• Korean Journal of Weed Science
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• v.8 no.3
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• pp.244-249
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• 1988

Some experiments were conducted to utilize the raphanus test as a bioassay method for plant growth regulaters and hormonal herbicides. Among seven radish cultivars, the response of Jangbaegminong was the most sensitive and quantitative to ${\alpha}$-NAA and its coefficient of variation value was the lowest. The optimum application time of test compounds was estimated seven to nine days after seeding. After ${\alpha}$-NAA treatment the curvature angle of radish cotyledonary petiols was sharply increased to the maximum value at 24 hours after and was changed by light and temperature conditions. The curvature response was observed by application of ${\alpha}$-NAA, phenoxy and indole compounds but often plant growth regulators, $GA_3$ benzyladenine, ABA and homobrassinolide was not detected by this method. So this bioassay was useful to evaluate the activity of a compound as an auxin or a hormonal herbicide.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.219-236
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• 1988

Bensulfuron concentrations of $10^{-7}$, $10^{-6}$, $10^{-5}$ and $10^{-4}M$ were applied to agar medium on susceptible (cv. KH 17854 and cv. IR 1846) and tolerant (cv. Chinsurah Boro II and IR 14252) rice cultivars were grown for microscopic inspection. Susceptible cultivars showed the decrease in shoot and root growth at the concentration of $10^{-5}M$ while ones showed no difference. Such a tendency was also observed from microscopic inspection in the elongation zone of shoot meristematic tissue. Seedlings grown in soil for 10 days were transfered to distilled water containing only bensulfuron solutions. There were significant differences between cultivars in terms of supression of shoot meristematic activity and swelling of cell volume. Observations of those cells made it clear that especially susceptible cultivars showed the irregular cell layering, vacuolation, cell swelling and partial damage in membrane of shoot tissue. The major response of root tips of susceptible cultivars showed the disorganization of cortex, rupture and contraction of membrane, inhibition of cell division, swelling and emergence of lateral root while tolerant ones showed no such responses.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.81-88
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• 1993

For searching the photosynthetic electron transport(PET) inhibitors, bio-rational screening system using thylakoid membranes extracted from wild and mutant cyanobacteria(Anacystis nidulans $R_2$) was developed. Generally, thylakoid membrane was more sensitive to the tested herbicides than the chloroplast from spinach in the Hill reaction. Higher resistant characteristics appeared in mutant D-5, Di-22 to diuron and mutant G-264 to atrazine as compared to wild type. To test the reaction of thylakoid membrane to herbicides, diuron and atrazine were applied simultaneously. Diuron and atrazine competed each other for binding with substituted amino acids, while diuron and dinoseb were non-competitive, and inhibiting activity was increased. Conclusively, bio-rational screening system using cyanobacteria was proved to be fast and efficient screening method for the development of PET inhibitors.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.243-251
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• 2010

The study was conducted to evaluate the weed suppressing effects of two winter cover crops, Chinese milk vetch (CMV) and rye, in minor cereal fields in 2009. The suppressing activities of cover crops were due to the allelopathy of cover crops during weed emerging periods and competitive activity during vegetative growth of weeds. Weed suppression by cover crops were changed from 26.5 g $m^{-2}$, 0.1 g $m^{-2}$ and 0.2 g $m^{-2}$ in control, rye field and CMV field, respectively, on June 22 to 428.6 g $m^{-2}$, 1 g $m^{-2}$ and 403.9 g $m^{-2}$ in control, rye field and CMV field, respectively, on July 22. The weed dry weights were further changed to 656.3 g $m^{-2}$, 607.8 g $m^{-2}$ and 511.8 g $m^{-2}$ in control, rye field and CMV field, respectively, on August 22. The suppressing effect of cover crops also observed in minor cereals. Plant height and dry weight of sorghum was reduced to 68.7% and 33.6% of handweeding, respectively, on August 5. The reduction was recovered to 82.7% and 55.6% of control, respectively, on August 26. In addition, heading date of minor cereals was delayed by 7 days with rye.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.42-53
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• 1996

