• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.5
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• pp.322-327
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• 2000

For the stable production of high quality tea, the freezing resistance is a very important character. Most of the farmers have planted out-pollinated seeds that are not genetically pure. So, with small sample, a quick and simple method is required to test freezing resistance of lots of germ-plasm and early generation of hybrids. The absorbances(A530 nm) of TTC reduction solution at -5$^{\circ}C$ were positively correlated with resistance to photoinhibition of PSII in 6 hour photoinhibitory treatments, being significantly fitted by simple linear regression ($R^2$=${0.64}^{**}$). Chlorophyll fluorescence measured by Fv/Fm was found to be very useful in evaluating the relative levels of freezing resistance in tea.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.142-148
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• 2014

Effect of silicon (Si) nutrition on growth and temperature stress tolerance of Nephrolepis exaltata 'Corditas' grown in a soilless substrate was examined. In vitro-grown acclimatized plantlets were transplanted into the pots containing a coir-based substrate. A nutrient solution containing 0, 50, or $100mg{\cdot}L^{-1}$ Si was supplied through a drip-irrigation system. After 5 months of cultiv ation, S i-treated and -untreated p lants were grown at 10, 25, or $40{\pm}1^{\circ}C$ under a 12 h photoperiod with $530{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD and 60% RH. After 7 days, chlorophyll content and chlorophyll fluorescence parameters were measured. Silicon nutrition had a negative effect on growth characteristics of N. exaltata 'Corditas'. However, Si-treated plants had more tolerance to temperature stress than the control plants. The Fv/Fm value was not significantly different when the plants were exposed to $25^{\circ}C$. However, significant difference in Fv/Fm was recorded when plants were exposed to 10 or $40^{\circ}C$. Thus, Fv/Fm could be used as an indicator of low and high temperature tolerance in ferns. The present study also suggests that application of Si may be used to enhance temperature tolerance of ferns.

• Journal of Life Science
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• v.20 no.8
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• pp.1173-1180
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• 2010

We investigated changes in photosynthesis and activity of ascorbate peroxidase (APX) that scavenges ROS as responses to oxidative stress induced by salinity in rice (Oryza sativa L.). Photosynthetic efficiency of rice leaves, monitored in terms of Fv/Fm, declined with the increase of salt concentration (100-300 mM NaCl). Salinity caused an increase of $H_2O_2$ in leaves of rice, with an increase of APX activity. Among total APX isoforms, an isoform of stromal-APX 1 in leaves of rice was completely inactivated by 300 mM NaCl, but was not affected by chilling or drought. The results suggest that salt stress acts in quite a different mechanism in relation to the activity of stromal-APX from that of other stresses such chilling and drought. We carried out RT-PCR for analysis of genes expression of APX isoforms as affected by salt stress. The expression of cytosolic APX/thylakoid-bound APX genes in leaves of rice exposed to salt stress was increased, while stromal APX gene expression rapidly declined.

• BMB Reports
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• v.33 no.3
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• pp.256-262
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• 2000

In this study the disassembly process of chlorophyII (ChI)protein complexes of a stay-green mutant (ore10 of Arabidopsis thaliana) was investigated during the dark incubation of detached leaves. During this dark-induced senescence (DIS), the Chi loss was delayed in the mutant, while the photochemical efficiency of photosystem II (PSII) or Fv/Fm was accelerated when compared with the wild type (WT) leaves. This indicates that the decrease in Fv/Fm is a separate process and not causally-linked to the degradation of Chi during DIS of Arabidopsis leaves. In the native green gel electrophoresis of the Chi-protein complexes, which was combined with an additional twodimensional SDS-PAGE analysis, the delayed senescence of this mutant was characterized by the appearance of an aggregate at 1 d or 2 d, as well as very stable light harvesting complex II (LHCII) trimers until 5 d after the start of DIS. The polypeptide composition of the aggregates varied during the whole DIS at 5 d. Dl protein appeared to be missing in the aggregates. This result supports the idea of a faster depletion of functional PSH in the mutants compared with WT, as suggested by the earlier reduction of Fv/Fm and the stable Chl a/b ratio in the mutants. At 5 d, the WT leaves also often showed aggregates, but the polypeptide composition was different from those of ore10. The results presented suggest that the formation of aggregates, or stable LHCII trimers in the stay-green mutants, is a way to structurally protect Chi-protein complexes from serious proteolytic degradation. Detailed disassembly processes of Chi-protein complexes in WT and ore10 mutants are discussed.

