• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.54-54
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• 2019

Apple (Malus domestica) is one of the most economically important fruits in Korea. But virus infection has decreased sustainable production of apple and caused the serious problems such as yield loss and poor fruit quality. Virus or viroid infection including Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple mosaic virus (ApMV) and Apple scar skin viroid (ASSVd) has been also reported in Korea. In many cases, apple is infected with virus and viroid with no specific symptoms, the damage caused by the virus are unaware significantly. In our research, we tried to eliminate viruses in the rootstock for the disease-free seedlings of the apple dwarfing rootstock M.9 and M.26. The method of virus elimination was meristem culture, heat($37^{\circ}C$, 6weeks) treatment and chemistry($Ribavirin^{(R)}$) treatment. The analytical methods commonly used for the detection of virus is Enzyme-linked Immuno-Sorbent Assay(ELlSA) and Reverse Transcription-polymerase Chain Reaction(RT-PCR). RT-PCR method was more 30% sensitive than ELISA method. Efficiency of method eliminate virus appeared meristem method > heat treatment > chemistry treatment. The higher acquisition rate of disease-free seedlings is 30~40% on meristem treatment. In meristem treatment, the apple dwarfing rootstock M.9 gained infection ratio of ACLSV, ASPV and ASGV were 45%, 60% and 50% respectively. In the apple dwarfing rootstock M.26, infection ratio of ACLSV, ASPV and ASGV were 40%, 55%, 55%, respectively. Based on our results, it was found that most effective method of disease-free seedlings apple dwarfing rootstocks was by meristem treatment than heat method and chemistry treatment.

• Journal of Plant Biotechnology
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• v.46 no.1
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• pp.45-55
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• 2019

TheCitrus grandis Osbeck is a special product in the Jeju island. The product has been as a remedy for liver damage and hang over. This study demonstrates how to investigate and compare the antioxidant, phenol content, tyrosinase and ${\alpha}$-glucosidase inhibitory activity, antimicrobial, and alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activity with the C. grandis leaves extracted in different ethanol concentrations. From the yield, a 20% ethanol extract demonstrated the highest results among the other extracts. The distilled water extract showed the most abundant in a total phenol content and highest ABTS radical scavenging activity and reducing power assay. In the DPPH radical scavenging activity, ${\alpha}$-glucosidase and tyrosinase inhibitory assay (used ${\text\tiny{L}}$-tyrosine as substrate), the 80% ethanol extract exhibited a higher value than other extracts. The 60% ethanol extract showed prominent activities in the tyrosinase inhibitory (used ${\text\tiny{L}}$-dopa as substrate), ADH and ALDH activity assay. In the minimum inhibitory concentration (MIC) assay, 60% and 80% ethanol extracts inhibited the bacterial growth almost similarly. Moreover, the gram-positive bacteria was more restrained than the gram-negative bacteria. The resultsrevealed that the distilled water and 80% ethanol extract showed a relatively higher antioxidant activity compared to other extracts. The 60 ~ 80% ethanol extracts demonstrated potential tyrosinase, ${\alpha}$-glucosidase inhibitory, antimicrobial, ADH and ALDH activities. Therefore, the C. grandis is suggested to be considered as a functional material for various proposes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.135-142
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• 2022

In this study, lap spliced ultra-high strength reinforced concrete beams were tested and the code criteria for calculating the lap splice length which was affected by the transverse reinforcement and concrete covering performance were reviewed. The main variables for test were set as fiber volume fraction and transverse reinforcing bar arrangement to improve the confining performance of the concrete cover. The change of the confining performance of concrete cover according to the increase in the fiber mixing amount at 1% and 2% volume ratio was examined, and D10 stirrups with a spacing of 100 mm were placed in the lap spliced region. As a result of the test, the specimens confined by the stirrups showed a sudden drop of load bearing capacity with horizontal cracking at the position of tensile longitudinal reinforcement. However, horizontal cracks were not appeared at the location of longitudinal reinforcement for the specimens with steel fiber. And these specimens showed gradual decrease of load bearing capacity after experiencing peak load. In particular, it was found that the strain at the position of the tensile longitudinal reinforcements of the specimens to which the mixing ratio of 2% was applied exceeds the yield strain. As a result of measuring the strain on the concrete surface, it was found that the fiber was more effective in preventing damage to the concrete surface than the stirrups for short lap spliced region.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.81-88
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• 1983

This experiment was conducted to study about influenced inorganic element contents of flag leaf and chaff with different nitrogen and silicate application in Jinan (sea level 303m). The recommended rate of fertilizer application above N 15kg/10a was poor for dry production increment in cold in July elevation and was demanded increment of silicate. In the elevation of cold in July high rates of nitrogen application produced more incomplete grain and a reduced cold tolerance. These effects were due to over-content of soluble nitrogen within flag leaf and disturbance of uptaking potassium and silicate. On the other hand, the application of silicate could increase yield by promoting resistance to cold- damage. The application of increasing level of nitrogen resulted in increasing the contents of total nitrogen and phosphate in both sterile and fertile glumes. The contents of potassium and calcium were the highest at the level of nitrogen 10 - 15kg/10a, but magnessium was rather high at low nitrogen levels. It is interesting that at any level of nitrogen, over 6% higher silicate contents were noted in the fertile chaff than in the sterile chaff. Application of increasing level of silicate fertilizer decreased total nitrogen contents, but increased the contents of phosphate, potassium. and silicate in the chaff. Increasing rate of silicate content by increasing silicate addition was remarkably higher in the fertile chaff than in the sterile chaff.

