• ALGAE
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• v.20 no.3
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• pp.233-238
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• 2005

The photosynthetic parameters of dark- adapted minimum fluorescence (Fo) and maximum quantum yield of charge separation in PSII (Fv/Fm) were measured in transverse sections of eight species of marine Phaeophyceae (species of Laminariales, Fucales, Desmarestiales, Chordariales) using pulse amplified modulation (PAM) fluorometry. Within each transverse section fluorescence was measured in three regions corresponding to outer cortical and meristoderm cells, inner cortical cells and innermost medullary cells. Minimum fluorescence declined from 19-74% (mean of 39%) from outermost to innermost cells. Maximum quantum yield varied from 0.51-0.59 in outermost cell layers and this was reduced to 0.23-0.40 in innermost cell layers, with an average reduction of 50%. Despite the reduction Fo in medullary cells (inner), medullas of all species showed maximum quantum yields consistent with a photosynthetic role in carbon fixation. These results show that medullary cells of complex brown algae have more than a role in structure, storage or transport, and may also provide an important role in carbon fixation.

• Journal of Ginseng Research
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• v.34 no.4
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• pp.274-281
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• 2010

This experiment was conducted to examine ginseng lines resistant and susceptible to high-temperature injury and to investigate characteristics of the selected lines: leaf burning phenomenon, chlorophyll content, quantum yield, and maximum light interception rate. The leaf burning phenomenon incidence rates of the resistant lines Yunpoong, high-temperature injury resistance (HTIR)1, HTIR2, and HTIR3 were low: 5.8%, 3.6%, 4.0%, and 1.9%, respectively. Resistance of the susceptible lines Chunpoong, high-temperature injury susceptible (HTIS)1, and HTIS2 was high: 58.5%, 23.2%, and 21.7%, respectively. The chlorophyll content (SPAD value) of the resistant lines Yunpoong, HTIR1, HTIR2, and HTIR3, which were exposed to high temperatures and intense light, remained as high at 24.8, 27.9, 24.9, and 30.6, respectively, but that of the susceptible lines Chunpoong, HTIS1, and HTIS2 was low at 21.0, 21.1, and 20.1, respectively. During the summer season, the quantum yield of the resistant lines (Yunpoong, HTIR1, HTIR2, and HTIR3) changed little, but that of the susceptible lines (Chunpoong, HTIS1, and HTIS2) changed dramatically. The maximum light interception rate (Fm/Fv value) for the resistant lines (Yunpoong, HTIR1, HTIR2, and HTIR3) was as high as 0.848, 0.794, 0.805, and 0.813, respectively, while that of the susceptible lines (Chunpoong, HTIS1, and HTIS2) was 0.678, 0.642, and 0.717, respectively. Based on these results, the high-temperature injury-resistant lines seemed to be less susceptible to high light, even at high temperatures. Future studies on red ginseng quality and its active ingredients in resistant ginseng lines and field experimentation will be conducted to verify the potential of the resistant lines.

• The Plant Pathology Journal
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• v.34 no.3
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• pp.236-240
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• 2018

Crop yield is critically related to the physiological responses and disease resistance of the crop, which could be strongly affected by high temperature conditions. We observed the changes in the growth of barley under higher than ambient air-temperature conditions using a temperature gradient field chamber (TGFC) during winter and spring. Before the stem extension stage of barley growth, Cladosporium sp. spontaneously appeared in the TGFC. The severity of disease became serious under warmer temperature conditions. Further, the stomata closed as the severity of the disease increased; however, stomatal conductance at the initial stage of disease was higher than that of the normal leaves. This was likely due to the Iwanov effect, which explains that stressed plants rapidly and transiently open their stomata before longer-term closure. In this study, we tested three optical methods: soil-plant analysis development (SPAD) chlorophyll index, photochemical reflectance index (PRI), and maximum quantum yield (Fv/Fm). These rapid evaluation methods have not been used in studies focusing on disease stress, although some studies have used these methods to monitor other stresses. These three indicative parameters revealed that diseased barley exhibited lower values of these parameters than normal, and with the increase in disease severity, these values declined further. Our results will be useful in efficient monitoring and evaluation of crop diseases under future warming conditions.

