• Korean Journal of Medicinal Crop Science
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• v.10 no.5
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• pp.409-414
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• 2002

This study was carried out in order to investigate the main traits related to photosynthesis by multiple regression analysis. The photosynthetic rate showed more significant increase in shaded leaves of plant than in non-shaded leaves of plant after shading treatment for 44 days. Negative correlation was found between net photosynthetic rate and SLA(specific leaf area). However, the values obtained from the linear equation were different and were highly significance. From the above results, net photosynthetic rate of shading treatment is higher than that of control in the same SLA. We also found that there were correlation between stomatal conductance and SPAD as well as net photosynthetic rate and stomatal conductance. By the multiple regression analysis, SPAD value, SLA, stomatal conductance and leaf water potential showed a higher correlation coefficient of $r=0.848^{**}$. From the results, out of 4 factors(SPAD value, SLA, stomatal conductance, leaf water potential) stomatal conductance was main factor in the view points of partial regressing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.466-476
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• 1993

Field experiment was carried out to study the new and old leaf development and photosynthesis of sorghum-sudangrass hybrid 855F, pearl millet Suwon No.6 and barnyard millet in cutting and non-cutting plots from the 2nd cutting day(September, 17th). Leaf regrowth of sorghum-sudangrass hybrid and pearl millet begun after the 2nd cutting day, except barnyard millet. Photosynthetic rate of new leaf blades in cutting plots reached to higher level than old leaf at 12th to 20th day after cutting(DAC). Stomatal density of leaf blade of each crop in non-cutting plot was observed higher pearl millet and sorghum-sudangrass hybrid than barnyard millet. New leaf blade of each crop in cutting plot was showed complete development in stomata size, form and vascular bundles in 12th DAC. Non-structural carbohydrates(NSC) contents of stembase in sorghum-sudan hybrid which had 17 %, the highest among three forages decreased daily into 8th DAC and begun to increase from 20th DAC. But, those of pearl millet and barnyard millet in cutting plots were about 10 % at cutting day and inclined to decrease continuously into the 20th DAC and reached about 3～4% in 32nd DAC. These results showed that regrowth energy of sorghum-sudangrass hybrid was mainly dependent on non-structural carbohydrates of stembase until 12th DAC, but pearl millet had active lower leaves supported its regrowth by concurrent photosynthesis. As barnyard millet which did not reserve enough NSC, its regrowth fail to survive under low temperature. Also, late regrowth of rest two forage crops was delayed with decreasing daily temperature after mid-September.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.353-359
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• 1988

Variations in photosynthetic capacities of leaves differing in thickness were explained on the basis of relationships between gas exchange and internal leaf structure. The relative importance of gas diffusion and of biochemical processes as limiting for leaf photosynthesis was also determined. Mesophyll cell surface was considered to be the limiting internal site for gas diffusion. and cell volume to be indicative of the sink capacity for CO$_2$ fixation. Increases in cell surface area were assumed to reduce proportionately mesophyll resistance to the liquid phase diffusion of CO$_2$. Increased cell volume was thought to account for a proportional increase in reaction rates for carboxylation, oxygenation. and dark respiration. This assumption was tested using chamber-grown Glycine max (L.) Merr. cv. Amsoy plants. Plants were grown under 200, 400, and 600 ${\mu}$mol photons m$\^$-2/ s$\^$-1/ of PAR to induce development of various leaf thickness. Photosynthetic CO$_2$ uptake rates were measured on the 3rd and 4th trifoliolate leaves under 1000 ${\mu}$mol photons m$\^$-2/ s$\^$-1/ of PAR and at the air temperature of 28 C. A pseudo -mechanistic photosynthesis model was modified to accommodate the concept of cell surface area as well as both cell volume and surface area. Both versions were used to simulate leaf photosynthesis. Computations based on volume and surface area showed slightly better agreement with experimental data than did those based on the surface area only. This implies that any single factor, whether it is photosynthetic model utilized in this study was suitable for relating leaf thickness to leaf productivity.

• Journal of The Korean Association For Science Education
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• v.29 no.6
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• pp.712-729
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• 2009

This study aims to research high school students' misconception of botanic photosynthesis and respiration, and as the measure of rectifying the misconception, to develop the teaching program based on Driver's conceptual change model, applying it to classes and observing the effect. Selected as the research subject was sixty-six students in 1st year of a highschool located in Busan who had chosen Biology Learning as discretionary subject, with their conceptual level on botanic photosynthesis and respiration researched through tests in drawing and descriptive writing. As a consequence of applying drawing as a way of classifying the levels of students' misconception on photosynthesis and respiration, many students' drawings included their misconception caused by textbooks or scientists, but after application of Driver's conceptual change model, they drew scientific drawings including the fundamental factors of botanic photosynthesis and respiration such as light, carbon dioxide, water, glucose, oxygen, leaf, chloroplast, mitochondria, stoma, and energy. Likewise, as a result of the descriptive writing test implemented for researching the students' conception on the various aspects of botanic photosynthesis and respiration, many students in the pretest showed misconception on the point of time and location at which botanic photosynthesis and respiration occur, botanic nutrient, the role of a leaf in photosynthesis, and the relation between botanic photosynthesis and respiration, but after teaching based on Driver's conceptual change model, their misconceptions on photosynthesis and respiration were rectified to a high degree.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.239-239
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• 2017

