• Korean journal of applied entomology
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• v.50 no.3
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• pp.253-256
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• 2011

The walnut leaf beetle, Gastrolina depressa, belongs to family Chrysomelidae (Coleoptera), and is one of the major pests of walnut trees. G. depressa eggs were oval and dark orange. The three G. depressa larval instars were gray in color. The larval period was approx. 8.14 days ($24^{\circ}C$, 16L:8D). Adults of both sexes were dark blue, and females were larger than males. Overwintered adults emerged in late April, and laid eggs in clusters on young leaves of the host tree. Mature 3rd instar larvae pupated after a short prepupal period. Adults emerged starting mid-May and entered into diapause shortly afterward.

• Journal of Korean Society of Forest Science
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• v.89 no.5
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• pp.666-676
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• 2000

For the study of morphological variation of Q. variabilis natural population in Korea, 19 populations were selected through the country in considering latitude, longitude, and geographical characters. Thirty trees were randomly selected from each population and 60 mature leaves were sampled from each tree. Four characters (leaf blade length, maximum blade width, petiole length, and vein number) were measured, and their ratios (the ratio of blade length to maximum blade width, the ratio of blade length to petiole length, the ratio of petiole length to vein number, upper 1/3 blade width to maximum blade width, and upper 1/3 blade width to lower 1/3 blade width) were calculated. 1. Analysis of variance for all leaf characters were significantly different among populations and among individuals within population. Contributions of variance among individuals within population in all the characters were higher than those among populations. Therefore, selection of plus trees may be preferable to desirable populations for breeding program of Q. variabilis. 2. Among principal component analysis for leaf characters, primary 2 principal components appeared to be major variables for leaf form of Q. variabilis because of the loading contribution of 80.5%. The first contribution component was petiole length/vein number and petiole length ; the second one was upper 1/3 blade width/maximum blade width, upper blade width/lower 1/3 blade width and vein number, respectively. 3. Latitude was positively correlated with blade length/maximum blade width and blade length/petiole length, but negatively correlated with petiole length/vein number, upper 1/3 blade width/maximum blade width, upper 1/3 blade width/lower 1/3 blade width, petiole length, and vein number. But, for longitude and altitude the former two traits and the later five traits exhibited the negative and positive correlation, respectively. 4. Cluster analysis using complete linkage method for leaf characters showed two groups to Euclidean distance 1.6. They were group I of population 1. 4, 5, and 13 and group II of population 2, 3, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, and 19. However, group II was divided again to Euclidean distance 1.3, that is a group including population 3, 7, 10, 14, 15, and 17(group II-1) and the other group comprising population 2, 6, 8, 9, 11, 12, 16, 18, and 19(group II-2). This cluster could be mainly observed due to difference among population in aspect (group I : NE, group II-1 : SE, and group II-2 : SW).

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.88-94
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• 2013

Brown patch caused by Rhizoctonia solani AG-1 IB occurred on Kentucky bluegrass during late May through early October 2010 at golf course in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass for spring season were leaf blights dying from the leaf tip, which appeared patches of brown color in the field. However, it appeared patches of dark brown color or gray brown color in fall. The fungus (B-7 isolate) of brown patch was isolated from the diseased leaf tissue and cultured on potato-dextrose agar (PDA) for identification. The young hyphae had acute angular branching and few septa and mature hyphal branches showed about 90-degree angles and development of monilioid cells, which were morphologically identical to Rhizoctonia solani AG-1 IB reported previously. DNA sequences of ribosomal RNA gene (internal transcribed spacer) of the fungus were homologous with similarity of 99% to those of Rhizoctonia solani AG-1 IB isolates in GenBank database, confirming the identity of the causal agent of the disease. Pathogenicity of the fungus was also confirmed on the creeping bentgrass and Kentucky bluegrass by Koch's postulates. This is the first report of brown patch on Kentucky bluegrass caused by Rhizoctonia solani AG-1 IB in Korea.