• Korean Journal of Remote Sensing
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• v.40 no.3
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• pp.275-284
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• 2024

Monitoring crop growth changes and water content is crucial in the agricultural sector. This study utilized drones equipped with Short Wavelength Infrared (SWIR) sensors, sensitive to moisture changes, to observe soybeans' growth and water content variations. We confirmed that as soybeans grow more vigorously, their water content increases and differences in irrigation levels lead to decreases in vegetation and moisture indices. This suggests that waterlogging slows down soybean growth and reduces water content, highlighting the importance of detailed monitoring of vegetation and moisture indices at different growth stages to enhance crop productivity and minimize damage from waterlogging. Such monitoring could also preemptively detect and prevent the adverse effects of moisture changes, such as droughts, on crop growth. By demonstrating the potential for early diagnosis of moisture stress using drone-based SWIR sensors, this research suggests improvements in the efficiency of large-scale crop management and increases in yield, contributing to agricultural production.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.377-383
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• 2023

The effects of exogenous sodium nitroprusside (SNP, nitric oxide donor) on the growth, yield, photosynthetic characteristics, and antioxidant enzyme activity of kimchi cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) was studied under the low temperature conditions. Kimchi cabbages were treated with SNP of three concentrations (7.5, 15, 30 mg·L^-1) for three times at four-day intervals and exposed to low temperature (16/7℃) stress for seven days. SNP treatment induced increases of net photosynthetic rate (Pn), stomatal conductance (Gs), intracellular CO₂ concentration (Ci) and transpiration rate (Tr) under the stress condition with the highest level after the third treatment. The contents of malondialdehyde (MDA) and H₂O₂ were significantly lower in the treatment of SNP compared to the non-treated control. The activity of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), increased in treated plants by up to 38, 187, 24 and 175%, respectively compared to the non-treated control. SNP-treated and untreated plants had similar growth characteristics. Compared to the control group, SNP-treatment increased fresh weight and leaf area by 5%. Overall, our findings suggest that the application of sodium nitroprusside to the leaves contributes to reducing physiological damage and enhancing the activities of antioxidant enzymes, thereby improving low temperature stress tolerance in kimchi cabbage.

• Journal of Mushroom
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• v.7 no.4
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• pp.173-181
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• 2009

These studies were investigated for effect of concentration of sodium chloride on occurrence and growth of fruitbody in oyster mushroom, Pleurotus ostreatus. When the mycelia were inoculated and cultured on the PDA plate added with the different concentrations of sodium chloride, the growth of them were not affected at the concentration of 0.5%, started to decrease at 1.0% as compared with the PDA plate without sodium chloride, and they did not grow at 5.0%. When tested at the column filled with sawdust, the tendency was similar, but the decreasing rate of mycelial growth was gentle. In sawdust bottle cultivation sprinkled with the different concentration of sodium chloride solution at the different stage, the productivity and quality of fruitbody started to decrease at 3.0% of the solution and the yield at the treatment of 10.0% solution was only 47% of that in non-treated bottles. Treated at the different stages of mushroom development, treatment just after mushroom sprout did not show any different from that just after scraping spawn from the complete grown bottles. The sprinkle treatment at this stage looked better than that of the soaking with the solution before mushroom sprout. The yield at this treatment with 10% solution showed little damage with that of 90% of non-treated bottle. Sprinkle treatment during mushroom growth stage did not affect and showed almost same to non-treated bottle except the treatment with 10.0% solution. The treatment of this stage showed better results of growing characters than the treatment after and before mushroom sprouting even 10% solution. Morphological characteristics of oyster mushroom do not distinguish to treatment of different stage and concentration of sodium chloride solution. The analyzing data of quality on underwater usually used for oyster mushroom in Inchon, Yeongjong and Kanghwa area showed over-concentration to the standard for edible water and agricultural water. But it was not confirmed whether this water quality could affect to mushroom cultivation.