The enhancement of leaf photosynthetic capacity can have the potential to improve the seed yield of soybean. Key targets for the increase of leaf photosynthetic capacity remains unclear in soybean. Peking, Chinese local variety, has been the useful material for soybean breeding since it shows various resistances against biotic and abiotic stress. Sakoda et al., 2017 reported that Peking had the higher capacity of leaf photosynthesis than Enrei, Japanese elite cultivar. They identified the genetic factors related to high photosynthetic capacity of Peking. The objective of this study is to elucidate the physiological basis underlying high photosynthetic capacity of Peking. Peking and Enrei were cultivated at the experimental field of the Graduate School of Agriculture, Kyoto University, Kyoto, Japan. The sowing date was July 4, 2016. Gas exchange parameters were evaluated at the uppermost fully expanded leaves on 43, 49, and 59 days after planting (DAP) with a portable gas exchange system, LI-6400. The leaf hydraulic conductance, $K_{leaf}$, was determined based on the water potential and transpiration rate of the uppermost fully expanded leaves on 60 DAP. The morphological traits related to leaf photosynthesis were analyzed at the same leaves with the gas exchange measurements. The light-saturated $CO_2$ assimilation rate ($A_{sat}$) of Peking was significantly higher than that of Enrei at 43 and 59 DAP while the stomatal conductance ($g_s$) of Peking was significantly higher at all the measurements (p < 0.05). It suggested that high $A_{sat}$ was mainly attributed to high $g_s$ in Peking. $g_s$ is reported to be affected by the morphological traits and water status inside the leaf, represented by $K_{leaf}$, in crop plants. The tendency of the variation of the stomatal density between two cultivars was not consistent throughout the measurements. On the other hand, $K_{leaf}$ of Peking was 59.0% higher than that of Enrei on 60 DAP. These results imply that high $g_s$ might be attributed to high $K_{leaf}$ in Peking. Further research is needed to reveal the mechanism to archive high $g_s$ on the basis of water physiology in Peking. The knowledge combining the genetic and physiological basis underlying high photosynthetic capacity of Peking can be useful to improve the biomass productivity of soybean.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.103-116
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• 2023

Background: This study analyzed the physiological adaptations of a woody plant, Vitex rotundifolia, in Goraebul coastal sand dunes from May to September 2022. Environmental factors and physiological of plants growing under field and controlled (pot) conditions were compared. Results: Photosynthesis in plants growing in the coastal sand dunes and pots was the highest in June 2022 and July 2022, respectively. Chlorophyll fluorescence indicated the presence of stress in the coastal sand dune environment. The net photosynthesis rate (P_N) and Y(II) were highest in June in the coastal sand dune environment and July in the pot environment. In August and September, Y(NPQ) increased in the plants in the coastal sand dune environment, showing their photoprotective mechanism. Chlorophyll a and b contents in the pot plant leaves were higher than those in the coastal sand dune plant leaves; however, chlorophyll-a/b ratio was higher in the coastal sand dune plant leaves than in the pot plant leaves, suggesting a relatively high photosynthetic efficiency. Carotenoid content in the coastal sand dune plant leaves was higher in August and September 2022 than that in the pot plant leaves. Leaf water and soluble carbohydrate contents of the coastal sand dune plant leaves decreased in September 2022, leading to rapid leaf abscission. Diurnal variations in photosynthesis and chlorophyll fluorescence in both environments showed peak activity at 12:00 hour; however, the coastal sand dune plants had lower growth rates and Y(II) than the pot plants. Plants in the coastal sand dunes had higher leaf water and ion contents, indicating that they adapted to water stress through osmotic adjustments. However, plants growing in the coastal sand dunes exhibited reduced photosynthetic activity and accelerated decline due to seasonal temperature decreases. These findings demonstrate the adaptation mechanisms of V. rotundifolia to water stress, poor soils, and high temperature conditions in coastal sand dunes. Conclusions: The observed variations indicate the responses of the V. rotundifolia to environmental stress, and may reveal its survival strategies and adaptation mechanisms to stress. The results provide insights into the ecophysiological characteristics of V. rotundifolia and a basis for the conservation and restoration of damaged coastal sand dunes.

