• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.1-11
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• 2021

Soil moisture plays a critical role in hydrological processes, land-atmosphere interactions and climate variability. It can limit vegetation growth as well as infiltration of rainfall and therefore very important for agriculture sector and food protection. Recently, due to the increased damage from drought caused by climate change, there is a frequent occurrence of shortage of agricultural water, making it difficult to supply and manage stable agricultural water. Efficient water management is necessary to reduce drought damage, and soil moisture management is important in case of upland crops. In this study, soil moisture was calculated based on the water balance model, and the suitability of soil moisture data was verified through the application. The regional soil moisture was calculated based on the meteorological data collected by the meteorological station, and applied the Runs theory. We analyzed the spatiotemporal variability of soil moisture and drought impacts, and analyzed the correlation between actual drought impacts and drought damage through correlation analysis of Standardized Precipitation Index (SPI). The soil moisture steadily decreased and increased until the rainy season, while the drought size steadily increased and decreased until the rainy season. The regional magnitude of the drought was large in Gyeonggi-do and Gyeongsang-do, and in winter, severe drought occurred in areas of Gangwon-do. As a result of comparative analysis with actual drought events, it was confirmed that there is a high correlation with SPI by each time scale drought events with a correlation coefficient.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.81-91
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• 2020

This study was conducted to analyse climate change impact on agriculture infrastructure and propose improved measures on vulnerable areas. Recently, Climate change has resulted in damaging effects on agricultural fields through increases in drought intensity and flood risk. It is expected that this impact will increase over time. This study shows that Gyeong-gi and Chung-nam provinces are affected by drought and Gyeong-buk and Gyeong-nam provinces are affected by heavy rain. However, there are also regional variations within each province. Agricultural infrastructure affected by drought may also be affected by heavy rain. Increased damages on the infrastructure due to increased extreme weather events require preventive measures especially in vulnerable areas. In order to minimize the damage by climate change, we need to introduce a reform in the system which selects project region by analysing climate change impacts. Furthermore, impact assessment of climate change from projects such as 'water supply diversification', 'flooded farmland improvement', and 'irrigation facility reinforcement' also need to be adopted to improve the measures. The results of this study are expected to provide a foundation for establishing measures on coping with climate change in the agricultural sector.

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.302-310
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• 2016

A study aimed at identifying putative drought responsive genes that confer tolerance to water stress deficit in tea plants was conducted in a 'rain-out shelter' using potted plants. Eighteen months old drought tolerant and susceptible tea cultivars were each separately exposed to water stress or control conditions of 18 or 34% soil moisture content, respectively, for three months. After the treatment period, leaves were harvested from each treatment for isolation of RNA and cDNA synthesis. The cDNA libraries were sequenced on Roche 454 high-throughput pyrosequencing platform to produce 232,853 reads. After quality control, the reads were assembled into 460 long transcripts (contigs). The annotated contigs showed similarity with proteins in the Arabidopsis thaliana proteome. Heat shock proteins (HSP70), superoxide dismutase (SOD), catalase (cat), peroxidase (PoX), calmodulinelike protein (Cam7) and galactinol synthase (Gols4) droughtrelated genes were shown to be regulated differently in tea plants exposed to water stress. HSP70 and SOD were highly expressed in the drought tolerant cultivar relative to the susceptible cultivar under drought conditions. The genes and pathways identified suggest efficient regulation leading to active adaptation as a basal defense response against water stress deficit by tea. The knowledge generated can be further utilized to better understand molecular mechanisms underlying stress tolerance in tea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2019.09a
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• pp.22-22
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• 2019

