• Applied Biological Chemistry
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• v.48 no.3
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• pp.252-257
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• 2005

Three-dimensional quantitative structure-activity relationships (3D-QSARs) for the herbicidal activities against pre-emergence barnyard grass (Echinochloa crus-galli) by new 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpropion amide derivatives were studied quantitatively using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methodologies. The best CoMFA model (AI-2) and CoMSIA model (AII-4) were derived from an atom based fit alignment and a combination of CoMFA fields. The herbicidal activities from CoMFA and CoMSIA contour maps showed that the activity will be able to be increased according to the substituents variation on the N-phenyl ring.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.69-71
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• 2000

The herbicidal activities ($pI_{50}$) with alkoxy (RO-) groups on the azomethine nitrogen atom in 5-(2,3-dihydro-2,2-dimethylbenzothiophene-7-yl)-2-(1-(alkoxyimino)butyl)-3-hydroxy-2-cyclohexene-1-one derivatives against various weeds were measured in the flooded and in the paddy conditions. Particularly, i-propoxy subsutuent, 5 of them showed excellent herbicidal activity at a rate of 4kg/ha with pre-emergence against barnyard grass (Echinochloa crus-galli) with good selectivity on rice plant (Oryza sativa). The results of the structure-activity relationships (SAR) analyses are shown that the alkyl subsituents with higher hydrophobicity (logp>0) and electron donating (${\sigma}^*<0$) group as a new substrate rather than alkoxy substituents seems to be contribute to the herbicidal activity with pre-emergence.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.38-45
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• 2007

Laboratory and greenhouse experiments were conducted to determine the herbicidal effect of two types of ${\delta}$-aminolevulinic acid (ALA), microbiologically-produced ALA (Bio-ALA) and synthetically produced ALA (Synthetic-ALA), on plant growth and chlorophyll content of Chinese cabbage. ALA effect on early plant growth was greatly concentration dependant, showing significant inhibition at higher concentrations. Both pre- and post-emergence application of ALA exhibited significant degree of photodynamic phytotoxicity. Older plants with many leaves were more tolerant to ALA than younger plants, showing less injury. No significant difference in herbicidal activity of two types of ALA, Bio-ALA and Synthetic-ALA, on plant height and chlorophyll content of Chinese cabbage was observed. However, residual biological activity and physico-chemical properties of Synthetic-ALA were more stable than those of Bio-ALA. Our results suggest that ALA had herbicidal potential with both pre- and post-emergence application, and that the chemical may be a valuable mean of eco-friendly weed control based on natural microbial substance.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.262-265
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• 2006

A series of N-[4-chloro-2-fluoro-5-(2-(substituted)pyrimidinyloxy)phenyl]-3,4,5,6-tetrahydrophthalimides was synthesized, and the herbicidal activities of those derivatives were evaluated through pre- and post-emergence application under upland conditions in a greenhouse. The results showed that most compounds resulted in stronger herbicidal activities on broadleaf weeds than on grass weeds. The N-[4-chloro-2-fluoro-5-(2-pyrimidinyloxy)phenyl]-3,4,5,6-tetrahydrophthalimide showed the best weed control efficacy and marginal corn safety at a rate of 60 g/ha through pre-emergence application.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1473-1483
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• 2014

Reports of herbicide resistance events are proliferating worldwide, leading to new cultivation strategies using combinations of pre-emergence and post-emergence herbicides. We analyzed the impact during a one-year cultivation cycle of several herbicide combinations on the rhizobacterial community of glyphosate-tolerant Bt-maize and compared them to those of the untreated or glyphosate-treated soils. Samples were analyzed using pyrosequencing of the V6 hypervariable region of the 16S rRNA gene. The sequences obtained were subjected to taxonomic, taxonomy-independent, and phylogeny-based diversity studies, followed by a statistical analysis using principal components analysis and hierarchical clustering with jackknife statistical validation. The resilience of the microbial communities was analyzed by comparing their relative composition at the end of the cultivation cycle. The bacterial communites from soil subjected to a combined treatment with mesotrione plus s-metolachlor followed by glyphosate were not statistically different from those treated with glyphosate or the untreated ones. The use of acetochlor plus terbuthylazine followed by glyphosate, and the use of aclonifen plus isoxaflutole followed by mesotrione clearly affected the resilience of their corresponding bacterial communities. The treatment with pethoxamid followed by glyphosate resulted in an intermediate effect. The use of glyphosate alone seems to be the less aggressive one for bacterial communities. Should a combined treatment be needed, the combination of mesotrione and s-metolachlor shows the next best final resilience. Our results show the relevance of comparative rhizobacterial community studies when novel combined herbicide treatments are deemed necessary to control weed growth.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.159-165
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• 2012

