• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.410-410
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• 2018

Evaporative Demand Drought Index (EDDI)는 미국해양대기관리처 (National Oceanic and Atmospheric Administration, NOAA)에서 2016년에 개발한 가뭄지표로, 기존의 가뭄지표가 주로 강수량과 기온에 초점을 두고 가뭄을 판단하는 반면 토양의 수분 스트레스의 신호를 바탕으로 증발산수요의 상대적인 변화를 계산하여 가뭄지표에 대한 조기 경보를 제공한다. EDDI는 강수량을 이용한 기존의 가뭄지수와 달리 증발/산 요구량 (evaporative demand)에 초점을 맞춰 보다 짧은 시간의 척도와 공간 분포 및 시계열 결과의 도출로 잠재적 가뭄 예보에 활용할 수 있어 가뭄의 조기 경보 및 가뭄 모니터링 도구로 사용할 수 있다. 현재 NOAA에서는 EDDI Map Archive(https://www.esrl.noaa.gov/psd/eddi/)를 활용하여 1980년부터 현재까지 1-week부터 12-months 시간척도의 미국 전역의 EDDI 지도를 제공하고 있으며, 짧은 기간의 급속하게 발생하는(rapid-onset) Flash drought의 조기경보지표로 활용되고 있다. 본 연구에서는 최근 3년간 우리나라에 발생한 극심한 가뭄 사상을 대상으로 EDDI의 적용함으로서 시공간적 가뭄 특성을 파악하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.225-225
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• 2018

우리나라의 밭의 용수공급시설을 갖춘 면적은 140천ha로 전국 밭면적의 18.5% 수준('15.7월 행정조사)에 그쳐 논에 비해 열악한 수준이다. 밭작물은 작물의 생육시기와 기수, 농업환경에 민감하고 토양수분 부족 및 가뭄에 직접적인 영향을 받는다. 가뭄이 지속되면 토양수분 결핍이 발생하고 식생 수분 스트레스가 증가하여 밭작물의 생산성에 많은 영향을 미치고 있다. 따라서 가뭄시 밭작물의 생산성 저하, 농작물 수급 불안 등 직접적 영향 및 손실을 줄일 수 있는 방안 대책이 시급하다. 밭관개 용수 지역은 대부분 지하수를 개발 이용하고 있는 실정이고, 논에서의 이모작 지역은 부분적으로 지하수를 이용하고 있으나 대부분 강우에 의존하고 있는 상태이다. 시설하우스 지역도 대부분 지하수를 이용하고 있으며 부분적으로 용수로에서 취수하여 사용하고 있다. 밭농업용수확보는 거의 대부분 지하수를 이용하고 있으며 개인관정 이용시 가뭄에 용수부족으로 인한 집단화가 필요하다. 가뭄 상습 밭 지역의 안정적 밭용수 공급을 위해 기존 논농업 위주의 수리시설물을 활용하여 농업용수를 절약하고 아울러 기존의 개별 용수공급 방식 대비 집단화된 관개방법을 통한 농업용수 절약 방안을 연구하고자 한다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.3
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• pp.277-284
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• 2011

To investigate the effects of arbuscular mycorrhizal (AM) symbiosis on N uptake and its assimilation under drought-stressed conditions in white clover, total $^{15}N$ amount and $^{15}N$ amount incorporated into $NO_3^-$, amino acids and soluble proteins were quantified by $^{15}N$ tracing during 7 days of water treatment. Under well-watered conditions, there were no significant effects of AM symbiosis on all parameters analyzed in this study. Drought stress decreased total $^{15}N$ amount both in AM and non-AM plants, with a lower rate in AM plants (-13.8%) relative to non-AM plants (-28.5%) at day 7. Drought significantly increased $^{15}N-NO_3^-$ amount in non-AM plants. The amount of $^{15}N$-amino acids was 1.26-fold and 1.33-fold higher, respectively, in leaves and roots of AM plants compared to those of non-AM ones. Drought decreased the amount of $^{15}N$-soluble proteins in leaves at day 7, with a higher rate in non-AM plants than in AM ones. These results clearly indicate that AM colonization effectively alleviating the decrease in N uptake, amino acids and proteins synthesis caused by drought stress.

