• Journal of Bio-Environment Control
• /
• v.31 no.3
• /
• pp.204-211
• /
• 2022

To produce a high quality crop, light is an essential environmental factor in greenhouse cultivation. In the winter season, solar radiation is weak than other season. Therefore, using supplemental light during a low radiation period can increase the crop growth and yield. This study was conducted to select the economical supplemental light source for greenhouse cultivation in pepper during the low radiation period. The green pepper (Capsicum annuum 'Super Cheongyang') was transplanted on 5 September 2019. Supplemental lighting treatment was conducted from 1 January 2020 to 31 March 2020. RB LED (red and blue LED, red:blue = 7:3), W LED (white LED, R:G:B = 5:3:2), and HPS (high-pressure sodium lamp) were used as the supplemental light source. Non-treatment was used as the control. The plant height, SPAD, and number of nodes of pepper plants have no significant differences by supplemental light sources. However, the number of ramifications plants was the greatest in RB LED light source. Moreover, supplemental lighting increased photosynthesis of the pepper plant, and especially, the RB LED had the highest photosynthesis rate during supplemental lighting period. Also, the yield of pepper increased in the supplemental lighting treatment than in the control, and the RB LED had the greatest yield than other light sources. The electricity consumption was the highest in W LED and the lowest in HPS light. Through the economic analysis, the RB LED had high economic efficiency. In conclusion, these results suggest that using RB LED for supplemental light source during low radiation in pepper greenhouse increase the yield and economic feasibility.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.1
• /
• pp.22-32
• /
• 1997

This experiment was conducted to obtain information for the cultivation of Korean valerian(Valeriana lauriei var. dasycarpa Hara) which will be useful for medicinal and aromatic resources. The effect of different temperature conditions, light intensities and soil water conditions on growth, yield and component of essential oil of V. fauriei were measured at the Dankook University, Cheonan, and a study on the shading treatment was at Umsung, Chungchongbukdo, and Jinbu, Kangwondo, in 1995. V. laudei was planted at five different temperature conditions, 10, 15, 20, 25 and 3$0^{\circ}C$, eight light intensity conditions, 1, 000, 2, 500, 5, 000, 20, 000, 30, 000, 40, 000, 50, 000 and 60, 000lux, six soil water contents, 30, 45, 55, 70, 80 and 90％ of the saturated soil, during growth stage. Shading treatment was three conditions, 0, 25 and 50％, during the daytime in field conditions. Photosynthesis had a highly significant relationship with temperature conditions in a quadratic regression model, from which the temperature for the plant growth was estimated to be 17.7$^{\circ}C$. A highly significant quadratic regression was noted between temperature and leaf width or root weight of V. fauriei. It was estimated from the regression equation that the optimum temperature for root growth was 20.3$^{\circ}C$. The content of essential oil and extract rate of root was the highest in the 15~2$0^{\circ}C$. Photosynthesis also was significantly affected by light intensity in a quadratic regression model, from which the optimum light intensity for the growth was estimated to be 40, 000lux. Root yield was more produced in Jinbu than that of in Umsung. The root yield was increased by the shading treatment in Umsung, whereas it was decreased by the shading treatment in Jinbu. The content of essential oil was not affected by the shading treatment of plants during the cultivation, while the compositions of components of essential oil were related to the growing locations. As soil water content was higher, the growth and content of root extract were increased. The optimum soil moisture for the growth of V. fauriei was 80~90％ of the saturated soil. In summary, the results indicated that the growth, yield and component of essential oil in V. fauriei were affected by environmental factors as well as soil moisture.

• Journal of Korean Society of Forest Science
• /
• v.113 no.1
• /
• pp.88-96
• /
• 2024

This study was conducted to determine the optimal light conditions for the in situ and ex situ conservation and restoration of Osmanthus insularis, a rare plant species in South Korea. Evaluations included the growth performance, leaf morphological features, photosynthetic characteristics, and photosynthetic pigment contents of seedlings grown from April to November under different light conditions (100%, 55%, 20%, and 10% relative light intensity). The shoot lengths and root collar diameters did not differ significantly with relative light intensity. The dry weights of leaves, stems, and roots and the leaf number were highest at 55% relative light intensity. The leaf shape showed morphological acclimation to light intensity, with leaf area decreasing and thickness increasing as the relative light intensity increased. Several leaf parameters, including photosynthetic rate and stomatal conductance at light saturation point, net apparent quantum yield, and dark respiration, as well as chlorophyll a, chlorophyll b, and carotenoid contents, were all highest at 55% relative light intensity. Under full light conditions, the leaves were the smallest and thickest, but the chlorophyll content was lower than at 55% relative light intensity, resulting in lower photosynthetic ability. Plants grown at 10% and 20% relative light intensity showed lower chlorophyll a, chlorophyll b, and carotenoid contents, as well as decreased photosynthetic and dark respiration rates. In conclusion, O. insularis seedlings exhibited morphological adaptations in response to light intensity; however, no physiological responses indicating enhanced photosynthetic efficiency in shade were evident. The most favorable light condition for vigorous photosynthesis and maximum biomass production in O. insularis seedlings appeared to be 55% relative light intensity. Therefore, shading to approximately 55% of full light is suggested for the growth of O. insularis seedlings.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.16 no.4
• /
• pp.196-205
• /
• 2011

