• Korean Journal of Medicinal Crop Science
• /
• v.23 no.1
• /
• pp.43-48
• /
• 2015

This study was carried out in order to investigate the photosynthesis response and leaf characteristics of Peucedanum japonicum growing in forest farming. The experiment was performed by leaf mold (pine tree and chestnut tree) and shading levels (0%, 35%, 50% and 75% shading). Light relative intensity was 100% (full sunlight), 60.3% (35% shading), 35.1% (50% shading), and 17.4% (75% shading) respectively. Light response curves of pine-leaf mold and chestnut-leaf mold were the highest in control (full sunlight) and these were getting lower in the higher shading level. Photosynthesis capacity and light saturation point were indicated higher in chestnut-leaf mold within the same shading level. As the shading level increased, maximum photosynthesis rate decreased. And apparent quantum yield was not indicated statistically significant difference from all treatment. Leaf area, leaf length and leaf width were significant higher in 35% shading and control under chestnut-leaf mold in all treatment. As the shading level increased, LAR (leaf area ratio), SLA (specific leaf area) and SPAD value decreased in pine-leaf mold and chestnut-leaf mold. As a result of surveying the whole experiment, P. japonicum is judged better growth and higher yield by maintaining 35% shading (relative light intensity 60%) under chestnut-leaf mold in forest farming.

• Korean Journal of Medicinal Crop Science
• /
• v.15 no.4
• /
• pp.276-284
• /
• 2007

To investigate the influence of shading materials with growing stages in Panax Ginseng C. A. Meyer, the diurnal change of photosynthesis, stomatal conductance, transpiration and its any correlation were measured. The net photosynthetic rate and stomatal conductance of ginseng were higher in the morning than in the broad day. The net photosynthetic rate was increased as the PAR (Photosynthetically Action Radiation) was increased and it was reached the maximum at the $200\;{\mu}mol/m^2/s$ of PAR in overall leaves. Transpiration rate was increased in the afternoon compared to in the morning. The transpiration rate was higher in rain shelter shading plate than in polyethylene net. A linear equation was obtained between net photosynthetic rate and stomatal conductance in the morning. SPAD was higher in rain shelter shading plate than in polyethylene net through all growth stages. It may result from the decrease of growth progress. From investigating photosynthetic characteristics, we concluded that shading plate of rain shelter was more an efficient material to ginseng growth.

• ALGAE
• /
• v.17 no.2
• /
• pp.83-87
• /
• 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
• /
• v.8 no.2
• /
• pp.195-199
• /
• 1995

This study was conducted to investigate the Net photosynthesis and respiration rates among the varieties of Soybean(Eunha, Pangsa and Paldal that have high yields) at various leaf temperature and light intensity at the stage of $V_5$. The relations between the Net photosynthesis rate and SLW(specific leaf weight) and chlorophyll content were also investigated. 1. Net photosynthesis rates at $25^{\circ}C$ were $21.5mgdm^{-2}h^{-1}$ in cv. Eunha, $20.2mgdm^{-2}h^{-1}$ in cv. Pangsa and $18.5mgdm^{-2}h^{-1}$ in cv. Paldal. 2. Most cultivars of Soybean showed the maximum rates of Net photosynthesis at $25^{\circ}C$, especially in cv. Eunha. Also Net photosynthesis rates differed depending on the leaf shape. Long leaf shape(cv. Eunha) was better than round leaf shape(cv. Paldal) in Net photosynthesis rate. 3. Respiration rates of leaves in Eunha, Pangse and Paldal were $0.56mgdm^{-2}h^{-1}$ at $15^{\circ}C$, $0.79mgdm^{-2}h^{-1}$ at $20^{\circ}C$ $1.15mgdm^{-2}h^{-1}$ at $25^{\circ}C$ and $1.37mgdm^{-2}h^{-1}$ at $30^{\circ}C$. 4. Specific leaf weight were $3.1mg/cm^2$ in Pangsa, $3.5mg/cm^2$ in Eunha and Paldal. No signlficant difference were showed in net photosynthesis rates and specific lear weight. 5. Leaf chlorophyll content were $2.48{\mu}g/gF.W.$ in Eunha, $2.19{\mu}g/gF.W.$ in Pangsa and $1.67{\mu}/g F.W.$ in Paldal. Significant difference were showed in Net photosynthesis rates and Leaf chlorophyll content. 6. The estimated compensation points at which net photosynthesis approached zero were $10{\mu}Em^{-2}s^{-1}$ in Eunha, Pangsa, and Palda at 1$5^{\circ}C$. The compensation point in cv. Eunha at $20^{\circ}C$ was $12P{\mu}Em^{-2}s{-1}$ while $13{\mu}Em^{-2}s{-1}$ in Pangsa and Palda. The compensation point in cv. Paldal at $25^{\circ}C$ was $18{\mu}Em^{-2}s{-1}$ while $16{\mu}Em^{-2}s{-1}$ in Eunha and Pangsa. The compensation point in cv. Palda at $30^{\circ}C$ was $23{\mu}Em^{-2}s{-1}$ Palda while $13{\mu}Em^{-2}s{-1}$ in Eunha and Pangsa.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.22 no.4
• /
• pp.233-238
• /
• 2020

