• The Korean Journal of Ecology
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• v.24 no.2
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• pp.93-100
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• 2001

One-year-old cottonwood (Populus deltoides Bartr.) clones, which were classified as sensitive or tolerant, were exposed to 150 n1/1 ozone (O$_3$) over 8 days for 8 hours each day under glass chamber conditions with natural sunlight. The leaves of the sensitive clone had black stipple and bifacial necrosis after $O_3$ treatment. Photosynthesis and stomatal conductance were measured before, during, and after the $O_3$ treatment. The photosynthetic rates due to $O_3$ treatment were decreased 51 percent and 34 percent on the sensitive and tolerant clone, respectively. The stomatal conductance of the sensitive clone was more than 40 percent higher than that of the tolerant clone regardless of the $O_3$ treatment. As light intensity increased, the $O_3$ effect on photosynthesis was clear. Compared to the previous growth chamber studies, our natural light exposure system was able to maintain a stable photosynthetic responses of the control treatment throughout the fumigation period. In addition, changes in assimilation versus intercellular $CO_2$ concentration (A/C curves) showed that $O_3$ decreased the slope and asymptote of the curves for the sensitive clone. This indicates that $O_3$ decreases the biochemical capacity of photosynthesis on the sensitive clone. Chlorophyll contents and fluorescence of the two clones were analyzed to examine the $O_3$ effects on photosystem 11, but $O_3$ did not impact these variables on either clone. Although the tolerant clone did not show any foliar injury, we could not find any ecophysiological defensive responses to $O_3$ treated. Stomatal conductance of the tolerant clone was originally much lower than that of the sensitive one. Thus, the mechanisms of the tolerant clone in this system are to narrowly open stomata and efficiently maintain photosynthesis with a more durable biochemical apparatus of photosynthesis under $O_3$ stress. The sensitive clone has higher photosynthetic capacity and more efficient light reaction activity than the tolerant one under charcoal filtered condition, but is not as resilient under stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.560-567
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• 1991

Photosynthetic variation in field grown soybean [Glycine max (L.) Merr. cv Hodgson78］ was studied in relation to leaf anatomical variation. Variations in mesophyll morphology were accentuated by manipulating source and sink size. At R3 stage, two treatments were started: one was thinning and continu-ous debranching(6. 5 plants rather than 26 plants per m of row and remaining plants were debranched weekly), and the other was continuous partial depodding (allowing only one pod to develop at each mainstem node). Gas exchange characteristics, mesophyll cell volume and surface area per unit leaf surface, and microclimatic parameters were measured on the intact terminal leaflet at the 10th node. Observations were made 5 times with 3 to 4 day intervals starting R4 stage. Two models were used to compute leaf photosynthetic rates: one considered no effect of mesophyll morphology on photosynthesis, and the other considered potential effects of variations in mesophyll cell volume and surface area on diffusion and biochemical processes. Seventy nine percent of total photosynthetic variations observed in the experiment was explained by the latter, while 69% of the same variations was explained by the former model. By incorporating the mesophyll morphology concept, the predictability was improved by 14.6% in the field condition. Additional Index Words: photosynthesis model, leaf anatomy, Glycine max (L.) Merr., mesophyll surface area, mesophyll cell volume.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.2
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• pp.79-84
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• 2007

This study was carried out to investigate the effects of growing period and cultivars on physiological characteristics and photosynthetic rates of kenaf in Cheorwon, Korea, The possibility of their utilization as forage plant was also discussed. A split plot design composing 3 growing periods (53, 84 and 115 days after sowing) and 3 cultivars (Dowling, Everglade-41 and Tainung-2) was applied for this experiment. Leaf photosynthetic rate was highest 28.6 $CO_2{\mu}mol\;m^{-2}s^{-1}$ in Everglade-41 at the beginning of August when solar irradiation was most intense. In the final biomass of kenaf, Dowing wa the highest among cultivars, with 534.6g/F.W./plant and 109.6g/D.W./plant, respectively. In addition, Dowling was the best in stem thickness among cultivars evaluated. Our results exhibited that all cultivars planted in Cheorwon exhibited decreased yield production compared to a previous report experimented in Jaeju. It may result that cultivation in Jaeju utilized wider planting space and longer cultivating time. In the basis of our data, it is suggest that extending cultivation time and using wider planting space should increase yield in Cheorwon with potential utilization of kanef as a forage crop.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.156-160
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• 2013

Global warming affects terrestrial ecosystem productivity including photosynthesis and plant growth. This study was conducted to investigate the effect of experimental warming on chlorophyll contents and net photosynthetic rate of Quercus variabilis Blume seedlings. One-year-old Q. variabilis seedlings were planted in control and warmed plots in April 2010. The air temperature of warmed plots was increased by $3^{\circ}C$ compared to control plots using the infrared lamp from November 2010. Total chlorophyll contents were higher in warmed plots than those in control plots in May, July, August, September and October, 2012, however, the differences were statistically significant only in October. Net photosynthetic rates were also higher in warmed plots than those in control plots in May (57.0%), September (21.4%), and October (89.6%), however, the differences were significant only in May and October. Higher chlorophyll contents and net photosynthetic rate of warmed plots in spring and fall might be related to the extended growing season length.

