• Korean Journal of Medicinal Crop Science
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2020

Background: This study was conducted to investigate the effects of NaCl concentration on the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of Crepidiastrum sonchifolium. Methods and Results: As treatments, we subjected C. sonchifolium plants to four different concentrations of NaCl (0, 50, 100 and 200 mM). We found that the photosynthetic parameters maximum photosynthesis rate (P_{N max}), net apparent quantum yield (Φ), maximum carboxylation rate (V_cmax), and maximum electron transport rate (J_max) were significantly reduced at an NaCl concentration greater than 100 mM. In contrast, there was an increase in water-use efficiency with increasing NaCl concentration, although in terms of growth performances, leaf dry weight, root dry weight, stem length, and total dry weight all decreased with increasing NaCl concentration. Furthermore, leakage of electrolytes, as a consequence of cell membrane damage, clearly increased in response to an increase in NaCl concentration. Analysis of the polyphasic elevation of chlorophyll a fluorescence transients (OKJIP) revealed marked decrease in flux ratios (Φ_PO, Ψ_O and Φ_EO) and the PI_abs, performance index in response to treatment with 200 mM NaCl, thereby reflectings the relatively reduced state of photosystem II. This increase in fluorescence could be due to a reduction in electron transport beyond Q^-_A. We thus found that the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of C. sonchifolium significantly increased in response to treatment with 200 mM NaCl. Conclusions: Collectively, the findings of this study indicate that C. sonchifolium shows relatively low sensitivity to NaCl stress, although photosynthetic activity was markedly reduced in plants exposed to 200 mM NaCl.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.60 no.1
• /
• pp.1-7
• /
• 2015

The photochemical characteristics were analyzed in the context of sowing time and different levels of fertilized nitrogen during the maize (Zea mays L.) growth. When maize was early sawn, the fluorescence parameters related with electron-transport, in photosystem II (PSII) and PSI, were effectively enhanced with the higher level of fertilized nitrogen. Highest values were observed in maize leaves grown in double N-fertilized plot. The photochemical parameters were declined in the progress of growth stage. In early growth stage, the fluorescence parameters were highest, and then reduced to about half of the parameters related with electron transport on PSII and PSI at middle and late growth stages. In 1/2 N plot, the photochemical energy dissipation was measured to 13% in term of active reaction center per absorbed photon resulting in decrease in performance index and driving force of electron. This decrease induced to lower the photochemical effectiveness. In 2 N plots, the electron transport flux from $Q_A$ to $Q_B$ per cross section and the number of active PSII RCs per cross section were considerably enhanced. It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective.

• Journal of Plant Biotechnology
• /
• v.40 no.3
• /
• pp.156-162
• /
• 2013

Plant tolerance to drought is a beneficial trait for stabilizing crop productivity under water deficits. Here we report that genetically engineered Chinese cabbage expressing Arabidopsis $H^+$-pyrophosphatase (AVP1) shows enhanced physiological parameters related to drought tolerance. In comparison with wild type plants under soil water deficit stress created by cessation of irrigation, soil water potential in pot with AVP1-expressing plants was more rapidly decreased that might lead to increased relative water content in leaves, while both genotypes had indistinguishable wilting phenotypes. Transgenic plants subjected to drought treatment also exhibited higher photosystem II quantum yield in addition to lower electrolyte leakage and $H_2O_2-3,3^{\prime}$-diaminobenzidine content when compared to wild type plants.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.7 no.2
• /
• pp.156-163
• /
• 2005

This study was conducted to compare the physiological and biochemical responses of P. orientalis and L. tulipifera in response to ozone. One-year-old seedlings of P. orientalis and L. tulipifera were exposed to 100 ppb ozone concentration for 2, 4, or 8 hr/day for 1 week. Photosynthesis, stomatal conductance and ozone uptake rate were measured daily, and chlorophyll fluorescence, carboxylation efficiency, chlorophyll content, and SOD activity were measured after 1 week. In P. orientalis, photosynthesis and stomatal conductance were not decreased in the 2h/day ozone treatment, but the L. tulipifera response was more sensitive even in the 2h/day ozone treatment. Increased treatment time decreased photosynthesis and stomatal conductance. Chlorophyll fluorescence was not significantly different among treatment times. However, carboxylation efficiency decreased with increased treatment time, and L. tulipifera was more sensitive than P. orientalis. Chlorophyll content did not differ with species or treatment time. SOD activity response was greater in L. tulipifera than in P. orientalis, increasing to $131\%$ of pretreatment observations. Therefore it was concluded that L. tulipifera was more responsive and had lower ozone tolerance than P. orientalis.