• Journal of Life Science
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• v.32 no.10
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• pp.743-748
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• 2022

The garlic chive (Allium tuberosum Rotter) is a prominent herb species in Asia and other nations of the world. Garlic chives is a favorite vegetable and used to garnish noodles in Korea. The effects of various doses of N, P, and K fertilizers and drought stress on the chlorophyll content in the leaves of garlic chives were investigated. The evaluations showed that chlorophyll a content was 0.386 at 10 mg/l N fertilizer and 0.584 at 50 mg/l N fertilizer. The treatment group showed a significant difference with regard to the contents of chlorophylls a and b and total chlorophyll at the 5% level (p<0.05). Pearson's correlation coefficient (Pearson's r) for chlorophylls a and b and total chlorophyll were 0.940, 0.966, and 0.971, respectively. The highest content of chlorophylls a and b and total chlorophyll in the leaves was recorded at 40 mg/l P fertilizer, while the values corresponding to 50 mg/l P fertilizer were lower than those for 40 mg/l P fertilizer. The content of total chlorophyll evaluated at 10 mg/l K fertilizer was 0.312 and that at 50 mg/l was 0.589. The simple linear regression showed the relationship between chlorophyll efficiency aand moisture. The slope factors of the dark-level fluorescence yield (Fo), the maximum fluorescence yield (Fm), the quenched state (Fv), and the maximal PSII quantum yield (Fv/Fm) for chlorophyll-efficient indicators were -0.931, 0.972, 972, and 0.950, respectively. NPK fertilizers and drought stress affected the chlorophyll content and efficiency of A. tuberosum.

• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.705-711
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• 2015

Management of soil water and fertilization is known to primarily affect physiological properties and yield in plant. The effect of soil water potential and nitrogen application on characteristics of photosynthesis and chlorophyll fluorescence in Schisandra chinensis Baillon was investigated on a sandy loam soil. Net photosyntheis rate and transpiration rate increased as a photon flux density and was highest at -50kPa of soil water potential. Light compensation point ($1.5{\mu}molm^{-1}s^{-1}$) and dark respiration ($0.13{\mu}molCO_2m^{-1}s^{-1}$) was lowest at -50 kPa but maximum photosynthesis rate ($13.10{\mu}molCO_2m^{-1}s^{-1}$) and net apparent quantum yield ($0.083{\mu}molCO_2m^{-1}s^{-1}$) was highest at -50 kPa. As results of chlorophyll fluorescence by OJIP analysis, maximum quantum yield (Fv/Fm) of photosystem II (PSII) and PIabs was higher in treatments of -50 kPa and -60 kPa respectively, which reflects the relative reduction state of PSII. But the relative activities per reaction center such as ABS/RC and DIo/RC were low with decreasing soil water potential. Net photosyntheis rate and transpiration rate were highest at treatment of soil testing 1.0 times ($92kgha^{-1}$). Application of nitrogen resulted in high Fv/Fm, $PI_{abs}$ and low ABS/RC, DIo/RC. This result implies that -50 kPa of soil water potential and nitrogen fertilizer may improve the efficiency of photosynthesis through controlling a photosystem in Schisandra chinensis Baillon.

• 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.

• Korean Journal of Environmental Agriculture
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• v.39 no.2
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• pp.138-141
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• 2020

BACKGROUND: Fresh weight is one of the major quality measurement factors in determining the quality of fresh fruits. A practical method has been developed for rapid and non-destructive measurement using the Chlorophyll Fluorescence Image (CFI) technique to estimate changes in fresh weight of post-harvest products. METHODS AND RESULTS: Kiwifruit (Actinidia deliciosa) was used and measured for the fresh weight and CFI under different temperature conditions at 0, 10, and 20℃, from 0 to 21 days after storage (DAS). We observed the fresh weight of kiwifruit and measured the surface image for determining F_v/F_m value in terms of maximum quantum yield on each day. To estimate freshness of kiwifruit we applied linear regression between the measured fruit weights and F_v/F_m values. Results showed that fruit weights were reduced by 4% at 0℃, 6% at 10℃, and 14% at 20℃ for 21 days, respectively. And also, the value of Fv/Fm was shown as decreasing trend at all temperature conditions, especially at 20 ℃. Fv/Fm values showed highly significant correlation (R²>0.9) with fresh weight of kiwifruit at all different storage temperatures. CONCLUSION: Thus, CFI technique can be useful to estimate the fresh weight of kiwifruit.