• Korean Journal of Plant Tissue Culture
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• v.25 no.1
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• pp.51-56
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• 1998

This study was carried out in order to establish plant regeneration via somatic embryogenesis from leaf explant of Ostericum koreanum Kitagawa and to elucidate the effects of NAA and cytokinins (kinetin, BA) on the abnormalities of somatic embryo and the relationship between thecotyledon numberand germinability. Calli were formed on leaf explants cultured on MS agar medium supplemented with various concentrations (0, 0.1, 0.5, 1, 2 mg/L) of NAA and cytokinins. The calli were white, watery and soft, became browning during cultures. Somatic embryos were formed from pale yellowish calli derived browning calli. High frequency somatic embryos were observed on MS medium containing 1 mg/L NAA and 0.1 mg/L BA after 60 days of culture. The mature somatic embryos germinated into plantlets without subculture after 2 weeks. The frequency of normal somatic embryo with two cotyledons was 39.8%. On the other hand, cotyledonary abnormalities of somatic embryos were observed at considerable frequency: 33.6% of somatic embryo with one cotyledon, 15.3% cotyledons with three, 8.2% four cotyledons and 3.1% jar shaped cotyledon. Germination frequency of somatic embryos with two cotyledons was 97.4%, and that of the embryos with abnormal cotyledon was almost similar to that of embryos with two cotyledons, except jar shaped somatic embryos (33.3%).

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.37-43
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• 2000

Effects of silicon application on development of colonies of Sphaerotheca fuliginea were examined. Cucumber plants were applied with nutrient solutions amended with different concentrations of soluble silicon and selected leaves were inoculated with known concentrations of conidia of the pathogen. Colony number per leaf, colony area per leaf, and germination rate of conidia of S. fuliginea collected from the inoculated leaves were reduced as silicate concentrations in the nutrient solutions increased from 0.05 to 4.10 mM. The increase in resistance of plants to mildew infection was apparently due to silicate accumulation in leaves, and there was no correlation between cation or ionic strength effects and the silicate treatments. Silicate treatment in growth medium remarkably suppressed powdery mildew development on cucumber. Colonies of mildew fungus were visible with over approx. 38.3% of the mature leaf surface, while that of the leaves in high Si plants was 2.3% observed at 51 days after transplanting. No significant differences were observed between 1.7 mM and 3.4mM silicate treatments. Conidial germination rates were significantly reduced by increasing Si amendments. Conidial germination ranged from 14.7 to 20.3% for plants grown in low Si solution(<1.40 mM), and from 9.0 to 12.4% for plants grown in high Si solution(>1.8 mM). Foliar applications of Si with ${\geq}$ 17.0 mM decreased the number of powdery mildew colonies. Persistence of Si foliar sprays effects on cucumber demonstrated that the 17 mM Si spray applied 4 days before inoculation with S. fuliginea reduced mildew colony formation. The relationship was positive and linear.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.3
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• pp.102-106
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• 2008

This study was carried out to evaluate the relationships between stand attributes and litterfall amounts in a 28-year old Quercus acutissima stand. Eighteen sampling plots of $20m{\times}20m$ were chosen and litterfall was collected from May 2005 to December 2006. There was no correlation between stand attributes(tree density, mean diameter at breast height, mean height, basal area) and litterfall amounts except for flower and miscellaneous litter for the study period. There were no significant relationships between leaf litter and basal area(r=0.02, 0.05; P=0.93, 0.83) and between leaf litter and tree density(r=-0.10, 0.05; P=0.85, 0.69). Also, leaf litter was affected neither by mean diameter at breast height(r=-0.08, 0.30; P=0.73, 0.22) nor by mean height(r=-0.24, 0.09; P=0.34, 0.70). Other litter amounts such as bark, branch, and acorn showed no relationships with the stand attributes (P>0.05). The lack of significant relationships between litterfall amounts and stand attributes could be due to the closed canopy with a complete crown cover in this mature oak stand.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.158-165
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• 2019

The effects of microbubbles on glucosinolate accumulation and growth of watercress (Nasturtium officinale R. Br.) were investigated. Watercress plant at the 4th mature leaf stage (2 weeks old) were exposed to microbubbles or non-microbubbles generated in an Otsuka-house nutrient solution for 3 weeks in a controlled environment culture room. Stem length of the watercress grown under the microbubbles was 41% shorter than that of the non-microbubbles, showing significantly different. However, shoot fresh and dry weights, root length, leaf length, leaf width, SPAD, and quentum yield of the watercress were not significantly different between treatments. Glucoiberin, glucobrassicin, gluconapin, gluconasturtiin of the watercress grown under microbubbles, excepted for 4-methoxyglucobrassicin, were significantly higher than those of the watercress grown in non-microbubbles. In addition, watercress grown under microbubbles for 3 weeks contained 85% (${\mu}mol/g$ DW) and 65% (${\mu}mol/plant$) more total glucosinolate, respectively. Results indicated that microbubbles generated in a deep flow technique hydroponics system could increase the accumulation of glucosinolate without growth reduction.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.309-316
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• 1988