• Journal of Korean Society of Forest Science
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• v.105 no.1
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• pp.78-85
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• 2016

This study was carried out to determine the effects of shading and leaf mold treatment on growth characteristics and photosynthesis responses of Peucedanum japonicum in forest farming. It is very valuable as a sort of health food, so that the demand for the vegetable has increased recently. The experiment can not only increase the yield but also contribute to the development of eco-friendly technology for high-quality P. japonicum. It was performed by shading treatments (full sunlight, 35%, 50% and 75% shading) and leaf mold treatments (control, pine tree and chestnut tree). Height, stem diameter, root collar diameter, number of stem and dry weight were the highest in chestnut-leaf mold under full sunlight. Leaf area, leaf length and leaf width were the highest in chestnut-leaf mold under 35% shading. Photosynthetic rate, conductance to $H_2O$, transpiration rate and water use efficiency were the highest in chestnut-leaf mold under full sunlight. Specially, photosynthetic rate was higher under chestnut-leaf mold in all shading treatment, and getting lower in the higher shading rate. As a result of surveying the whole experiment, it is concluded that P. japonicum grows nicely by maintaining 35% shading under chestnutleaf mold in forest farming. Thus, it is the most effective way to increase the yield for high-quality P. japonicum with eco-friendly technology.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.560-567
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• 1991

Photosynthetic variation in field grown soybean [Glycine max (L.) Merr. cv Hodgson78］ was studied in relation to leaf anatomical variation. Variations in mesophyll morphology were accentuated by manipulating source and sink size. At R3 stage, two treatments were started: one was thinning and continu-ous debranching(6. 5 plants rather than 26 plants per m of row and remaining plants were debranched weekly), and the other was continuous partial depodding (allowing only one pod to develop at each mainstem node). Gas exchange characteristics, mesophyll cell volume and surface area per unit leaf surface, and microclimatic parameters were measured on the intact terminal leaflet at the 10th node. Observations were made 5 times with 3 to 4 day intervals starting R4 stage. Two models were used to compute leaf photosynthetic rates: one considered no effect of mesophyll morphology on photosynthesis, and the other considered potential effects of variations in mesophyll cell volume and surface area on diffusion and biochemical processes. Seventy nine percent of total photosynthetic variations observed in the experiment was explained by the latter, while 69% of the same variations was explained by the former model. By incorporating the mesophyll morphology concept, the predictability was improved by 14.6% in the field condition. Additional Index Words: photosynthesis model, leaf anatomy, Glycine max (L.) Merr., mesophyll surface area, mesophyll cell volume.

• Korean Journal of Plant Resources
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• v.9 no.3
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• pp.274-278
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• 1996

This study was conducted to examine the dry matter production and leaf photosynthesis under different fertilizer application in Yacon(Polymnia sonchifolia)plants. Under field conditions, dry matter production of stable mature application plot(S-1) was much larger than non-treated control plot(CTL), but bulb dry weight of 10kg nitrogen application plot per 10a (N-10) was not differentiated from CTL. The maximum photosynthetic rates increased in Yacon plants grown at S-1 while in the rates of CTL reduced under glasshouse in the same treated pot condition. The optimum temperature for the highly photosynthetic rates is about $34{\pm}3^{\circ}C$, and the rates did decrease by stomatal resistance below 28℃. The estimated light saturation point was $1200{\mu}mol{\cdot}m^{-2}s^1$. The results of this study indicate that soil conditions were highly related to dry matter production and leaf photosynthesis rate in Yacon plants.

• The Korean Journal of Ecology
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• v.26 no.4
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• pp.165-172
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• 2003

The objectives of this study were to examine the physiological responses to ozone and to measure ozone uptake rates of Betula species exposed to relatively high concentration of pollutants. At the end of the growing season, photosynthesis, pigments contents, antioxidants (SOD and GR) and ozone uptake rates were measured or estimated at the leaves of five Betula species (Betula costata, B. davurica, B. platyphylla var. japonica, B. schmidtii and B. ermanii) exposed to 100ppb ozone concentration. On the termination of the experiment, growth effects were determined by measuring leaf area and dry weights of leaf, stem and root. Ozone treatment showed the significant reduction the leaf area and dry weight of four Betula species, except for B. ermanii. Shoot / root (SR) ratio of five species represented two different types. SR ratio of B. costata and B. davurica were lower than control, in contrast, SR ratio of B. platyphylla var. japonica, B. schimidtii and B. emani, were higher than that of control. The photosynthetic responses of five species were different in responses to ozone exposure. Four species, except for B. emanii, maintained or increased the stomatal conductance, but B. emanii decreased both stomatal conductance and photosynthesis. SOD activities of five species decreased by the ozone exposure, especially B. ermanii showed the largest reduction, GR activities of B. platyphylla var. japonica and B. schmidtii increased, B. costata and B. emanii decreased. Instantaneous ozone uptake rate was the highest at the leaves of B. ermanii and B. costata, ozone uptake per seedling was the highest at the leaf of B. schmidtii and B. emanii. It was concluded that B. costata, B. davurica and B. platyphylla var. japonica, appeared the growth reduction and visible ozone injury, were sensitive species to ozone, and B. schmidtii with the increased antioxidant activity and B. ermanii without the growth reduction were relatively resistant species to high ozone concentration at the early growing stage.