• Horticultural Science & Technology
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• v.31 no.2
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• pp.146-152
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• 2013

The photosynthetic rates according to leaf positions in tomato plants were investigated in relation to leaf age and flowering rate. In the experiment investigating the diurnal change of photosynthetic rates, three leaves below the 4th cluster was checked every hour from 2 hours before sunrise and 3 hours after sunset. It was checked twice with the replication of 3 plants. The photosynthetic rate increased sharply for 1 hour right after sunrise and remained steady until 2 hours before sunset. This trend can be applied to determine the irrigation schedule. In the experiment investigating the photosynthetic rates according to leaf positions, it three leaves below each clusters from 1st to 4th cluster were checked. Flowering rate was also investigated. The photosynthetic rates showed a decreasing tendency steadily after flowers bloomed fully, regardless of the leaf position. It seems to be because the leaves below the cluster with fully-bloom flowers lost their activities. This result suggests the flowering rate or the position of flower has deep relation with the photosynthetic rates of the concerned leaves. From the results the leaves under flowering cluster may be the good part to investigate the photosynthetic rate to evaluate the crop's activity, even the photosynthetic rates are different according to the position of clusters.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.733-737
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• 2011

We investigated the effect of artificial warming on chlorophyll contents and net photosynthetic rates of 2-year-old Quercus variabilis seedlings in a nursery open-field experiment site. 64 seedlings were each planted in $1m{\times}1m$ plots (n = 4) and warmed with infrared lamps. The air temperature in warmed plots was $3^{\circ}C$ higher than that of control plots. Chlorophyll contents and net photosynthetic rates were measured in May, July, August, September and October, 2011. In May, September and October chlorophyll contents and net photosynthetic rates were significantly higher in warmed plots than in control plots. However, there were no significant differences in chlorophyll contents and net photosynthetic rates between warmed plots and control plots in July and August. It seemed that early developed leaves of warmed plots in May with higher chlorophyll contents could lead to higher net photosynthetic rates whereas there was no difference in net photosynthetic rates due to saturation of chlorophyll contents in July and August. Increased biosynthesis of chlorophyll due to warming might increase net photosynthetic rates in September and October.

• The Korean Journal of Ecology
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• v.18 no.1
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• pp.137-146
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• 1995

Acer pseudo-sieboldianum, A. ginnala, A. negundo and A. saccharinum were selected as materials for the studies on the seasonal fluctuation of chlorophyll content and photosynthetic rates. In all the four species during the growing season except in October, the principal component that determined the total chlorophyll content was chlorophyll a. Content of chlorophyll b increased with leaf age, but that of chlorophyll a decreased. In contrast to A. saccharinum and A. pseudo-sieboldianum which showed their maximum chlorophyll content in June, A. negundo, which showed the highest chlorophyll content of the four species, exhibited its maximum chlorophyll content in July, whereas September in the case of A. ginnala. The fluctuation of chlorophyll content was similar to that of air temperature, and it increased till July. But chloprophyll content showed a significant relationship in early stage of leaf development, and there could be any interdependence between them in accordance with the seasonal change, no longer. In all four species light compensation points decreased in accordance with the seasonal change, and the maximum photosynthetic rates were obtained in August. Respiratory rates were shown no significant difference among species, and they decreased according to the adbance of season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.1
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• pp.93-101
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• 2008

The effects of $CO_2$ enrichment on growth of maize (Zea mays L.) were examined. Parameters analyzed include growth characteristics, yields, photosynthetic rates, evaporation rates and photosynthesis-related characteristics under elevated $CO_2$. 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 silking stage. The plants were exposed to two elevated $CO_2$ of 500, 700ppm and ambient levels (350 ppm). Chalok 1 and GCB 70 germinated three days after seeding, and germination rates were faster in the elevated $CO_2$ than the control. Germination rates displayed significant differences among the $CO_2$ treatments. At the seedling stage, leaf area, top dry weight, and photosynthetic rates, and plant height indicated positive relationship with elevated $CO_2$ concentrations. At the $5{\sim}6$ leaf stage, $CO_2$ concentration also indicated positive relationship with plant height, leaf area, top dry weight, and photosynthetic rates. At the silking stage, increased plant height of Chalok 1 was noted in the $CO_2$ treatments compared to the control. No significant differences were noted for GCB 70, in which leaf area decreased but photosynthetic rates increased progressively with $CO_2$ concentration. Stomatal aperture was a little bigger in the elevated $CO_2$ than the control. $CO_2$ concentration was negatively related to stomatal conductance and transpiration rates, resulting in high water use efficiency.

