• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.231-238
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• 2018

Chlorophyll fluorescence, chlorophyll content, graft-taking and growth of grafted cucumber seedlings as affected by photosynthetic photon flux (PPF) of LED lamps were analyzed in this study. Four PPF levels, namely 25, 50, 100, $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ were provided to investigate the effect of light intensity on the chlorophyll fluorescence, chlorophyll content, graft-taking and growth of grafted cucumber seedlings. Air temperature, relative humidity, and photoperiod for graft-taking were maintained at $25^{\circ}C$, 90%, $16h{\cdot}d^{-1}$, respectively. Maximum quantum yield (Fv/Fm) of rootstock as affected by PPF was found to be 0.84-0.85 and there was no significant change in Fv/Fm. Even though Fv/Fm of scion measured at 2 days after grafting was lowered to 0.81-0.82, after then it gradually increased with increasing PPF. At 4 days after grafting, the chlorophyll content extracted from scion increased with increasing PPF. Graft-taking ratio of grafted cucumber seedlings was 90-95% as PPF was ranged from $25{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ to $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. However, the graft-taking ratio of grafted seedlings healed under PPF of $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was decreased to 80%. Maximum PPF measured required for smooth joining of rootstock and scion was assumed to be $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. At healing stage of grafted cucumber seedlings, Fv/Fm of scion decreased and at least two days after grafting were required for rooting of grafted seedlings. Chlorophyll fluorescence response of rootstock and scion was linked to light irradiation. Therefore, it was concluded that physical environment including light and humidity during healing process of grafted seedlings should be controlled more precisely to facilitate root formation and to prevent scion from lowering Fv/Fm. Further studies are required to investigate the effects of root development and joining of vascular bundles of grafted seedlings on the chlorophyll content of scion.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.57-57
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• 2019

실내 수준에서 조사되는 광량조건에 따른 자생 상록활엽 2종의 생육과 광화학반응을 조사하였다. 식물재료는 3년생 사철나무(Euonymus japonicus Thunb.) 및 2년생 돈나무[Pittosporum tobira (Thunb.) W. T. Aiton] 실생묘로 유리온실에서 재배하면서 실험에 사용하였다. 실내 광량은 10, 50, 100 및 200 PPFD(${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$)로 달리하여 8주간 재배하였으며, 광주기(12/12 h), 온도($25{\pm}1^{\circ}C$), 습도($55{\pm}3%$) 및 관수(1회/3일)조건은 고정되었다. 생육특성 및 광화학반응의 요인들이 측정되었으며, 동일기간 동안 유리온실에서 재배된 식물을 대조구로 사용하였다. 실험의 결과, 사철나무는 100, 200 PPFD의 광량에서 대조구에 비해 초장, 줄기직경, 엽수 및 엽장의 생육반응이 우수하였으며, 엽록소함량은 100 PPFD 이상의 광량에서 감소하였다. 또한 100 PPFD 이상의 광량에서 스트레스지수(Fm/Fo), 최대양자수율(Fv/Fm) 및 전자전달효율(ETo/RC)이 감소하였으며, 이는 대조구와도 유사한 경향이었다. 돈나무는 모든 광량조건에서 줄기직경과 엽폭을 제외하고 대조구와 관계없이 생육반응이 일정하였다. 그러나 스트레스지수와 최대양자수율은 10 PPFD 처리구에서 가장 낮게 조사되었고, 비광학적 에너지의 손실(DIo/RC)은 2.53으로 가장 높았다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.55-55
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• 2019

본 연구에서는 실내에 조사되는 다양한 광량하에서 녹나무과 목본 2종을 재배하면서 생육반응을 조사하였다. 식물재료는 참식나무[Neolitsea sericea (Blume) Koidz.]와 후박나무(Machilus thunbergii Siebold & Zucc.)의 3년생 실생묘를 사용하였다. 실험공간은 광량을 10, 50, 100 및 200 PPFD (${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$)로 달리하였으며, 광주기(12/12 h), 온도($25{\pm}1^{\circ}C$), 습도($55{\pm}3%$) 및 관수(1회/3일) 조건이 동일하게 유지되는 밀실로 조성되었다. 각 광량조건 하에서 8주간 재배된 식물의 생육특성 및 광화학반응이 조사되었으며, 유리온실에 동일 기간동안 재배한 식물과 비교하였다. 연구 결과, 참식나무는 광량에 관계없이 초장을 제외한 전반적인 생육반응이 유사하였으며, 엽록소함량(SPAD)은 광량이 증가함에 따라 감소하는 경향이었다. 최대양자수율(Fv/Fm) 및 스트레스지수(Fm/Fo)는 200 PPFD에서 유의한 차이를 나타냈으며, 이는 대조구와 유사한 경향이었다. 후박나무는 대조구와 비교하여 모든 광량조건에서 초장이 감소하였으며, 특히 10 PPFD에서는 잎의 탈락에 따른 관상가치가 저하되었다. 엽록소함량은 100, 200 PPFD 광량에서 감소하였으며, 대조구도 유사한 경향을 나타냈다. 또한 유리온실의 대조구와 100, 200 PPFD 광량에서 최대양자수율, 스트레스지수 및 PSII 성능지수(Pi_Abs)의 유의한 차이가 확인되었다.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.273-280
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• 2003