To investigate the contribution of macroalgae to biogeochemical nutrients and carbon cycles, we measured the uptake rates of nutrients and $CO_2$ and characteristics of fluorescence of Saccharina japonica (Laminaria japonica Areschoug) using an incubation method in an acrylic chamber. From January to May 2011, S.japonica was sampled at Ilkwang, one of well-known macroalgae culture sites around Korea and ranged 46~288 cm long and 4.8~22.0 cm wide of whole thallus. The production rate of dissolved oxygen by S. japonica (n=25) was about $6.9{\pm}5.8{\mu}mol\;g^{-1}$ fresh weight(FW) $h^{-1}$. The uptake rate of total dissolved inorganic carbon ($TCO_2$), calculated by total alkalinity and pH, was $8.9{\pm}7.9{\mu}mol\;g^{-1}\;FW\;h^{-1}$. Mean nutrients uptake were $175.6{\pm}161.1\;nmol\;N\;g^{-1}\;FW\;h^{-1}$ and $12.7{\pm}10.1\;nmol\;P\;g^{-1}\;FW\;h^{-1}$. There were logarithmic relationships between thallus length and uptake rates of nutrients and $CO_2$, which suggested that younger specimens (<100-150 cm) were much more efficient at nutrients and $CO_2$ uptake than old specimens > 150 cm. There was a positive linear correlation ($r^2$=9.4) existed between the dissolved oxygen production rate and the $TCO_2$ uptake rate, suggesting that these two factors may serve as good indicators of S. japonica photosynthesis. There was also positive linear relationship between maximal quantum yield ($F_v/F_m$) and production/uptake rates of dissolved oxygen, $TCO_2$ and phosphate, suggested that $F_v/F_m$ could be used as a good indicator of photosynthetic ability and $TCO_2$ consumption of macroalgae. Maximum relative electron transport rate ($rETR_{max}$) of S. japonica increased as thallus grew and was high in distal part of thallus which may be resulted from the increase of photosynthetic cell density per area. The annual $TCO_2$ uptake by S. japonica in Gijang area was estimated about $1.0\sim1.7{\times}10^3C$ ton, which was about 0.02-0.03% of carbon dioxide emission in Busan City. Thus, more research should be focused on macroalgae-based biogeochemical cycles to evaluate the roles and contributions of macroalgae to the global carbon cycle.

• Journal of Bio-Environment Control
• /
• v.27 no.4
• /
• pp.341-348
• /
• 2018

To investigate the effect of light sources on the growth and photosynthesis of the dwarf apple rootstock M.9 for the production of standard seedlings, the plants were cultivated in a controlled environment for 6 weeks. The sources of light are six treatments [Red (R), Blue (B), White (W), RBUV (R7B3 containing UV-A), RBW (R3B1W1), SMF (high pressure sodium + metal halide + fluorescent lamp) under $154{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Growth characteristics of apple seedlings varied depending on artificial light source at 3 weeks and 6 weeks. The plant height of apple seedling was high in the R, RBUV, RBW, and SMF light sources at 3 weeks, and in the R light at 6 weeks. There was no significant difference on stem diameter among the treatments at 3 weeks, but showed high in RBUV and RBW light at 6 weeks. Leaf number was the highest in RBUV light at 3 and 6 weeks. The chlorophyll content (SPAD value) was high in the B and RBUV light at 3 weeks, but it was not significant at 6 weeks. The growth rate to height of the R light (1.12mm/day) was the highest among the treatments, followed by RBUV, RBW, SMF, W and then B. Leaf area was the highest in RBUV and RBW lowest in B. Specific leaf area was high in W and fresh and dry weight were high in RBUV. The photosynthetic rate at 6 weeks was highest in the B and lowest in the R. Stomatal conductivity and transpiration rate were higher in the B and W compared to the other light sources. Therefore, we are considered that light sources for growth of dwarf apple rootstock M.9 seedlings are suitable the R, RBUV, and RBW light sources with a high mixing ratio of Red and Red +Blue.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.15 no.3
• /
• pp.130-144
• /
• 2013