• Spatial Information Research
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• v.17 no.1
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• pp.117-129
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• 2009

South Korea has been undergoing spring drought periodically and diverse researches using vegetation index have been carried out to monitor spring droughts. The strength of the vegetation index-based drought monitoring is that the monitoring method enables efficient spatio-temporal grasp of changes in drought events. According to the development of low resolution satellite images such as MODIS, which are characterized by outstanding temporal resolution, the use of the method is expected to increase. Drought analysis using vegetation index considered only meteorological factor as a cause that affects vitality of vegetation. But many indirect and direct factors affect vegetation stress, So many uncertainties are involved in such method of analysis. To secure objectivity of drought analysis that uses vegetation index it is therefore necessary to compare the method with most representative drought analysis tools that are used for drought management. In this study, PDSI and SPI which a meteorological drought index that quantifies drought and that is used as a basic index for drought monitoring and MODIS NDVI are compared to propose correlation among them and to show usefulness of drought assessment that uses vegetation index. This study shows changing patterns of NDVI and SPI 6-month are similar and correlation between NDVI and SPI was highest in inland vegetation cover.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.143-150
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• 2003

Korea has plentiful precipitation but rainfall events concentrate on several months of rainy season in her weather condition. Korea, therefore, experiences drought for a given period every year. Moreover the soil has usually low water holding capacity, as it is composed coarse particles originated from the granite. Response of several oaks and the Korean red pine (Pinus densiflora) on water stress showed that water budget was significant factor determining vegetation distribution. In addition, dehydration level due to cold resistance mechanism of several evergreen plants during the winter season was closely related to their distribution in natural condition. Experimental result under water stress showed that the Korean red pine was very tolerant to desiccation but the seedlings showed high mortality during the dry season. The mortality tended to proportionate to soil moisture content of each site. A comparison between soil moisture content during June when it is severe dry season and moisture content of the culture soil when the pine seedlings reached the permanent wilting point due to water withheld proved that high mortality during the dry season was due to water deficit. Water potential of sample plants measured during the exposure experiment to the air pollutant showed a probability that water related factors would dominate the occurrence of visible damage and the tolerance level of sample plants. In both field survey and laboratory experiment, plants exposed to air pollution showed more rapid transpiration than those grown in the unpolluted condition. The result would due to injury of leaf surface by air pollutants. Aluminum (Al/sup 3+/) increased in the acid soil not only inhibits root growth but also leads to abnormal distribution of root system and thereby caused water stress. The water stresses due to air pollution and soil acidification showed a possibility that they play dominating roles in inducing forest decline additionally to the existing water deficit due to weather and soil conditions in Korea. Sludge, which can contribute to improve field capacity, as it is almost composed of organic matter, showed an effect ameliorating the retarded growth of plant in the acidified soil. The effect was not less than that of dolomite known in widely as such a soil ameliorator. Litter extract contributed also to mitigate the water stress due to toxic Al/sup 3+/. We prepared a model showing the potential interaction of multiple stresses, which can cause forest decline in Korea by synthesizing those results. Furthermore, we suggested restoration plans, which can mitigate such forest decline in terms of soil amelioration and vegetation restoration.

• Proceedings of the Korean Society of Grassland Science Conference
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• 2002.09a
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• pp.22.1-22
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• 2002

• Journal of Life Science
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• v.28 no.3
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• pp.376-387
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• 2018

Among a variety of environmental stresses heat, cold, chilling, high salt, drought, and so on exposed to plants, drought stress has been reported as a crucial factor to adversely affect the growth and productivity of plants. Therefore, to understand the mechanism for the drought stress signal transduction pathway in plants is more helpful to develop useful crops that display the enhanced tolerance against drought stress, and to expand crop growing areas. The signal transduction pathway for the drought stress in plants is largely categorized into two types; ABA-dependent pathway and ABA-independent pathway. It has been reported that two transcription factors, AREB/ABF and DREB2, play predominant roles in ABA-dependent and ABA-independent pathways, respectively. In addition to transcriptional regulation mediated by AREB/ABF and DREB2 transcription factors, post-translational modification (such as phosphorylation and ubiquitination) and epigenetic control are importantly involved in the signal transduction for drought stress. In this paper, we review current understanding of signal transduction pathway on drought stress in plants, especially focusing on the biological roles of a variety of signaling components related to drought stress response. Further understanding the mechanism of drought resistance in plants through this review will be useful to establish theoretical basis for developing drought tolerant crops in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.326-326
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• 2019

