• Plant Resources
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• v.7 no.1
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• pp.77-86
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• 2004

The reduced ratio of red:far-red (R:FR) light acts as a measure of the proximity of competitors and plants can detect the potentially competing neighbor plants by perceiving reflected R:FR signals and initiate the response of “shade avoidance” before actual shading occurs. The phytochrome system is responsible for monitoring the changes in the R:FR and initiating the shade avoidance response. The response to low R:FR ratio was studied in a white aspen Populus alba clone ‘Bolleana’ using two filter systems: a clear plastic filter system that allows a R:FR ratio less than 1.0 to pass from adjacent border plant reflection; and a special commercial plastic that blocks FR light and creates a R:FR ratio above 3.0. The reduced R:FR signals enhanced the stem elongation in response to competition at the expense of relative stem diameter growth. Trees grown inside clear chambers were 27 ％ taller than trees grown inside the FR-blocking filter chambers. Stem taper of clear chamber trees was 16％ less than the FR-blocking filter trees. Low R:FR also induced 22％ more stem dry weight and 13％ greater petiole length per leaf compared to the FR-blocking filter trees. There were no statistically significant differences in leaf area, leaf number increment, and total dry weight between the two light filter treatments.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.408-415
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• 2023

Alzheimer's disease constitutes a large proportion of all neurodegenerative diseases and is mainly caused by excess aggregation of amyloid beta (Aβ), which results in oxidative stress, inflammation, and apoptosis in the neurons. Populus tomentiglandulosa belongs to the Salicaceae family and is widely distributed in Korea; the antioxidant activities of the extract and fractions from P. tomentiglandulosa have been demonstrated in previous studies. Specifically, the ethyl acetate (EtOAc) fraction of P. tomentiglandulosa (EtOAc-PT) shows the most powerful antioxidative activity. Therefore, the present study investigates the protective effects of EtOAc-PT against neuronal damage in Aβ_25-35-stimulated SH-SY5Y cells. EtOAc-PT restored cell viability significantly as well as inhibited the levels of reactive oxygen species and lactate dehydrogenase release compared to the Aβ_25-35-induced control group. Furthermore, the inflammation- and apoptosis-related protein expressions were investigated to demonstrate its neuroprotective mechanism. EtOAc-PT downmodulated the expressions of inducible nitric oxide synthase, cyclooxygenase-2, B-cell lymphoma 2 associated X, and B-cell lymphoma 2. Thus, the findings show that EtOAc-PT has protective effects against Aβ_25-35 by suppressing oxidative stress, inflammation, and apoptosis.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.703-708
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• 2014

This study was conducted to investigate effects of soil amendments on survival rate and growth of seedlings in a semi-arid region, Mongolia. 2-year-old Populus sibirica and Ulmus pumila seedlings were planted in alkaline sandy soils and treated with 2 levels of nitrogen, elemental sulfur, artificial moisture retention and converted loess. After 4 months, the seedling survival rate of both species decreased as the amount of nitrogen increased. Nitrogen has been generally known to increase seedling survival rate and growth by supplying nutrients, however, reduced survival rate in this study might be affected by consequential increase in soil osmotic pressure, which was caused by excessive nitrogen fertilization. The root collar diameter (RCD) growth of both species increased significantly by the treatment of converted loess, and only RCD growth of P. sibirica increased by the artificial moisture retention treatment. Although P. sibirica is drought-tolerant, it is in the group of Populus spp. which requires a high capacity of available water. Conversely, the elemental sulfur treatment showed no effect on survival rate and RCD growth for both species due to the low oxidation of sulfur in arid soils. The extended monitoring of seedling growth and soil characteristics is required to elucidate the long-term effects of soil amendments in the semi-arid region, and the further studies are also needed to examine the appropriate amount of fertilizers for both species.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.372-379
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• 1994