In this study, we examined the effect of high temperature of urban area on the physiological response of apple tree including the photosynthesis, shoot growth, and fruit quality of 'Fuji'/M.9 apple trees planted at Daegu urban area (DUA) and Gunwi rural area (GRA) for 2 years (2009-2010). During the apple growing season (April-October), the average air temperature of DUA was about $3.0^{\circ}C$ higher than that of GRA and the total rainfall of DUA was 130 mm more than that of GRA. During fruit enlargement stage (June-August), the number of days that recorded daily mean temperature of over $30^{\circ}C$ were ten on DUA in 2010, but there was no day when such temperature was experienced in 2009. Average air temperature of DUA during the maturation stage (September-October) was $19.8^{\circ}C$, which was $4.0^{\circ}C$ higher than that of GRA. The higher temperature of over $30^{\circ}C$ during fruit enlargement stage decreased the photosynthetic rate, shoot growth, fruit weight, and soluble solid content of 'Fuji'/M.9 apple tree. The moderate temperature of about $20^{\circ}C$ during maturation stage increased the photosynthetic rate and soluble solid content of 'Fuji'/M.9 apple tree, but decreased fruit red color. In regional comparison with GRA, photosynthetic rate of DUA was changed from lower before rainy season to higher after rainy season. Fruit weight was higher in DUA than that of GRA. However, fruit weight between DUA and GRA did not show the difference when accumulated days that recorded daily maximum temperature over $35^{\circ}C$ of DUA was increased. Compared to the GRA, soluble solid content of DUA was higher, but fruit red color of DUA was less. These results indicate that the poor red coloring is the most problematic in 'Fuji'/M.9 apple tree by global warming and urbanization.

• Horticultural Science & Technology
• /
• v.28 no.4
• /
• pp.609-617
• /
• 2010

The effect of vase water temperature and leaf number on water relations and senescence responses was determined in cut roses. Freshly harvested 'Red Sandra' roses were re-trimmed to 50 cm leaving two or four upper leaves and held in one of three solutions: ambient temperature distilled water ($23^{\circ}C$; AT-DW), low temperature distilled water ($7^{\circ}C$; LT-DW) and low temperature preservative solution (LT-PW). Flowers were kept in an environmental controlled room. Treatment effects evaluated were vase life, flower diameter, and changes in fresh weight and water uptake. Differences in water relations were determined by measuring $CO_2$ assimilation, stomatal conductance, and stem water flux rate (SFR). The water uptake rate was significantly increased in roses in LT-DW and decreased in those in LT-PW. While showing lower solution uptake rate during vase period, roses in LT-PW exhibited greatest fresh weight, longest positive water balance duration and largest flower diameter. Flowers with two leaves attached exhibited a higher fresh weight and improved water balance, thereby extending vase life. $CO_2$ assimilation rate and stomatal conductance were significantly decreased by placing flowers in LT-PW, yet increased by reducing leaf number to two leaves on the flower stems. Compared to the upper stem, the SFR of the basal stem of roses in AT-DW was lower, whereas SFR in basal stems of roses in LT-DW was much higher, suggesting that low-temperature water improved the hydraulic conductance in the stems. In contrast, roses in LT-PW had a stable SFR during the experimental period and displayed a similar pattern in SFR between upper and basal portions of the stems. Consequently, the vase life of cut roses in LT-PW and LT-DW was extended by more than eight and four days, respectively, compared to those in AT-DW.

• Journal of Wetlands Research
• /
• v.20 no.4
• /
• pp.363-369
• /
• 2018

One of the recent environmental problems is climate change due to the increase of atmospheric $CO_2$, which causes ecological changes and various environmental problems. Therefore, various studies are being carried out to reduce $CO_2$ in the world in order to solve various environmental problems caused by increase of $CO_2$. The $CO_2$ reduction using microalgae is an environmentally friendly method by using photosynthesis reaction of microalgae. However, most studies using single species. There is no study on the $CO_2$ fixing efficiency of microalgae in natural rivers. Therefore, this study was to identify the microalgae in the Sum river and to analyze the growth characteristics of microalgae in the river to obtain optimal culture conditions. And the changes of biomass and chlorophyll-a of microalgae were analyzed according to $CO_2$ concentration and injection rate. The purpose of this study was to investigate the fixing efficiency of carbon dioxide in microalgae in natural rivers. Six kinds of dominant species were observed as a result of the identification of microalgae in Sum river(Ankistrodesmus falcatus, Scenedesmus intermedius, Selenodictyum sp., Xanthidium apiculatum var. laeve, Cosmarium pseudoquinarium, Dictyosphaerium pulchellum). All of these species were green algae. Biomass and chlorophyll-a increased with the increase of $CO_2$ concentration and biomass and chlorophyll-a increased faster flow rate at the same $CO_2$ concentration. Also, the quantity of $CO_2$ fixation on the microalgae tended to be higher when the flow rate of injected gas was faster. This study can be referred as being significant in the micro-algae in river. In addition, the optimal conditions for $CO_2$ fixation of microalgae in rivers and the quantification of the quantity of $CO_2$ fixation from microalgae in rivers can be used as basic data for future policy of $CO_2$ reduction.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.29 no.1
• /
• pp.28-41
• /
• 2024

