• Journal of Forest and Environmental Science
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• v.34 no.3
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• pp.258-261
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• 2018

Drought alters soil microorganisms; however, it is still not clear how soil microbes respond to severe drought conditions. In this study, the responses of soil bacterial community to experimental drought in a coniferous stand were examined. Six $6m{\times}6m$ plots with three replicates of control and drought treatments were delimited. PCR amplification and Illumina sequencing were conducted for cluster analysis of soil bacterial community and species richness and species diversity was analyzed. Along the 393 days of simulated drought from July 2016 to October 2017, soil bacterial species diversity slightly increased whereas species richness decreased in both control and roof plots. Moreover, soil bacterial species richness more decreased in roof plots than in controls. Combining these results, soil bacterial activity might have been altered by simulated drought.

• Journal of Forest and Environmental Science
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• v.34 no.3
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• pp.253-257
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• 2018

Climate models forecast more frequent and a longer period of drought events which may impact forest soil carbon dynamics, thereby altering the soil respiration (SR) rate. We examine the simulated drought effects on soil $CO_2$ effluxes from soil surface partitioning heterotrophic and autotrophic soil respiration sources. Three replicates of drought plots ($6{\times}6m$) were constructed with the same size of three control plots. We examined the relation between $CO_2$ and soil temperature and soil moisture, each being measured at a soil depth of 15 cm. We also compared which factor affected $CO_2$ efflux more under drought conditions. Total SR, autotrophic respiration (AR) and heterotrophic respiration (HR) were positively correlated with soil temperature (p < 0.05), and the relationships were stronger in roof plots than in control plots. Total SR, AR, and HR were negatively correlated only in roof plots, and the only HR showed a significant correlation (p < 0.05, r = -0.59). Soil respiration rates were more influenced by soil temperature than by soil moisture, and this relationship was more evident under drought conditions.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.625-632
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• 2015

Drought is a severe abiotic stress that affects global crop production. A drought model was created for 'Toyonoka' Fragaria ${\times}$ ananassa, and the effects of drought stress on contents of proline, sugars, and antioxidant enzyme activities were investigated. Strawberry transplants with identical growth were chosen for the experiments and the randomized design included four replications (10 plants per block). The experimental sets differed in the moisture level of the culture medium relative to the range of moisture content as follows: control, 70-85%; mild drought stress, 50-60%; moderate drought stress, 40-50%; and severe drought stress, 30-40%. Drought stress was imposed by limiting irrigation. Plants were sampled and physiological parameters w ere measured on 0, 2, 4, 6, 8, and 10 days after the commencement of droughts tress. The water potential of strawberry leaves decreased in the plants under mild, moderate, and severe stress during the course of the water stress treatment and exhibited a significant difference from the control. Strawberry leaves subjected to drought stress had higher accumulation of proline, sugars, and malondialdehyde, and higher activities of superoxide dismutase, peroxidase, and catalase than leaves of control plants. Malondialdehyde levels increased in parallel with the severity and duration of drought stress. By contrast, antioxidant enzyme activity displayed dynamic responses to drought stress, first increasing and subsequently decreasing as the severity and duration of drought stress increased. These results suggest that strawberry plants respond to drought stress by altering the activities of antioxidant enzymes and the levels of osmotically active metabolites. These biochemical response changes may confer adaptation to drought stress and improve the capacity of plants to withstand water-deficit conditions.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.83-97
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• 2013

This study was carried out to suggest an experimental base in selecting the drought resistance of plants. Adopting the natural drought method, this paper studies the drought resistance of 12 kinds of ground cover plants. focusing on analyzing the changes of relative water content on leaf, relative electric conductivity and chlorophyll content in 12 kinds of plants, and and the relation between soil water content under drought stress. The drought resistance of the plants were subject to laboratory and rooftop drought resistance treatments. The Logistic model of nonlinear regression analysis was used to evaluate the lethal time that were predicted with the range of 10.4~30.1d on roof top, and 19.5~39.0d on hothouse. The result shows that with the increase of stress time, relative water content and chlorophyll content on leaf were in a downward trend; the relative electric conductivity was upward tendency. Among 12 species of ground cover plants, exclude Pulsatilla koreana, Ainsliaea acerifolia were selected for rooftop plants because they showed resist drought strongly and took adaptive ability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.48-53
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• 2002