The rhizobacterial composition varies according to the soil properties. To test if the effect of herbicides on the rhizobacterial communities of genetically modified NK603 glyphosate-tolerant maize varies according to different soil locations, a comparison was made between the effects of glyphosate (Roundup Plus), a post-emergence applied herbicide, and a pre-emergence applied herbicide (GTZ) versus untreated soil. The potential effect was monitored by direct amplification, cloning, and sequencing of the soil DNA encoding 16S rRNA, and high-throughput DNA pyrosequencing of the bacterial DNA coding for the 16S rRNA hypervariable V6 region. The results obtained using three different methods to analyze the herbicide effect on the rhizobacterial communities of genetically modified NK603 maize were comparable to those previously obtained when glyphosate-tolerant maize was grown in soil with different characteristics. Both herbicides decreased the bacterial diversity in the rhizosphere, with Actinobacteria being the taxonomic group most affected. The results suggest that both herbicides affected the structure of the maize rhizobacterial community, but glyphosate was environmentally less aggressive.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.45.1-45.1
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• 2020

Light bridges (LBs) are relatively bright structures that divide sunspot umbrae into two or more parts. Chromospheric LBs are known to be associated with various activities including fan-shaped jet-like ejections and brightenings. Although magnetic reconnection is frequently suggested to be responsible for such activities, not many studies presented firm evidence to support the scenario. We carry out magnetic field measurements and imaging spectroscopy of a LB where fan-shaped jet-like ejections occur with co-spatial brightenings at their footpoints. We study their fine photospheric structures and magnetic field changes using TiO images, Near-InfraRed Imaging Spectropolarimeter data, and Hα data taken by the 1.6 m Goode Solar Telescope. As a result, we detect magnetic flux emergence in the LB that is of opposite polarity to that of the sunspot. The new flux cancels with the pre-existing flux at a rate of 5.6×1018 Mx hr-1. Both recurrent jet-like ejections and their footpoint brightenings are initiated at the vicinity of the magnetic cancellation, and show apparent horizontal extension along the LB at a projected speed of 4.3 km s-1 to form the fan-shaped appearance. Based on these observations, we suggest that the fan-shaped ejections may have resulted due to slipping reconnection between the new flux emerging in the LB and the ambient sunspot field.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.199-205
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• 2010

This study was conducted to investigate the phytotoxic effects of 19 essential oils on seed germination and initial growth of rapeseed (Brassica napus L.). We found that anise, cinnamon, citronella, clove, geranium, lemongrass, mustard and pine oils completely inhibited germination of rapeseed at $100{\times}$ dilute solution. Based on the inhibition rates of rapeseed emergence and initial growth, three essential oils (cinnamon, clove, and geranium) were selected as potential bio-herbicides. Under pre-emergence applications of cinnamon, clove, and geranium oils at 90 kg ai $ha^{-1}$, rates of rapeseed emergence were 7.1, 25.0, and 3.6% and its initial growth were 22.0, 9.9 and 11.0%, respectively.

• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.11-16
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• 1986

Local difference in post-overwinter developmental periods was investigated by incubating the overwintered larvae collected from 8 locations at $25^{\circ}C$ begining January 15 and February 15. Based on the 2nd incubation test, it was found that Chunseong colony had the shortest pre pupal period of 17.9 days, while Gwangsan colony had the longest 27.7 days. In general, prepupal period showed negative correlation with latitudes. Average pupal periods were not significantly different among colonies. Adult emergence period showed the same trend as prepupal periods. Chunseong and Pyeongtaeg colonies emerged faster than the other colonies and showed a single peak of adult emergence, while Nonsan, Iri, Gwangsan colony showed several peaks of adult emergence.

• The Korea Journal of Herbology
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• v.24 no.4
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• pp.31-37
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• 2009

Objectives : The rapid progress seen in the Chinese medical and pharmaceutical industries since the mid.Ming Dynasty, and the resulting surge in demand for medicinal herbs led to the emergence of dedicated medicinal herb markets. A representative example was the medicinal herb market of Qizhou (today's Anguo) in Hebei Province. This paper examines various factors that contributed to the transformation and growth of Qizhou into and as a major medicinal herb market of China. Methods : Along with the examination of geographical factors, this study attempts to link the development of Qizhou as a center for medicinal herbs trade with legends related to the Medicine Lord Temple (Yao Wang Miao), a local shrine dedicated to the mythical Medicine Kings. Results : The main argument of this study is that although the emergence of Qizhou as China's largest marketplace for medicinal herbs was significantly helped by its proximity to Beijing, a huge source of demand, as well as its convenient location easily accessible from all parts of the country, and the large herbal production from surrounding areas, the single.most important contributing factor was the body of legends attributing to this city a magical healing energy. Conclusions : The example of Qizhou may also suggest that in pre.modern eras, legends related to supernatural healing power, associated to a city or town, were as important contributing factors to its emergence and growth as a dedicated medicinal herb market as its location or ease of access.