• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.461-470
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• 2019

This study was carried out to quantify the drought stress in grafted watermelon seedlings non-destructively by using chlorophyll fluorescence (CF) imaging technique rather than the visual judgment. Six-day old watermelon seedlings were grown under uniform irrigation for 3 days, and then given drought stress. Afterward, the sensor for the measurement of water content in plug tray cell unit was used to classify the drought-stress level into nine groups from D1 (53.0%, sufficient moisture state) to D9 (15.7%, extremely dry stress), and the 16 CF parameters were measured. In addition, re-irrigation was performed on the drought stressed seedlings(D5 - D9) to determine the growth and photosynthesis recovery level, which was not confirmed by visual judgment. The kinetic curve patterns of CF in three different drought stressed seedling groups were found to be different for the early detection of drought stress. All the 16 CF parameters decreased continuously with exposure to drought stress and drastically decreased from D5 (32.1%) where the visual judgment was possible. The fluorescence decline ratio (Rfd_Lss) started to decrease from the initial drought stress level (D5 - D6), and the Maximum PSII quantum yield (Fv/Fm) was significantly decreased in the later extreme drought stress range (D7 - D9) by re-irrigation recovery test. Thus, Rfd_Lss and Fv/Fm parameters were finally selected as potent indicators of growth and photosynthesis recovery in the initial and later stages of drought stress. Also, to the differences in the numerical values of the individual chlorophyll fluorescence parameters, the drought stress level was intuitively confirmed through the image. These results indicate that Rfd and Fv/Fm can be considered as potential CF parameters for the detection of low and extremely high drought stress, respectively. Furthermore, Fv/Fm can be considered as the best CF parameters for recovery at re-irrigation.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.154-161
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• 2013

This study was conducted to investigate the physiological responses of Bupleurum latissimum, endangered plants by light condition. We investigated photosynthetic parameters, chlorophyll contents and chlorophyll fluorescence under different shading treatments (Shaded 50%, 70%, 90% and non-treated). Results showed that net apparent quantum yield (AQY) and chlorophyll contents were significantly increased with elevating shading level. However, light compensation point (LCP) and dark respiration ($R_d$) were shown the opposite trend. Especially, non-treated exhibited photoinhibition such as reduction of chlorophyll contents and maximum photosynthesis rate ($Pn_{max}$) also variation trend of stomatal conductance ($g_s$), and transpiration rate (E) were decreased to prevent water loss. Photosynthetic rate ($P_{Nmax}$) and photochemical efficiency (Fv/Fm) of 90% treatment showed a drastic reduction in July. This implies that photosynthetic activity will be sharply decreased with a long period of low light intensity. The 50% treatment showed relatively higher photosynthetic activity than other treated. This result suggested that growth and physiology of B. latissimum adapted to 50% of full sunlight.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.153-161
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• 2012

This study was conducted to investigate the chlorophyll contents, photosynthetic characteristics and chlorophyll fluorescence of Cirsium setidens and Pleurospermum camtschaticum by shading treatment. Two species were grown under non-treated (full sunlight) and three different shading condition (88~93%, 65~75% and 45%~55% of full sunlight) for the experiment. Total chlorophyll content, photochemical efficiency (Fv/Fm), specific leaf area (SLA), and net apparent quantum yield were increased with elevating shading level but decreased dark respiration under the low light intensity. Therefore, light absorption and light utilization efficiency were improved under the low light intensity. 45~55% of full sunlight in C. setidens and 65~75% of full sunlight in P. camtschaticum showed best maximum photosynthetic rate, net apparent quantum yield and photochemical efficiency. On the other hand, non-treated showed lower maximum photosynthetic rate, photochemical efficiency, and chlorophyll content than treated ones. These results suggest that growth of P. camtschaticum adapted to 65~75% of full sunlight and C. setidens adapted to 45~55% of full sunlight.

