• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.311-318
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• 2022

Salicylic acid (SA), a phenolic compound, plays a pivotal role in regulating a wide range of physiological and metabolic processes in plants such as antioxidant cellular defense, photosynthesis, and biotic and abiotic stress responses during the growth and development. We examined the effect of exogenous SA application (100 mg·L^-1) on the growth, yield, photosynthetic characteristics, lipid peroxidation, and antioxidant enzyme activity of chili pepper plants under high temperature and drought stress conditions. SA treatment induced increases of net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) under the stress condition with the highest level after the third treatment. The contents of malondialdehyde and H₂O₂ were significantly lower in the third treatment of SA compared to the control. The activity of ascorbate peroxidase, catalase, peroxidase and superoxide dismutase, increased in treated plants by up to 247, 318, 55 and 54%, respectively compared to the nontreated control. There was no significant difference in the growth characteristics between SA-treated and nontreated plants, while the SA treatment increased marketable yield (kg/10a) by about 15% compared to the nontreated control. Taken together, these results suggest that foliar application of SA alleviates physiological damages caused by the combination of drought and heat stress, and enhances the photosynthetic capacity and antioxidant enzyme activities, thereby improving tolerance to a combination of water deficit and heat stress in chili pepper plants.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1501-1511
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• 2015

As essential trace elements, copper and zinc play important roles in many physiological events in plants. In excess, however, these elements can limit plant growth. This study selected a heavy metal-tolerant plant by analyzing seed germination and biomass of alfalfa (Medicago sativa), canola (Brassica campestris subsp. napus var. nippo-oleifera), Chinese corn (Setaria italica), and a sorghum-sudangrass hybrid (Sorghum bicolor ${\times}$ S. sudanense), and determined heavy metal uptake capacity by analyzing biomass, chlorophyll a fluorescence, and heavy metal contents under high external copper or zinc levels. The seed germination rate and biomass of the sorghum-sudangrass hybrid were higher under copper or zinc stress compared to the other three plants. The plant biomass and photosynthetic pigment contents of the sorghum-sudangrass hybrid seedlings were less vulnerable under low levels of heavy metals (${\leq}50ppm$ copper or ${\leq}400ppm$ zinc). The maximum quantum yield of PSII ($F_v/F_m$) and the maximum primary yield of PSII ($F_v/F_o$) decreased with increasing copper or zinc levels. Under high copper levels, the decline in $F_v/F_m$ was caused only by the decline in $F_m$, and was accompanied by an increase in non-photochemical quenching (NPQ). The $F_v/F_m$ declined under high levels of zinc due to both a decrease in the maximum fluorescence ($F_m$) and an increase in the initial fluorescence ($F_o$), and this was accompanied by a marked decrease in photochemical quenching (qP), but not by an increase in NPQ. Accumulations of copper and zinc were found in both aboveand below-ground parts of plants, but were greater in the below-ground parts. The uptake capacity of the sorghum-sudangrass hybrid for copper and zinc reached 4459.1 mg/kg under 400 ppm copper and 9028.5 mg/kg under 1600 ppm zinc. Our results indicate that the sorghum-sudangrass hybrid contributes to the in situ phytoremediation of copper or zinc polluted soils due to its high biomass yield.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.38-53
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• 1998

This study quantified annual net carbon uptake by urban landscape trees and provided equations to estimate it for Ginkgo biloba, platanus occidentalis, Zelkova serrata and Acer palmatum, based on measurement of exchange rate for two years growing seasons from Sep., 1995 to Aug., 1997. The carbon uptake was significantly influenced by photosynthetic capacity, photon flux density and pruning. Ginkgo biloba showed the highest rate of net CO\sub 2\ uptake per unit leaf area and Acer palmatum did the lowest rate among those species. A tree shaded by adjacent building over the growing seasons showed net CO\sub2\ uptake per unit leaf area much lower than another tree of the same species less shaded. Annual net carbon uptake per tree was 19kg for Zelkova serrata, but only 1 kg for Ginkgo biloba and Platanus occidentalis with crown volume dwarfed from pruning. One Zekoval serrata tree annually offset carbon emission from consumption of about 32 liter of gasoline or 83 kWh of electricity. Strategies to improve CO\sub 2\ uptake by urban landscape trees include planting of species with high potosynthetic capacity, sunlight-guaranteed road and building layout for street trees, planting of shade-tolerant species in the north of buildings, and relocation of utility lines to underground and minimized pruning.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.147-152
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• 2012