Green stem disorder (GSD) of soybean (Glycine max (L.) Merr.) is characterized by delayed senescence of stems with normal pod ripening and seed maturation (Hobbs, 2006). GSD complicates harvesting of soybeans by significantly increasing the difficulty in cutting the affected plants. There is also the potential for moisture in the stems to be scattered on the seed, reducing the grade and storability of the seed. Not only the cause of GSD is yet unknown, but also GSD cannot be evaluated until maturity, therefore the method to evaluate GSD in early growth stage with high sensitivity is necessary. In previous studies, it has been reported that vegetative storage protein (VSP) accumulates and the syndrome of GSD appears in soybean after depod treatment (Fischer, 1999). Soybean VSP is a storage protein which is abundant in young sink leaves and degraded during seed fill (Wittenbach, 1982). Hence, we have established a system to quantify VSP of high sensitivity by using standard protein made by genetically transformed E. coli and specific antibody against VSP, and studied the relationship between VSP and GSD, by depod experiment and drought/excess wet experiments. The result of depod experiment with the cultivar 'Yukihomare' was the same with the previous studies, VSP accumulated much more than control and the syndrome of GSD appeared in soybean in depod treatment. Drought and excess wet had different impact on GSD. Excess wet caused GSD of the cultivar 'Tachinagaha (GSD susceptible)', while drought caused a little syndrome of GSD in the cultivar 'Touhoku 129 (GSD resistant)'. The accumulation of VSP differed between the two cultivars over time. In conclusion, the accumulation of VSP came along with the emergence of GSD. Different cultivars showed different response to drought and excess wet. In the future, it is expected that the dynamics of VSP will be elucidated in detail, leading to the development of early diagnosis technology for green stem disorder and the elucidation of mechanism of soybean GSD.

• Journal of Korean Society of Rural Planning
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• v.24 no.4
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• pp.47-55
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• 2018

Currently in the drought evaluation, which is a supplier-oriented standard that applies storage rates of reservoirs, evaluation for users that use agricultural water is not done. Therefore, this study established drought evaluation items for drought evaluation based on farmers' judgement, conducted a survey on farmers and experts, compared and analyzed weighted value between two groups, and then classified the evaluation standards per each evaluation item. The agricultural drought evaluation items are 5 major items of water supply lapse rate, agricultural weather, agricultural irrigation facility, crop and soil, and 12 subsections for regional characteristics and opinions of consumers that use water to be reflected. The result of analyzing weighted value of farmers and experts' major items shows that farmers is agricultural irrigation facility(0.219), water supply lapse rate(0.211), agricultural weather(0.204), crop(0.183) and soil(0.183). Experts is agricultural weather(0.297), agricultural irrigation facility(0.202), water supply lapse rate(0.189), crop(0.162) and soil(0.150), which displays difference between the two groups. The agricultural drought criteria standards are established based on precedent studies and cases, and grades of evaluation items are 1st grade(extreme stage), 2nd grade(warning stage), 3rd grade(alert stage) and 4th grade(attention stage). The above analysis per each consumer-oriented agricultural drought evaluation item and the analysis on the standards of evaluation grades are expected to be used as a basic resource for establishing agriculture drought policy and selecting drought area in the future.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.272-279
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• 2011

Root colonization of Arabidopsis thaliana with Pseudomonas chlororaphis O6 induces systemic tolerance against diverse pathogens, as well as drought and salt stresses. In this study, we demonstrated that 11 genes in the leaves were up-regulated, and 5 genes were down-regulated as the result of three- to five-days root colonization by P. chlororaphis O6. The identified priming genes were involved in cell signaling, transcription, protein synthesis, and degradation. In addition, expression of selected priming genes were induced in P. chlororaphis O6-colonized plants subjected to water withholding. Genes encoding defense proteins in signaling pathways regulated by jasmonic acid and ethylene, such as VSP1 and PDF1.2, were additional genes with enhanced expression in the P. chlororaphis O6-colonized plants. This study indicated that the expression of priming genes, as well as genes involved in jasmonic acid- and ethylene-regulated genes may play an important role in the systemic induction of both abiotic and biotic stress due to root colonization by P. chlororaphis O6.

