• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.3
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• pp.124-131
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• 2012

This study was carried out to evaluate a possible change in freeze risk for 'Changhowon Hwangdo' peach buds in three major peach growing areas under the future climate projected by RCP8.5 emission scenario. Mean values of the monthly temperature data for the present decade (2000s) and the future decades (2020s, 2050s, 2080s) were extracted for farm lands in Icheon, Chungju, and Yeongcheon-Gyeongsan region at 1km resolution and 30 sets of daily temperature data were generated randomly by a stochastic process for each decade. The daily data were used to calculate a thermal time-based dormancy depth index which is closely related to the cold tolerance of peach buds. Combined with daily minimum temperature, dormancy depth can be used to estimate the potential risk of freezing damage on peach buds. When the freeze risk was calculated daily for the winter period (from 1 November to 15 March) in the present decade, Icheon and Chungju regions had high values across the whole period, but Yeongcheon-Gyeongsan regions had low values from mid-December to the end of January. In the future decades, the frequency of freezing damage would be reduced in all 3 regions and the reduction rate could be as high as 75 to 90% by 2080's. However, the severe class risk (over 80% damage) will not disappear in the future and most occurrences will be limited to December to early January according to the calculation. This phenomenon might be explained by shortened cold hardiness period caused by winter warming as well as sudden cold waves resulting from the higher inter-annual climate variability projected by the RCP8.5 scenario.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.65-74
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• 2008

Traffic management is becoming an important issue in turfgrass practise on golf course. The objective of this study was to investigate the combined impact of different traffic times and types of fertilization. Traffic treatment was applied in morning (AM), noon, and afternoon (PM). Fertilizers used include faster-release fertilizer (21-17-17) and slow-release fertilizers (12-6-18, 11-3-22, 20-3-20, 10-3-10). Experiment was conducted from Oct. 1 to Nov. 30, 2005 on a nursery putting green of Incheon Grand Golf Club. The growth and quality of creeping bentgrass (Agrostis polustris cv. 'Seaside II') were evaluated on visual leaf color, leaf texture, shoot density, and root length. The measurement at 20 days after treatment, turfgrass color and leaf texture showed the best result on 10-15-10 + Noon-traffic plot. Turf quality and traffic tolerance were not different at Am and Pm traffic treatment. However, traffic stress in early morning and late evening caused the most severe damage to the turfgrass. Shoot density was the highest in 10-15-10 + Noon-traffic treatment but root length was not different among treatments after 30 day measurement. Among the fertilizers, slow release fertilizer resulted in higher turf quality and traffic tolerance than fast release fertilizer, however, shoot density did not showed a significantly different. For the fast recuperation of turfgrass from traffic injury in the early winter, it is recommended to avoid early morning and late evening traffic such as cup replacement and other maintenance practise. It is also recommended to delay the first tee-up time and ending early for last tee time during cold weather season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.13
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• pp.93-105
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• 1973

Differential tolerance of rice varieties, Tongil and Mangyung(or Milsung) varieties, against herbicides combined with Simetryne was investigated by the rate of application in 4 places; Jeonju, Gwangju, Iri and Milyang, whose soil textures were Lic, Sic, CL and Lic respectively. The results are summarized as follows: 1) Jeonju a. Initial crop injury At the rate of 2kg/10a prod. no initial crop injury was caused(both to Mangyung and Tongil varieties) on light clay soil, even when treated at high temperature of $30^{\circ}C$ and above. Crop injury was first caused at 3kg/l0a prod. to Tongil variety and the damage increased in proportion to the increase of application rate, while no crop injury was caused to Mangyung variety even at high rate of 5kg/l0a prod. b. Yield Tongil variety: Under high temperature condition in a vinyl house no statistical difference was observed between treated and hand weeding plot at the rates of 3kg/l0a prod. and below. Under air temperature conditions no statistical difference was observed between treated and hand weeding plot at the rates of 4kg/l0a prod. and below. Mangyung variety: No statistical difference was observed between treated and hand weeding plot at the rates of 5kg/l0a prod. and below both under air and high temperature conditions. 2) Gwangju a. Initial crop injury Although almost the same tendency as in Jeonju was observed, a little lighter crop injury was observed in general in Gwangju than in Jeonju at the time of application. And so, no crop injury was caused to Tongil variety until 4kg/l0a prod. and above. b. Yield Tongil variety: No statistical difference was observed between treated and hand weeding plot at 4kg/l0a prod. and below. Mangyung variety: No statistical difference was observed between treated and hand weeding plot at 4kg/l0a prod. and below. 3) Iri No crop injury was caused both to Tongil and Mangyung varieties at 4kg/l0a prod. and below. Also, no reduction of grain yield was observed. 4) Milyang A little lighter crop injury was observed in general. No crop injury was caused to Milsung variety at 5kg/l0a prod. ; Only a slight crop injury was caused to Tongil variety. Yield: No statistical difference was observed between treated and hand weeding plot both of Tongil and Milsung varieties even at 5kg/l0a prod. and below.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.273-280
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• 2003

