• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.1
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• pp.75-84
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• 2015

This study was conducted to investigate the effects of high temperature and drought on growth performance, photosynthetic parameters and photosynthetic pigment contents of Liriodendron tulipifera L. seedlings. The seedlings were grown in controlled-environment growth chambers with combinations of four temperature ($-3^{\circ}C$, $0^{\circ}C$, $+3^{\circ}C$, $+6^{\circ}C$; based on the monthly average for 30 years in Korea) and two water status (control, drought). Temperature rise increased growth, total dry weight and leaf area in all water status. Also photosynthetic rate, dark respiration, stomatal conductance and transpiration rate increased with increasing temperature. In contrast, growth and photosynthetic parameters of L. tulipifera seedlings were lower in $-3^{\circ}C$ than $0^{\circ}C$. But temperature rise decreased water use efficiency in all water status. Temperature rise increased photosynthetic pigment contents of leaf. Also chlorophyll a/b ratio increased with increasing temperature. In conclusion, the elevated temperature lead to causes growth increase through the increase of energy production by higher photosynthetic rate during a growth period of L. tulipifera seedlings.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.187-193
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• 2007

Higher plants can be categorized as C3, C4 or CAM according to their photosynthetic pathways, and some succulent plants are known to shift their patterns of photosynthesis from C3 to CAM in response to environmental stresses such as salt treatment or water deficiency. To investigate fundamental photosynthetic patterns and the induction of pattern shifts (C3, CAM, C3-CAM etc.) as a result of environmental stresses, we measured the water content, diurnal changes in pH, net $CO_2$ exchange, transpiration rate, total ionic contents, and osmolality of Kalancoe daigremontiana, Sedum kamschaticum and Sedum sarmentosum which belong to Crassulaceae known as representative CAM plant, after 10 days of drought treatment. S. kamschaticum and S. sarmentosum did not show a significant difference in diurnal pH variation in the treatment and control conditions. However, the pH of drought-treated Kalancoe was low at night and high in the daytime, with a pH value between 4 and 5. Typical CAM plants display a net $CO_2$ exchange that increases at night and decreases in the daytime. Kalancoe displayed the predicted pattern. However, S. kamschaticum and S. sarmentosum showed a photosynthetic pattern more typical of C3 plants, and did not show changes in photosynthetic pattern under drought stress. Kalancoe also showed a transpiration rate typical for CAM pho-tosynthesis, whereas the transpiration rates of S. kamschaticum and S. sarmentosum were in the typical range for C3 photosynthesis. Kalancoe had high total ionic contents during the night, which decreased somewhat during the daytime, whereas S. kamschaticum and S. sarmentosum displayed the opposite pattern. This result is similar to the diurnal patterns of changes in pH in the three plant species, which suggests a relationship between pH and ionic contents. S. sarmentosum showed lower osmolality under drought stress than in the control condition, whereas the osmolality of Kalancoe and S. kamschaticum did not differ between conditions. S. sarmentosum may have maintained internal water content by lowering its osmolality and raising its total ionic contents. In conclusion, Kalancoe displayed the characteristic responses of a typical CAM plant, whereas S. kamschaticum and S. sarmentosum displayed aspects of the C3 photosynthetic pattern under drought conditions. These results suggest that S. kamschaticum and S. sarmentosum (Crassulacea) in Korea overcome drought stress by increasing solute and ionic contents internally rather than changing their photosynthetic pattern from C3 to CAM under drought stress.

• ALGAE
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• v.18 no.1
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• pp.83-88
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• 2003

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.64.1-64.1
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• 2008

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.101-109
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• 2008

The content of chlorophyll a, b have generally increased for Fraxinus rhynchophylla and Fraxinus mandshuricain the order of month of June B>C and >D. Therefore we suppose the photosynthesis rate will increase if the moisture level is high and in regardless of the growth stage.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.151-155
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• 1983

Photosynthetic activity of two rice varieties "Suweon 318, Nagdongbyeo" and two species of grass weeds, two species of sedge weeds, and four species of broadleaf weeds was measured at 5, 10, 20, 30, 40, 50 Klux light intensity. Relative photosynthetic activity of weed species was high in the decreasing order in Cyperus serotinus, Echinochloa grusgalli var caudata, Bidens tripartita, Monochoria vaginalis, and Ludwigia prostrata, while respiration rate was high in Bidens tripartite, Monochoria vaginalis and Cyperus serotinus. Light saturation point of Monochoria vaginalis and Sagittaria pygrnaea may be considered as at 30 klux and photosynthetic rate of other weed species increased with increasing light intensity. Photosynthetic activity of weed species was generally two times higher than rice at the light intensity of 50 klux and increased more than rice as light intensity increased. Photosynthetic activity per leaf dry weight and specific leaf area was higher in broadleaf weeds than in grass and sedge weed species.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.173-182
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• 2010