• Journal of Plant Biology
• /
• v.38 no.1
• /
• pp.87-93
• /
• 1995

For understanding physiological nature of phototaxis in Synechocystis sp. PCC 6803 PTX(S. 6803 PTX), we examined the effects of some metabolic inhibitors and cation ionophore on the phototactic movement. In the presence of DCMU, which blocks the photosynthetic electron transport just after photosystem II acceptor, there was no inhibitory effect on the phototaxis up to $100\;\mu\textrm{M}$. Instead, the respiratory electron chain inhibitor such as sodium azide dramatically impaired the phototaxis in S. 6803 PTX. These observations indicate that the phototaxis is linked not to photo-phosphorylation, but to respiratory phosphorylation. When the cells were treated with un couplers such as CCCP or DNP, which dissipate the electrochemical gradient of proton($\Delta\mu_{H}+$) across the cytoplasmic membrane, these chemicals did not affect phototaxis. In contrast, when cells were treated with DCCD or NBD which deprive cells of A TP but leave $\Delta\mu_{H}+$ intact across the membrane, the phototactic movement was severly reduced. These results imply that ATP production, not proton motive force, is involved in the phototactic movement in this organism as a driving motive force. The application of specific calcium ionophore A23187 strongly impaired positive phototaxis. Calcium fluxes should be engaged in the sensory trans-duction of phototactic orientation. Finally, when ethionine was supplimented to culture media, the photomovement of this organism was inhibited. This implies that methylation/demethylation mechanism controls the process of phototaxis in S. 6803 PTX like chemotaxis in E. coli and Salmonella typhimurium.murium.

• Journal of Plant Biology
• /
• v.38 no.4
• /
• pp.373-380
• /
• 1995

Photoinhibition of photosystem (PS) n was induced in primary leaves of 25 day-old peppers grown $100\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1},\;at\;25^{\circ}C$. The modulation of PSII functionality in vivo was induced by varying both irradiance ($0-3000\;{\mu}molm^{-2}{\cdot}s^{-1}$) and duration (0-70 min) of light treatment. The functionality of PSII was investigated in terms of photochemical efficiency of PSII (Fv/Fm) and quantum yield of $O_2$ evolution, and expressed as a function of photon exposure [$mol\;photons{\cdot}m^{-2}$, the product of irradiance and duration of light treatment (Bell and Rose, 1981)]. Contrary to the linear decline of Fv/Fm ratio showing 50% decreases by absorption of $10\;mol\;photons{\cdot}m^{-2$, quantum yield of $O_2$ evolution decreased biphasically with increasing photon exposure, showing 50% decreases by absorption of $5.5\;mol\;photons{\cdot}m^{-2}$. Treatment of low temperature at $15^{\circ}C$ for 30 min alone did not affect the functionality of PSII, but high temperature ($45^{\circ}C$) significantly inactivated PSII activity. However, when Jeaves of pepper were subjected to low or high temperature in the presence of light, PSII was substantially photoinactivated. These results suggest the presence of different photoinhibitory mechanisms at low and high temperature.rature.

• Korean Journal of Weed Science
• /
• v.15 no.3
• /
• pp.224-231
• /
• 1995

Paraquat, the representative bipyridilium herbicide, has high phytotoxic activity through generating toxic oxygen species such as superoxide, hydrogen peroxide and hydroxy radical. The response patterns of plants to paraquat were various. It was assumed that the different response was derived from different antioxidative mechanisms including antioxidative enzymes and antioxidant. Paraquat treatment increased reducing sugar content and malondialdehyde formation at 35 days after treatment in a dose-dependent manner but chlorophyll content decreased. Glutathione content increased by paraquat treatment and tolerant species showed more glutathione content than susceptible species. Superoxide dismutase activity increased with the increase in paraquat concentration and that was higher in tolerant species than susceptible species. Photosynthetic activity(PSII activity) was affected by paraquat, so the susceptible species showed more reduced oxygen evolving capacity than tolerant species. Catalse, NADPH-cytochrome C reductase, and malate dehydrogenase, the enzymes tested in this study, showed that the activities decreased by paraquat treatment. Further studies are necessary to determine whether antioxidative system cause the tolerance to paraquat.