• Journal of Wetlands Research
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• v.20 no.1
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• pp.27-34
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• 2018

Reproductive phenology and physiological responses of Epilobium hirsutum L. to moisture content and nutrient content of soil were analysed in order to obtain basic data for effective conservation and restoration. Epilobium hirsutum L. is a perennial plant. But Epilobium hirsutum L. grew reproductively in all moisture and nutrient gradients. Flower bud, flowers and peduncle were respectively ripened in earlier under highest moisture condition and highest nutrient condition. And, number of flowers and peduncle were more quickly increased under highest moisture condition and highest nutrient condition. Chlorophyll content was high under highest moisture condition and higher middle moisture condition. However, we found no significant difference of chlorophyll content regard to nutrient gradients. There was no difference in minimum chlorophyll fluorescence among all moisture and nutrient gradients. The photochemical efficiency values of PS II were 0.75 in all moisture gradients, and it was 0.78 in highest nutrient gradient. The chlorophyll content of Epilobium hirsutum L. increased as the moisture content increased, and the Fv/Fm value increased as the organic matter increased. Our results showed that high moisture and nutrient content of soil advance their breeding season and promote reproductive growth. It might be important basic informations for the maintenance of population and the management of habitat of Epilobium hirsutum L. an endangered plant species.

• Journal of Photoscience
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• v.3 no.1
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• pp.23-28
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• 1996

To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3122-3127
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• 2007

Water resource can be examined using biological sensors. Algae has been one of the biological sensors used to evaluate and monitor the water pollution. The monitoring system, however, could determine whether the examined water was safe or not. It needs additional expensive chemical test to figure out the cause of the water pollution. In this study, an endeavor is given to identify the toxicant in the water using the shape of the chlorophyll fluorescence induction curve(FIC) from algae using monitoring system. Fundamental curves are obtained from the experiments with specified amount of toxicant. Baysian method is utilized to determine the unknown toxicant in the water by comparing it with the fundamental curves. The results shows that the proposed method works fairly well.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.73-78
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• 2008

Water resource can be examined using biological sensors. Algae has been one of the biological sensors used to evaluate and to monitor the water pollution. The monitoring system, however, has not been used to determine what kind of the toxicological substance is in the water. It needs additional expensive chemical test to figure out the cause of the water pollution. In this study, an endeavor is made to identify the toxicant in the water using the shape of the chlorophyll fluorescence induction curve(FIC) from algae using monitoring system. Fundamental curves are obtained from the experiments with specified amount of toxicant. Baysian method is utilized to determine the unknown toxicant in the water by comparing it with the fundamental curves. The results shows that the proposed method works fairly well.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.15-26
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• 2007

Surface water is the main drinking water source in Korea. Algal bloom caused by phytoplankton in reservoir is common event in every summer season. To prevent or control the algal blooms, artificial circulation system has been adopted in many reservoirs, including Hoengseung reservoir. Total 7 hydraulic-gun-aerators were installed around the intake tower in Hoengseung reservoir since 2000. This study is to elucidate the effects of hydraulic-gun-aerators on phytoplankton bloom, pH, DO, temperature and evaluate the selective withdrawal and vertical distribution of phytoplankton by means of submersible fluorescence probe, which features high correlation with a standard ISO method (r=0.90, P<0.0001) for chlorophyll-a quantification.

• Journal of Photoscience
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• v.8 no.2
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• pp.43-53
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• 2001

a, a parameter that describes how effectively photoinactivated PS II units protect their functional neighbours; car, carotenoids; ΔpH, transthylakoid pH difference; D1 protein, psbA gene product in the PS II reaction centre; f, functional fraction of PS II: F$\_$v//F$\_$m/, the ratio of variable to maximum chlorophyll a fluorescence; k$\_$d/, rate coefficient for degradation of D1 protein; k$\_$i/ and k$\_$r/, rate coefficient for photoinactivation and repair of PS II, respectively; NADP+, oxidized nicontinamide adenine dinucleotide phosphate; P680, the primary electron donor in the PSII reaction centre; Ph, pheophytin; PS, photosystem; Q$\_$A/, first quinone acceptor of an electron in PS II; R$\_$s/, the gross rate of D1 protein synthesis.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.455-457
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• 2006

The effects of UV-B irradiation on the growth and photosynthetic activity were investigated in seedlings of sunflower(Helianthus annuus L.). The first leaves irradiated with UV-B were retarded in growth but simultaneously acquired a remarkably decreased chlorophyll fluorescence ratio compared with the non-irradiated leaves. The Fv/Fm ratio decreased by 13 % compared to the control after 2 d, and was kept to be lower than the control level until 5 d. From the results it is suggested that UV-B radiation may induce reduced biomass production and decrease in photosynthetic rate in sunflower plants.