• Journal of Bio-Environment Control
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• v.11 no.3
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• pp.121-126
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• 2002

This study was conducted to investigate the effect of high concentration of sodium salts and chlorides in soil on the growth of tomato and the uptake of minerals. The growth inhibition rates of plant height and dry weight were different depending on salts, but they were not related to the electric conductivities (EC) and acidities (pH) in the soil solution. The orders of growth inhibition were Cl, SO$_4$, CO$_3$, PO$_4$＞NO$_3$ in the sodium salts series, and Na, K, Mg, NH$_4$＞Ca in the chlorides. The growth inhibition rates of the sodium salts series tended to be larger than those of the chloride series. Yield was lower 30%~10% in the sodium salt and chloride series than in the control. Chlorophyll content, photosynthetic rate and stomatal conductance were lower in the sodium salts and chloride series than in the control. Mineral concentration was lower in sodium salts and chlorides than in control. The nitrate absorption was inhibited in all salts except for NaNO$_3$ and NH$_4$Cl, and specially in NaCl and Na$_2$SO$_4$ treatments of the sodium salts and in KCl treatment of chloride series. K concentration was reduced NaCl and Na$_2$SO$_4$ treatments compared with the other salts. In the sodium salt series, calcium and magnesium concentration were decreased antagonistically when sodium concentration was increased.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.256-261
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• 2013

The spacing between plug cells and cell volume of each plug cell for nursing tomato seedlings were studied to know the effects on seedling growth and early yield. There were four treatments. The spacing of plug cells was done (OK) or not (NO) in case of cell spacing. The cell number in a plug tray was set to 40 or 50 in case of cell volume. The growth environment and irrigation regime were the same in all of the treatments during the experiment period. The photosynthetic rates, seedling qualities, yield and yield speed were significantly affected by both of the treatments. The photosynthetic rates and seedling qualities were the best in 40S-OK following by 50S-OK, 40S-NO, and 50S-NO while the yield was the best in 40S-OK following by 40S-NO, 50S-OK, 50S-NO. It means the spacing gives more impact than the cell volume in the stage of nursing but the cell volume gives more impact than the spacing after the stage of nursing. In the conclusion the spacing of plug cells in appropriate nursing stage is needed with the appropriate cell volume to make high quality of seedlings and high yield.

• Journal of Korean Society of Forest Science
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• v.84 no.3
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• pp.306-318
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• 1995

To investigate the effect of low light intensities and the inoculation of Frankia and/or Alpova diplophloeus on the symbioses development and their host growth, red alder(Alnus rubra Bong.) seedlings were grown in an air - filtered walk - in growth chamber with either $N_2$ - fixing Frankia inoculation or N - fertilization and live or dead spore inoculation of the ectomycorrhizal fungus A. diplophloeus(Zeller & Dodge) Trappe & Smith. When they were 20 weeks old, the seedlings were grown under three levels of light intensities of 680, 320 and $220{\mu}mol/m^2/s$ PPFD(photosynthetic photon flux density) for three weeks. PPFD of 220 significantly decreased the development of A. diplophloeus mycorrhizae and nodules, the rates of $N_2$ - fixation and $CO_2$ exchange, and the growth of tile seedlings. PPFD 320 significantly decreased the $CO_2$ exchange rate only. Frankia inoculation significantly increased mycorrhiza formation and seedling growth. Alpova inoculation significantly increased seedling growth but not nodule development and $N_2$ - fixation. None of the symbionts affected $CO_2$ exchange rates. Frankia was more critical for seedling growth and mycorrhizal development than the mycorrhizal fungus for seedling growth and nodule development.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.1
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• pp.11-15
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• 2005