This study was conducted to investigate the photosynthetic R. micranthum by natural habitats. In the results, natural habitats didn't affect values of light saturated point, light compensation point and photosynthetic capacity of R. micranthum. We investigated light response curve and chlorophyll content at each habitat. Light compensation points were 11.8 ${\mu}mol\;m^{-2}\;s^{-1}$, 11.5 ${\mu}mol\;m^{-2}\;s^{-1}$ and 10.4 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri, and Mt. Worak. Light saturation points showed that R. micranthum is shade tolerant specie which has the light saturation point approximately 500~600 ${\mu}mol\;m^{-2}\;s^{-1}$. Photosynthetic rates of R. micranthum leaves were 5.5 ${\mu}mol\;m^{-2}\;s^{-1}$, 5.4 ${\mu}mol\;m^{-2}\;s^{-1}$ and 5.6 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri and Mt. Worak. On the other hand, since between $20^{\circ}C$ and $30^{\circ}C$, it appeared that the values of net photosynthetic rates of R. micranthum leaves in all sites were high. Especially, the rates were highest at $25^{\circ}C$. Because of low stomatal transpiration rate in saturation radiance, the moisture utilization efficiency in Yeonha-ri was lower than other habitats. Rates of chlorophyll a, chlorophyll b, and total chlorophyll content in Mt. Worak were no significant difference. Therefore R. micranthum has characteristic of shade tolerant species. The moderate temperature for R. micranthum is between $20^{\circ}C$ and $30^{\circ}C$.

• The Korean Journal of Ecology
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• v.28 no.5
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• pp.321-326
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• 2005

We investigated the effects of pollutants on two pine species (Pinus koraiensis and Pinus rigida) in an industrial region, using a physiological approach. We measured the growth and physiological parameters (photosynthetic activity and chemical contents) of the pine trees in relation to environmental pollutants. The concentrations of manganese (Mn), fluorine (F) and chlorine (CI) in needles of two pine species at the damaged site were significantly higher than those at the control site, and concentrations of essential elements (P) and chlorophyll in needles at the damaged site were significantly lower than at the control site. The light-saturated net photosynthesis $(P_{sat})$, apparent quantum yield $(\Phi)$, carboxylation efficiency (CE) of both pines at the damaged site were significantly lower than those at the control site. The length of shoots and survivorship of needles of two pines at the damaged site were significantly lower than those at the control site. Especially, at damaged site, growth of shoots and needle longevity of P. koraiensis are larger than those of P. rigida.

• Rapid Communication in Photoscience
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• v.1 no.1
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• pp.21-24
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• 2012

Influence of gamma rays on the cyanobacterium Synechocystis sp. PCC 6803 cells was investigated in terms of a bidirectional hydrogenase, which is encoded by hoxEFUYH genes and responsible for biohydrogen production. Irradiated cells revealed a substantial change in stoichiometry of photosystems at one day after gamma irradiation at different doses. However, as evaluated by the maximal rate of photosynthetic oxygen evolution, maximal photochemical efficiency of photosystem II, and chlorophyll content, net photosynthesis or photosynthetic capacity was not significantly different between the control and irradiated cells. Instead, transcription of hoxE, hoxH, or lexA, which encodes a subunit of bidirectional hydrogenase or the only transcriptional activator, LexA, for hox genes, was commonly enhanced in the irradiated cells. This transcriptional enhancement was more conspicuously observed immediately after gamma irradiation. In contrast, hydrogenase activities were found to somewhat lower in the irradiated cells. Therefore, we propose that transcription of hox genes should be enhanced by gamma irradiation in a LexA-mediated and possibly photosynthesis-independent manner and that this enhancement might not induce a subsequent increase in hydrogenase activities, probably due to the presence of post-transcriptional and/or post-translational regulatory mechanisms.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.333-341
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• 2010