• Korean Journal of Environmental Agriculture
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• v.15 no.4
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• pp.425-433
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• 1996

Pepper plants were water-logged at 0, 5, 10 and 15 cm at transplanting and flowering stages under the condition of greenhouse. Treatment of water-logging times were 6, 12, 24, 48 and 120 hours. The results obtained are summarized as follows. At the transplanting stage, plant height, number of leaves, shoot and root fresh weight decreased by water-logging at 0cm for 24 hours and at 5cm or more for 6 hours. Number of fallen leaf was negligible by 12 hours water-logging at 0cm, however, its increased by more increased the water-logging depth and time. Diffusion resistance and chlorophyll content of leaf, and root activity decreased at more than 24 hours of water-logging regardless of the water-logging depth treatments. Photosynthesis and respiration rate diminished by increased the water-logging depth at 120 hours water-logging treatment. Plant diseases, mainly anthracnose(Colletotrichum) occurred in proportion to increase the depth and time of water-logging. It was not possible to control the diseases by fungicides. At the treatment of foliar spray of urea for recovery to water-logging damage, the efficiency was not found on plant height, but the number of leaves. Number of fruit and weight of fruit per plant showed no difference from no water-logging to 24 hours water-logging at 0cm, but its decreased that more than 24 hours water-logging at 0cm and more than 6 hours water-logging at 5cm or more. The averaged weight of a fruit on survival plants increased by more hours and deeper water-logging. There was positive correlation between all the investigated characteristics of growth and yield. There was, however, negative correlation between the characteristics and diffusion resistance of leaf stomata. The correlation between number of fallen leaf and averaged weight of a fruit was not significant. At flowering stage, number of fruit and weight of fruit per plant showed a similar tendency to no water-logging and by 12 hours water-logging at 0cm and 5cm, but significantly decreased at more than 24 hours water-logging from 0 to 5cm, and more than 6 hours water-logging at 10cm or more. The averaged weight of a fruit on survival plants increased by more hours and deeper water-logging except for 120 hours water-logging at all water depths.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.133-137
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• 2016

'Sinano Sweet' apple trees were defoliated at intervals of a month from May to October to simulate damage occured by hail and typhoon in Korea, accordingly fruit yield, reserve accumulations and return bloom were investigated. As the more severe defoliation degree was and earlier defoliation time was, fruit weight and fruit yields were more decreased. Fruit weight and yields of 30% defoliated trees, regardless of the defoliation time, showed no significant difference with those of control. Because carbohydrate contents of the 2-year old branches defoliated before August were even lower than those of branches defoliated after September, it was considered that defoliation time is more effective on the carbohydrate content than defoliation degree. Among the trees defoliated before August, 50% defoliated trees at August contained the lowest carbohydrate by 50% of control. Time and degree of defoliation had an effect on the number of flower buds following year. The number of return bloom in trees defoliated from May to July was decreased by delay of defoliation time and was the lowest in trees defoliated at July. On the other hand, it was not have a significant different between control and trees defoliated since August. Relationship between the number of return bloom and carbohydrate reserves showed positive correlation. As a result, it is considered that fruit thinning, when defoliation occurred in the growing season, needs for strengthening the sink function of remained individual fruit effect on fruit enlargement and for increaseing the carbohydrate reserve effect on return bloom.

• Korean Journal of Organic Agriculture
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• v.26 no.3
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• pp.409-425
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• 2018

Occurrence and yield characteristics of lepidopteran insect pests in both PUR (paddy-upland rotation) and CU (continuing upland) fields for 8 maize (Eolrukchal 1, Heugjeom 2, Miheukchal, Ilmichal, Heukjinjuchal, Chalok 4, Mibaek 2, Daehakchal) and 7 sorghum (Hwanggeumchal, Anzunbaengisusu, Moktaksusu, Sodamchal, DS-202, Nampungchal, Donganme) varieties was surveyed. The population of Ostrinia furnacalis adults showed 3 times highest peaks in 2016. In addition, the damaged ratios of maize and sorghum leaves and stems were increased depending on the growth periods of the crops and those by O. furnacalis larvae were also increased steeply in mid August. The damaged ratios of maizes such as Miheukchal, Eolrukchal 1, Ilmichal, Heugjeom 2, and Mibaek 2 by O. furnacalis larvae were statistically different (P=0.05) between organically managed PUR and CU fields. Except for DS202 among sorghum varieties, the damaged ratios of the other ones were high and similar (50-92%) in the CU field. The ear damaged ratio of maize varieties by lepidopteran larvae including O. furnacalis and Helicoverpa armigera was from 5 to 38% in Chalok 4 and Heukjinjuchal, respectively, and Daehakchal gave relatively higher damage ratio in the PUR field (33%) than in the CU field (14%). The ear ratio of Sodamchal and DS-202 varieties in the PUR field was 94 and 82%, and all sorghum varieties were damaged over 78% by lepidopteran larvae in the CU field. Interestingly, the correlation coefficients between the damaged ratio and invasive pores on their stems by O. furnacalis larvae were positive (maize $r=0.69_{paddy-upland}$, $0.95_{continuing}$; sorghum $r=0.93_{paddy-upland}$, $0.97_{continuing}$, respectively). Additionally, the correlation coefficients between the damaged ratio and the ear weight or the thousand kernel weight (g) of maizes and sorghums by lepidopteran larvae were negative (maize $r=-0.38_{paddy-upland}$, $-0.49_{continuing}$; sorghum $r=-0.70_{paddy-upland}$, $-0.57_{continuing}$, respectively). These results indicate that the focused management on lepidopteran insect pests occurring maizes and sorghums cultivated in PUR and CU fields is an important strategy to secure their yields.