosythesis of chlorophyll of the micro-element definition cells were measured. It generally, growth rate, respiratory and photosynthetic activities, and biosynthesis of chlorophyll of the micro-element deficient cells decreased more or less, compared with those of the normal cells. The growth of the algal cells in an iron-free medium were retarded severely with the chlorosis, and the photosynthetic activity of the cells decreased remarkably even though the low content of chlorophyll in the cells owing to the iron-deficiency is considered. Therefore, it is deduced that iron takes part in the photosynthetic process itself, possibly by its participation in the photo phosphorylation coupled with electron transport. Respiratory activity of boron-deficient cells showed the most severe decrease whereas those of the molybdenum-deficient cells showed very slight decrease in spite of severe growth retardation.