• Journal of Photoscience
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• v.8 no.1
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• pp.1-7
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• 2001

The deteriorative effect of ultraviolet-B(UV-B) radiation on photosynthesis was assessed by the simultaneous measurement of O$_2$ evolution and chlorophyll(Chl) fluorescence in green pepper. UV-B was given at the intensity of 1 W$.$m$\^$-2/, a dosage often encountered in urban area of Seoul in Korea, to detached leaves. Both Pmax and quantum yield of O$_2$ evolution was rapidly decreased, in a parallel phase, with increasing time of UV-B treatment. Chl fluorescence parameters were also significantly affected. Fo was increased while both Fm and Fv were decreased. Photochemical efficiency of PSII(Fv/Fm) was also declined, although to a lesser extent than Pmax. Both qP and NPQ were decreased similarly with increasing time of UV-B treatment. However, PS I remained stable. The addition of lincomycin prior to UV-B treatment accelerated the decline in Fv/Fm to some extent, suggesting that D1 protein turnover may play a role in overcoming the harmful effect of UV-B. The amount of photosynthetic pigments was less affected than photosynthetic response in showing decline in Chl a and carotenoids after 24 h-treatment. Presumptive flavonoid contents, measured by changes in absorbance at 270 nm , 300 nm and 330nm, were all increased by roughly 50% after 8 h-treatment. Among antioxidant enzymes, activities of catalase and peroxidase were steadily increased until 12h of UV-B treatment whereas ascorbate perxidase, dehydroascorvate reductase and glutathione reductase did not show any significant change. The results indicate that deteriorative effect of UV-B on photosynthesis precedes the protection exerted by pigment synthesis and antioxidant enzymes.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.1
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• pp.1-8
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• 2018

The purpose of this study was to investigate the effects of light intensity on the initial growth response of three woody plants for indoor landscaping; Ardisia pusilla, Clusia rosea and Fatsia japonica. The plants were planted in 10cm pots, the light intensities used were of four levels-15, 30, 60, $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD-and light irradiation time was set to 12/12 (day/night). Growth responses including plant height, leaf length, leaf width, chlorophyll fluorescence (Fv/Fm), SPAD and Hunter values were measured at 4-week intervals, and shoot weight and root weight of fresh and dry plants were measured after completion of the experiment. Fatsia japonica tended to show greater leaf length and leaf width as light intensity became greater, while other plants did not show any significant differences at different light intensities. The Fv/Fm value of the Ardisia pusilla was found to be stressed at 60 and $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, while the Fv/Fm values were within normal range with other plants or at other light intensity levels to show no stress. Only Clusia rosea showed significantly different SPAD values at $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and there was no significant SPAD value difference found with other plants or at other light intensity levels. While Hunter values of the Ardisia pusilla did not show any significant differences at any light intensity levels, Clusia rosea and Fatsia japonica showed specificity in L, a and b values at 60 and $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. Ardisia pusilla showed a big stem growth at $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and Clusia rosea showed a steady growth at 60 and $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$.

• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.240-249
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• 2022

Measuring chlorophyll fluorescence (CF) is a useful tool for assessing a plant's ability to tolerate abiotic stresses such as drought, waterlogging and high temperature. Korean ginseng is highly sensitive to water stress in paddy fields. To evaluate the possibility of non-destructively diagnosing waterlogging stress using chlorophyll fluorescence (CF) imaging techniques, we screened 57 ginseng accessions for waterlogging tolerance. To evaluate waterlogging tolerance among the 2-year-old Korean ginseng accessions, we treated ginseng plants with water stress for 25 days. The physiological disorder rate was characterized through visual assessment (an assigned score of 0-5). The physiological disorder rates of Geumjin, Geumsun and GS00-58 were lower than that of other accessions. In contrast, lines GS97-62, GS97-69 and GS98-1-5 were deemed susceptible. Root traits, chlorophyll content and the reduction rates decreased in most ginseng accessions. Further, these metrics were significantly lower in susceptible genotypes compared to resistant ones. All CF parameters showed a positive or negative response to waterlogging stress, and this response continuously increased over the treatment time among the genotypes. The CF parameter Fv/Fm was used to screen the 57 accessions, and the results showed clear differences in Fv/Fm between the susceptible and resistant genotypes. Susceptible genotypes had an especially low Fv/Fm value of less than 0.8, reflecting damage to the reaction center of photosystem II. It is concluded that Fv/Fm can be used as a CF parameter index for screening waterlogging stress tolerance in ginseng genotypes.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.209-216
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• 2004

