• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.169-174
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• 2017

BACKGROUND:Kiwifruit growers build their vineyards using many windbreaks to protect their kiwifruit vines from defoliation injury by strong winds such as typhoon. In this study, we have compared fruit quality, budbreak rate and floral bud as affected by windbreaks. And also we surveyed several microclimate indices of kiwifruit orchard depending on the covering materials of arch-type windbreaks. METHODS AND RESULTS: Five different windbreak materials including polyethylene film (PE), blue- and white-colored nets were tested in pipe-framed archtype kiwifruit vineyards as the covering materials. Photosynthetically active radiation (PAR), annual mean temperature (AMT) and chill unit (CU) as well as fruit quality were compared among the covering materials. In all treatments, annual PAR was more than $400{\mu}mol\;m^{-2}s^{-1}$, in which kiwifruit leaf could reach its maximum photosynthesis, since the leaves were emerged. Annual mean temperature was greater in 0.1 mm-PE covering as much as $1-2^{\circ}C$ than other windbreaks. In CU calculated by three different models, all windbreaks showed more than 1400 CU that is fully fulfilled CU for kiwifruit rest completion. There were no difference in budbreak rate among the covering materials. Fruit weight was heavier in 0.1 mm-PE and white-net (4 mm) than other windbreaks. CONCLUSION: Regardless of the windbreak materials, the PAR quantity was enough for kiwifruit photosynthesis. And CU for kiwifruit rest completion was fully achieved in all treatments. However, with respect to fruit weight, quantity of PAR, and AMT, etc., It is highly recommended for kiwifruit growers to choose 0.1 mm-PE and white-net (4 mm) as for their windbreaks materials.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.373-380
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• 2020

This study was conducted to investigate the effect of elevated temperatures on the growth and physiological responses of peach 'Mihong' (Prunus persica). We simulated three different temperature conditions in the sunlight phytotron rooms from April 25 to July 5, 2019; Control (average temperature in normal years in Jeonju city), +3.4℃ treatment (expecting temperature in mid-21st century), +5.7℃ treatment (expecting temperature in late 21st century). The shoot numbers and lengths were increased while the temperature was increased, but the leaf areas were not statistically different. The harvest dates were July 1, June 24 and 21 at the control, +3.4℃, and +5.7℃, respectively. The fruit weights were increased at +3.4℃ but decreased at +5.7℃ compared to the control. The tree yield was the highest in the +3.4℃ (2,898g), followed by the control (2,746g) and the +5.7℃ (2,404g). These are related to the result that the average of maximum photosynthesis rate at 3.4℃ (14.93μmol·CO₂·m^-2·s^-1) was higher than those at the control (13.79μmol·CO₂·m^-2·s^-1) and +5.7℃ (13.20μmol·CO₂·m^-2·s^-1) from mid-May to early June, the fruit growing season. Also, the stomatal densities were higher at the +3.4℃ (229ea/㎟), compared to the control (181ea/㎟). The rate of floral bud differentiation affecting the yield in the following year was the lowest at the +5.7℃. These results suggest that a temperature elevated to 3.4℃ in the future may give a positive effect on the yield and quality of peach 'Mihong' while a temperature elevated above 5.7℃ may affect negatively.

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

• Journal of Ginseng Research
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• v.4 no.2
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• pp.197-221
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• 1980

