• Korean Journal of Organic Agriculture
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• v.27 no.1
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• pp.45-56
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• 2019

The study I was initiated in six private 'Campbell Early' vineyards in parts of Jeollanam-do province to relieve symptom of fruit blight mostly due to a high temperature occurred in Summer. High percentage of fruit blight was observed for medium growth of grape trees non-irrigated. In the study II, grape trees treated with 0%, 30% and 60% shade films were investigated for the tree responses, including fruit blight symptom in the research plots. Harvesting time was advanced approximately two weeks by the 30% shade treatment. High percentage of shades increased total shoot length per tree and decreased shoot diameter, with the greatest number of shoots observed for the 30% shade-treated grapes. Light intensity in the tree canopy was approximately 26% decreased by 30% shade treatment. Marketable harvested fruits per tree were 50.6 of 30% shade treatment, 33.6 of 0% shade, and 42.8 of 60% shade. The 30% shade treatment decreased to 11.8% of cluster blight per tree and to 11.2% of berry blight per cluster. The 30% shade treatment increased cluster weight, berry weight, soluble solid contents, and anthocyanin contents.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.253-258
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• 2018

Phytoplankton community was studied in relation to a typhoon at Bok-gyo Bridge area in Juam Lake, Korea. In August 31, 2000, a typhoon (Prapiroon) was passed by Juam Lake with great power enough to destroy summer stratification of Juam Lake. Destratification resulted in temporal mixing of the whole water column and changed the physical and chemical properties of water bodies, and caused the changes of the biological properties. The transparency decreased from 195 cm before the typhoon to 84 cm after the typhoon with the resuspension of the bottom sediment. In the vertical distribution of the phytoplankton population, the maximum population was measured at depth of 2 m before the typhoon. However, immediately after the typhoon, the population distributed evenly throughout the entire water layers. The carbon biomass of the phytoplankton was also highest at the depth of 2 m before the typhoon, but immediately after the typhoon, it was uniformly distributed throughout the whole water layers. The vertical profiles of the concentrations of chlorophyll a, however, did not show a significant difference before and after the typhoon. The typhoon induced destratification and restratification altered the taxa of the phytoplankton. The major dominant phytoplankton taxa before the typhoon was diatoms including Aulacoseira granulata, but the green algae overwhelmed the diatoms in cell number and biomass after the typhoon. The chlorophycean dominance was replaced by cyanophycean dominance with the heavy rain and descent of water temperture at the end of September.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.48-59
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• 2019

This study analyzed the water quality characteristics and developed empirical models prior to and after the construction of Baekje Weir, in the Geum River watershed between 2004-2017. The comparative evaluation of the surface water chemistry before and after the four major river projects on the weirs indicated that total phosphorus (TP), based on annual data, rapidly decrease after the construction of the weir while the total nitrogen(TN) decreased. Conversely, chlorophyll-a (CHL) concentration, which is a good indicator of primary productivity, increased after the construction of the weir together with an increase in specific conductivity. Simply put, the construction of the weir led to the decrease in concentrations of N and P due to the increased water residence time (WRT), whereas the CHL :TP ratio greatly increased in magnitude. The regression analysis of the empirical model indicated that CHL had no significant relation (r=0.068, p=0.6102, n=58) with TP before the weir construction, but had a relation with TP after the weir construction (r=0.286, p<0.05, n=56). Therefore, such conditions resulted in an increase in primary productivity on a given unit of phosphorus, resulting in frequent algal blooms. In contrast, seasonal suspended solids (SS) and TP increased during the monsoon period, compared to the pre-monsoon, thereby showing positive correlations (r>0.40, p<0.01, n=163) with precipitation. If the government consistently discharges water from the weir, the phosphorus concentration will be increased due to its reversion to a lotic waterbody from a lentic waterbody hereby reducing algal blooms in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.264-273
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• 2016