Saline conditions invoke oxidative stress attributed to the overproduction of reactive oxygen species (ROS). Changes in quantum efficiency and antioxidative enzyme activity upon salt treatment were examined in a salt-tolerant plant, Atriplex gmelini, to test the hypothesis that salt tolerance of A. gmelini is due to the increased activity of antioxidative enzymes. A. gmelini showed optimum growth at 100 mM NaCl producing 116% of the shoot dry weight over control plants in 0 mM NaCl treatment. Healthy growth persisted up to 300 mM NaCl treatment maintaining normal internal water content and dry weight. No photochemical stress or damages on antioxidative defense system was obvious in plants of 2 and 4 day salt treatment which was indicated by increased quantum efficiency (Fv/Fm value), decreased stress index (Fo/Fm value), and increased activity of antioxidative enzymes such as SOD, APX, GR. However, the plants treated with 400 mM NaCl showed decrease in growth and in antioxidative enzyme activity although the enzyme activity was still higher than that of the 0 mM NaCl treated plants (l31%, 114%, and 134% of the SOD, APX, and GR activity, respectively). Interestingly, another important antioridative enzyme that scavenges H₂O₂ in plant cells, CAT, showed rapid decrease in its activity as salt concentration increased; 38%, 22%, 15% of the 0 mM NaCl treated plants at 200, 300, 400 mM NaCl treatments, respectively. It appears that the enzymes in ascorbate-glutathione cycle such as APX and GR play the major roles in scavenging ROS produced by salt stress in A. gmelini. After 6 days of salt treatment, the damage in photochemical and antioxidative defense system was indicated by decreased Fv/Fm value and increased Fo/Fm value. A. gmelini appears to cope with short term salt treatment by enhanced activity of the antioxidative defense system, whereas long term stress invoke oxidative stress by increased ROS due to the damages in photochemical and antioxidative system.

• The Korean Journal of Ecology
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• v.19 no.2
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• pp.151-163
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• 1996

To investigate the early symptoms of light-chilling, alterations of chlorophyll fluorescence transients were monitored in cucumber (Cucumis sativus L. cv. Ilmichungjang) leaves. During 24 h chilling, decreases in (Fv)m/Fm, qE and qQ, and an increase in Fo were observed. The chilling effects were not recovered at room temperature, and a significant increase in Fo was observed during the recovery period. After 6 h chilling, ‘dip’(D) level of the transients became obscure, and the negative slope after ‘peak’(P) disappeared. The first derivative (dFv/dt) of the fast fluorescence rise curve was used to obtain more accurate information about the changes in the transients. The maximal rate of the fluorescence increase in the D-p rise curve (Fr) has been the most frequently used chilling stress indicator. However, a correct value of Fr could not be measured when the D level became obscure. This problem was overcome by introducing a new indicator, HFr (dFv/dt at Fv = 1/2 (Fv)m), and HFr gave very similar values to Fr. To monitor the changes in curvature around D level, another new parameter, ${\Delta}S$(D-Fr), was also introduced. These three parameters decreased very sensitively during light-chilling. In addition, increases in these parameters were observed during the first 2 h chilling, but this increase in Fr was also observed in pea leaf discs dark-chilled for 15 min, suggesting that this very early change is a common response to chilling in both pea and cucumber leaves. Quenching coefficients were also very sensitive to chilling, especially qE. Discussion on the usage of these parameters as chilling stress indicators is given in the text.

• Journal of Environmental Science International
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• v.6 no.4
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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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.506-515
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• 2003

Six barley varieties that showed different degree of drought tolerance were grown with and without drought stress treatment (control), and investigated for the temporal changes in growth and several physiological traits after drought treatment. Soil water potential was -0.05 ㎫ at the initial stage of drought treatment and dropped to -0.29 ㎫ at 19 days after withholding irrigation. Soil water potential (SWP) maintained at -0.05 ㎫ in the control. The dry weight (DW) under the drought treatment were reduced compared to the control as follows: Dicktoo-S (short awn), 69% ; Dicktoo-L (long awn), 70%; Dicktoo-T (tetra), 86%; Dongbori-1, 69%; Suwonssalbori-365, 55% and Tapgolbori, ,37%. Dicktoo lines and Dongbori-1 were more tolerant than Suwonssalbori-365 and Tapgolbori. Leaf relative water contents (RWC) and leaf water potential (LWP) decreased obviously under the drought condition, the decrease being greater especially in the less drought-tolerant barley genotypes. Dongbori-1 and Dicktoo-L in drought treatment showed net photosynthesis of 38% and 17% compared to the control, respectively, and the other four genotypes much lower photosynthesis of 1.1% to 7.0%. Stomatal conductance, mesophyll conductance, and the photochemical efficiency (Fv/Fm) of PS II were reduced by drought treatment, the reduction being greater in drought-sensitive genotypes. The drought-tolerant genotypes had greater osmotic adjustment (OA) capacity under water stress. Thus, the decrease of RWC and LWP was lower and the turgor pressure conservation capacity was higher under water stress in drought-tolerant genotypes. Drought-tolerant genotypes showed less decrease of photosynthesis because stomatal conductance, mesophyll conductance and the ratio (Fv/Fm) of the variable to maximal fluorescence of drought-resistant genotype was decreased less in the drought stress condition. In conclusion, the drought-tolerant genotypes had better water conservation capacity through efficient OA, and this led to the lower decrease of photosynthesis and growth in water stress condition.