• Journal of Soil and Groundwater Environment
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• v.22 no.5
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• pp.13-22
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• 2017

Accurate assessment of agricultural groundwater usage is an essential task to cope with drought that occurs irregularly in time and location. In this study, the agricultural groundwater usage was calculated in nationwide public wells (1,386 bedrock wells) during 5-year period (2010-2014) by using electric power consumption and well specification data. National average of agricultural groundwater usage per each well was estimated as $66.2m^3/day$, corresponding to 21.6% of total permitted volume of groundwater in each well. Chungcheong Nam-do had the highest usage with 38-55.6%. The value increased to 58.1% when the total permitted volume was based upon the supply standard against drought, and the value reached 100% in Chungcheong Nam-do. In Ganghwa distirct that suffered from severe drought in recent years, the average groundwater usage was 61.4%. In 2014, when the drought was the most severe with 45% precipitation of the average annual rainfall, the nationwide usage was turned out to be 25.6%, indicating about 4% higher than average agricultural groundwater usage 21.6%. Therefore, the quantitative assessment of groundwater usage in this study signifies that adequate use of groundwater is crucial to cope with agricultural drought.

• Journal of Environmental Science International
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• v.29 no.11
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• pp.1099-1108
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• 2020

In this study, the capacity of supplying agricultural water to 13 districts was analyzed by calculating the necessary water supply for the arable land of Gunwi-gun and examining the capacity of supplying water to reservoirs, streams, pumping stations, collection sites, and groundwater wells in Gunwi-gun. As a result, among the 13 districts the second district was found to be short of water by 1.2×10⁶ tons/year. In general, local governments establish drought measures by selecting drought disaster risk zones. While selecting drought-risk areas, some water-poor areas that do not have water sources should be selected, even if the entire area has a sufficient water supply. The water-supply evaluation at the regional level was insufficient for locating areas without water sources, but most areas with water sources, such as streams, reservoirs, and pumping stations, were found to have no shortage of water. To locate water shortage areas without water sources, GIS analysis conducted a field survey of areas with a distance of 4 or less than that of water sources analyzed by GIS analysis. Sixty-nine sites in 13 districts were selected for the on-site survey and six areas of water shortage were identified in areas other than the second district.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.461-470
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• 2019

This study was carried out to quantify the drought stress in grafted watermelon seedlings non-destructively by using chlorophyll fluorescence (CF) imaging technique rather than the visual judgment. Six-day old watermelon seedlings were grown under uniform irrigation for 3 days, and then given drought stress. Afterward, the sensor for the measurement of water content in plug tray cell unit was used to classify the drought-stress level into nine groups from D1 (53.0%, sufficient moisture state) to D9 (15.7%, extremely dry stress), and the 16 CF parameters were measured. In addition, re-irrigation was performed on the drought stressed seedlings(D5 - D9) to determine the growth and photosynthesis recovery level, which was not confirmed by visual judgment. The kinetic curve patterns of CF in three different drought stressed seedling groups were found to be different for the early detection of drought stress. All the 16 CF parameters decreased continuously with exposure to drought stress and drastically decreased from D5 (32.1%) where the visual judgment was possible. The fluorescence decline ratio (Rfd_Lss) started to decrease from the initial drought stress level (D5 - D6), and the Maximum PSII quantum yield (Fv/Fm) was significantly decreased in the later extreme drought stress range (D7 - D9) by re-irrigation recovery test. Thus, Rfd_Lss and Fv/Fm parameters were finally selected as potent indicators of growth and photosynthesis recovery in the initial and later stages of drought stress. Also, to the differences in the numerical values of the individual chlorophyll fluorescence parameters, the drought stress level was intuitively confirmed through the image. These results indicate that Rfd and Fv/Fm can be considered as potential CF parameters for the detection of low and extremely high drought stress, respectively. Furthermore, Fv/Fm can be considered as the best CF parameters for recovery at re-irrigation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.10a
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• pp.237-237
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• 2017