Timber harvesting impacts on soil microbial populations and respiration rates were examined in naturally regenerating trembling aspen(Populus tremuloides Michx.) stands on two contrasting soils, an Omega loamy sand (sandy mixed, frigid Typic Udipsamment) and an Ontonagon clay loam (very fine, mixed Glossic Eutroboralf). Five timber harvesting disturbances were simulated during winter of 1990 and spring of 1991, including commercial whole-tree harvesting(CWH), winter logging trail+CWH, logging slash removal+CWH(LSR), forest floor removal+LSR(FFR), and spring compaction+FFR. Regardless of soil types, total soil respiration rates of each stand decreased slightly or remained the same after harvesting while microbial population increased progressively during the first two years following harvesting. Microbial populations increased more rapidly and constantly at the sandy site than at the clayey site, which may indicate that the soil physical and chemical conditions changed more drastically for microbial activity following timber harvesting at the sandy site than at the clayey site. However, two kinds of treatment applications-three levels of organic matter removal and two levels of compaction-did not result in significant differences in microbial population or total soil respiration rate at each site during the first two post-harvest years. Total soil respiration of the aspen stands, sum of root respiration and microbial respiration, was a poor index for the microbial activity in this study because aspen kept an active root system for the successive root-sprouts even after harvesting, which resulted in a large portion of root respiration in total respiration.

• Journal of Korean Society of Forest Science
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• v.71 no.1
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• pp.90-98
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• 1985

Inheritance of four isozymes, GOT, ACP, MDH and ADH, in Populus alba ${\times}$ P. glandulosa was investigated with starch gel electrophoresis. All four isozymes showed bands. For GOT, six or seven loci were postulated and observed segregation of hybrids at five variable loci was in agreement with expected segregation. Two loci were postulated in ACP; one locus showed no variation but the other locus showed variation. As one additional band was found in P. alba ${\times}$ P. alba (italy), hybrids from P. alba ${\times}$ P. alba ${\times}$ P. glandulosa showed more variation than hybrids from P. alba ${\times}$ P. glandulosa. One monomorphic locus and two variable loci were postulated in MDH. For ADH, both parents were turned out as homozygotes but for different alleles and thus all progenies were heterozygotes. ADH in hybrids seems to be a dieter enzyme as it showed on additional band between two parental bands. There were no variation in band betweens of four enzymes among the clones of P alba and P. glandulosa, respectively.

• Journal of Korea Foresty Energy
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• v.7 no.1
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• pp.22-27
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• 1987

Above ground biomass production of one-year-old hybrid poplars was investigated to select the best clones which are suitable for short rotation forestry. The results were as follows: 1. Average dry weight of Populus alba X P. glandulosa Fl clones was 2.86 for stem,0.41 for branches 0.70 for leaves and 3.97 t/ha for total. and the ratios of green weight to dry weight were 0.47 for stem,0.36 for branches,0.31 for leaves and 0.42 for total. Dry weight of Populus nigra X P. maximowiczii Fl clones was 1.48 for stem, 0.54 for branches.0.71 for loaves and 2.73t/ha for total, and the ratios of green weight to dry weight were 0.42 for stem. 0.37 for branches, 0.28 for leaves and 0.36 for total. 2. Biomass production (green and dry weight)of Populus alba X P. glandulosa F1 clones can be predicted by diameter measurement only, but biomass production of Populus nigra X P. maximowiczii F1 clones can not be predicted by any of investigated characteristics. 3. Dry weight distribution of pepulus alba X P. glandulosa Fl clones were 73$\%$ for stem, 10$\%$ for branches and 17$\%$ for leaves, and dry weight distribution of P. Populus nigra X P. maximowiczii F1 clones were 54$\%$ for stem, 20$\%$ for branches and 26$\%$ for leaves.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.59-64
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• 2014

This study describes analysis of genetic diversity and spatial genetic structure of Korean poplar (Populus koreana Rehder) in Mt. Odae using I-SSR markers. P. koreana is a deciduous broad-leaved tree species that primarily grows in the alpine valleys of China, Russia and North Korea. In South Korea, P. koreana is found limitedly in Gangwon province. Especially, the population in Mt. Odae is located on the southern limit line, its importance is emphasized from the genetic resource conservation perspective. The Shannon's diversity (I=0.230) and the expected heterozygosity (He=0.151) were relatively low as compared with those of other plant species. Spatial autocorrelation analysis using Tanimoto's distance showed that the genetic patch was founded within 400 m. It is suggested that individual trees for ex situ conservation should be sampled with a minimum distance of 400 m between trees.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.19-25
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• 2017