The carbon balance serves as a valuable indicator of a plant's physiological status under diverse environmental conditions. We investigated the photosynthetic and respiratory responses of the Asian surfgrass Phyllospadix iwatensis along the northeast coast of the Korean peninsula in response to changing water temperature (ranging from 5℃ to 30℃) to estimate the seasonal whole-plant carbon balance through a series of incubation experiments. The maximum gross photosynthetic rate (P_max) showed a significant difference among the temperature treatments, while there was no significant difference in photosynthetic efficiency (α). The maximum gross photosynthetic rate of P. iwatensis reached its peaks at 20℃ treatment (101.65 μmol O₂ g^-1 DW h^-1) but decreased rapidly at 30℃. The saturation irradiance (I_k), compensation irradiance (I_c), and respiration rate (R) of P. iwatensis exhibited significant differences among the temperature treatments. The saturation irradiance increased up to 20-25℃ (121.59-124.50 μmol photons m^-2 s^-1) and sharply decreased at 30℃. The compensation irradiance and respiration rate increased steadily with rising water temperature. The ratio of P_max to R (P_max:R ratio) was the highest at 5℃ but dramatically decreased at 30℃. The whole-plant carbon balance, calculated based on photosynthetic parameters, respiration rates, and biomass, exhibited distinct seasonal variation, increasing during winter and spring and decreasing during summer and fall, which is consistent with the highest in situ growth in spring and severely limited growth at the highest water temperature conditions. Phyllospadix iwatensis displayed a negative carbon balance during late summer, fall, and winter, but demonstrated a positive carbon balance during spring and early summer. Our findings suggest that the rising seawater temperatures associated with climate change may lead to significant alterations in the seagrass ecosystem functioning along the rocky shores of the Korean east coast.

• Proceedings of the Ginseng society Conference
• /
• 1990.06a
• /
• pp.149-154
• /
• 1990

Various rates of 2, 4-2 were sprayed on 2 and 3 year old ginseng plants as fouler spray to define the critical concentration. No apparent plant injury was noticeable for those ginseng plants when application concentration of 2, 4-D doubled the recommended dosage (70 mil 10a). Neither abnormal fouler change occurred nor any inhibition in leaf and stem growth was resulted for the plants treated with 2, 4-D concentrated two times of the recommended dosage. When the rates of 2, 4-D application were increased greater than this level, injury ratings increased linearly with the rates of 2, 4-D application and plant growth was inhibited. Ethylene gas was not produced from the ginseng plant treated with 2 times concentrated 2, 4-D, how- ever the ginseng plants produced 0.03 to 0.09 ppd ethylene gas when the rate of application were increased 3 and 4 times, respectively. On the other hand the soybean treated with the recommended amount of 2i-D produced ethylene gas of 10-20 times higher compared with ginseng plants and died. Photosynthesis ability of the ginseng leaf was significantly decreased by 2, 4.D fouler application but it was recovered 4 weeks after 2, 4-D fouler treatment. The herbicide 2, 4-D was appreciated to 2, 3 and 4 years old ginseng plants as fouler spray with the rates of 0.5, 1.0, 1.5 and 2.0 times of the recommended dosage to define the effects of 2, 4-D on the plant growth and root yield of the ginseng, There were no significant differences in the leaf and stem growth between untreated and 2, 4-D treated plant. Berry maturing of 3 and 4 year old ginseng was not influenced by 2, 4-D. The root weight of 4 years old ginseng plant was not reduced b). application of 2, 4-D concentrated 2 times of the recommended dosage. Application time of the herbicide 2, 4-D had no effects on the leaf or stem growth of 2, 3 and 4 year old year old ginseng plants. When the ginseng seedling was treated with 2, 4-D, detrimental phenomena as stem bending and deceleration of seedling leaf margin occurred, but stem bending was recovere d in a few day.