• Journal of Ecology and Environment
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• v.32 no.3
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• pp.149-158
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• 2009

American sycamore seedlings were grown in chambers with two different ozone concentrations ($O_3$-free air and air with additional $O_3$) for 45 days. Both the control and the $O_3$ chambers included non-fertilized and fertilized plants. After 18 days of $O_3$ fumigation, seedlings were placed in a clean chamber for 27 days. Seedlings under ozone fumigation showed a significant decrease in pigment contents and photosynthetic activity, and a significant increase in lipid peroxidation. Fertilization enhanced physiological damage such as the inhibition of photosynthetic activity and the increase of lipid peroxidation under ozone fumigation. During the recovery phase, the physiological damage level of seedlings increased with ozone fumigation. In addition, physiological damage was observed in the fertilized seedlings. Superoxide dismutase (SOD) and glutathione reductase (GR) activities of $O_3$-treated seedlings increased up to 33.8% and 16.3% in the fertilized plants. The increase of SOD activity was higher in the fertilized plants than in the non-fertilized plants. Negative effects of ozone treatment were observed in the biomass of the leaves and the total dry weight of the fertilized sycamore seedlings. The $O_3$-treated seedlings decreased in stem, root and total dry weight, and the loss of biomass was statistically significant in the fertilized plants. In conclusion, physiological disturbance under normal nutrient conditions has an effect on growth response. In contrast, in conditions of energy shortage, although stress represents a physiological inhibition, it does not seem to affect the growth response.

• 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.

• KSBB Journal
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• v.14 no.4
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• pp.414-421
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• 1999

The influenced of light intensity, cell density, and light pathlength on photosynthetic activity of Chlorella vulgaris were investigated. Since the light respon curve varied according to reaction conditions, the parameters estimated from nonlinear regression were proved to be apparent and could not be applied to various situations. The light response model incorporating the light penetration through the microalgal suspension was developed based upon the spatial distribution of the photosynthetic activity. This model showed a good agreement with experimental data at different cell densities and light intensities. Using the model the effects of cell density and light pathlenth were simulated and some dicussions about optimization of operation conditions of photobioreactors were carried out. Concludingly, the developed model can be useful for predicting microalgal photosynthesis and for determining the optimal operating conditions.

• The Plant Pathology Journal
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• v.16 no.5
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• pp.257-263
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• 2000

Infection with rice blast fungus (Magnaporthe grisea) significantly reduced foliar net photosynthesis (A) of rice cultivars: Ilpoom, Hwasung, and Choochung in greenhouse experiments. By measuring the amount of diseased leaf area with a computer image analysis system, the relation between disease severity (DS) and net photosynthetic rate was curvilinearly correlated (r=0.679). Diseased leaves with 35% blast symptom can be predicted to have a 50% reduction of photosynthesis. The disease severity was linearly correlated (r=0.478) with total chlorophyll (chlorophyll a and chlorophyll b) per unit leaf area(TC). Light use efficiency was reduced by the fungal infection according to the light response curves. However, dark respiration (Rd) did not change after the fungal infection (p=0.526). Since the percent of reduction in photosynthesis greatly exceeded the percent of leaf area covered by blast lesions, loss of photosynthetic tissue on an area basis could not by itself account for the reduced photosynthesis. Quantitative photosynthetic reduction can be partially explained by decreasing TC, but cannot be explained by decreasing Rd. By photosynthesis (A)-internal CO$_2$ concentration (C$_i$ curve analysis, it was suggested that the fungal infection reduced ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, ribulose-1,5-bisphosphate (RuBP) regeneration, and inorganic phosphate regeneration. Thus, the reduction of photosynthesis by blast infection was associated with decreased TC and biochemical capacity, which comprises all carbon metabolism after CO$_2$ enters through the stomata.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.303-309
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• 2006

The study examined the effects of $CO_2$ enrichment on growth of soybean (Glycine max). Two soybean varieties were used, Taekwang and Cheongja. The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of $28/21^{\circ}C$ at the seedling stage and $30/23^{\circ}C$ from the flowering stage. The plants were exposed to the two elevated $CO_2$ levels of 500 and 700 ppm and the ambient level of 350 ppm. Results of the experiment showed that at the second-node trifoliate stage of the two varieties, the elevated $CO_2$ increased plant height, leaf area and dry weight. The elevated $CO_2$ also raised the photosynthetic rate of soybean as compared to the ambient level. From the beginning bloom stage to the full maturity stage of the two varieties, the elevated $CO_2$ increased plant height, leaf area, seed weight and photosynthetic rate. The stomatal conductance and transpiration rate decreased on long days relative to short days of treatment. Through the entire stages, the elevated $CO_2$ increased the water use efficiency of soybean plants because stomatal conductance and transpiration rate decreased at the elevated $CO_2$ levels relative to the ambient level.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.100-104
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• 2004

This study was conducted to investigate the effect of the salinity on growth, inorganic ion content, and photosynthetic rate ($\textrm{P}^{N}$) in Korean ginseng (Panax ginseng C.A. Meyer) with complex fertilizer (CF) and NaCl concentrations. The salinity was applied to plant using NaCl and CF, and controlled an EC as 0.0, 1.0, 2.0 and 3.0 dS $\textrm{m}^{-1}$. The salinity treated three times at 35, 42 and 49 d after transplanting. The leaf area in different electrical conductivity (EC) decreased only the higher NaCl 1.0 dS $\textrm{m}^{-1}$. The root growth increased with CF and especially, it was two times higher at 3.0 dS $\textrm{m}^{-1}$ than that of control. But the root growth sharply decreased with NaCl compared to CF. The light saturation point of Korean ginseng was around 100 $\mu\textrm{mol}\;\textrm{m}^{-2}\textrm{s}^{-1}$ photosynthetically active radiation (PAR), and $\textrm{P}^{N}$ increased as CF increased but decreased with NaCl especially at the late growth stage. The $\textrm{Na}^{+}$ content in Korean ginseng increased sharply with NaCl.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.3
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• pp.208-214
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• 2022