• Journal of Photoscience
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• v.5 no.4
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• pp.169-174
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• 1998

Photosynthetic responses to dehydration were examined by the simulataneous measurement of O2 evolution and chlorophyll (Chl) fluorescence in green pepper leaves. Dehydration was induced by immersing the plant roots directly in the Hoagland solution containing varying concentration (2-30%) of polyethylene glycol(PEG-6000) . Water potential of the leaf was decreased time-and concentation -dependently by PEG-treatment. The decrease in water potential of leaf was correlated with the decrease in both the maximal photosynthesis (Pmax) and quantum yield of O2 evolution, but Pmax dropped more rapidly than quantum yield at all water deficit conditions tested. However, Chl fluorescence parameters were not affected much. Dehydration did not change the initial fluorescence (Fo) and maximum photochemical efficiency(Fv/Fm) of photosystem(PS) II. Both the photochemical quenching (qP) and non-photochemical quenching(NPQ) were not changed by dehydration under low PFR(50 $\mu$mols m-2s-1 ). In contrast, under high PFR(270$\mu$mols m-2s-1)qP was slightly decreased while NPQ was greatly increased. The fast induction kinetics of Chl fluroecence showed no change in Chl fluorescence pattern by dehydration at high PFR (640 $\mu$mols m-2s-1 ), but exhibited a significant drop in peak level(Fp)at low PRFR (70$\mu$mols m-2s-1 ). PS I oxidation and reduction kinetics revealed normal reduction but delayed oxidation to P-700+, suggesting no lesionin electron flow from PSII to PSI , but impaired electron transport to NADP+,These results suggest that water stress caused by PEG-treatment results in the reduction of photosynthesis, promarily due to the reducted electron trasport from PSI to NADP+ or hampered subsequent steps involving Calvin Cycle.

• Journal of Plant Biology
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• v.36 no.2
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• pp.133-140
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• 1993

The photosynthetic activities in relation to oxygen evolution rates, quantum yield, CO2 uptake rates and room temperature chlorophyll fluorescence were investigated in cotyledons of cucumber seedlings exposed to low temperature (at 4$^{\circ}C$) for 24 h. Light-chilling caused more inhibition on light-saturated maximum oxygen evolution rates, quantum yield, and CO2 uptake rates than dark-chilling did in the cucumber plant. Light-chilling induced more marked increase in Fo and decrease in (Fv)m/Fm than dark-chilling did in the room temperature chlorophyll induction kinetics. The above results affected by chilling in the light are considered to be associated with the partial damage of the reaction center of PS II and the decreased photosynthetic activities. There occurred a large decrease in qQ with little change in qNP in the light-chilling plant. When light- and dark-chilled plants were recovered at room temperature for 24 h and their chlorophyll fluorescences were induced with light doubling technique, light-chilled plants showed more smaller magnitude and rate of fluorescence relaxation than dark-chilled plants. These suggest that light-chilling might cause some alterations in transthylakoid pH formation, and that photosynthetic apparatus of cucumber cotyledons is more susceptible to light-chilling. In the fast fluorescence induction kinetics, FR was decreased by 60% in the light-chilled plants with reference to $25^{\circ}C$ light-grown plants, while the dark-chilled plants showed a decreased rate of only 20% with reference to $25^{\circ}C$ dark-treated plants for 24 h, indicating that cucumber seedling is very sensitive to chilling stress. So, it is certain that chilling injury to the photosynthetic apparatus is strongly dependent on the presence of light in cucumber seedlings.