Process-based model (PBM), based on the interactions between endogenous physiological processes and many environmental factors, can be a powerful tool for estimating crop growth and productivity. Carbon acquisition and biomass accumulation are the main components in PBM, so it has become important to understand and integrate gas exchange process in crop model. This study aimed to assess the applicability of FvCB model (a leaf model of C3 photosynthesis proposed by Farquhar, von C aemmerer, and Berry (1980)) in onion (Allium cepa L.). For parameterization, two early-maturing onion cultivars, 'Singsingball' and 'Thunderball', grown in a temperature gradient plastic film house, were used in measuring leaf net CO2 assimilation rate (A), and then, parameter estimation was carried out for four parameters including Vcmax (maximum rate of carboxylation), Jmax (maximum rate of electron transport), TPU (rate of triose phosphate utilization), and Rd (Dark respiration rate). The gas-exchange model calibrated in this research is expected to be able to explain the photosynthetic responses of onion under various environmental conditions (R2=0.95***).

• Journal of the Korean Society of Tobacco Science
• /
• v.17 no.1
• /
• pp.20-26
• /
• 1995

This study was carried out to obtain the basic data which include the change of the photosynthetic rate and protein content according to growth stage in the process of senescence of tobacco plant The photosynthetic rate was the maximum with 26.31$\mu$mol.CO2/m2.sec and stomatal resistance was the minimum with 0.2552cm/sec at 15th days after leaf emergence. However, after 50 days the photosynthesis was very little occurred. During leaf developments the number of chloroplast was increased and reached at the maximum at 25th days after emergence of leaf, thereafter, it was decreased gradually. The content of protein increased continuously and showed the highest value at 15th days after leaf emergence. The degradation rate of soluble protein was more rapid than that of insoluble protein at early stage of senescence. The range of decrement in the insoluble protein was low at late stage of senescence. The content of Rubisco, the key enzyme of photoamthesis, corresponded to about 50% of soluble protein and reached to the maximum at 150 days after leaf emergence. As the senescence progressed, the content of large subunit(UV) of Rubisco showed a tendency to decrease more rapidly than that of small subunit(SSU). The total amount of amino acids was the highest at 15th days after leaf emergence.

• ALGAE
• /
• v.31 no.1
• /
• pp.49-59
• /
• 2016

Ulva pertusa, a common bloom-forming green alga, was used as a model system to examine the effects of elevated carbon dioxide (CO₂) and temperature on growth and photosynthetic performance. To do this, U. pertusa was grown under four temperature and CO₂ conditions; ambient CO₂ (400 μatm) and temperature (16℃) (i.e., present), elevated temperature only (19℃) (ET; i.e., warming), elevated CO₂ only (1,000 μatm) (EC; i.e., acidification), and elevated temperature and CO₂ (ET and EC; i.e., greenhouse), and its steady state photosynthetic performance evaluated. Maximum gross photosynthetic rates (GP_max) were highest under EC conditions and lowest under ET conditions. Further, ET conditions resulted in decreased rate of dark respiration (R_d), but growth of U. pertusa was higher under ET conditions than under ambient temperature conditions. In order to evaluate external carbonic anhydrase (eCA) activity, photosynthesis was measured at 70 μmol photons m⁻² s⁻¹ in the presence or absence of the eCA inhibitor acetazolamide (AZ), which inhibited photosynthetic rates in all treatments, indicating eCA activity. However, while AZ reduced U. pertusa photosynthesis in all treatments, this reduction was lower under ambient CO₂ conditions (both present and warming) compared to EC conditions (both acidification and greenhouse). Moreover, Chlorophyll a and glucose contents in U. pertusa tissues declined under ET conditions (both warming and greenhouse) in conjunction with reduced GP_max and R_d. Overall, our results indicate that the interaction of EC and ET would offset each other’s impacts on photosynthesis and biochemical composition as related to carbon balance of U. pertusa.

