• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.270-276
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• 2016

The objective of this study was to find a rapid determination of the hot air stress in maize (Zea mays L.) leaves using a portable chlorophyll fluorescence imaging instrument. To assess the photosynthetic activity of maize leaves, an imaging analysis of the photochemical responses of maize was performed with chlorophyll fluorescence camera. The observed chlorophyll imaging photos were numerically transformed to the photochemical parameters on the basis of chlorophyll a fluorescence. Chlorophyll a fluorescence imaging (CFI) method showed that a rapid decrease in maximum fluorescence intensity ($F_m$) of leaf occurred under hot air stress. Although no change was observed in the maximum quantum yield ($F_v/F_m$) of the hot air stressed maize leaves, the other photochemical parameters such as maximum fluorescence intensity ($F_m$) and Maximum fluorescence value ($F_p$) were relatively lowered after hot air stress. In hot air stressed maize leaves, an increase was observed in the nonphotoquenching (NPQ) and decrease in the effective quantum yield of photochemical energy conversion in photosystem II (${\Phi}PSII$). Thus, NPQ and ${\Phi}PSII$ were available to be determined non-destructively in maize leaves under hot air stress. Our results clearly indicated that the hot air could be a source of stress in maize leaves. Thus, the CFI analysis along with its related parameters can be used as a rapid indicating technique for the determining hot air stress in plants.

• Journal of Plant Biotechnology
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• v.39 no.4
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• pp.253-260
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• 2012

On the basis of the reported agriculturally valuable phenotypes resulted from ectopic overexpression of Arabidopsis vacuolar $H^+$-PPase (AVP1), we generated the Chinese cabbage lines expressing AVP1 which then subjected to salt stress to determine the AVP1 expression if it consistently confers the capability for increasing biomass and enhancing tolerance to salinity in other species. Collectively, here we demonstrate that the transgenic young plants show more vigorous growth and higher tolerance to salt stress than wild-type ones. Increased biomass phenotype by AVP1 expression was supported by comparing fresh and dry weights of transgenic and wild type plants grown under normal condition, while higher salt tolerance trait was confirmed by tracing the kinetics of photosystem II quantum yield and DAB-staining under gradually intensified salt stress induced by MS salt or NaCl, followed by normal condition.

• Applied Biological Chemistry
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• v.43 no.2
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• pp.130-135
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• 2000

Photodegradation rate of flupyrazofos in aqueous solution were measured under various test conditions mainly following the guidelines of U.S. EPA and OECD. It was observed that the flupyrazofos was degraded by simple hydrolysis but not degraded by light in pure water. Using acetone as a known photosensitizer, the minimal concentration of acetone needed to photo-degrade the flupyrazofos in % and molar terms were 0.047% and 0.006, respectively. When treated with acetone, it was also found that the ringlet oxygen is a very effective photo oxidant in the degradation of flupyrazofos, but the effect of hydroxyl radical was not observed at the treatment level of hydroxyl radical, isopropylbenzene. In an actinometer experiment, quantum yield of flupyrazofos (0.4 ppm with 2% acetone) was $17.66{\times}10^{-5}$ and degradation rate and half-life were 0.038/hr and 18.2 hours, respectively.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.331-338
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• 2009

This present study was conducted to investigate photosynthetic characteristics, chlorophyll fluorescence, chlorophyll contents, and growth performances of containerized seedling and bare root seedling of Quercus acutissima growing under different fertilizing schemes. Both of containerized seedling and bare root seedling of Quercus acutissima showed good photosynthetic capacity and apparent quantum yield in the seedlings applied with one gram refining fertilizer (each of N, P, and K is 19%) diluted in one liter water. And chlorophyll contents also showed higher in the seedlings applied with the above fertilization scheme. The seedlings also showed good relative growth performances of root collar diameter, seedling height, total biomass, and leaf area in the some treatment scheme. In most of the treatments, containerized seedlings showed better photosynthetic capacity, apparent quantum yield, chlorophyll contents, and growth performances than bare root seedlings.

• 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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.141-148
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• 2008

This study was conducted to investigate the photosynthetic responses of four Oak species (Quercus mongolica, Q. serrata, Q. acutissima and Q. variabilis) by shading treatment. We investigated light response curve, photosynthesis (A)-intercellular $CO_2$ concentration (Ci) curve, leaf growth and chlorophyll content at the level of 35, 55 and 75% shading treatments and under the full sunlight. In our results, Q. variabilis and Q. acutissima showed increased leaf growth, chlorophyll content and net apparent quantum yield but reduced chlorophyll a/b and carboxylation efficiency under the low light intensity. Therefore, light absorption and light utilization efficiency were improved under the low light intensity. Q. mongolica showed the similar responses that Q. variabilis and Q. acutissima showed, but net apparent quantum yield was reduced. The effects of shading treatment on Q. serrata were lower than those of other three species.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.106-114
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• 2009

This present study was conducted to investigate photosynthetic characteristics, chlorophyll fluorescence, chlorophyll contents of Allium victorialis var. platyphyllum, Ligularia fischeri, Ligularia stenocephala growing under four different light intensity regimes (full sun, and 64~73%, 35~42%, 9~16% of full sun). Three wild vegetables showed good photosynthetic capacity in July. Allium victorialis var. platyphyllum showed best photosynthetic capacity and apparent quantum yield in 35~42% of full sun. But Ligularia fischeri and Ligularia stenocephala showed best photosynthetic capacity and apparent quantum yield in full sun and decreased as the shading level increaese. As the shading level increased, the total chlorophyll contents increased with a significant difference in three wild vegetables.