Habitat observation, cultural experience of old and present plantation, weather factors in relation to crop stand and water physiology of root and leaf were reviewed. According to habitat observation ginseng plants love water but plate wit talus well grow at drained place with high moisture content in air and soil while ginseng plants were not found in dry or wet place. According to cultivation experience ginseng plants require abundant water in nursery and main field but most old planters believe that ginseng plaints are draught-loving thus require little water. The experience that rain especially in summer i.e unfavorable might be due to mechanical damage of leaves arid leaf disease infection, or severe leaf fall which is caused by high air temperature and coinsided with rain. According to crop stand observation in relation to weather factors abunsant water increased each root weight but decreased total yield indicating tile increase of missing root rate. Rain in summer was unfavorable too. Though rain in June was favorable for high yield general experience that cloudy day and rain were unfavorable might be due to low light intensity under shade. Present leading planters also do loot consider the importance of water in main field. Water content is higher in top than in root and highest in central portion of root and in stem of top. For seedling the heavier the weight of root is tile higher the water content while it reveries from two years old. Water potential of intact root appeared to be -2.89 bar suggesting high sensitivity to water environment. Under water stress water content severly decreased only in leaf. Water content of leaf appeared to be 78% for optimum, below 72% for functional damage and 68% for perm anent wilting. Transpiration or curs Principally through stomata in lower side of leaf thus contribution of upper side transpiration decreased with the increase of intensity. Transpiration is greater in the leaves grown under high light intensity. Thus water content is lower with high light inte nsity under field condition indicating that light is probable cause of water stress in field. Transpiration reached maximum at 10K1ut The decrease of transpiration at higher temperature seems to be due to the decrease of stomata aperture caused by water stress. Severe decrease of photosynthesis under water stress seems to be principally due to functional damage which is not caused by high temperature and Partly due to poor CO2 supply. Water potential of leaf appeared to be -16.8 bar suggesting weakness in draught tolerance. Ginseng leaves absorb water under high humidity. Water free space of leaf disc is %mailer than that of soybean leaf and water uptake appears to be more than two steps.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.180-191
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• 2015

Marine environmental characteristics and primary productivity of phytoplankton were investigated in seaweed bed of northwestern coast of Jeju Island during Autumn, 2014. The trophic state based on dissolved inorganic nitrogen and phosphorus was mesotrophic. The Redfield ratio was less than 16, indicating that nitrogen was the limiting factor for the growth of phytoplankton. Dissolved organic nitrogen and phosphorus accounts for 63 and 46% of the dissolved total nitrogen and phosphorus, respectively. Light utilization efficiency (${\alpha}$) and maximum photosynthetic capacity ($P_m{^B}$) were highest in the Donggwi (third-year marine forest), followed by Gonae (one-year marine forest), Biyangdo (natural seaweed bed) and Geumneung (whitening area). The primary productivity of phytoplankton in the Donggwi, Gonae and Biyangdo also was higher than that in the Geumneung. Although nitrogen is the limiting factor, enriched dissolved organic nitrogen might play an important role to maintain primary productivity. In addition, phytoplankton community through photosynthesis could produce about 14% of phytoplankton carbon in one hour. These results will be able to use the important information for material cycle and ecological valuation of seaweed bed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.81-96
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• 2011

Sediment oxygen demand(SOD) and denitrification rates were measured in four major estuaries(Suncheon Bay, Seomjin river estuary, Goseong stream estuary and Masan Bay) in south coast of Korean peninsula from March of 2009 to May 2010 to estimate organic matter cleaning capacity. SOD was estimated from the temporal dissolved oxygen concentration change and isotopic pairing technique was employed to measure denitrification. Sediment oxygen demand(SOD) was ranged from -5.1 to 24.6 mmole $O_2m^{-2}d^{-1}$ and denitrification rate was ranged from 0.0 to 3.9 mmole $N_2m^{-2}d^{-1}$in the study area. SOD was the highest in Masan Bay(-2.2 to 19.2, average = 10.2 mmole $O_2m^{-2}d^{-1}$) and Suncheon, Goseong, Tae-an and Seomjin followed. Denitrification was also the highest in Masn Bay(0.0 to 3.9, average = 1.0 mmole $N_2m^{-2}d^{-1}$) and Goseong, Seomjin, Suncheon and Taean followed. The effect of benthic photosynthesis by microphytobenthos on denitrification was evident in some season of Tae-an, Seomjin, and Masn Bay. The increased oxygen level produced by photosynthesis stimulated nitrification without severe adverse effect on denitrification and, as a result, coupled nitrification and denitrification was enhanced in these areas. A difference of seasonal patterns of denitrification at each site depended on relative importance of denitrification on different nitrate source($D_w$: nitrate from water column and $D_n$: nitrated produced during nitrification). Denitrification was maximum during spring in Goseong, Suncheon and Masan Bay. On the contrary, denitrification was the highest during summer in Tae-an and Seomjin estuary.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.312-319
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• 2021