급격한 기후변화가 지속되면서 농업환경은 다양한 환경적 변화를 직면하고 있다. 기후변화로 일어난 이상기후 중 지구온난화와 이상 강수는 농업활동에 큰 영향을 끼치는 요소로 분석되었다. 특히 이상 강수로 인한 가뭄현상은 작물의 수분 공급을 저해하고 이로 인한 생산량 감소는 영농활동과 식량안보에 부정적 영향을 끼칠 것으로 분석되었다. 현재에도 발생하고 있는 가뭄현상으로 인하여 다양한 관개 방법이 진행 중이나 적절한 필요수량이 아닌 관습적 방법으로 관개를 진행하고 있는 실정이다. 우리나라의 1인당 강수량은 세계 1인당 평균 강수량의 1/6 정도이며, 따라서 수자원 절약이 가능한 효율적인 관개수량의 산정이 시급한 실정이다. 이에 본 연구는 미국 농무성(U.S. Department of Agriculture, USDA)와 텍사스 농업생명연구소(Texas A&M Agrilife Research Center)가 개발한 APEX 모델을 활용하여 1) 강수와 작물의 수분스트레스의 관계 및 특성을 평가하고, 2) 대표작물 세가지(고추, 배추, 콩)에 대하여 고정관개 조건에서 생산량과 관개수량의 관계를 분석한다. 그리고 3) 고정관개 조건을 바탕으로 과거 실측자료, 가뭄 시나리오, 그리고 풍수 시나리오에 대한 자동관개 모의를 진행하였다. 이 결과 현재 다양한 지역에서 행해지는 관행적 관개수량과 차이를 보였다. 따라서 본 연구는 향후 수자원 보존을 위한 밭, 논의 적정 관개수량 연구를 위한 기초자료로 활용될 것으로 기대된다.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.46-50
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• 2013

Some rhizobacteria producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase can make plant to continue growth under the stress conditions through lowering the level of phytohormone, ethylene which inhibits the plant growth and accelerates plant aging. In this study, some rhizobacteria producing ACC deaminase have been isolated from the rhizosphere of plants grown at sand beaches, and identified as Escherichia hermannii m-2, Enterobacter asburiae m-4, Pseudomonas thivervalensis BD2-26 and Pseudomonas brassicacearum subsp. neoaurantiaca BD3-35 through sequencing of 16S rRNA genes. Strain BD3-35 showed the highest activity of ACC deaminase among the isolates, 20.26 ${\alpha}$-ketobutyrate ${\mu}M/mg$ protein/h. Strains BD3-35 and BD2-26 secreted a phytohormone cytokinin, and strains m-4 and m-2 could produce auxin and abscisic acid, respectively. When these bacteria were applied to the 7-day old tomato plant under drought stress for 7 days, strains BD3-35, m-2, and m-4 increased the length of tomato root by 14, 15, and 35%, respectively, and strains m-2, BD2-26 and BD3-35 increased the dry weight of tomato plant by 22, 33, and 68%, respectively compared to the uninoculated control tomatoes. Therefore, these rhizobacteria may be utilized as a microbial fertilizer for the plants under drought stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.77-84
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• 2022

This study aimed to evaluate the growth, yield, and grain quality characteristics of rice varieties that were subjected to water stress during the tillering stage. We also sought to identify whether water stress could be indicated via the plants' response to chlorophyll fluorescence. In this study, we induced water stress by intentionally cutting off water for 30 days, starting 15 days after transplanting the rice varieties to a greenhouse. We analyzed nine rice varieties, including Ilpum, which is the most frequently cultivated variety in Gyeongsangbuk-do, South Korea. The control group was planted in a paddy field where irrigation was entirely dependent on rainfall. Our results revealed that the heading stage of the nine studied varieties occurred approximately ten days earlier in the rain shelter than in the field. Moreover, the rice yield, head rice rate, and palatability score decreased by 18.6%, 17.1%, and 8.3%, respectively, while protein content increased by 20.2% compared with the control group. The Saenuri and Haimi varieties showed the lowest reduction in yield under the water stress conditions, while the Daebo and Samkwang varieties showed the highest reduction in yield. The chlorophyll fluorescence response after re-irrigation was measured between July 30^th and August 17^th. The ratio of variable fluorescence to maximum chlorophyll fluorescence (F_V/F_M) values failed to recover to their baseline values, resulting in either no change or a reduction in fluorescent response, even after re-irrigation of Daebo and Samkwang varieties. These results can be utilized as empirical data for drought-affected farms to select resistant varieties that can respond to spring drought in the southern plains of Gyeongsangbuk-do.