• Korean Journal of Environmental Biology
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• v.20 no.3
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• pp.197-204
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• 2002

Gourd seeds were irradiated with the doses of 0-20 Gy to investigate the effect of the low dose $\gamma$-radiation on the early growth and physiological activity. The stimulating effects of the low dose y- radiation on the early growth were not noticeably high, but were increased generally at 4-16 Gy irradiation group. The catalase and peroxidase activity of cotyledon from seeds irradiated with $\gamma$- radiation were increased at 8 Gy irradiation group. The photochemical activity of leaf was noticeably high at 4 Gy irradiation group. The photochemical yield of PSII, estimated as Fv/Fm, decreased with increasing illumination time by 50% after 4 hrs in the control and 8 Gy irradiation group, while Fo slightly increased. However, Fv/Em in the 4 Gy irradiation group decreased by 40% of inhibition, indicating that photoinhibition decreased by the low dose $\gamma$- radiation. Changes in the effective quantum yield of PSII, $\varphi_{PSII}$ and 1/Fo- l/Fm, a measure of the rate constant of excitation trapping by the PSII reaction center, showed similar pattern to Fv/Em. NPQ decreased by 70% after photoinhibitory treatment with showing similar pattern between the control and the irradiation group. These results showed the positive effect of low dose $\gamma$- radiation on the seedling growth and the reduction of photoinhibition in the 4 Gy irradiation group.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.209-214
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• 2001

Physiological responses of rice to the flooding time of different water turbidity (clear water, sub-muddy water, muddy water) were analyzed as photosynthesis, chlorophyll fluorescence, transpiration, and physiological recovery. Photosynthetic rate was higher as turbidity increased and decreased as flooding time was extended. Floodings of 36 hrs and 42 hrs were resulted in 25% and 50% decrease of photosynthetic rate, respectively. Transpiration rate was higher in high turbidity (increased 30%, 25%, and 20% in clear, sub-muddy, and muddy water, respectively) and in increased floodings. Fv/Fm decreased as increased turbidity and flooding time. About 20% decrease of Fv/Fm was recorded in 48 hrs and 36 hrs after flooding with clear water and sub-muddy water(including muddy water), respectively. Total nitrogen was decreased with flooding treatment. Significant decrease of total nitrogen was occurred 36 hrs after flooding with muddy water, Dry weight measured 2 weeks after flooding treatment as an indication of recovery of flooding stress didn't show significant difference with turbidity, but significantly decreased as flooding time was prolonged. About 25% and 50% decreases were found in 24 hrs and 42 hrs flooding time, respectively. furthermore, 48 hrs of flooding with sub-muddy and muddy water resulted in no physiological recovery. Photosynthetic rate was decreased 15% and 10% with clear water and muddy water(including sub-muddy water), respectively. The rate was dramatically decreased 42 hrs after flooding. Transpiration rate increased about 20% regardless of turbidity and flooding time. We found transitory decrease of photosynthetic and transpiration rate at the point of 24 hrs after flooding and right after do-flooding.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.124-130
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• 2006

To explore the development of photoprotective mechanisms, chlorophyll a fluorescence, chlorophyll and carotenoid content and antioxidant enzyme activity in leaves were investigated at different vitality and leaf development stage of Alnus firma Sieb. et Zucc under tailing condition. The lowest maximum photochemical efficiency (Fv/Fm) in leaves of high- and low-vitality plants were observed at 12:00 pm and 2:00 pm, respectively, and the decrease of Fv/Fm in leaves of all plants were almost completely restored at 6:00 pm. Fv/Fm of full-expansion leaves was higher than that of emergence leaves at all measurement time. Chlorophyll, ${\beta}$-carotene and xanthophyll content in leaves of high-vitality plants and in full-expansion leaves were higher when compared to those of low-vitality plants and emergence leaves. Especially xanthophyll contents in both stage leaves of high-vitality plants were higher than 8.7 times and 18.8 times those of low-vitality plants. Only SOD activity was seen significant difference between leaf stage in leaves of high-vitality plants.