This study was conducted to find out the influence of water stress from May to June on photosynthesis, shoot growth and fruit quality of apple trees. Fuji'/M.9 apple trees were root pruned at full bloom (30th April), parallel to the row of 30 cm or 60 cm from the trunk, to one side or both sides of trunk. The average value of afternoon leaf water potential from May to June of the no root pruning was maintained over -1.80 MPa, but that of root-pruning treatments was maintained under -1.80 MPa. In the comparison of average value of leaf water potential from May to June by root-pruning degree, the root pruning both sides at 30 cm from trunk was lowest (-2.06 MPa), followed by the root pruning both sides at 60 cm (-2.02 MPa) and the root pruning one side at 30 cm (-1.91 MPa). Root pruning one side at 30 cm or both sides at 60 cm reduced photosynthetic rate from May to June by 80% or 65%, respectively, compared with no root pruning. So, the degree of decreasing total shoot length or average fruit weight compare to the no root pruning of the root pruning one side at 30 cm was 25% or 11%, respectively, and those of the root pruning both sides at 30 cm was 45% or 15%, respectively. However, the soluble solid content and fruit color of the root pruning was higher than those of the no root pruning, and those of the root pruning both sides was higher than root pruning one side. These results indicate that the fruit enlargement was decreased when the average value of average leaf water potential from May to June was under -1.80 MPa, and the shoot growth was decreased when that was under -2.00 MPa.

• Journal of Bio-Environment Control
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• v.30 no.3
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• pp.212-217
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• 2021

This experiment was conducted to compare effects of summer pruning at different times and dormant pruning on shoot growth and yield of northern highbush blueberry. Using 7 (2018) to 9 (2020) years old 'Duke' bushes grown in 180 L containers, summer pruning was treated on June 20 (around 30 days after harvest), July 20, and August 20 consecutively in both 2018 and 2019 removing 30% of the total woods, while dormant pruning (conventional) was on January 20 in both 2019 and 2020. Summer pruning reduced shoot growth the following year, especially when treated in late summer. Total shoot length per bush decreased to 47%, 37%, and 33% on October 15, 2020 in June, July, and August pruning, respectively, compared with that of dormant pruning. Summer pruning at different times in 2018 and 2019 did not affect berry characteristic in the following year. Yield per bush was not significantly changed in 2019, but it decreased by 21 to 38% in 2020 in the summer pruning treatments compared with 2.9 kg of the dormant pruning. It was concluded that consecutive summer pruning in 'Duke' under unheated plastic house could weaken the shoot growth with reducing yield.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.175-183
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• 2016

BACKGROUND: There's a long rainy season during the Summer in Northeast Asia, including Korea. Heavy rainfall during this season causes harm to tree's root, and damped injury in the pear has been continuously reported. Pear Research Institute is breeding damp resistant rootstocks and investigating their mechanisms to relieve damped damages in the pear.METHODS AND RESULTS: Seedlings of Pyrus betulaefolia and P. calleryana were divided into two groups: control and damped, respectively. Damped group was treated by constant irrigation for 77 days and control group was maintained to keep the soil moisture pressure between 0 and -10 kPa. After the treatment, we analysed trees' growth rate, chlorophyll content, amino acids and total phenolic compounds. As a result, P. betulaefolia was sensitive to damped treatment while P. calleryana did not have significant differences between the control and damped treatment. It was observed that total contents for phenolic compounds were dramatically increased in P. betulaefolia while trees' growth rate, chlorophyll b and general amino acid contents were lowered by damping treatment.CONCLUSION: In some pear cultivars, growth habit is suppressed by damped damage. Pyrus calleryana displayed tolerances to damped damage in growth rate and some organic compound contents compared to P. betulaefolia. So we recommend to exploit P. calleryana as a pear rootstock rather than using P. betulaefolia.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.306-310
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• 2011

