• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.306-312
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• 2020

This study was conducted to investigate cucumber plants response to greenhouse environments by solar shading in greenhouse in the summer. In order to estimate heat stress reduction of cucumber plants by solar shading in greenhouse, we measured and analyzed physiological conditions of cucumber plants, such as leaf temperature, leaf-air temperature, rubisco maximum carboxylation rate, maximum electron transport rate, thermal breakdown, light leaf respiration, etc. Shading levels were 90% mobile shading of full sunlight, 40% mobile shading of full sunlight and no shading(full sunlight). The 90% shading screen was operated when the external solar radiation is greater than 650 W·m^-2. Air temperature, solar radiation, leaf temperature, leaf-air temperature and light leaf respiration in the 90% shading of full sunlight was lower than those of 40% shading and no shading. Rubisco maximum carboxylation rate, arrhenius function value and light leaf respiration of the 90% shading were significantly lower than those of 40% shading and no shading. The thermal breakdown, high temperature inhibition, of 90% shading was significantly higher than that of 40% shading and no shading. Therefore, these results suggest that 90% mobile shading made a less stressful growth environment for cucumber crops.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.166-174
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• 1995

This experiment was conducted to investigate a cause of summer depression of cool season turfgrass, using nine cultivars in warm season and twenty-eight cool season turfgrasses. Even though an average of apparent photosynthesis(APS) per fresh weight was 13.09 mg $CO_2$/g/h in warm season turfgrass and 7.75 mg $CO_2$/g/h in cool season turfgrass, the Creeping bentgrass in cool season type was higher than Kikuyugrass and Bahiagrass in warm season type. The optimum temperature for the heighest APS was $30^{\circ}C$ in warm season type and $25^{\circ}C$ in cool season type. In $CO_2$ compensation point(CCP) as an index of dark respiration, it was higher in cool season turfgrass(75.6ppm) than warm season turfgrass(29.5ppm). In warm season type, even though the temperature increased from $25^{\circ}C$ to $40^{\circ}C$ the CCP was not increased. But the higher temperature rises the more increased CCP in cool season type. Dark respiration(DR) was higher in cool season type than warm season type under various temperature conditions, but the increasing ratio of DR with the temperature increment was not so much differed between two types.

• Journal of Plant Biology
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• v.27 no.4
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• pp.253-261
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• 1984

Leaf discs isolated from the pea seedling grown in nutrient solution containing 5mM ammonia or nitrate exhibited a half level of photorespiration as compared with the nitrogen free control. The manifestation of the ammonia effect appeared somewhat earlier than that of nitrate effect, but this difference subsided as the culture periods was extended. The total amount of ${CO}_2$ fixed by leaves from nitrogen-supplemented seedlings showed approximately 1.5 fold increase over the control with the ammonia effect being manifested earlier than the nitrate effect. The activities of peroxisomal serine: glyoxylate aminotransferase were always higher with ammonia than nitrate, the two types of nitrogen source, however, had similar effect on conversion rate of glyoxylate into glycine. These results indicate that exogenous ammonia does not act directly as an effector of this aminotransferase in vivo. But changes in the level of the pool size of glycine and serine, both of which are the intermediates of photorespiratory process, suggest that exogenous ammonia inhibit the transformation of serine from glycine metabolically.

• Journal of Plant Biology
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• v.25 no.3
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• pp.105-111
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• 1982

These studies were undertaken to elucidate the reasons for the low productivity of ginseng by comparing the rate of $CO_2$-fixation and photorespiration, variation in the amounts of intermediates and enzyme activities of glycolate oxidase and catalase in ginseng with those of potato. The ability of $CO_2$-fixation in ginseng was found to be one half of that of potato and there were significant differences between those two plants in the rate of $^{14}C$ incorporated into glutamate, aspartate, malate and 3-PGA, but little differences in P-glycolate, glycolate, serine and glycine. The ratio of photorespiration to dark respiration and the activities of glycolate oxidase and catalase in the two species were about same, but ginseng showed higher ratio in photorespiration to total $CO_2$-fixation than potato did. These results indicated that the low productivity of ginseng may resulted from the low $CO_2$-fixation ability and high rate of photorespiration.

• Journal of Plant Biology
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• v.22 no.3
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• pp.81-84
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• 1979

Catalase, glycolate oxidase, hydroxypyruvate and NADPH-glyoxylate reductases activities in cell free extracts from leaves of 3 cultivars, Suwon 264, IR 36 and Jin Heung of rice plants were studied at different growing stages. Catalase and glycolate oxidase shows inclining activities toward the maximum vegetative growth whereas declining activities in either the enzymes were noticed during the maturing stage. After the photoperiodic condition exhibit increasing hydroxypyruvate and NADPH-glyoxylate reductases activities with time until maturing stage. No significant differences were found in the enzyme activities, and in analytical data of nitrogen, chlorophyll contents, dry weight and soluble proteins among the 3 cultivars.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.46-50
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• 1984

Four rice cultivars (two japonicas and two japonica x indica hybrids) were grown in the hydroponic medium in order to investigate the photorespiration rate and ribulose-1, 5-bisphorphate carboxylase (EC 4, 1, 1;39) activity. The results were as follows: 1. Photorespiration rate was increased by the increasing light intensity as well as photosynthesis until light saturation point. Hangangchalbyeo of a hybrid variety had higher photorespiration rate than two japonicas(Jiniubyeo and Seolakbyeo) and one hybrid(Nampungbyeo) tested at ear formation stage. 2. Ribulose-1, 5-bisphosphate carborylase of hybrids were very sensitive to temperature showing lower activities at low temperature and much higher activities at high temperature than that of japonicas.

