• Korean Journal of Soil Science and Fertilizer
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• v.12 no.2
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• pp.77-82
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• 1979

Wilting and transpiration charactistics of Panax ginseng leaves were investigated at two temperature levels. Water potential and water absorption characteristics of leaf segments were also observed. Soybean leaves were compared. 1. Ginseng leaves were thiner, higher in water content and lower in dehydration rate. But time required to reach permanent wilting point (pwp) was less than half of that of soybean leaves because water content at pwp was about two times higher (80% of initial water for ginseng and 50% for soybean leaves). The time was shorter under high air temperature. 2. Transpiration rate was about a quater of soybean leaves and lower at $33^{\circ}C$ than $23^{\circ}C$, indicating that ginseng leaves are less tolorant to high air temperature. 3. Ginseng leaf segment showed smaller water free space but greater water deficit and little difference in was absorption rate. 4. Water potential of leaves measured by liquid immersion method was lower than that of soybean leaves. 5. Above results strongly suggest that ginseng plants are more susceptible to water stress. Thus greater light intensity during leaf growing stage (April to June) is recommendable to increase stomate frequency resulting greater transpiration rate and high temperature tolerance during July and August. Abundant water around roots seems to be beneficial as long as oxygen is not limited in rhizosphere.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.371-381
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• 1988

The purpose of this study was to investigate the physiological response to salt treatments in the leaves of several tree species. The results obtained were as follows : 1. The water potential of tree leaves damaged with various salt concentrations did not change nearly for 10 hours after treatment. As time elapsed after treatment, however, the higher salt concentration in soils, the higher leaf water potential was observed. 2. Leaf water potential of species intolerant to salt was higher than tolerant species due to the severe dehydration from cells. 3. According to the water relation parameters obtained from P-V curves, the values of ${\pi}_{\sigma}$ and ${\pi}_{\rho}$ in the damaged leaves were higher, but those of $V_{\rho}/V_{\sigma}$ and Emax were lower than those of the intact leaves. 4. The photosynthesis rate of tree leaves decreased remarkably with increasing the salt concentrations in soils, and it decreased faster for species intolerant cintolerant to salt.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.91-100
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• 2022

Ticks are the arthropod vector capable of transmitting diverse pathogens, which include bacteria, viruses, protozoan and fungi. Ticks are able to survive under stressful environmental conditions. One of evolutionary outcomes of these obligatory hematophagous arthropods is the survival for extended periods of time without a blood meal during off-host periods. Water conservation biology and heat tolerance have allowed ticks to thrive even under high temperatures and low relative humidity, thus they have become highly successful arthropods as they are distributed globally. Tick osmoregulatory physiology is a complex mechanism, which involves multiple osmoregulatory organs (salivary glands, Malpighian tubules, hindgut and synganglion) for the acquisition and excretion of water and ions. Blood feeding and water vapor uptake have been early reported as the primary passages for ixodid tick to acquire water. Recently, we have learned that ticks can actively drink environmental water allowing hydration. The acquired water can be traced to the salivary glands (type I acini) and the midgut diverticula. This opens new avenues for tick management through the delivery of toxic agents into their drinking water, in addition to an alternative strategy for the study of tick physiology. Here we address the osmoregulatory physiology in the ixodid ticks as a potential target physiological mechanism for tick control. We discuss the implications of water drinking behavior for tick control through the delivery of toxic agents and discuss the dermal excretion physiology as an additional pathway to induce tick dehydration and tick death.

• 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.