• Journal of Plant Biology
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• v.36 no.2
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• pp.133-140
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• 1993

The photosynthetic activities in relation to oxygen evolution rates, quantum yield, CO2 uptake rates and room temperature chlorophyll fluorescence were investigated in cotyledons of cucumber seedlings exposed to low temperature (at 4$^{\circ}C$) for 24 h. Light-chilling caused more inhibition on light-saturated maximum oxygen evolution rates, quantum yield, and CO2 uptake rates than dark-chilling did in the cucumber plant. Light-chilling induced more marked increase in Fo and decrease in (Fv)m/Fm than dark-chilling did in the room temperature chlorophyll induction kinetics. The above results affected by chilling in the light are considered to be associated with the partial damage of the reaction center of PS II and the decreased photosynthetic activities. There occurred a large decrease in qQ with little change in qNP in the light-chilling plant. When light- and dark-chilled plants were recovered at room temperature for 24 h and their chlorophyll fluorescences were induced with light doubling technique, light-chilled plants showed more smaller magnitude and rate of fluorescence relaxation than dark-chilled plants. These suggest that light-chilling might cause some alterations in transthylakoid pH formation, and that photosynthetic apparatus of cucumber cotyledons is more susceptible to light-chilling. In the fast fluorescence induction kinetics, FR was decreased by 60% in the light-chilled plants with reference to $25^{\circ}C$ light-grown plants, while the dark-chilled plants showed a decreased rate of only 20% with reference to $25^{\circ}C$ dark-treated plants for 24 h, indicating that cucumber seedling is very sensitive to chilling stress. So, it is certain that chilling injury to the photosynthetic apparatus is strongly dependent on the presence of light in cucumber seedlings.

• ALGAE
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• v.30 no.2
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• pp.103-119
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• 2015

Photosynthetic rates of the large centric diatom Coscinodiscus granii were measured by means of multicolor variable chlorophyll fluorescence imaging, single cell $^{14}C$ assimilation, and optical $O_2$ sensor measurements during light acclimatization of cultures grown at five different irradiances: 50, 150, 235, 332, and $450{\mu}mol$ photons $m^{-2}\;s^{-1}$. Photo-acclimatization was evident from changes of cellular chlorophyll a content, growth rates, and light response curves. Each of the applied methods evaluates different parts and reactions in the photosynthetic apparatus, which makes a direct quantitative comparison of rates difficult, although a different degree of correlation were found between all three methods. However, when used in combination, they provide information about the internal relationship of photosynthetic pathways as well as the variation in photosynthetic capacity between individual cells within a single algal culture.

• ALGAE
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• v.17 no.2
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• pp.83-87
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• 2002

Photosynthetic parameters of Scendesmus quadricauda, such as the maximum photosynthetic rate ($P_{max}$), photosynthetic efficiency (α) and the initial saturation intensity of irradiance for photosynthesis ($I_K$) were obtained using photosynthesis-irradiance (P-I) curve in a phosphorus-limited chemostat. S. quadricauda exhibitied no photoinhibition until at 200 μmol·$m^{-2}$ . $P_{max}$ (r=0.963, P=0.002) and $I_K$(r=0.904, P=0.013) showed linear relationships with growth rate. Chlorophyll-α concentration and cell dry weight decreased at higher growth rates, ut chlorophyll-α content per cell dry weight increased. The increase in photosynthetic rates at higher growth rates was due to the increase of $P_{max}$ and $I_K$ which was caused mainly by the increase in the absolute amount of chlorophyll-α rather than the increased photosynthetic efficiency of individual chlorphyll-α. The α did not show a significant relationship with growth rate (r=0.714, P=0.111). The cell quota of carbon (r=0.554, P=0.254) was not correlated with growth rate, but cell quota of nitrogen (r=0.818, P=0.047) and phosphorus (r=0.855, P=0.030) exhibited linear correlations with growth rate.

