• Applied Biological Chemistry
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• v.47 no.3
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• pp.351-356
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• 2004

Holographic quantitative structure activity relationships (HQSAR) as 2D QSAR between the herbicidal activities against root and shoot of rice plant (Orysa sativa L.) and barnyardgrass (Echinochloa crus-galli), and structures of A=3,4,5,6-tetra-hydrophthalimino, B = 3-chloro-4,5,6,7-tetrahydro-2H-indazolyl and C = 3,4-dimethylmaleimino substituents in 1-(5-methyl-3-phenylisoxazolin-5-yl)methoxy-2-chloro-4-fluorobenzene derivatives were studied and discussed. The statistical results of four HQSAR models for the herbicidal activities against root and shoot of the two plants showed the best predictability of the herbicidal activities based on the cross-validated $r^2\;_{cv}\;(q^2=\;0.760{\sim}0.924)$, non cross-validated conventional coefficient $(r^2\;_{ncv}\;=\;0.868{\sim}0.970)$ and PRESS values $(0.123{\sim}0.261)$. The results indicated that the qualities of HQSAR models for barnyardgrass were slightly higher than that of rice plant. And also, the predictability of HQSAR models were higher $(q^2\;=\;HQSAR\;>\;CoMFA)$ than CoMFA but the conventional coefficients of HQSAR models lower $(r^2\;=\;HQSAR\;<\;CoMFA)$ than CoMFA. Moreover, from the contribution maps, it was founded that the selectivity between the two plants depends upon the 2-fluoro-4-chloro-5-alkoxyanilino and $R_3$ substituent on the C-phenyl ring. These features suggest where to modify a molecular structure in order to improve its selective of herbicidal activities against barnyardgrass.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.54-63
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• 1996

This study was conducted to investigate the anatomical and ultrastructural responses of the oxyfluorfen-tolerant and -susceptible rice cultivars with barnyardgrass, a typical susceptible weed by oxyfluorfen and the herbicides having similar mode of action treatment. After the treatment of $10^{-5}M$ oxyfluorfen, the tolerant rice cultivars no showed the structural damage of leaf surface, but the susceptible rice cultivate was damaged in the wax and the susceptible barnyardgrass was even destroyed in the tissue irregularly. Also in the susceptible rice cultivars and barnyardgrass the thickness of leaf blade was greatly decreased. The anatomical change was not observed in the tolerant rice cultivars but epidermal cells, mesophyll cells and bundle sheath cells were badly broken in the susceptible rice cultivars and barnyardgrass and especially after 24 hours of the treatment the structure of susceptible rice cultivars was completely disintegrated. The irregularity of chloroplast shape and the distortion of chloroplast envelope were generally observed and the starch tended to decrease by oxyfluorfen treatment regardless of rice cultivars. Such a structural damage were appeared more badly in the susceptible rice cultivars and bamyardgrass than in the tolerant rice cultivars. By the treatment of diphenyl ether herbicides, the thickness of leaf blade greatly reduced in the order of oxyfluorfen > acifluorfen > bifenox > oxadiazon, and the susceptible rice cultivars showed more reduction than the tolerant rice cultivars. Especially, the susceptible rice cultivars showed that the leaf structure was badly broken down with damage epidermal cells and bundle sheath cells.

• The Korean Journal of Pesticide Science
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• v.5 no.2
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• pp.58-61
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• 2001

A greenhouse study was conducted to evaluate the effect of R(+), S(-) and racemic mixture of fenoxaprop-ethyl on rice and barnyardgrass. In addition, in wire acetyl-coenzyme A carboxylase inhibition to those chiral compounds was determined. In the greenhouse trial, the R(+) and S(-) fenoxaprop showed respectively tile highest and the lowest biological activity on both plants. This dose-response in whole plant level was consistent with the result of in vitro dose-response of acetyl-coenzyme A carboxylase. These results corfirmed tllat the R(+) isomer is biologically more active than the S(-) isomer, and the target site of fenoxaprop is the enzyme acetyl-coenzyme A carboxylase. It was an interesting result that rice safety was improved in the S(-) isomer compared with the R(+), and the respective selectivity index was 1.5 and 0.57 in a greenhouse experiment; however, those values resulting from ACCase assay were not substantially different each other at in vitro level. Those results suggested that the fundamental selectivity of fenoxaprop-ethyl between rice and barnyardgrass would not exist at target site level.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2006.06a
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• pp.21.1-21.1
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• 2006

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.72-75
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• 2000

3,4-Dimethyl-N-[4-chloro-2-fluoro-5-{(pyrazolylmethyl)oxy}phenyl]maleimides or 3,4,5,6-tetrahydro-N-[4-chloro-2-fluoro-5-{(pylazolylmethyl)oxy} phenyl]phthalimides were prepared and evaluated their herbicidal activities under paddy conditions. Those compounds which have N-methyl-5-pyrazolylmethyloxy moiety showed good tolerance in transplanted rice and strong herbicidal activities on barnyardgrass below 60 g/ha of dose.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.101-106
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• 2006

