• Journal of Environmental Science International
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• v.29 no.10
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• pp.989-996
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• 2020

This study was conducted to determine the effect of low temperature and low radiation conditions on the yield and quality of hot pepper at an early growth stage in Korea. In plastic greenhouses, low temperature, low temperature with covered shading treatments were set 17 to 42 days after transplanting. The pepper growing degree days decreased by 5.5% due to the low temperature during the treatment period. Radiation decreased by 74.7% due to the covered shading. After commencing treatments, pepper plant growth decreased with low temperature and low radiation. Analysis of the yield showed that the first harvest was delayed by low radiation. The cumulative yields of 119 days after transplanting were 1,956, 2,171, and 2,018 g/㎡ for control, low temperature, and low temperature with low radiation respectively. Capsaicin and dihydrocapsaicin concentrations in pepper fruit decreased with low temperature and low radiation. To investigate the photosynthetic characteristics according to the treatment, the carbon dioxide reaction curve was analyzed using the biochemical model of photosynthesis. Results showed that the maximum photosynthetic rate, V_cmax (maximum carboxylation rate), J (electric transportation rate), and TPU (triose phosphate utilization) decreased at low temperatures; the maximum photosynthetic rate, J, and g_m (dark respiration rate) were reduced by shading. These results indicate that low temperature and low radiation can retard early growth, yield, and quality, but these can also be recovered 119 days after planting. Based on the results, the yield and quality of pepper can recover from abiotic stresses with proper cultivation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.241-241
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• 2017

Sweet potatoes (Ipomoea batatas (L.) LAMK.,) have been cultivated in Central and South America for about 2000 years and are now grown mainly in Asia and South America. Sweet potatoes are annual in the temperate region, but are classified as perennial in the tropical region. In 2000, the cultivation area of sweet potatoes decreased to about 16,000 ha in 2000, but the cultivation area increased slightly in recent 20,000 ha in Korea. Sweet potatoes do not show higher maximum dry matter production of 120 ~ 150g per plant, and the leaf area index (LAI), which maximizes dry matter production, is known as 3.0 ~ 4.0. As the leaf area increase, the penetration of light into the canopy becomes poor, and sufficient photosynthesis cannot be achieved in the lower leaves, on the other hand the respiration increase, which results in poor dry matter production. This study was conducted to know the responses of sweet potatoes to intensive shading treatment of 80% shading. This experiment was conducted for about 42 days from September 6, 2016 to October 18, 2016 at Gyeongsang National University Experimental Farm, Jinju, Korea. The plant canopy was shaded with black nylon 80% shade cloth suspended 1.2 m above the ground. The photosynthetic rate, stomatal conductance, chlorophyll fluorescence, SPAD and NDVI were measured in 3 replicates every 7 days after shading initiation. After the fresh weight was measured, the samples were dried at $80^{\circ}C$ in a dry oven and measured. By the 80% shading treatment, chlorophyll fluorescence of the treated plants was slightly higher than that of the control, the SPAD value was higher by 3.4 and NDVI value was higher by 0.01. However, photosynthetic rate and stomatal conductance were lower than those of the control. The stomatal conductance of the control were two times higher than those of the control and the photosynthetic rate of the control was four times higher than that of the control. In control, plant showed a tendency to steadily increase in fresh weight and dry weight. However, in the case of shading treatment, the tendency to increase in the fresh and dry weight of tuberous roots was not clear. The fresh weight of shoot showed a tendency to increase steadily while the difference between treatment and control was not large, but tended to decrease after frost.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.250-260
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• 2019

This study assessed clove germination, shoot growth, photosynthesis and bulb development of southern-type garlic (Allium sativum L.) in a temperature gradient tunnel (TGT), to examine the impacts of increases in temperature on the growth of garlic and find a way to minimize them. The temperatures in the middle and outlet of the TGT were 3.2℃ and 5.8℃ higher, respectively, than the ambient temperature at the tunnel inlet. The germination of garlic cloves was late at temperatures of ambient+3℃ (in the middle of the TGT) and ambient+6℃ (at the outlet) than at ambient temperature (at the inlet). However, bolting and the timing of maximum leaf number per plant were faster at ambient+3℃ or +6℃ than at ambient temperature. Shoot growth was generally greater at ambient temperature. Bulb growth did not significantly differ according to cultivation temperatures, but fresh and dry weights were slightly higher at ambient temperature and ambient+3℃ in the late growth stage. The photosynthesis rate (A), stomatal conductance (g_s), and transpiration rate (E) were higher at ambient+3℃ than at ambient temperature. Furthermore, at ambient+3℃, the net photosynthetic rate (A_max) was high, while the dark respiration rate (R_d) was low. At ambient temperature and ambient+3℃, bulb development was healthier, resulting in better productivity and more commercial bulbs, while at ambient+6℃, the bulbs were small and secondary cloves developed, resulting in low commercial value. Therefore, at elevated temperatures caused by global warming, it is necessary to meet the low-temperature requirements before clove sowing, or to delay the sowing time, to improve germination rate and increase yield. The harvest should also be advanced to escape high-temperature stress in the bulb development stage.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.524-531
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• 2004