• ALGAE
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• v.36 no.2
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• pp.137-146
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• 2021

Intertidal macroalgae are regularly exposed to hypo- or hypersaline conditions which are stressful. However, red algae in New Zealand are generally poorly studied in terms of salinity tolerance. Consequently, two native (Bostrychia arbuscula W. H. Harvey [Ceramiales], Champia novae-zelandiae [J. D. Hooker & Harvey] Harvey [Rhodymeniales]) and one introduced red algal taxon (Schizymenia spp. J. Agardh [Nemastomatales]) were exposed for 5 days in a controlled salt stress experiment to investigate photosynthetic activity and osmotic acclimation. The photosynthetic activity of B. arbuscula was not affected by salinity, as reflected in an almost unchanged maximum quantum yield (F_v/F_m). In contrast, the F_v/F_m of C. novae-zelandiae and Schizymenia spp. strongly decreased under hypo- and hypersaline conditions. Treatment with different salinities led to an increase of the total organic osmolyte concentrations with rising salt stress in B. arbuscula and Schizymenia spp. In C. novae-zelandiae the highest organic osmolyte concentrations were recorded at S_A 38, followed by declining amounts with further hypersaline exposure. In B. arbuscula, sorbitol was the main organic osmolyte, while the other taxa contained floridoside. The data presented indicate that all three red algal species conspicuously differ in their salt tolerance. The upper intertidal B. arbuscula exhibited a wide salinity tolerance as reflected by unaffected photosynthetic parameters and strong sorbitol accumulation under increasing salinities, and hence can be characterized as euryhaline. In contrast, the introduced Schizymenia spp. and native C. novae-zelandiae, which preferentially occur in the mid-intertidal, showed a narrower salinity tolerance. The species-specific responses reflect their respective vertical positions in the intertidal zone.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.163-169
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• 1991

The photochemical and photophysical properties of N-(2-haloarylmethyl)pyridinium, N-(arylmethyl)-2-halopyridinium, N-(2-haloarylmethyl)-2-halopyridinium salts and N-(2-halobenzyl)-isoquinolinium salt are studied. The pyridinium salts photocyclize to afford isoindolium salts, while the isoquinolium salts do not. In the photocyclization of N-(2-chlorobenzyl)-2-chloropyridinium salts, pyrido[2,1-a]-4-chloroisoindolium salt is formed by the cleavage of chlorine of pyridinium ring. This indicates that the excited moiety is not the phenyl ring, but the pyridinium ring. The triplet states of the pyridinium salts are believed to be largely involved in the photocyclization, since oxygen retards most of the reaction. Some assistance of a ${\pi}$-complex between the excited chlorine moiety of the salt and phenyl plane of the same molecule is required to explain the reactivity of the salts. N-(Benzyl)-2-chloropyridinium salt is two times more reactive than N-(2-chlorobenzyl)pyridinium salt. N-(Benzyl)-2-chloropyridinium salt can form ${\pi}-complex$ effectively because of the electron-rich phenyl group. The ${\pi}$-complex affords an intermediate, phenyl radical by cleaving the chlorine atom. The photocyclized product, isoindolium salt is obtained by losing the hydrogen atom from the phenyl radical. The reactive pyridinium salts 1a, 2a and 3a have a low fluorescence quantum yield (${\Phi}F$ < 0.01) and a higher triplet energy (ET > 68 kcal/mole) than the unreactive quinolinium salt. The unreactivity of isoquinolinium salt can be understood in relation to its high fluorescence quantum yield and its low triplet energy $(E_T = 61 kcal/mole).$.

• Korean Journal of Ecology and Environment
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• v.54 no.2
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• pp.120-124
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• 2021

In order to understand the vegetative role of Glycine soja, we studied the basic physiological characteristics between Glycine soja and Glycine max. For this study, the light intensity (μmol m^-2 s^-1) on leaf surface, leaf temperature (℃), transpiration rate (mmol m^-2 s^-1), photosynthetic rate (μmol m^-2 s^-1), substomatal CO₂ partial pressure (vpm) of Glycine soja and Glycine max were measured, and the quantum yield, photosynthesis rate per substomatal CO₂ partial pressure were calculated. In the results of simple regression analysis, the increasing quantum yield decreases leaf temperature both of Glycine soja and Glycine max and the increasing leaf temperature decreases transpiration rate in case of Glycine soja. However, in case of Glycine max, the increasing leaf temperature decreases substomatal CO₂ partial pressure, photosynthetic rate, and photosynthetic rate per substomatal CO₂ partial pressure as well as transpiration rate. Also, increasing transpiration rate increases substomatal CO₂ partial pressure while decreases photosynthetic rate per substomatal CO₂ partial pressure. Thus, Glycine soja is relatively more easily adaptable to severe environments with low soil nutrients and high light levels. Compared to Glycine max susceptible to water loss due to a water-poor terrestrial habitat, the physiological traits of Glycine soja has a high average transpiration rate and are less susceptible to water loss will act as a factor that limits the habitat according to soil moisture.