This study was conducted to investigate the effect of elevated carbon dioxide on the growth and physiological responses of peach 'Mihong' (Prunus persica). We simulated three different carbon dioxide conditions based on climate change scenarios RCP 8.5 in the sunlight phytotron rooms from April 22 to July 6, 2020; 400 µmol·mol^-1(present condition), 700 µmol·mol^-1 treatment(expecting carbon dioxide concentrations in mid-21st century), 940 µmol·mol^-1 treatment (expecting carbon dioxide concentrations in late 21st century). The average of maximum photosynthesis rate at 700 µmol·mol^-1(16.06 µmol·CO₂·m^-2·s^-1) was higher than those at 400 µmol·mol^-1(14.45 µmol·CO₂·m^-2·s^-1) and 940 µmol·mol^-1(15.96 µmol·CO₂·m^-2·s^-1) from May 22 to July 2. However, stomatal conductances at 700 µmol·mol^-1 and 940 µmol·mol^-1 were lower than those at the control. Also, the carbon dioxide saturation point in all treatments was reduced from 1,200 µmol·mol^-1 in the early stage of growth to 600-800 µmol·mol^-1 in the late stage of growth. The stomatal densities were decreased as carbon dioxide increased. The shoot lengths were decreased while the carbon dioxide was increased, but the increase of trunk diameter and leaf areas, shoot numbers were not statistically different. The fruit weight at 700 µmol·mol^-1(152.5 g) was higher than those at the control(141.8 g) and 940 µmol·mol^-1(147.4 g). The soluble solids were higher at 700 µmol·mol^-1, 940 µmol·mol^-1 compared to the control. These results suggest that a carbon dioxide elevated to 700 µmol·mol^-1 in the future may give a positive effect on the yield and fruit quality of peach 'Mihong' while a carbon dioxide elevated above 940 µmol·mol^-1 may affect negatively such as early senescence and loss of fruit set.

• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.88-96
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• 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
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• v.16 no.4
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• pp.196-205
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• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.65-74
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• 1972

A local rice variety, Jinheung and newly bred IR667-Suwon 214 were grown in $5m^2$ concret pot with two spacings and two nitrogen levels and their ripening structure and its function were comparatively investigated to elucidate the causes of unusually low ripened grain ratio of IR667 lines. The following differences between two varieties were found. 1. Though IR667 had much lower ripened grain ratio (64%) than Jinheung (85%) grain yield(790 kg/10a) of IR667 was higher than that (760 kg/10a) of Jinheung. 2. Number of ripined grain per net assimiration rate (NAR) at 10 days after heading was a little higher in IR667 (6,490) than in Jinheung (6,360) consiting to lower grain weight ($29.9{\times}10^{-3}g$) in IR667 than $31.2{\times}10^{-3}g$ of Jinheung. But number of total grain per NAR was much higher (10,530) in IR667 than 7,290 of Jinheung indicating that it was the probable cause of low ripened grain ratio of IR667. 3. Extinction coeificient (K) was 0.115 in IR667 and 0.200 in Jinheung, thus IR667 could construct greater ripening structure per unit area. 4. Number of grain per LAI was decreased with increasing LAI at heading and the decreasing rate was similar for both IR667 and Jinheung. 5. Critical leaf area index at which crop growth rata (CGR) is maximum was 6.5 for IR667 and 5.2 for Jinheung. Below 5.2 of LAI net assimilation rate was always higher an Jinheung throughout the growing season. 6. The estimated optimum leaf area index having maximum grain yield was 7.4 for IR667 and 6.2 for Jinheung at 10 days after heading. However, actual leaf area index was 6.2 for IR-667 and 4.7 for Jinheung and these were even below critical leaf area index. 7. The decrease of LAI during ripening period was great in IR667 but photosynthesis per $m^2$ was decreased more rapidly in Jinheung. 8. Net assimilation rate (NAR) decreased with the increase of LAI at any time of ripening period. The decreasing rate of NAR with the increase of LAI was greater in IR667 with ripening. The greater decreasing rate of NAR in IR667 seemed to be attributed to low photosynthetic activity and high respiratory loss due to the requirement of higher optimum temperature of ripening. 9. Grain yield-ripened grain ratio curve showed less contribution of dry matter yield after heading to grain yield in IR667 than in Jinheung due to unfavorable ripening environment(specialy air temperature) indicating that yield of IR667 could most effectively increased through the improvement of ripening environment.