This study examined the changes in the distribution of nitrogenous compounds in various parts of 3- and 4-year-old persimmon (Diospyros kaki cv. Fuyu) with fruits (fruited) and without fruits (defruited). The effect of the changes was then related to the storage and their reutilization for new growth in the following year. From June 15 to November 1, the partitioning of amino acids among perennial parts of fruited trees was inconsistent, whereas that of defruited trees was characterized by a significant increase. Compared with the fruited trees, amino acids accumulated in the perennial parts of defruited trees were 1.66 g and 3.48 g more in 3- and 4-year-old trees, respectively. Of the total proteins increased during this period, the proportions distributed to the perennial parts of the tree were less than 50% for fruited trees, but they were more than 90% for defruited trees. Roots were the strongest sink for proteins; percent proteins in the roots amounted to 94 in defruited 3-year-old trees and 76 in 4-year-old trees. Compared with the proteins accumulated in perennial parts of fruited trees, those of defruited trees were 1.64 g more in 3-year-old and 2.58 g more in 4-year-old trees. During this period, the nitrogenous compounds decreased by 0.50-0.56 g in the leaves of fruited trees, while they increased by 0.66-0.78 g in their fruits. During the new growth from April 10 to June 10 of the following year, amino acids decreased both in the fruited and defruited trees. Proteins, especially in the root, decreased in the trees that had been previously defruited. More amino acids and proteins were found in the newly grown parts of the defruited trees. Compared with the fruited trees, the defruited trees accumulated nitrogenous compounds more in roots than in the other parts of the perennial parts. The reserve nitrogenous compounds contributed to the new shoot growth and fruit set in the following year.

• Journal of Korean Society of Forest Science
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• v.94 no.3 s.160
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• pp.191-196
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• 2005

This studies were conducted to compare ozone sensitivity among half-sib families of Japanese red pine (Pinus densiflora S. et Z.). 90 families were exposed in walk-in type chambers to charcoal-filtered air and 100 ppb ozone for 8 hours daily, 5 consecutive months. We surveyed the foliar injury, Relative DRC (diameter at root collar) growth and relative dry weight after fumigation. After 5 months of exposure, foliar injury ranged from 1.9% at tolerant group to 15.2% at sensitive group. Relative DRC growth rates showed increased 12% at tolerant group, but reduced 23% at sensitive group. Total dry weight increased 17% at tolerant group, otherwise reduced by 33% at sensitive group, relative to the control. The root biomass showed more sensitive than the other part biomass. On the basis of the results of these screening studies, families Kangwon 04, 16, 26, 27 and 73 were determined to be tolerant; Kangwon 40, 52, 83, Gyeonggi 01 and Gyeongbuk 20 to be sensitive to ozone. Considerable genetic variation in ozone responses occurred, as shown by differences in sensitivities among families and among groups. These results indicate that tolerant groups of P. densiflora exhibited a high degree of resistance to ozone pollution injury.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.288-293
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• 2015

BACKGROUND: This study was conducted to investigate the effect of the unexpected early loss of leaves on a newly-bred kiwifruit on the regrowth of axillary buds the current season and the early growth and development the following year.METHODS AND RESULTS: The vines were defoliated on Jul. 18, Aug. 16, and Sep. 17 in 2012 and on Jul. 16, Aug. 13, and Sep. 12 in 2013. The vines were defoliated 0 (control), 50, and 100% of the total number of leaves on a vine. The regrowth of axillary buds at 30 days after defoliation increased in proportion to defoliation degrees regardless of the defoliated time. Defoliation the previous season did not influence percent budbreak the next season. Percentage of floral shoots of the control vines was 27.4%, each bearing 2-3 flowers. In those vines defoliated 100% in August and September, however, percent floral shoots and number of flowers significantly reduced.CONCLUSION(S): Defoliation in July, August, and September didnot affect percent budbreak the following year regardless of degrees of defoliation. A 100% defoliation in August and September significantly reduced flowering the following year compared to the control; that in August resulted in no floral buds at all.

• Spatial Information Research
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• v.23 no.2
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• pp.31-38
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• 2015

Remote sensing data is used to increasing efficiency on benthic cover type survey. Satellite and aerial imagery has variance of reflectance by water column effect even if bottom is consisted with same cover type and condition. This study tried to analyze advances of surveying extent and accuracy through water column correction of CASI-1500 hyperspectral image. Study area is coast of Gangneung city, South Korea where benthic environment is rapidly changing with bleaching of coral reef. Water column correction coefficient was estimated using regression models between water reflectance ($R_W$) and depth for sand bottom then the coefficients were applied to whole image. The results shows that expanded interpretable depth from 6-7m to 15m and decreased variation of reflectance by depth. Additionally, water column corrected reflectance image shows 13%p increased accuracy on benthic cover type classification.