• Journal of Ginseng Research
• /
• v.8 no.1
• /
• pp.65-74
• /
• 1984

This experiment was carried out to study the effects of light intensity and soil water regimes on the growth of ginseng seedling. The results were as follows: 1. The maximum light intensity and optimum temperature in 1,le photosynthesis of ginseng seedling were 10,000 lux and 23 $^{\circ}C$. Respiration rate was increased at high temperature. 2. Air and soil temperature under the shading were increased as the increase of light intensity but soil water contents were decreased as the increase of light intensity, whereas air and soil temperature were decreased as the increase of precipitation under the shade b5: soil water contents were increased as the increase of precipitation under the shade. 3. The higher the transmittance of the shade, the greater the specific leaf weight (S.L.W.) and stomatal density. In contrast, however, the contents of total chlorophyll, chlorophyll a and b, and stomatal length was decreased. There was no any significant difference light intensity of the a/b ratio of chlorophyll. 4. The highest photosynthesis was occurred in ginseng leaves grown under the shade 5% L.T.R. and net photosynthesis rates increased with increasing soil water contents. 5. Optimum condition for usable seedling yield were 5% L.T.R. and 3.3% precipitation under the shade. Useless seedling increased with increasing precipitation under the shade.

• Journal of Environmental Science International
• /
• v.27 no.4
• /
• pp.251-259
• /
• 2018

This study was conducted to determine the effects of combination of air temperature and soil water content on the growth, physiological disorder rate, and yield of hot peppers. The study was carried out in a typical plastic house (open on one side and with ventilation fans on the other side), which was maintained with gradient air temperature (maximum difference in air temperature: $6^{\circ}C$). The deficit irrigation (DI) treatment commenced 65 days after transplanting. The height of plant and fresh and dry weights of the stem increased at high air temperature (ambient + $6^{\circ}C$, extreme high temperature; EHT). Furthermore, the leaf area decreased significantly with the DI treatment. There were no significant differences in the stem diameter, number of branches, and fresh and dry weights of the leaves among all the treatments. The net photosynthesis rate of the full irrigation (FI) treatment was higher than that of the DI treatment. The photosynthesis rate at ambient air temperature was $19.7{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$, the highest among all the treatments; however, the photosynthesis rate of the EHT treatment decreased by 60% ($12.3{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$). Additionally, the formation of guard cells in the leaf was abnormal with the EHT treatment, and there was a decrease in translocation efficiency. The effects of air temperature treatment were more pronounced on the physiological disorder rate and yield. The physiological disorder rate of the EHT treatment was the highest under the DI treatment condition. The yield of the AFI (ambient air temperature with full irrigation) treatment was 3,771 kg/10a, the highest among all the treatments; however, the yield of the EHT treatment with DI and FI was 1,282 and 1,327 kg/10a, respectively. These results indicate that growth and physiological disorder rate improved with the EHT treatment; however, there was a decrease in yield. Furthermore, the formation of guard cells was abnormal and malfunctional.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.29 no.1
• /
• pp.89-97
• /
• 1984

This study was carried out to investigate the effect of seasonal changes on some of the morphological and physiological characteristics, including the photosynthetic abilities and dark respiration, of young ginseng plants due to planting location under shading. The results obtained are as follows: 1. Seedlings and 2-year old plants planted in the back rows appeared to have broader leaf area, and their leaf weight greatly increased in September. Chlorophyll content was significantly reduced in September rather than in June and the plants in the back rows had more chlorophyll content than those in the front rows. 2. There was no difference in the light compensation point between the front and back rows in June, while in September the light compensation point of 2-year old ginseng leaves was much lower for plants in the back rows compared with those in the front rows. A difference in the light saturation point was not noticeable between plants in the front and back rows in June and September. But the light saturation point of 2-year old ginseng leaves at $15^{\circ}C$ was high in June, while it was high at $20^{\circ}C$ high in September. 3. Maximum photosynthetic ability was attained at $15^{\circ}C$ in June and at $20^{\circ}C$ in September. During June no significant difference in photosynthetic ability was found between plants in the front and back rows, but in September the amount of photosynthesis was significantly increased at the leaves of seedlings as well as 2-year old plants planted in the back rows. 4. The optimum temperature for maximum photosynthesis in 2-year old plants ranged from $14.0^{\circ}C$ to $14.5^{\circ}C$ in June and from $19.5^{\circ}C$ to $20.5^{\circ}C$ in September. However, the optimum temperature for maximum photosynthesis in the seedlings was from $21.2^{\circ}C$ to $21.6^{\circ}C$ in September, but a significant difference in the optimum temperature for the maximum photosynthesis in seedlings and 2-year old plants was not noticeable between the front and back rows. 5. The respiration rate was rather high in seedlings compared with 2-year old plants. During September the respiration rate in seedlings was much lower in the back rows than in the front rows. The rate of increase in the respiration of 2-year old plants was higher at September than June. The increase in respiration rate due to temperature was more significant in seedlings than 2-year old plants. 6. In September, the level of $Q_{10}$ in 2-year old plants was much lower than that found in seedlings. During June, 2-year old plants showed lower $Q_{10}$ levels at a temperature difference between $15^{\circ}C$ and $25^{\circ}C$; but in September this occurred at a temperature difference between $20^{\circ}C$ and $30^{\circ}C$.