• Korean Journal of Plant Resources
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• v.29 no.4
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• pp.393-399
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• 2016

This study was conducted to elucidate the photosynthetic response to the environment and establish optimum cultivation conditions for the Korean endemic plant, Aster koraiensis. Photosynthetic characteristics according to growth stage, light, CO₂, and soil water potential were investigated. During the first year of transplanting, photosynthetic rates were drastically increased until June, after which they slowly declined, During the second year, photosynthetic rates declined throughout the entire growth period. The highest level of light compensation point was shown the early growth stage. Photosynthetic rates affected by intercellular CO₂ concentration were maintained or decreased over the CO₂ saturation point. The lowest CO₂ compensation point was 16.1 μmol·mol⁻¹ during March. The morphological changes of leaves were observed due to shading with chlorophyll contents increasing. Photosynthetic rates were higher at 0% and 50% shading treatments than at 75%. There were rarely any morphological changes of leaves due to soil moisture, however, changes to leaf compactness were observed. Photosynthetic rate, apparent quantum yield, and respiration rate increased, whereas water use efficiency decreased over −25 kPa of soil moisture.

• ALGAE
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• v.19 no.3
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• pp.207-216
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• 2004

Characteristics of photosynthesis-light and photosynthesis-temperature relationships were seasonally compared among 4 species, two temperate Sargassurn (S. ringgoldianum and S. spathulophyllum) and two temperate kelp (Ecklonia cava and Eisenia bicyclis), growing in the same habitat in Oura Bay, Shimoda, central Japan. The photosynthesis-irradiance (P-I) curve of each species at the in situ temperature and the photosynthesis-temperature (P-T) curve at near saturation irradiance (400μmol·m^(-2)·s^(-1)) were determined by using differential gas-volumeters. Maximum photosynthetic rates (Prnax) for P-I curves of the two Sargassurn species were higher from summer to autumn than from winter to spring, while those of the two kelp species showed little difference among seasons. Net photosynthetic rates (Pn) at 100-400μmol·m^(-2)·s^(-1) of the Sargassurn species were higher than those of the kelp species in autumn, spring and summer, while in winter the rates were about the same between the Sargassurn and kelp species. Among seasons, the light saturation index (1k) values, dark respiration rates and light compensation points of Sargassurn species differed more than those of kelp species. Optimum temperature for P-T curves of Sargassurn species was 29℃ and that of kelp species was 27℃ in summer, while in winter the former was 27℃ and the latter was 25℃. Pn at 400 μmol·m^(-2)·s^(-1) at 10-33℃ of Sargassurn species were considerably higher than those of kelp species from spring to summer, while from autumn to winter the rates at 5-27℃ were about the same between the two. At supra-optimum temperatures, Pn of kelp species decreased more sharply than those of Sargassurn species in each season. These facts indicate that the two temperate Sargassurn species have a higher potential photosynthetic performance under warmer conditions than the two temperate kelp species even though they grow in the same habitat.

• Journal of Photoscience
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• v.1 no.2
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• pp.95-105
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• 1994

Experiments were carried out to investigate whether P, deficiency in detached 25 mM mannose-feeding led to a decline of the photosynthetic electron transport rates through acidification of the thylakoid lumen. With increasing mannose-feeding time, the maximal CO2 exchange rates and the maximal quantum yields of photosynthesis decreased rapidly up to 6 h by 73% then with little decrease up to 12 h. The ATP/ADP ratio declined by 54% 6 h after the treatment and then recovered to the control level at 12 h. However, the NADPH/NADP~ ratio was not significantly altered by mannose treatment. Electron transport rates of thylakoid membranes isolated from 6 h treated leaves did not change, but they decreased by 30% in 12 h treated leaves. The quenching analysis of Chl fluorescence in mannose-treated leaves revealed that both the fraction of reduced plastoquinone and the degree of acidification of thylakoid lumen remained higher than those of the control. The reduction of PSI in mannose fed leaves was inhibited due to acidification of thylakoid lumen (high qE). The reduction of primary quinone acceptor of PSII was inhibited by mannose feeding. Mannose treatment decreased the efficiency of excitation energy capture by PSII. Fo quenching was induced when treated with mannose more than 6 h, and had a reverse linear correlation with (Fv)m/Fm ratio. These results suggest that Pi deficiency in Chinese cabbage leaves reduce photosynthetic electron transport rates by diminishing both PSII function and electron transfer from PSII to PSI through acidification ofthylakoid lumen, which in turn induce the modification of photosynthetic apparatus probably through protein (de)phosphorylation.