This study was conducted to investigate the effects of nitrogen fertilization on physiological characteristics and growth of Populus sibirica seedlings in a semi-arid area, Mongolia. 2-year-old P. sibirica seedlings were planted in May, 2015 with applications of urea 5 g (N1), 15 g (N2), 30 g (N3) and ammonium sulfate 33 g (NS; same nitrogen amount with N2) to each seedling. Chlorophyll contents were significantly different among treatments in August, but not in June and July. The lower chlorophyll contents in August than those in June and July might be related to leaf senescence. In June and July, net photosynthetic rate was higher in NS and N2 than in the control. Unlike the tendency of photosynthesis, transpiration rate was highest in N2, but lower in NS than in any other nitrogen treatments. Relative growth rate of root collar diameter was significantly higher only in NS than in the control and it of height did not differ among treatments. Leaf area in nitrogen treatments was not significantly different from that in the control. Ammonium sulfate seemed to be more suitable fertilizer than urea for the early growth of P. sibirica seedlings in the study site. However, as the effects of urea and ammonium sulfate on soils and seedlings were different, further studies would be necessary to determine the optimal amount of ammonium sulfate.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.31-37
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• 2002

In order to select proper plants for phytoremediation at heavy metal contaminated areas, eight species of non-edible plants were cultivated at the heavy metal contaminated soils near a metal smelter. The content of the absorbed heavy metals (Cd, Cu, Pb and As) at different part of the plants were analyzed. Plants included five tree species (Populus nigra x P. maximowiczii, Euonymus japonica, Acer palmantum, Celtis sinensis, Buxus microphylla), two flower species (Rhododendron lateritium, Calendula officinalis), and lawn (Zoysia japonica). Biomass yield of tree species was higher than those of flower or lawn species. Heavy metals were highly accumulated in roots compared to those In leaves and stems. The concentrations of Cd, Cu, Pb, and As in Buxus microphylla were greater than those in other plant species. Total absorbed Cd and Pb contents, from high to low by each plant in experimental plots were in the order of Populus nigra x P. maximowiczii, Celtis sinensis and Acer palmantum. They were Celtis sinensis, Populus nigra x P. maximowiczii and Buxus microphylla for Cu, and Buxus microphylla, Acer palmantum and Populus nigra x P. maimowiczii for As. It was estimated that among eight plant species used in the experiment Populus nigra x P. maximowiczii, Buxus microphylla, Acer palmantum, and Celtis sinensis were the most effective species for phytoremediation in the heavy metals polluted areas considering biomass yield and heavy metal uptake.

• Journal of Korean Society of Forest Science
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• v.73 no.1
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• pp.33-42
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• 1986

This study was carried out to investigate the optimum conditions for isolation and culture of mesophyll protoplasts from Populus alba ${\times}$ P. glandulosa. The results obtained from the experiments are as follows; 1) The suitable concentration of BAP for shoot multiplication was 0.4 mg/l. 2) High yield and viability of isolated protoplasts were obtained by our high enzyme-short time incubation method. 3) Optimum enzyme concentrations for mesophyll protoplast isolation were Cellulase 2%, Macerozyme 0.8%, Hemicellulase 1.2%, Driselase 2%, and Pectolyase Y-23 0.05%. 4) 0.6M mannitol in enzyme solution was the most effective for protoplast isolation and viability. 5) The most adequate pH level of enzyme solution was pH 5.6. 6) The effect of DTT and MES buffer was significant. 7) For protoplast purification, 0.6M sucrose was the most proper concentration. 8) The adding effect of Dextran T40 in floating solution was important. 9) The mesophyll protoplasts isolated through our high enzyme-short time incubation method revealed successful response to culture condition over 3 weeks of culture.