This study was aimed to assess the effects of microclimate factors on lettuce chlorophyll fluorescent responses and to develop an environment control system for plant growth by adopting a simple genetic algorithm. The photosynthetic responses measurements were repeated by changing one factor among six climatic factors at a time. The maximum Fv'/Fm' resulted when the ambient temperature was $21^{\circ}C,\;CO_2$ concentration range of 1,200 to 1,400 ppm, relative humidity of $68\%$, air current speed of $1.4m{\cdot}s^{-1}$, and the temperature of nutrient solution of $20^{\circ}C$. In PPF greater than $140{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, Fv'/Fm' values were decreased. To estimate the effects of combined microclimate factors on plant growth, a photosynthesis efficiency model was developed using principle component analysis for six microclimate factors. Predicted Fv'/Fm' values showed a good agreement to measured ones with an average error of $2.5\%$. In this study, a simple genetic algorithm was applied to the photosynthesis efficiency model for optimal environmental condition for lettuce growth. Air emperature of $22^{\circ}C$, root zone temperature of $19^{\circ}C,\;CO_2$ concentration of 1,400 ppm, air current speed of $1.0m{\cdot}s^{-1}$, PPF of $430{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and relative humidity of $65\%$ were obtained. It is feasible to control plant environment optimally in response to microclimate changes by using photosynthesis efficiency model combined with genetic algorithm.

• Korean Journal of Environmental Biology
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• v.20 no.4
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• pp.303-308
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• 2002

3-weeks old Commelina was transferred to and grown in Hoagland solution ($\pm$ 100 $\mu{M}$ $Cd^{2+}$, 100 $\mu{M}$ $Cd^{2+}$ ＋ 100$\mu{M}$ $Ca^{2+}$, 100 $\mu{M}$ $Cd^{2+}$ ＋ 200 $\mu{M}$ EGTA) for two weeks and then a number of physiological activities was investigated. $Cd^{2+}$ reduced total chlorophyll content up to 29% at a week and 75% at two weeks. In the treatment of $Cd^{2+}$ ＋ $Ca^{2+}$, the total chlorophyll content was reduced to 29% at a week and 80% at two weeks. $Cd^{2+}$ reduced 24% of Fv/Fm after two weeks. In case of $Cd^{2+}$ ＋ $Ca^{2+}$, Fv/Fm was reduced 55% at a week, but after two weeks, the plants were almost dead and Fv/Fm could not be measured. When EGTA was treated with $Cd^{2+}$, the value of Fv/Fm was not affected. There were no differences of water potential between the control and the treatment of $Cd^{2+}$+EGTA toy a week, but in other treatments. water potential was reduced. $Cd^{2+}$ reduced about 21% of water potential and $Cd^{2+}$ ＋ $Ca^{2+}$ reduced 43% of water potential after two weeks. $Cd^{2+}$ inhibited 21% of photosynthetic activity at a week and 32% at two weeks. In case of photosynthetic activity, $Cd^{2+}$ ＋ $Ca^{2+}$ inhibited 58% at a week and 73% at two weeks. $Cd^{2+}$+EGTA inhibited 15% of photosynthetic activity at a week and 21% at two weeks. Similar results were found in stomatal conductance. From the above results, it was observed that the treatment of $Ca^{2+}$ with $Cd^{2+}$ induced more reduction of a series of physiological responses than those of the treatment of $Cd^{2+}$ alone. Therefore, it could be concluded that $Ca^{2+}$ did not reduce the toxicity of $Cd^{2+}$, but enhanced $Cd^{2+}$ -induced physiological toxicities, but EGTA induced an decrease of $Cd^{2+}$ -induced physiological toxicities.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.1
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• pp.28-34
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• 2017

This study was carried out to investigate growth characteristics of woody plants that are widely used indoors in accordance with irrigation frequency and to find the optimum irrigation conditions for plants that help to improve the indoor environment. Four woody plants used in this study included Ardisia pusilla, Clusia rosea, Fatsia japonica, and Ficus elastica. They were planted in pots with a diameter of 10cm and cultivated in three different irrigation frequencies: two times per week, one time per week, and one time per two weeks. After 120 days, they were measured by plant height, fresh weight, dry weight, SPAD value, leaf color, leaf water potential, chlorophyll fluorescence (Fv/Fm), and photosynthetic rate. The average soil moisture content was $48.8{\pm}2.1%$ in two times per week, $25.2{\pm}4.4%$ in one time per week, and $10.3{\pm}2.4%$ in one time per two weeks. For A. pusilla, leaf water potential was higher, and Fv/Fm value was 0.731 in two times per week irrigation, showing more wetness. For A. pusilla, F. japonica and F. elastica photosynthetic rate was significantly lower in one time per two weeks irrigation, appearing to be more sensitive to drying than C. rosea. When irrigated one time per week, with the soil's volume average moisture content of 25%, all four woody plants used in this experiment proved to grow smooth. Thus, it was determined to be good for use in indoor landscaping.