The objective of our study was to investigate the major reasons for the different growth and visible injury on the needles of black pine growing in Ulsan and Yeocheon industrial complex areas, South Korea. After 12 years of growth, we collected climatic and air pollutant data, and analyzed soil properties and the physiological characteristics of black pine needles. Annual and minimum temperatures in Ulsan were higher than those in Yeocheon from 1996 to 2008. Ozone ($O_3$) was the pollutant in greatest concentration in Yeocheon, and whereas the $SO_2$ concentration in most areas decreased gradually during the whole period of growth, $SO_2$ concentration in Yeocheon has increased continuously since 1999, where it was the highest out of four areas since 2005. Total nitrogen and cation exchange capacity in Yeocheon soil were significantly lower than those of Ulsan. The average growth of black pine in Yeocheon was significantly smaller than that in Ulsan, and the growth of damaged trees represented a significant difference between the two sites. Photosynthetic pigment and malondialdehyde content and antioxidative enzyme activity in the current needles of black pine in Yeocheon were not significantly different between damaged and healthy trees, but in 1-year-old needles, there were significant differences between damaged and healthy trees. In conclusion, needle damage in Yeocheon black pine can be considered the result of long-term exposure to oxidative stress by such as $O_3$ or $SO_2$, rather than a difference in climatic condition or soil properties, and the additional expense of photosynthate needed to overcome damage or alleviate oxidative stress may cause growth retardation.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.131-135
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• 2005

Under sulfur deprived conditions, PS II and photosynthetic $O_2$ evolution by Chlamydomonas reinhardtii UTEX 90 are inactivated, resulting in shift from aerobic to anaerobic condition. This is followed by hydrogen production catalyzed by hydrogenase. We hypothesized that the photosynthetic capacity and the accumulation of endogenous substrates such as starch for hydrogen production might be different according to cell age. Accordingly, we investigated (a) the relationships between hydrogen production, induction time of sulfur deprivation, increase of chlorophyll after sulfur deprivation, and residual PS II activity, and (b) the effect of initial cell density upon sulfur deprivation. The maximum production volume of hydrogen was 151 ml $H_2$/l with 0.91 g/l of cell density in the late-exponential phase. We suggest that the effects of induction time and initial cell density at sulfur deprivation on hydrogen production, up to an optimal concentration, are due to an increase of chlorophyll under sulfur deprivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.2
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• pp.169-174
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• 1982

Light intensities under and above shading material were measured at different layers (upper, middle and lower layers) and lines (lst, 3rd and 5th lines) on clear and cloudy days in S-year-old ginseng plant populations. Rates of photosynthesis and respiration were also measured in field. Light intensities of the 1st lines at upper and lower layers were relatively high as compared with the 3rd and the 5th lines, and there were no remarkable difference between the 3rd and the 5th line. But in middle layer, the light intensity of each line differed considerably. As compared with fair and clear day, the day of clear but much diffuse light showed high light intensity under shading. Relative light intensity was higher on cloudy day than on clear day. There were notable differences of photosynthetic rates among the lines and the rearest lines exhibited the lowest rates. But it was not considered that even the front plants demonstrated the maximum photosynthetic capacity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.100-106
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• 2001

This investigation was performed to study the influence of benomyl on photosynthetic pigments and enzymes in soybean leaves. Chlorophyll and pheophytin levels were reduced by benomyl 45 days after greening. These results indicate that chlorophyll a and b, and pheophytin must be controlled by benomyl. SDS-PAGE analysis showed that 50 and 14.5 kD polypeptides represented as large and small subunits of rubisco. In the both of these subunits, the band intensity of the control was significantly higher than that after benomyl treatment, indicating that these two subunits are affected by benomyl. Benomyl strongly inhibited both the activity and content of rubisco as its concentration was gradually increased. However, it remains unclear whether this reduction of rubisco level was due to a reduced level of rubisco activase. Two major polypeptides of 46 and 42 kD were identified as rubisco activase subunits by SDS-PAGE. The intensity of these two bands was shown to be higher in the control than after benomyl treatment. These results indicate that the rubisco decrease resulting from increased benomyl concentrations was caused by rubisco activase. A significant decrease in both the activity and content of rubisco activase by benomyl was also observed. There results suggest that the decrease in rubisco level caused by benomyl is accompanied by a decrease in both the activity and content of rubisco activase.