• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.397-407
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• 2017

This research aims to analyze and compare the drought resistance of 7 species of landscape trees commonly grown in Korea. The 7 species are: Camellia japonica, Rhaphiolepis indica, Quercus glauca, Machilus thunbergii, Daphniphyllum macropodum, Dendropanax morbifera and Cinnamomum camphora. In order to analyze their drought resistance, the samples were left without irrigation for 30 days (05/09/2016 ~ 05/10/2016), during which period their respective drought resistor, relative water content, electrolyte elution figures and proline content were measured. As the non-irrigation proceeded, C. camphora was the first to wither, followed by D. morbifera, then D. macropodum, then M. thunbergii, then Q. glauca, then R. indica then finally C. japonica. Of the 7 species, Q. glauca, C. japonica and R. indica can be considered highly drought resistant, since they survived for longer than 3 weeks without irrigation. Relative water content (RWC) plummeted dramatically after the first 15 days of non-irrigation. Whereas RWC readings of C. camphora, D. morbifera, D. macropodum and M. tunbergii dropped by 40% or more, the other 4 species reported a relatively low rate of decrease at 20% or lower. The Camellia japonica, the R. indica and Q. glauca, which were the species with relatively high drought resistance, showed low proline content and electrolyte elution figures, whereas those of C. camphora, D. macropodum, D. morbifera and M. tunbergii were higher. Analysis through the nonlinear regression analysis logistic model showed that non-irrigation proved fatal for the 7 sample species in a range of 22.7 to 37.6 days. The C. japonica, R. indica, Q. glauca and M. tunbergii demonstrated a high drought resistance of 30 days or longer, whereas C. camphora, D. morbifera and D. macropodum had a low resistance of 25 days or less to drought from lack of water. In conclusion, out of the 7 species of broad-leaved evergreen trees tested, C. japonica, R. indica and Q. glauca seem to be suitable for use as landscape trees, owing to their high drought resistance.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.564-577
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• 2016

Salinity stress limits plant cultivation in many areas worldwide; however, persimmon (Diospyros spp.) has high tolerance to salt. Five accessions of Diospyros [three of Diospyros lotus (accession numbers 824, 846, and 847); one of Diospyros kaki var. sylvestris (869); and one of Diospyros virginiana (844)] were chosen for analysis of salinity stress. We compared the effects of salt stress on plant growth, relative water content (RWC), malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide content ($H_2O_2$), and antioxidative enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD; and ascorbate peroxidase, APX) in leaves of healthy potted seedlings from each of the five accessions after salt treatment for 25 days. Salt stress affected the growth of plants in all five accessions, with all three D. lotus accessions showing the most severe effect. Salt stress increased membrane lipid peroxidation in all accessions, but a stronger increase was observed in the three D. lotus accessions. Moreover, accumulation of $H_2O_2$ was faster in salt-sensitive D. lotus compared to salt-tolerant D. virginiana 844. The activities of all antioxidant enzymes increased in D. virginiana 844 and in D. kaki var. sylvestris 869; the activities of SOD, CAT, and APX were at similar levels in D. virginiana 844 and D. kaki var. sylvestris 869, but POD activity was stimulated to a greater extent in D. virginiana 844. The activities of all antioxidant enzymes (except POD) decreased in D. lotus 824 and increased (except for SOD) in D.lotus 846. The activities of SOD and APX decreased in D. lotus 847, whereas POD and CAT activities both increased. Relative water content decreased significantly in D. lotus. No significant changes in lipid peroxidation or relevant antioxidant parameters were detected in any of the accessions in controls treated with 0.0% NaCl. D. virginiana 844 had higher antioxidant capacity in response to salinity compared to other persimmon rootstocks. These results indicate that changes of these key physiological variables are related to salinity resistance in different accessions of persimmon.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.128-132
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• 1983

The water relations parameters such as original osmotic pressure $(\Pi_0)$, osmotic pressure $(\Pi_p)$, at the incipient plasmolysis, the volume of osmotic water $(V_o)$ at the full turgor, the relative water content $(RWC^*)$ at the incipient plasmolysis, the volume of osmotic water$(V_p)$ at the incipient plasmolysis, the volume of symplasmic and apoplastic water$(w_s)$ at the maximum turgor, $V_pV_o, \; V_oW_s, \; W_sD_w, \; V_oF_w$ and the elastic modulus were measured through the pressure chamber (DIK-PC-40 Model) technique with the Williams and Geumgangdaerip soybean cultivar shoots. The original osmotic pressure$(\P $i_{0}$ )$, of the both cultivars shoots were appeared insignificant differences as 8.1 bar and 7.8 bar respectively. The osmotic pressure($\pi$$_{p}$ ) at the incipient plasmolysis was 9.0 bar in Williams and 10.4 bar in Geumgangdaerip. The relative water content(RW $C^{*}$) at the incipient plasmolysis was 86.0 per cent in Geumgangdaerip and 92.6 per cent in Williams. The ratio of volume of osmotic water( $V_{p}$ ) at the incipient plasmolysis to total symplasmic water$(V_o)$ , i.e., $V_p/V_o$ was 83.4 per cent in Geumgangdaerip and 90.4 per cent in Williams. The elastic modulus of Geumgangdaerip shoots showed higher value than Williams$(8.5 $\times$ 10^2bar)$ as $1.6 \times10^5$ bar.r.