This experiment was conducted to investigate the changes of growth and maturity and to clarify the function of supernodulating characters, excessive nodules and high biological nitrogen fixation rate (BNF), on maturity in response to different planting time in supernodulating soybean mutants. Two supernodulating soybean mutants, Sakukei4 and SS2-2, and their parent cultivars, Enrei and Shinpaldalkong2, were planted on May 24 and June 15, 2004. The degrees of the shortening of growth days by the planting time delay were 18 to 22 days in four cultivar, and there were no significant differences among the cultivars. However, four cultivars showed the different maturity properties. Sakukei4, mutated from Enrei, showed later maturity than that of Enrei, and 882-2, mutated from Shinpaldalkong2, showed earlier maturity than that of Shinpaldalkong2. The plant and nodule dry weights at R6 stage of Sakukei4 showed the smallest decrement and those of SS2-2 was showed the largest decrement by the delay of planting time. The photosynthetic rates of Sakukei4 during the late reproductive growth period were slowly decreased, however those of SS2-2 were steeply decreased in two planting time treatments. Overall, the growth of Sakukei4 was decreased slowly, however the growth of SS2-2 was decreased sharply according to the delay of planting time. The percentage of seed yield of Sakukei4 in June planting plot compared with May planting plot at R8 stage was $92\%$, which was the lowest decreasing rate of yield among the cultivars, and in the case of SS2-2, it was in $76\%$, the highest one. These results indicated that the responses of supernodulating mutants by the delay of planting time were very similar to the wild types. This means supernodulating characters in supernodulating soybean mutants might not affect to the maturity property. Additionally, the maturity property could be considered as an important characteristics to decide or to select on the developments of supernodulating soybean mutants, which have a low productivity by an excessive nodules, especially.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.14-23
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• 2013

This study evaluated the influence of light quality and intensity during healing and acclimatization on the $CO_2$ exchange rate, growth, and morphogenesis of grafted pepper (Capsicum annuum L.) transplants, using a system for the continuous measurement of the $CO_2$ exchange rate. C. annuum L. 'Nokkwang' and 'Tantan' were used as scions and rootstocks, respectively. Before grafting, the transplants were grown for four weeks in a growth chamber with artificial light, where the temperature was set at $25/18^{\circ}C$ (light/dark period) and the light period was 14 hours $d^{-1}$. The grafted pepper transplants were then healed and acclimatized under different light quality conditions using fluorescent lamps (control) and red, blue, and red + blue light-emitting diodes (LEDs). All the transplants were irradiated for 12 hours per day, for six days, at a photosynthetic photon flux (PPF) of 50, 100, or 180 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The higher PPF levels increased the $CO_2$ exchange rate during the healing and acclimatization. A smaller increase in the $CO_2$ exchange rates was observed in the transplants under red LEDs. At a PPF of 180 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, the $CO_2$ exchange rate of the transplants irradiated with red LEDs was lowest and it was 37% lower than those irradiated with fluorescent lamps. The $CO_2$ exchange rates of transplants irradiated with blue LEDs was the highest and 20% higher than those irradiated under fluorescent lamps. The graft take was not affected by the light quality. The grafted pepper transplants irradiated with red LEDs had a lower SPAD value, leaf dry weight, and dry matter content. The transplants irradiated with blue LEDs had longer shoot length and heavier stem fresh weight than those irradiated with the other treatments. Leaves irradiated with the red LED had the smallest leaf area and showed leaf epinasty. In addition, the palisade and spongy cells of the pepper leaves were dysplastic and exhibited hyperplasia. Grafted pepper transplants treated with red + blue LEDs showed similar growth and morphology to those transplants irradiated with fluorescent lamps. These results suggest that high-quality grafted pepper transplants can be obtained by healing and acclimatization under a combination of blue and red lights at a high PPF level.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.28-41
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• 2024

The carbon balance serves as a valuable indicator of a plant's physiological status under diverse environmental conditions. We investigated the photosynthetic and respiratory responses of the Asian surfgrass Phyllospadix iwatensis along the northeast coast of the Korean peninsula in response to changing water temperature (ranging from 5℃ to 30℃) to estimate the seasonal whole-plant carbon balance through a series of incubation experiments. The maximum gross photosynthetic rate (P_max) showed a significant difference among the temperature treatments, while there was no significant difference in photosynthetic efficiency (α). The maximum gross photosynthetic rate of P. iwatensis reached its peaks at 20℃ treatment (101.65 μmol O₂ g^-1 DW h^-1) but decreased rapidly at 30℃. The saturation irradiance (I_k), compensation irradiance (I_c), and respiration rate (R) of P. iwatensis exhibited significant differences among the temperature treatments. The saturation irradiance increased up to 20-25℃ (121.59-124.50 μmol photons m^-2 s^-1) and sharply decreased at 30℃. The compensation irradiance and respiration rate increased steadily with rising water temperature. The ratio of P_max to R (P_max:R ratio) was the highest at 5℃ but dramatically decreased at 30℃. The whole-plant carbon balance, calculated based on photosynthetic parameters, respiration rates, and biomass, exhibited distinct seasonal variation, increasing during winter and spring and decreasing during summer and fall, which is consistent with the highest in situ growth in spring and severely limited growth at the highest water temperature conditions. Phyllospadix iwatensis displayed a negative carbon balance during late summer, fall, and winter, but demonstrated a positive carbon balance during spring and early summer. Our findings suggest that the rising seawater temperatures associated with climate change may lead to significant alterations in the seagrass ecosystem functioning along the rocky shores of the Korean east coast.