Photosynthetic activities and primary production of phytoplankton were investigated in Lake Gocheonam from October 1999 to August 2000. As an estuary lake with a barrage in the Southwestern coast of the Korean peninsula, the lake has received more attention after it became known as the habitat of large population of rare and endangered bird- Baikal Teal. As the lake had high algal biomass ranging from $20\mu{g}\;chl-aL^{-1}\;to\;125\mu{g}\;chl-aL^{-1}$ in average values and rich eutrophication indicator species, the freshwaters were in a very productive or hypertrophic state. In the results obtained from the phytoplankton incubation in the laboratory, the maximum photosynthetic rate $(P_{max})$ varied according to seasons and sampling stations. Photo- synthetic activities were higher during the warm season than the cold seasons and the serial order of $P_{max}$ was August dominated with Microcystis, April with Chlamydomonas and Nitzschia, October with Chlamydomonas and January with Stephanodiscus. The water of the lake was persistently turbid throughout the year due to strong winds from the adjacent sea. Despite the water turbidity, the phytoplankton productions estimated from a mathematical model had very broad range from 18mg C $m^{-2}day^{-1}\;to\;10,300mg\;C\;m^{-2}day^{-1}$.

• BMB Reports
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• v.46 no.12
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• pp.575-581
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• 2013

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from $CO_2$ via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech 'factories' to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development.

• Korean Journal of Medicinal Crop Science
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• v.28 no.1
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• pp.1-8
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• 2020

Background: This study was conducted to investigate the effects of NaCl concentration on the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of Crepidiastrum sonchifolium. Methods and Results: As treatments, we subjected C. sonchifolium plants to four different concentrations of NaCl (0, 50, 100 and 200 mM). We found that the photosynthetic parameters maximum photosynthesis rate (P_{N max}), net apparent quantum yield (Φ), maximum carboxylation rate (V_cmax), and maximum electron transport rate (J_max) were significantly reduced at an NaCl concentration greater than 100 mM. In contrast, there was an increase in water-use efficiency with increasing NaCl concentration, although in terms of growth performances, leaf dry weight, root dry weight, stem length, and total dry weight all decreased with increasing NaCl concentration. Furthermore, leakage of electrolytes, as a consequence of cell membrane damage, clearly increased in response to an increase in NaCl concentration. Analysis of the polyphasic elevation of chlorophyll a fluorescence transients (OKJIP) revealed marked decrease in flux ratios (Φ_PO, Ψ_O and Φ_EO) and the PI_abs, performance index in response to treatment with 200 mM NaCl, thereby reflectings the relatively reduced state of photosystem II. This increase in fluorescence could be due to a reduction in electron transport beyond Q^-_A. We thus found that the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of C. sonchifolium significantly increased in response to treatment with 200 mM NaCl. Conclusions: Collectively, the findings of this study indicate that C. sonchifolium shows relatively low sensitivity to NaCl stress, although photosynthetic activity was markedly reduced in plants exposed to 200 mM NaCl.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.401-409
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• 2021

This study aimed to estimate the photosynthetic capacity of tomato plants grown in a semi-closed greenhouse using temperature response models of plant photosynthesis by calculating the ribulose 1,5-bisphosphate carboxylase/oxygenase maximum carboxylation rate (V_cmax), maximum electron transport rate (J_max), thermal breakdown (high-temperature inhibition), and leaf respiration to predict the optimal conditions of the CO₂-controlled greenhouse, for maximizing the photosynthetic rate. Gas exchange measurements for the A-C_i curve response to CO₂ level with different light intensities {PAR (Photosynthetically Active Radiation) 200µmol·m^-2·s^-1 to 1500µmol·m^-2·s^-1} and leaf temperatures (20℃ to 35℃) were conducted with a portable infrared gas analyzer system. Arrhenius function, net CO₂ assimilation (A_n), thermal breakdown, and daylight leaf respiration (R_d) were also calculated using the modeling equation. Estimated J_max, A_n, Arrhenius function value, and thermal breakdown decreased in response to increased leaf temperature (> 30℃), and the optimum leaf temperature for the estimated J_max was 30℃. The CO₂ saturation point of the fifth leaf from the apical region was reached at 600ppm for 200 and 400µmol·m^-2·s^-1 of PAR, at 800ppm for 600 and 800µmol·m^-2·s^-1 of PAR, at 1000ppm for 1000µmol of PAR, and at 1500ppm for 1200 and 1500µmol·m^-2·s^-1 of PAR levels. The results suggest that the optimal conditions of CO₂ concentration can be determined, using the photosynthetic model equation, to improve the photosynthetic rates of fruit vegetables grown in greenhouses.