• Korean Journal of Plant Resources
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• v.23 no.4
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• pp.374-378
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• 2010

Determining plant moisture characteristics is an essential study not only for cultivation, but also for ex-situ conservation. In this study, employing pressure-volume curve we examined moisture characteristics of Rhododendron micranthum, known as rare plant, with the aim of its ex-situ conservation. Several individuals growing in Mt. Worak, Youngwol-gun Yeonha-ri and Bongwa-gun Seokpo-ri were selected for this study, from which we collected leaves. The original bulk osmotic pressure at maximum turgor(${{\Psi}_o}^{sat}$)was -1.5 MPa in those of Mt. Worak and Seokpo-ri, which is somewhat lower than that of Yeonha-ri(-1.2 MPa). It appeared that the osmotic pressure at incipient plasmolysis(${{\Psi}_o}^{tlp}$) of leaves collected in both Mt. Worak and Seokpo-ri were -1.29 MPa, and -1.26 MPa, respectively, which are lower than that of Yeonha-ri(-1.02MPa). Maximum bulk modulus of elasticity($E_{max}$) was 14.0 MPa, 8.67 MPa in leaves collected from both Seokpo-ri and Mt. Worak, respectively, those value of which were approximately 3 times higher than that of Yeonha-ri(4.00 MPa). The values of $RWC_{tlp}$(Relative water content at incipient plasmolysis) of leaves collected in three areas, were roughly 83%, suggesting that Rhododendron micranthum has relatively high capability of containing water. Our finding on moisture characteristics of Rhododendron micranthum is similar to those of other Rhododendron spp. We suggest that individuals growing in both Worak and Seokpo-ri, are preferable to those in Yeonha-ri for ex-situ transplantation since those individuals are found to have better drought resistance.

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.3
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• pp.269-276
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• 2011

To investigate the physiological effects of mycorrhizal colonization on drought stress tolerance in white clover, the responses of leaf water potential (${\Psi}_{PL}$), relative water content (RWC), leaf dry mass, photosynthesis rate, transpiration, stomatal conductance, proline and ammonia were assessed periodically during 7 days in non-AM and AM plants under wellwatered or drought-stressed conditions. Under well-watered conditions, the examined parameters were not significantly changed or very little affected by AM symbiosis. Drought decreased water potential, relative water content, photosynthesis rate, transpiration and stomatal con ductance by 68.6%, 22.7%, 97.7%, 83.9% and 84.9%, respectively, in non-AM plants, meanwhile 46.8%, 13.4%, 50.3%, 44.8% and 54.7%, respectively, in AM plants. In addition, drought increased ammonia and proline by 31.8% and 162%, respectively, in non-AM plants, while 20.9% and 76.9%, respectively, in AM plants. These results clearly showed that mycorrhizal colonization significantly relieved the responses of physiological parameters to drought stress in white clover.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.217-232
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• 2018

Drought is a major obstacle to high agricultural productivity, worldwide. In drought, it is usually presented by the simultaneous action of high temperature and drying. Also there are negative effects of plant growth under drying conditions. In this study, the effect of Bacillus velezensis YP2 on plant growth-promotion and soil drying stress tolerance of kale plants, Brassica oleracea var. alboglabra Bailey, were investigated under two different conditions; greenhouse and field environments. Root colonization ability of B. velezensis YP2 was also analysed by using plating culture method. As a result of the greenhouse test, the YP2 strain significantly promoted the growth of kale seedlings in increasement of 26.7% of plant height and 142.2% of shoot fresh weight compared to control. B. velezensis YP2 have the mitigation effect of drying injury of kale by decreasing of 39.4% compared to control. In the field test, B. velezensis YP2 strain was also found to be effective for plant growth-promotion and mitigation of drying stress injury on kale plants. Especially, relative water contents (RWC; %) were higher in B. velezensis YP2 treated kales than in control at 7, 10, 14 day after non-watering. The root colonization ability of YP2 strain was continued at least for 21 days after soil drenching treatment of B. velezensis YP2. Our result suggested that enhancement of plant growth and drying injury reduction of kale plants were involved in kale root colonization by B. velezensis YP2, which might be contributed to increasing water availability of plants. Consequentially, the use of B. velezensis YP2 might be a beneficial influence for improving productivity of kale plants under drying stress conditions.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.354-364
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• 2020

This study was conducted to examine the potential of inducing salinity stress on cylindrical paper pot tomato seedlings to inhibit overgrowth. Potassium fertilizers, sulfate of potash (K₂SO₄), muriate of potash (KCl), and monopotassium phosphate (KH₂PO₄), were prepared as two solutions of (5 and 10) dS·m^-1 salinity level, respectively, to investigate the influence on tomato (Lycopersicon esculentum Mill.) seedling growth. We also investigated the adaptability and survivability of treated tomato seedlings with high-salinity potassium (10 dS·m^-1 KCl) to harsh environmental conditions (water deficit, low temperature, and storage conditions). Repeated addition of high-salinity level KCl, K₂SO₄, or KH₂PO₄ markedly decreased the dry matter of shoot and root, leaf area, and net assimilate rates (NAR) but increased the stem diameter of seedlings. Among the three sources, the relative growth rate of plant height (RGR_H) was most sensitive to KCl addition; increasing salinity levels of KCl solution decreased the RGR_H of seedlings. The compactness, which directly reflects the stocky growth index, increased in KCl or KH₂PO₄ treatments. After a week's water deficit, severely wilted seedlings were observed in control seedlings (untreated with KCl), but no wilted seedlings were observed in the KCl treated seedlings, and the relative water content (RWC) of the untreated seedlings significantly decreased by 23 %, while that of the pretreated seedlings only decreased by 8 %. The increase in ion leakage of KCl treated seedlings at low temperatures was less than that of untreated seedlings. Furthermore, there was far lower damage proportion on pretreated seedlings at (9, 12, and 15)℃ storage temperatures after 20 days, compared with on unpretreated seedlings. Our results suggest that high-salinity potassium fertilizer, especially KCl, is effective in preventing tomato seedling overgrowth, while it also improves tolerance.