Drought stress is a condition that occurs frequently in the field, it reduces of the agricultural yield of field crops. The aim of the study was to screen drought-adapted genotype of Italian rye grass. The experiments were conducted between the two Italian ryegrass (Lolium multiflorum L.) cultivars viz. Hwasan (H) and Kowinearly (KE). The plants were exposed to drought for 14 days. The results suggest that the morphological traits and biomass yield of KE significantly affected by drought stress-induced oxidative stress as the hydrogen peroxide (H₂O₂) level was induced, while these parameters were unchanged or less affected in H. Furthermore, the cultivar H showed better adaptation by maintaining several physiological parameter including photosystem-II (Fv/Fm), water use efficiency (WUE) and relative water content (RWC%) level in response to drought stress. These results indicate that the cultivar H shows improved drought tolerance by generic variation, improving photosynthetic efficiency and reducing oxidative stress damages under drought stress. These findings can be useful to the breeder and farmer for improving drought tolerance in Italian rye grass through breeding programs.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.203-209
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• 2010

This study was performed to investigate photosynthetic responses of 4 foliage plants in relation to light intensity, carbon dioxide concentration, and media, and to select efficient plants for the indoor environment control based on the results. Four foliage plants used in this study included Syngonium podophyllum, Schefflera arboricola cv. Hong Kong, Dieffenbachia amoena, and Dracaena deremensis cv. Warneckii Compacta. The plants cultivated in two different growth media, peatmoss and hydroball, and subjected to various light intensities (0, 30, 50, 80, 100, 200, 400, and $600\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD) and $CO_2$ levels (0, 50, 100, 200, 400, 700, 1000, and $1500\;{\mu}mol{CO_2}{\cdot}mol^{-1}$). As a result of the photosynthetic rate of foliage plants according to change of light intensity and $CO_2$ levels, Schefflera arboricola and Dieffenbachia amoena showed high apparent quantum yield, which stands for the photosynthetic rate under low light intensity, and both plants also recorded higher photosynthetic rate under high $CO_2$ concentration compared to the other two indoor plants. Dracaena deremensis showed the lowest photosynthetic rate under the low light intensity or high $CO_2$ concentration. There were inconsistent results in photosynthetic rate of foliage plants grown in peatmoss or hydroball. Higher photosynthetic rate was observed in Schefflera arboricola with peatmoss rather than hydroball as light and $CO_2$ concentration increased. However, hydroball had a positive effect on Dieffenbachia amoena in terms of photosynthetic rate. In case of Syngonium podophyllum, peatmoss induced higher photosynthetic rate according to increased light intensity, but there was no effect of media on the rate under various $CO_2$ treatements. In contrast, media did not affect to photosynthetic efficiency of Dracaena deremensis subjected to various light intensities and the rate of Dracaena deremensis with peatmoss was a little high when $CO_2$ concentration increased. In conclusion, potential plants for the indoor air pulification and environmental control were Schefflera arboricola and Dieffenbachia amoena because they showed high photosynthetic rate under typical indoor conditions, low light intensity and high $CO_2$ concentration.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.111-115
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• 1991

The green alga, Dunaliella salina under fed-batch cultivation produced 51.12 mg of hydrocarbon per liter with maintaining 0.313 (g dry wt/l). About 20% of hydrocarbon production yield based on dry biomass was obtained from both batch and fed-batch processes. Optimum culture conditions of light intensity, pH and salt concentration were obtained as 0.0080 (kJ/$cm^2$/h), 8.0 and 1.4 (g of NaCl/l), respectively by response surface analysis. The production of hydrocarbons in D. salina was closely correlated to cell growth. Fed-batch cultivation produced more hydrocarbons and maintained better cell growth than a batch process.

• Asian Journal of Turfgrass Science
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• v.11 no.4
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• pp.271-280
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• 1997

The short green period of zoysiagrass has been a problem in using for turf. This study was performed to check growth response of several wintergrasses under sunny and shady area in Korea. Wintergrasses of 5 species, 27 cultivars introduced from U.S.D.A., were used in this study. After establishment, two fluctuations of top growth were observed which varied according to the species; first, due to drought in May, second, due to high temperature and humidity from July to August. Red fescues and perennial ryegrasses showed severe growth retardation in sunny area during summer period. Kentucky bluegrasses and tall fescues maintained good Qualities nearly all the year round arid showed slight disease infections. Kentucky bluegrass 'Kenblue' and red fescue 'Agram' grown under shady area showed higher photosynthetic ability than under sunny area, except the temperature range from 30˚C to 40 ˚C under 40,000 lux light in red fescue 'Agram'. And the phorosynthesis was decreased at the temperature range from 35 ˚C to 40 ˚C. Key words: Wintergrass, Top growth, Visual rating, Photosynthesis, Poa pratensis. Festuca arundinacea, Pestuca rubra. Lolium perenne, Agrostis stolonifera.