• Korean Journal of Plant Resources
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• v.17 no.2
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• pp.139-146
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• 2004

Kenaf (Hibiscus cannabinus L.), an annual plant of the family Malvaceae, is considered to be the most promising for alternative plants with potential use as a non-wood fiber source. The objectives of this study were to select the optimum seeding date and adaptable cultivar among newly introduced kenaf cultivars (Everglades-41, Tainung-2 and Chingpi-3) in Jeju island, and to clarify the photosynthetic characteristics of those cultivars. Among the three cultivars, the fresh shoot weight per unit area of Chingpi-3 at harvest season showed highest through all seeding dates, that of while Everglades-41 was the lowest. The difference of shoot yield at harvest mainly due to seedling stand rate and plant number per unit area among the cultivars. The Chingpi-3 showed the highest shoot fresh weight in the seeding date of May 11 and decreased trend in the late seeding dates. Net photosynthesis rate was higher on Everglades-41 with entire type leaf than other two cultivars with palmate type leaf. The activity of ribulose-1,5-bisphosphate carboxylase/foxygenase (rubisco) estimated from the A-Ci curve showed highest in Chingpi-3 among three cultivars. These results suggest that Chingpi-3 might be adaptable cultivar with seeding date of around May 10 for kenaf production in Jeiu island.

• Korean Journal of Medicinal Crop Science
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• v.3 no.3
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• pp.181-186
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• 1995

This study was carried out to know the effect of temperature, light intensity and $CO_2$ con­centration on photosynthesis and respiration in Wasabi (Wasabia japonica Matsum). The optimum temperature for photosynthesis in Wasabi was $17{\sim}20^{\circ}C$ and dark respiration rate was increased with the increasing of tem­perature from, $15 ^{\circ}C\;to\;30^{\circ}C$. Light compensation point was $6.0\;{\mu}E\;m^{-2}s^{-1}$ in Wasabi and $36.7\;{\mu}E\;m^{-2}s^{-1}$ in Corn, and light saturation point was $600{\mu}E\;m^{-2}s^{-1}$, similar in Wasabi and Corn. $CO_2$, compensation point was 67.3ppm in Wasabi and 11.6 ppm in Corn. Photorespiration rate in Wasabi leaf at $l000{\mu}E\;m^{-2}s^{-1}$ light intensity was 3.3 mg$CO_2$, $dm^{-2}hr^{-1}$, and then was gradually decreased as light intensity decreased. Stomatal frequency was about $76\;mm^{-2}$ on the adaxial surface and $623\;mm^{-2}$ on the abaxial surface, and the size of stomata was about 1$12{\mu}m$ on the adaxial surface and $17{\mu}m$ on the abaxial surface of the leaf.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.51-56
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• 2016

Oxygen is a key factor in aerobic reactions and most biological activities. Visualization of oxygen distribution of a chemical process or biological system has been a very challenging object despite of its significance and potential impact. To monitor and visualize the spatial distribution of oxygen concentration, various techniques such as electro-chemical probe, polarographic electrode, LIF(laser-induced fluorescence) and so on have been introduced. Oxygen planar optode which utilizes the oxygen quenching of fluorescence light is one of the currently available methods for time-resolved visualization of oxygen distribution on a planar surface. In this study, we utilized VisiSens oxygen planar optode system to visualize the spatial distribution of oxygen concentration on leaves of Korean azalea. As a result, temporal variation of oxygen concentration distribution caused by respiratory activity of the leaf could be quantitatively monitored.

• Journal of Plant Biology
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• v.31 no.4
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• pp.277-288
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• 1988

The effects of ammonium ion and glutamate on CO2 fixation abilities and related carbon metabolism were investigated in pea (Pisum sativum L. cv. Sparkle) leaf discs under conditions favoring photorespiration (21% O2, 0.03% CO2) and nonphotorespiration (5% O2, 0.03% CO2). A concentration of more than 10 mM of NH4+ decreased the photosynthetic CO2 fixation and those inhibitory effects were more remarkable in 21% O2 than in 5% O2 conditions. The effect of glutamate on CO2 fixation was found to be independent of the O2 level, as glutamate increased the CO2 fixation under both 21% and 5% O2 conditions. L-methionine-dl-sulfoximine, an irreversible inhibitor of glutamate synthetase, however, inhibited the CO2 fixation markedly under 21% O2, but did not affect it under 5% O2 conditions. The treatment with NH4+ elevated the relative amounts of 14C incorporated into soluble components from 14CO2 with no relation to O2 levels, while glutamate increased 14C into insoluble components and neutral sugars. Glutamate, especially, seemed to stmulate the biosynthesis of starch under 5% O2 condition. These results indicated that NH4+ stimulated the degradation of sugar or starch and this proposal was confirmed by the increasing of pyruvate kinase activity in leaf discs treated with ammonium ion.