Common thistle contains water-soluble substances that are phytotoxic to neighboring plant species. A series of aqueous extracts from leaves, stems, roots and flowers of common thistle (Cirsium pendulum Fisch.) were assayed against alfalfa (Medicago sativa) seedlings to determine their allelopathy, and the results showed highest inhibition in the extracts from flowers and leaves, and followed by stems, and roots. The extracts at 40 g dry tissue $L^{-1}(g\;L^{-1})$ applied on filter paper in a Petri-dish significantly inhibited root growth of test plant by 87%. Methanol extracts at 100 g $L^{-1}$ from leaves inhibited root growth of alfalfa and barnyardgrass (Echinochloa crus-galli) by 89 and 98%, respectively. Hexane and ethylacetate fractions of common thistle reduced alfalfa root growth more than did butanol and water fractions. Incorporation into soil with the leaf residues at $100g\;kg^{-1}$ inhibited shoot fresh weights of barnyardgrass and eclipta (Eclipta prostrate) by 88 and 58%, respectively, showing higher sensitivity in grass species. These results suggest that common thistle plants had allelopathic potential for eco-friendly vegetation management, and that especially their activities were differently exhibited depending on plant part.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.15-18
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• 2000

A series of N-{2,4-dichloro-5-(3-pyrazolyl)Phenyl}imides 7 and 8 was prepared and evaluated their herbicidal activities. Those compounds in which either carboxylate or carboxamide moiety is on pyrazole moiety 7c-71 showed no herbicidal activity whereas, the compounds in which trifluoromethyl group is substituted in pyrazolyl moiety showed moderate herbicidal activities against barnyardgrass, monochria and flat-sedge under paddy conditions with good rice tolerance at rate 63-250 g/ha.

• Journal of Applied Biological Chemistry
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• v.43 no.1
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• pp.49-53
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• 2000

The in vitro metabolism of a new herbicide pyribenzoxim, {benzophenone O-[2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoyl]oxime} was studied using rice, barnyardgrass and rat liver microsomes. No metabolism of pyribenzoxim was observed with rice and barnyardgrass microsomes though the cvtochrome P450 was active, which was evidenced by the metabolism of cinnamic acid. With rat liver microsomes, four metabolites (M1, M2, M3, and M4) were produced while parent compound decreased. M1 and M2 were from the hydrolysis reactions and NADPH-dependent metabolites were M3 and M4 (major metabolite) which were hydroxylated by cytochrome P450. They were identified as bispyribac-sodium (M1), benzophenone oxime (M2), {benzophenone O-[2,6-bis[(5-hydroxy-4,6-dimethoxy-2-pyrimidinyl)oxy]-benzoyl]oxime}(M3), and {benzophenone O-[2[(5-hydroxy-4,6-dimethoxy-2l-pyrimidinyl)6-(4,.6dimethoxy-2-pyrimidinyl)oxy]benzoyl]oxime} (M4) through LC/MS/MS analyses. Based on the results obtained metabolic map of pyribenzoxim is proposed.

• Korean Journal of Weed Science
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• v.9 no.1
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• pp.1-15
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• 1989

The seventeen barnyardgrass [Echinochloa crus-galli (L.) Beauv.] accessions, which were collected national-widely in 1986 and selected two times through 1987, were experimented at 1988. To identify the ecological properties of the collected accessions of native barnyardgrass species as a weed, the experiment was conducted with Wagner pots in size of I/500a and under PE film house. 1. Accessions were classified into 5 specific groups in plant type properties by use of data from plant height, number of maximum tillers, erectness, culm length and panicle type, among others. 2. As for species identification, they were clustered into 3 similar groups and 2 individual species by use of data from color, first-glumer type, and erectness. 3. Four groups were identified for elongational properties by plant height of 22 days old seedling, length of culm, panical, leaf length and width, and inter-node and spikelet, among others. 4. Properties on quanititative growth were classified into 4 groups and 1 individual accession corresponding to differential plant height of 22 days old seedling, length of culm, panical, inter-node, leaf-sheath, spikelet, first-glumes length, grain, number of tillers, spike, and grain weight. 5. Due to different daily increasing rate in seedling height, dry weight, number of tillers and ratio in dry weight to plant height, the growth rate properties were clustered into 4 groups and one individual accession. 6. Properties on seedling growth were classified into 4 groups by use of differential date in length and width of first-leaf, plant height, number of tillers, and dry weight of young and medium aged seedling. 7. Responding to heading date, the accessions were classified into 3 groups : temperative sensitive, medium, and short-day length sensitive types, respectively. 8. By integrating of all quanititative and attributable characters, the seventeen accessions were clustered into 4 groups and 2 individual accessions.

• Korean Journal of Weed Science
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• v.14 no.3
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• pp.199-211
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• 1994

Butachlor applied pre-emergence at 3.6kg ai/ha inhibited the growth and developments of shoot of barnyardgrass under dry condition, whereas rice was unaffected. Growth of rice and barnyardgrass under water condition was severely inhibited by treatment of butachlor but that of transplanted rice was not affected. The inhibition rate was higher under water condition, in broadcast rice and direct seeded rice than under dry condition, drilled rice and transplanted rice, respectively. The major anatomical response of stem of barnyardgrass seedling to butachlor under dry condition were partial reduction in thickness and collapse of leaf sheath, while not in rice. Broadcast rice on soil under water condition appeared reduction and constriction of leaf primordia thickness, and barnyardgrass formed tubular-like leaves and showed inhibited elongation of apical meristem. On the other hand, transplanted rice did not show these responses.