To investigate the changes in the composition and pool size of carbohydrates under drought stress, white clover (Triforium repens L.) were exposed to -0.04 Mpa(well-watered, control) or to -0.12 Mpa (drought-stressed) of soil water potential during 28 days. Dry weight of leaves in drought-stressed plants was remarkably decreased by 45% within 14 days and 74% within 28 days compared to those of the control. Glucose concentration in drought-stressed plants was increased, while that of control was slightly decreased or remained at same level throughout experimental period. Fructose and sucrose concentrations in leaves were not significantly changed for drought-stressed plants, but those of the control were significantly decreased on plant after 14 days. Fructose and sucrose concentrations in stolon of control plants were sharply decreased, while that of drought-stressed plants was less varied. Those concentrations in roots were generally increased in drought-stressed plants. The concentration of total soluble sugars at 28 day was 438.0 and 632.6 mg $g^{-l}$ dwt. in control and drought stressed plants, respectively. Starch concentration of stolon and roots of control plants was significantly increased to 2.0 and 1.4 times of initial level, respectively, whereas those of drought stressed plants was nearly same level or slightly decreased compared to initial level.l.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.95-101
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• 2002

To investigate the changes in the composition and pool size of nitrogen metabolites under drought stress, white clover (Trifolium repens L.) were exposed to -0.04MPa (well-watered, control) or to -0.12MPa (drought-stressed) of soil water potential during 28 days. Dry weight of leaves in drought-stressed plants was remarkably decreased by 45% and 74% within 14 days and 28 days, respectively, compared with control. For nitrate concentration after 28 days of treatment, a significant difference (1.6 times higher in drought-stressed plants) was observed only in stolon. NH$_3$-NH$_4$$^{+}$ concentration in all three organs of drought-stressed plants linearly increased to more than 1.6 times higher level at 28 day when compared to the initial level (day 0), while the increasing rate in control was much less than that of drought-stressed plants. Proline concentrations in drought-stressed plants remarkably increased and reached to 7, 13 and 17 times higher level at 28 day compared to control. Protein concentration in leaves of drought-stressed plants tended to decrease, while it slightly increased during the first 14 days and reached a plateau afterward in control. There was not significant difference in the proteins concentration of stolon and roots throughout experimental period. On SDS-PAGE analysis, two major proteins specifically induced by drought stress (16-kD and 18-kD) were detected in stolon.n.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.13-13
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• 2022

Recently, stable crop production is threatened by the effects of climate change. In particular, it is difficult to consistently maintain agricultural policies due to large price fluctuations depending on the difference in total domestic rice production from year to year. For stable rice production amid changes in the crop growing environment, development of varieties with improved disease resistance and abiotic stress stability is becoming more important. In here, drought and cold tolerant trait have been studied. First, for the development of drought tolerant varieties, we analyzed which agricultural traits are mainly affected by domestic drought conditions. As a result, it was observed that drought caused by the lack of water during transplanting season inhibits the development of the number of tiller and reduces the yield. 'Samgang' was selected as a useful genetic resource with strong drought tolerant and stable tiller number development even under drought conditions by phenotype screening. Three of drought tolerant QTLs were identified using doubled haploid (DH) population derived from a cross between Nacdong and Samgang, a drought sensitive and a tolerant, respectively. Among these QTLs, when qVDT2 and qVDTl1 were integrated, it was investigated that the tiller number development was relatively stable in the rainfed paddy field conditions. It is known that the high-yielding Tongil-type cultivars are severely affected by cold stress throughout the entire growth stage. In this study, we established conditions that can test the cold tolerance phenotype with alternate temperature to treat low temperatures in indoor growth conditions similar to those in field conditions at seedling stage. Three cold tolerant QTLs were explored using population derived from a cross between Hanareum2 (cold sensitive variety, Tongil-type) and Unkwang (cold tolerant variety, Japonica). Among these QTLs, qSCT12 showed strong cold tolerant phenotype, and when all of three QTLs were integrated, it was investigated that cold tolerant score was relatively similar to its donor parent, Unkwang, in our experimental conditions. We are performing that development of new variety with improved cold tolerant through the introduction of these QTLs.