Several experiments were conducted to investigate the achene viability and growth characteristics of Eclipta prostrata (L.) L. No dormancy and no after-ripening requirement were found for E. prostrata achenes. When achenes were stored at room temperature, germination did not decrease with up to 5 months storage. Large differences in loss of viability of E. prostrata achenes occurred when different dehydration methods were used. Immediate dehydration resulted in high viability, but slow dehydration resulted in severe loss of viability. Achene viability at shallow burial depths (5 and 10 cm deep) was lower under upland soil conditions than under lowland soil conditions. Seedling growth was greatly reduced when flooding to a depth of 10 cm occurred at or before the 4-leaf stage. Flooding after the 4-leaf stage stimulated stem elongation. Branching started from the second week and usually terminated at the tenth week. Leaf size was determined by the branch which are related to the assimilate supply. Flowering of E. prostrata started during the fifth week after emergence, and mature achenes were produced from the sixth week. Ten to 14 days were needed for the achenes to mature. About 14,000 achenes were produced on each plant. Achene production per week increased from the sixth week to the tenth week and thereafter it declined. The average number of achenes per inflorescence decreased with delay in flowering.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.50-55
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• 1986

To get the basic information about ginseng seedling production, yields of ginseng seedling and soil physico-chemical components in 32 fields of Yang-Jik and 19 fields of Ban-Yang-Jik nursery were investigated. Germination rate is $78.5{\pm}3.0%$, $77.8{\pm}2.8%$ in Yang-Jik and Ban-Yang-Jik. Rate of number of mature seedlings to number of seeds planted is $62{\pm}13.5%$, $53{\pm}12.6%$ in Yang-Jik and Ban-Yang-Jik. Rate of number of available seedlings to number of seeds planted (Rate of available seedling) is $42{\pm}12.5%$, $26{\pm}12.1%$ in Yang-Jik and Ban-Yang-Jik. The number of available seedlings per Kan (Kan means $180{\times}90cm$ area) is $627{\pm}187$, $368{\pm}182$ in Yang-Jik and Ban-Yang-Jik. Rate of number of unusable seedlings to number of mature seedlings is 34%, 51% in Yang-Jik and Ban-Yang-Jik. It showed the negative correlation between amount of coarse sand and stem height, and central leaf length, on the other hand, possitive correlation between amount of extremely fine sand, and stem height, and central leaf length respectively. Rate of available seedling was positively correlated with amount of medium, fine and extremely fine sand, whereas negatively correlated with amount of coarse sand in Yang-Jik. Root weight per seedling was positively correlated with amount of medium, fine and extremely fine sand. Contents of organic matter, available phosphate and potassium in Ban-Yang-Jik were higher than those of Yang-Jik, but content of lime was higher in Yang-Jik compared to that of Ban-Yang-Jik. Possitive correlations were showed between leaf area per seedling and content of organic matter, and between stem height and content of lime in Yang-Jik. Root weight per seedling was positively correlated with content of organic matter and magnesium in Ban-Yang-Jik, but there is no correlation between any of soil chemical components and root weight in Yang-Jik.

• Nuclear Engineering and Technology
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• v.24 no.2
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• pp.121-129
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• 1992

Radio-tracer experiments on the Sr-90 absorption by rice and soybean from a sandy-loam soil of pH 6.35 treated with 5.2 and 31.2Bq Sr-90 per g-soil were carried out through pot cultivations. Sr-90 absorption rates of both crops increased till the mature stage when the rates were about 1.0%. Concentrations in their whole tops, however, decreased or changed little as they grew. Sr-90 concentrations in plant parts of both crops increased with the increase of those in soil. Soil-to-plant transfer coefficients of Sr-90 for rice and soybean at mature stages ranged, on the dry weight basis, from 0.07(unpolished seed) to 3.67(lean and from 0.86(seed) to 9.26(leaf), respectively. Only the unpolished rice seed showed a significant difference in the coefficient with 0.17 in 5.2Bq treatment and 0.07 in 31.2Bq treatment. Sr-90 retention rates of the upper 15cm soil after crop harvests were about 80% Sr-90 absorptions had no effect on the plant growth and yield of the crops.