Saline conditions invoke oxidative stress attributed to the overproduction of reactive oxygen species (ROS). Changes in quantum efficiency and antioxidative enzyme activity upon salt treatment were examined in a salt-tolerant plant, Atriplex gmelini, to test the hypothesis that salt tolerance of A. gmelini is due to the increased activity of antioxidative enzymes. A. gmelini showed optimum growth at 100 mM NaCl producing 116% of the shoot dry weight over control plants in 0 mM NaCl treatment. Healthy growth persisted up to 300 mM NaCl treatment maintaining normal internal water content and dry weight. No photochemical stress or damages on antioxidative defense system was obvious in plants of 2 and 4 day salt treatment which was indicated by increased quantum efficiency (Fv/Fm value), decreased stress index (Fo/Fm value), and increased activity of antioxidative enzymes such as SOD, APX, GR. However, the plants treated with 400 mM NaCl showed decrease in growth and in antioxidative enzyme activity although the enzyme activity was still higher than that of the 0 mM NaCl treated plants (l31%, 114%, and 134% of the SOD, APX, and GR activity, respectively). Interestingly, another important antioridative enzyme that scavenges H₂O₂ in plant cells, CAT, showed rapid decrease in its activity as salt concentration increased; 38%, 22%, 15% of the 0 mM NaCl treated plants at 200, 300, 400 mM NaCl treatments, respectively. It appears that the enzymes in ascorbate-glutathione cycle such as APX and GR play the major roles in scavenging ROS produced by salt stress in A. gmelini. After 6 days of salt treatment, the damage in photochemical and antioxidative defense system was indicated by decreased Fv/Fm value and increased Fo/Fm value. A. gmelini appears to cope with short term salt treatment by enhanced activity of the antioxidative defense system, whereas long term stress invoke oxidative stress by increased ROS due to the damages in photochemical and antioxidative system.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.833-847
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• 2016

Drought stress is a major agricultural limitation to crop productivity worldwide, especially by which leafy vegetables, plant leaves eaten as vegetable, could be more lethal. The study was carried out to know the effect of drought tolerance plant growth promoting bacteria (PGPB) on water stress of kale seedlings. A total of 146 morphologically distinct bacterial colonies were isolated from bulk soil and rhizosphere soil of leafy vegetables and screened for plant growth promoting microbioassay in greenhouse. Out of them the isolate SB19 significantly promoted the growth of kale seedlings in increasement of about 42% of plant height (14.1 cm), 148% of leaf area ($19.0cm^2$) and 138% of shoot fresh weight (1662.5 mg) attained by the bacterially treated plants compared to distilled water treated control (9.9 cm, $7.7cm^2$, 698.8 mg). Shoot water content of SB19 treated kale seedlings (1393.8 mg) was also increased about 152% compared with control (552.5 mg). The SB19 isolated from bulk soil of kale plant in Iksan, Korea, was identified as species of Bacillus based on 16S rRNA gene sequencing analysis. We evaluated the effect of drought tolerance by the Bacillus sp. SB19 on kale seedlings at 7th and 14th days following the onset of the water stress and watering was only at 7th day in the middle of test. In the survey of 7th and 14th day, there were mitigation effect of drought stress in kale seedlings treated with $10^6$ and $10^7cell\;mL^{-1}$ of SB19 compared to distilled water treated control. Especially, there were more effective mitigation of drought damage in kale seedlings treated with $10^7cell\;mL^{-1}$ than $10^6cell\;mL^{-1}$. Further, although drought injury of bacterially treated kale seedlings were not improved at 14th day compared with 7th day, drought injury of $10^7cell\;mL^{-1}$ of SB19 treated kale seedlings were not happen rapidly but developed over a longer period of time than $10^6cell\;mL^{-1}$ of SB19 or control. The diffidence of results might be caused by the concentration of bacterial suspension. This study suggests that beneficial plant-microbe interaction could be a important role of enhancement of water availability and also provide a good method for improving quality of leafy vegetables under water 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.

• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.137-146
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• 2007

Traffic causes more and more stress and injury to grasses on golf course green in Korea due to the increased playing. This study compared the effect of fertilizer component (Nitrate, Phosphate, Potassium) on turfgrass growth and quality golf course green under traffic stress during early winter. Experiment was conducted by using different fertilizer components for 2 months(Oct. 1 to Nov. 30, 2005). Turfgrass leaf color, leaf texture, density and traffic tolerance were evaluated visually, and the root length(cm) and tiller density(tiller/$cm^2$) were measured. Creeping bentgrass(Agrostis palustris cv. 'Seaside II') fromthe nursery of Incheon Grand Golf Club was used. Results of this study are as followings: 1). Turfgrass color was the best in A6(20-15-10) and A5(15-15-10) treatments in the N study. Leaf texture was not different among treatments. Turf quality and traffic tolerance were the highest In A5 and A6. Root length was the longest(15.8cm) in A6 (20-15-10). Root length increased with nitrogen levels. 2). Turf color of A9(5-7.5-5) and A10(15-22.5-15) was darkest in the comparison of P study. Leaf texture was the best in A4(10-15-10) and A9. Turf quality was the best in A10. A7(10-0-10). 3). In general, to recover turfgrass damage on the putting greens during low temperature period, fertilizer amount need to be increased; and nitrogen is better than phosphate and potassium for that purpose.