• Korean Journal of Environment and Ecology
• /
• v.30 no.5
• /
• pp.821-828
• /
• 2016

We examed physiological and flowering response of S. capitata, the endangered plant in Korea, under LED light conditions in plant factory to cultivate artificially for conservation. We cultivated S. capitata and measured its physiological responses and the number of flowers under red, blue, white, red+far-red mixed, red+blue mixed, and red+blue+white mixed light. The results showed that its photosynthetic rate and chlorophyll content were recorded relatively high in red+blue+white and red+blue mixed light respectively. Transpiration rate and stomatal conductance appeared relatively high in the white single light while water use efficiency was no difference. Photochemical efficiency of photochemical photosystem II by minimum and maximum chlorophyll fluorescence was the highest in the red+blue+white mixed light condition than other ones. The number of flowers of S. capitata was at its peak under the red light or red+far-red mixed light. Therefore, we conclude that the most efficient way to grow for flowering of S. capitata is to provide red light or red+far-red mixed light in the plant factory.

• Journal of Forest and Environmental Science
• /
• v.37 no.4
• /
• pp.315-322
• /
• 2021

The aim of this study was to investigate the sensitivity to environmental stress, and changes in the photosynthesis capacity in Abies koreana seedlings by age and to suggest the most effective age for restoration. To identify these physiological characteristics of A. koreana, the chlorophyll fluorescence and photosynthetic capacity of 1-, 2-, 3-, 5- and 6-year-old A. koreana seedlings were observed from June 2020 to June 2021. The maximum quantum efficiency of Photosystem II (Fv/Fm), a chlorophyll fluorescence measurement parameter, was strongly positively correlated with the monthly average temperature (1-year-old seedling: r=0.8779, 2-year-old seedling: r=0.8605, 3-year-old seedling: r=0.8697, 5-year-old seedlings: r=0.8085, and 6-year-old seedlings: r=0.8316). The Fv/Fm values were the lowest in winter (November 2020-March 2021). In addition, the Fv/Fm values of 1-, 2-, and 3-year-old seedlings in winter were lower than that of 5- and 6-year-old seedlings, while the Fv/Fm values in summer were relatively higher than those in winter. Further, the Fv/Fm values of seedlings of all ages decreased in August 2020, when the monthly average temperature was the highest. In particular, 1-year-old to 3-year-old seedlings showed Fv/Fm values less than 0.8. Further, the photosynthetic capacity measured in August 2020 increased with increasing seedling age. The analysis of variance results for summer Fv/Fm values showed significant differences in age-specific averages (p<0.05), and Duncan's multiple range test showed significant differences between 5- and 6-year-old seedlings and 1-, 2-, and 3-year-old seedlings (p<0.05). These results suggested that the 5- and 6-year-old seedlings were less sensitive to environmental stress and showed better photosynthetic capacity than the 1-, 2-, and 3-year-old seedlings. Therefore, 5-year-old or older A. koreana seedlings can be used as restoration materials because they can show increased adaptability and stable growth during transplantation due to their relatively high environmental resistance and photosynthetic capacity.

• Korean Journal of Environment and Ecology
• /
• v.28 no.5
• /
• pp.500-509
• /
• 2014

To prevent freezing of the road by fallen snow, Calcium chloride($CaCl_2$) as a deicer is used to very often and it can be harmful to roadside trees. This study was conducted to investigate the effects of Calcium chloride($CaCl_2$) as a deicer on growth and physiological traits of Acer triflorum according to different concentration of $CaCl_2$. We measured growth, chlorophyll contents, gas exchangement characteristics, chlorophyll fluorescence and mineral nutrition concentration in plant and soil. The experimental group was composed of four treatments including 0mM(control), 9mM(0.5 %), 18mM(1.0 %), 54mM(3.0 %). Before germinating new shoot, the dissolution of $CaCl_2$ was irrigated twice interval of a week. At 30 days after treatment, all treatments decreased total cholorophyll content, photosynthetic rate, transpiration rate, stomatal conductance and photochemical efficiency($F_v/F_m$) with increasing concentration of $CaCl_2$ and especially, they significantly reduced in 3.0 % treatment. In contrast, chlorophyll a/b ratio increased with an increase of $CaCl_2$ concentration and water use efficiency increased in 1.0 % and 3.0 % treatments. At 50 days after treatment, all treatments were decreased in chl a, chl b, total chlorophyll content, carotenoid content, photosynthetic capacity, photochemical efficiency($F_v/F_m$) and quantum yield of photosystem II(${\Phi}_{PSII}$) compared with control and 3.0 % treatments were withered. $Ca^{2+}$ and $Cl^-$ were accumulated in leaves and soil, which inhibited water absorption and electron transport and it caused the reduction of height growth rate more than 50 %. Although there was a little difference according to time and $CaCl_2$ concentration, all treatments decreased in growth rate and physiological activity slowed down. As time passed, these results got worse. Therefore we need to take a measure earlier in order to minimize damage of trees.