This study was conducted to investigate ozone sensitivity of physiological indicators and the difference in ozone tolerance of 8 families of Sophora japonica seedlings on the basis of the standardized physiological indicators. After ozone treatment, photosynthetic parameters, photosynthetic pigments and malondialdehyde (MDA) content, and antioxidative enzyme activities were analyzed from the leaves of S. japonica seedlings. Ozone tolerance indices among 8 families were calculated with the standardized physiological parameters. In addition, the reduction of carboxylation efficiency and apparent quantum yield were observed in the leaves of seven families, except for family No. 6 and 7, respectively. The apparent quantum yield varied from -27% to -61% of the control seedlings. Photosynthetic pigment content differed significantly among 8 families, but was not affected significantly by ozone treatment. Superoxide dismutase (SOD) activity increased from 7% to 64% after ozone exposure, and significant difference existed among 8 families. Ascorbate-peroxidase (APX) activity of 8 families increased by ozone treatment, and the activity of family No. 7 showed the highest increase (218%) in comparison to their respective control plants. On the basis of the standardized indices, family No. 6 showed the lowest tolerance by indicating higher reduction of both photosynthetic parameters and pigment content and lower increase of antioxidative enzyme activities. On the contrary, family No. 7 showed the highest tolerance as indicated by lower reduction of photosynthetic parameters, higher amounts of photosynthetic pigments, and higher enzyme activity.

• Journal of Ecology and Environment
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• v.43 no.3
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• pp.305-313
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• 2019

Background: This research aims to study the effect of climate change on the phenology, growth, and physiological traits of Silene capitata Kom., a Korean endangered species II. This study increased $CO_2$ concentration in a closed glass greenhouse, with the daily mean temperature and $CO_2$ concentration respectively being $4.61^{\circ}C$ and 93.63 ppm higher than the outside temperature (ambient conditions, control). The seeds of S. capitata were sown in control and treatment environments in March 2013 while seedlings were transplanted into individual pots in May 2013. To research phenological changes, the first day of the flowering and ripening of the plants transplanted in 2013 and first day of leafing in 2014 were observed. The growth and physiological responses of mature leaves were also studied in 2013. Results: There was no difference in the first day of flowering, but the first day of ripening was earlier in the treatment group than the control group. There was no difference in the number of rosette leaves between the two groups, but leaf area was wider in the treatment group than the control group. Transpiration rate and stomatal conductance were higher in the treatment group than the control group, chlorophyll content decreased, and photosynthetic rate and water use efficiency were the same for both groups. As a result of simple regression analysis among the transpiration rate, stomatal conductance, photosynthetic rate, and water use efficiency, stomatal conductance increased when transpiration rate increased. Stomatal conductance increased with photosynthetic rate in the control unlike in the treatment group. The photosynthetic rate and water use efficiency increased with transpiration rate in the control group unlike in the treatment group. Furthermore, water use efficiency increased as photosynthetic rate increased in both groups. Conclusion: Due to high $CO_2$ concentration, the photosynthetic rate was no longer controlled by the stomata, which appeared to suppress the excessive production of photosynthetic products by reducing chlorophyll content. It is believed that the phenological responses of S. capitata under climate change conditions will advance and that stable growth will be difficult in regions lacking moisture due to the high transpiration rate.

• The Korean Journal of Malacology
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• v.29 no.4
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• pp.291-301
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• 2013

This study researched and compared the sedimentation environment and photosynthetic pigments at Gomso (GS) -bay, Yoja (YJ) -bay and KangJin (KJ) -bay in May, 2012. It was shown that KJ-bay consist of C (clay) and M (mud), and GS-bay consists of Zs (silty sand) and Sz (sandy silt). Averagely, IL of YJ-bay was 4.98%, KJ-bay 6.10%, and GS-bay 1.45%. As for COD concentration, there were no places that exceeded Japanese sediment contamination standard 20 mg/g-dry. As for AVS concentration, in case of KJ-bay, two places exceeded Japanese sediment contamination standard 0.2 mg/g-dry. If we look into the average C/N ratio of bays, YJ-bay showed 8.50, KJ-bay 6.60, and GS-bay 5.52, thus all of them showed the characteristic of oceanic origin. As for the plankton make-up classified by photosynthetic pigments, diatom was dominant, and both ratios of pigment and C/chlorophyll. a showed the relatively lower distribution at GS-bay than at KJ-bay and YJ-bay. It is judged that this is related to the characteristic of flow-in, and it implies that predation process and decomposition by organic matters actively occurs at YJ-bay and KJ-bay.

• Korean Journal of Medicinal Crop Science
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• v.26 no.2
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• pp.181-187
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• 2018

Background: This study aimed to investigate out the influence of drought stress on the physiological responses of Dendropanax morbifera seedlings. Methods and Results: Drought stress was induced by discontinuing water supply for 30 days. Under drought stress, photosynthetic activity was significantly reduced with decreasing soil water content (SWC), as revealed by the parameters such as Fv/Fm, maximum photosynthetic rate ($P_{N\;max}$), stomatal conductance ($g_s$), stomatal transpiration rate (E), and intercellular $CO_2$ concentration (Ci). However, water use efficiency (WUE) was increased by 2.5 times because of the decrease in $g_s$ to reduce transpiration. Particularly, E and $g_s$ were remarkably decreased when water was withheld for 21 days at 6.2% of SWC. Dendropanax morbifera leaves showed osmotic adjustment of -0.30 MPa at full turgor and -0.13 MPa at zero turgor. In contrast, the maximum bulk modulus of elasticity ($E_{max}$) did not change significantly. Thus, Dendropanax morbifera seedlings could tolerate drought stress via osmotic adjustment. Conclusions: Drought avoidance mechanisms of D. morbifera involve reduction in water loss from plants, through the control of stomatal transpiration, and reduction in cellular osmotic potential. Notably photosynthetic activity was remarkably reduced, to approximately 6% of the SWC.