• Journal of Ginseng Research
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• v.6 no.1
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• pp.38-45
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• 1982

To determine the optimum light intensity for growth of ginseng plants, change of temperature, moisture content in son, occurrence alternaria blight, defoliation rate, chlorophyll contents, and growth of shoots and roots were investigated under different light intensity such as 5%, 10%, 20% and 30% light transmittance rare(L.T.R.). The results obtained were as follows. 1. Maximum temperature under the shading was increased as the increase of light intensity, whereas soil moisture content decreased 2. As the increase of light intensity, stem and Peduncle length, leaf area, and chlorophyll contents decreased significantly but length and width of the leaf was not significant, while stem diameter, special leaf weight and chlorophyll a/chl. b ratio increased 3. Stem color was shown dark purp!e as the increase of light intensity. 4. Photosynthesis during the day was highest at 9 A.M. and decreased as time passed in all plots. The means of photouynthesis during the day showed in the order of 20%, 10%, 30%, 5% L.T.R., and optimum light intensity for highest photosxthesis was 18.4% L.T.R. by theoritical equation. 5. It was showed a tendency that alternaria leaf blight of ginseng plants was increased as the increase of light intensity. 6. Defoliation rate of ginseng plants was increased as the increase of light intensity, especially all plants were defoliated by late June without shading. 7. Yield percentage of the rear line was increased as the increase of light intensity. Root weight per plant showed in the order of 20%, 10%, 30%, 5% L.T.R., and optimum light intensity for the best yield was 18.5% L.T.R. by theeritical equation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.314-320
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• 1984

Effects of phosphorous fertilizer on the growth habit and yield of monoculm and branch types of two leading sesame varieties was investigated. The photosynthetic rate of at each growing stage was high at the flowering stage. The photosynthetic rate of monoculm sesame variety, Pungnyeon was high prior to flowering stage, while the Kwangsan variety, branch type was high after the flowering stage. The level of phosphate were most effective in increasing photosynthesis when standard level of fertilizer was applied in both varieties. Kwangsan variety showed higher photosynthetic rate per unit area, higher NAR, and CGR and higher LAR and RGR at the maximum flowering stage than the Pungnyoeon variety. Those characters attained maximum level when standard levels of phosphorous fertilizer were applied. The protein and oil content of seeds were higher in Kwangsan variety compared with Pungnyeon. However, the carbohydrate of seeds was high for Pungnyeon variety. The highest protein content was attained when standard level of fertilizer were applied. The oil content appeared to increase as the level of applied fertilizer increased. The results suggest that the vegetative growth and seed yields of sesame may be enough with present level of fertilizers. However, higher amount of phosphorous fertilizer may be required to increase the oil content of sesame seeds.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.38-45
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• 2017

We investigated the effects of rising temperatures on the photosynthesis, mineral composition, and growth of radish (Raphanus sativus var. hortensis) in a winter cropping system using a temperature gradient tunnel to predict the impact of rising global temperatures. Vegetative growth, including shoot and root fresh and dry weights, shoot length, and root length and diameter, was high under elevated temperatures (ambient $+4^{\circ}C$ and $+7^{\circ}C$) compared with ambient temperature. At elevated temperatures, the N, P, Ca, Mg, and Fe contents were high in shoots, whereas in roots, the K, Ca, Mg, and Fe contents were high and the Cu content was low. The maximum photosynthetic rates ($22.1{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at ambient temperature $+4^{\circ}C$ and $22.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at ambient temperature $+7^{\circ}C$) at elevated temperatures were more than twice that ($9.7{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) at ambient temperature, whereas the water use efficiency was lower at elevated temperatures. These results suggest that rising global temperatures will lead to increased mineral absorption and photosynthesis in radish in winter cropping systems, subsequently favoring plant growth, although the water requirements will be high.