• Journal of Plant Biotechnology
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• v.41 no.2
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• pp.73-80
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• 2014

Pretreatment of chinese cabbage leaves with $100{\mu}M$ sodium nitroprusside (SNP), a nitric oxide (NO) donor, effectively improved their tolerance to subsequent $2{\mu}M$ paraquat (PQ)-induced oxidative damage. The fresh weight, and chlorophyll and protein contents in primary leaves treated with PQ alone were noticeably reduced over 24 h light incubation. However, these leaf injury symptoms were significantly alleviated with $100{\mu}M$ SNP pretreatment for 3 h prior to PQ exposure. In additions, the increase of the contents of malondialdehyde (MDA) and $H_2O_2$ due to PQ exposure were significantly inhibited by SNP pretreatment. Together with the protective effects of SNP against PQ toxicity in leaves, the changes of ascorbate-glutathione cycle enzymes activities were examined. In the PQ alone treatment, the activities of APX, DHAR, and GR after 6 h incubation were rapidly reduced and showed 19%, 50% and 39% respectively, compared with those of the control. However, the decreases in these enzyme activities were significantly inhibited by SNP pretreatment. As a result, their activities were higher than those of PQ alone treatment by 5 times, 2 times, and 1.5 times, respectively, at 6 h incubation. Thereafter, these enzymes decrease their activities gradually showing high levels than those of PQ alone. Based on the above results, it can be assumed that the activation of ascorbate-glutathione cycle by SNP pretreatment in chinese cabbage leaves exposed to PQ can prevent $H_2O_2$ accumulation, thereby leading to protection against PQ-induced oxidative stress. Also, these results indicate that NO acts as an protectant against PQ stress in the leaves of chinese cabbage.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.5
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• pp.677-685
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• 2018

Objective: The objective of the present study was to determine ammonium chloride tolerance of lactating dairy cows, by examining effects of negative dietary cation anion difference (DCAD) induced by ruminal ammonium chloride infusion on performance, serum and urine minerals, serum metabolites and enzymes of lactating dairy cows. Methods: Four primiparous lactating Chinese Holstein cows fitted with ruminal cannulas were infused with increasing amounts (0, 150, 300, or 450 g/d) of ammonium chloride in a crossover design. The DCAD of the base diet was 279 mEq/kg dry matter (DM) using the DCAD formula (Na + K - Cl - S)/kg of DM. Ammonium chloride infusion added the equivalent of 0, 128, 330, and 536 mEq/kg DM of Cl in treatments. According to the different dry matter intakes (DMI), the resulting actual DCAD of the four treatments was 279, 151, -51, and -257 mEq/kg DM, respectively. Results: DMI decreased linearly as DCAD decreased. Yields of milk, 4% fat-corrected milk, energy-corrected milk, milk fat, and milk protein decreased linearly as DCAD decreased. Concentrations of milk protein and milk urea nitrogen increased linearly with decreasing DCAD. Concentration of Cl- in serum increased linearly and concentration of PO43- in serum increased quadratically as DCAD decreased. Urine pH decreased linearly and calculated urine volume increased linearly with decreasing DCAD. Linear increases in daily urinary excretion of $Cl^-$, $Ca^{2+}$, $PO_4{^{3-}}$, urea N, and ammonium were observed as DCAD decreased. Activities of alanine aminotransferase, aspartate aminotransferase, and ${\gamma}-glutamyl$ transferase in serum and urea N concentration in serum increased linearly as DCAD decreased. Conclusion: In conclusion, negative DCAD induced by ruminal ammonium chloride infusion resulted in a metabolic acidosis, had a negative influence on performance, and increased serum enzymes indicating potential liver and kidney damage in lactating dairy cows. Daily ammonium chloride intake by lactating dairy cows should not exceed 300 g, and 150 g/d per cow may be better.

• The Journal of Engineering Geology
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• v.23 no.2
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• pp.161-170
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• 2013

We analyzed the effect of changing water level and turbidity on plants that serve to maintain slope stability on levees. In this experiment, soil collected from upstream of Imha Dam was placed in a water tank and planted with river plants of the Salix species: Salix gracilistyla, S. koreensis, and S. glanduosa. Plant regrowth was analyzed stage-by-stage during a recovery period. In addition, we assessed the tolerance of the plants to concentrated torrential rainfall and examined their recovery rates. The results indicate that in the case of these three Salix species, which are the most prevalent river plants in Korea, stem growth is arrested following serious damage and high turbidity. The possibility of regrowth was very low during the 20-day non-submerged recovery period. Although the number of leaves initially decreased during this period, subsequent regrowth was reasonably high: recovery in S. gracilistyla, S. koreensis, and S. glanduosa was up to 59.3%, 251.3%, and 148.4% respectively, compared with the initial condition.