• Journal of Forest and Environmental Science
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• v.35 no.4
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• pp.213-222
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• 2019

Climate change has been intensifying and affecting forest ecosystems. Over the years, the intensity and frequency of climate change have increased and the effects of climate change have been aggravating due to cumulative greenhouse gases such as CO₂, which has resulted in several negative consequences, drought being the main threat among all. Drought affects forest ecosystems directly and indirectly. Insufficient soil moisture, due to drought, may affect the growth of plants and soil respiration (SR), and soil temperature may increase because of desiccated soil. In addition, the mortality rate of plants and soil microorganisms increases. As a result, these effects could reduce forest productivity. Thus, in this article, we have presented various research studies on artificial drought using throughfall exclusion, and we have mainly focused on SR, which is significantly related to forest productivity. The research studies done worldwide were sorted as per the main groups of Köppen-Geiger climate classification and intensively reviewed, especially in tropical climates and temperate climates. We briefly reviewed the properties among the exclusion experiments about the temperate climate, which mostly includes Korean forests. Our review is not a proof of concept, but an assumption for adequate investigation of drought effects in the Korean forest.

• Korean Journal of Medicinal Crop Science
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• v.17 no.5
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• pp.328-334
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• 2009

Experimental purpose was to evaluate growth characteristic and abscisic acid (ABA) responses against salt/drought stresses. In the shoot biomass, creeping thyme was tolerated in mild NaCl stress, ranging 0 to 100 mM, while it was severely reduced in higher salinity. Under constant drought stress, the shoot biomass of creeping thyme showed a worse value compared to that of 100 mM NaCl treatment. Chlorophyll degradation was more severe in immature leaf than mature leaf under salt and drought stresses. In salt stress, immature leaf produced much amounts of ABA compared to mature leaf and also immature leaf showed faster increase of ABA than that of mature leaf. In drought stress, immature leaf responded to stress within 24 hours by the increase of ABA, while mature leaf responded to at 72 hours. Our results recommended that the optimal salinity level of creeping thyme was 50~100 mM NaCl.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.5
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• pp.1-8
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• 2013

In order to evaluate 2 extensive green roof systems(Sedum Box Roof System and Roof-rainwater Utilization System) for urban greening and select ground-cover plants, which can adapt well to the drought tolerance in an extensive green roof system on 12 species. This study was carried out in order to suggest an experimental base in assessment of the Green Roof-rainwater Utilization System and selecting the drought resistance of plants. Adopting the natural drought method, this paper studies the drought resistance of 12 kinds of ground cover plants. The drought-resistance of ground cover plants subjected to dry processing time were evaluated using relative water content on leaves, relative electric conductivity and chlorophyll content in 12 kinds of plants, and the relation between soil water content under drought stress. Drought resistance of the plants were subject to rooftop drought resistance treatments. The result showed that with the increase of stress time, the relative water content and chlorophyll content on leaves were in a downward trend while the relative electric conductivity was in an upward trend. Among the 12 species of ground cover plants, excluding Pulsatilla koreana, Ainsliaea acerifolia was selected for rooftop plants because they showed resistance to drought strongly and took adaptive ability. These results showed that drought tolerance of plants in Roof-rainwater Utilization System were stronger than the Sedum Box Roof System. Therefore, the Roof-rainwater Utilization System is good for plants. It helps them adapt well to the drought tolerance in rooftops and can be used for urban greening.