The tolerant and susceptible rice cultivars to oxyfluorfen were selected from 400 rice cultivars in a laboratory, and tested in comparison with barnyardgrass, a typical oxyfluorfen susceptible weed. The responses to oxyfluorfen in the different levels of calli, cells and protoplasts of the rice cultivars were investigated. $I_{50}$ value of the tolerant rice cultivars was about $10^{-4}M$, whereas that of the susceptible rice cultivars and barnyardgrass was about $10^{-6}M$, showing significant difference between the two groups. The growth rate of calli segregated from the tolerant rice cultivars was higher than that from the susceptible rice cultivars and barnyardgrass by treatment of oxyfluorfen to the calli. The growth rate of suspension-cultured cells of the tolerant rice cultivars was higher than that of the susceptible rice cultivars and barnyardgrass after treatment of oxyfluorfen. The viability of protoplasts from the tolerant rice cultivars was higher than that from the susceptible rice cultivars and barnyardgrass after one or two hours of oxyfluorfen treatment. The intactness of protoplasts from the tolerant rice cultivars was also higher than that form the susceptible rice cultivars and 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.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.321-328
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• 1995

Absorption, translocation, and metabolism study of $^{14}C$-bensulfuron were conducted to determine selectivity and herbicidal action of bensulfuron in two rice cultivars and three paddy weeds at different temperatures. 1. Absorption of $^{14}C$-bensulfuron was greater at 30/$25^{\circ}C$ than at 25/$20^{\circ}C$ and also in cv. Sangpung than in cv. Samgang, and Cyperus serotinus and Sagittaria pygmaea showed greater amount of absorption than Echinochloa crus-galli. 2. Translocation rate of bensulfuron was higher at 30/$25^{\circ}C$ than at 25/$20^{\circ}C$ and also in cv. Sangpung than in cv. Samgang, and C. serotinus showed highest translocation rate followed by the S. pygmaea and E. crus-galli. 3. In metabolism study, concentration of parent compound in rice plants was greater in cv. Sangpung which was susceptible to bensulfuron than in cv. Samgang. More amount of parent compound was distributed in shoots and root of C. serotinus and S. pygmaea than E. crus-galli. 4. It may suggested that sensitivity to bensulfuron between rice cultivars may be due to different inactivation metabolic ability and phytotoxicity of rice increased at high temperature since higher amount of bensulfuron was absorbed. Higher herbicidal activity of bensulfuron may caused by higher absorption and translocation in three weed species at high temperature.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.34-41
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• 1994

To better understand the allelopathic effect of sorghum(Sorghum vulgare L.), the inhibitory activities of water extracts of the stem, leaf and root, and of residues of the stem to major crops and weeds associated with them were evaluated. The allelopathic activity of sorghum plants was species specific, and depended on source and concentration. Germination, and shoot and root length of all test species were inhibited by the different concentrations of the stem extract. Among the crop species, radish showed the most inhibition, followed by wheat and rice. Maize was the least sensitive species. Of the weed species, Ipomoea triloba was most inhibited, followed by Echinochloa colona and Rottboellia cochinchinensis. The water extracts of leaves, stems, and roots significantly inhibited germination and seedling growth in E. colona and radish. The stem extract gave the greatest inhibitory effect on E. colona while all three extracts produced similar response in radish. In the greenhouse trial, sorghum stem residue placed on the soil surface as mulch significantly inhibited seedling growth in E. colona and radish, but not that in rice.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.71-75
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• 2015

Playground is frequently used for physical and sports activity by students as well as by common people, which is constructed with various cover materials on the ground. This research surveyed the surface temperature in Kyungpook National University Sangju campus playground which is covered with various cover materials [bare field, zoysiagrass (Zoysia japonica) turf field, urethane track, concrete field, epoxy field and artificial turf field] in Sangju, Gyeongsangbukdo, Korea. Temperature was measured 4 times per day at 09:00, 12:00, 15:00, and 18:00 from May to October 2014 in surface and 1 m height above the ground. Surface temperature was different, depending on cover materials and survey time. Bare field and zoysiagrass turf field was lower surface temperature than other sites. Higher surface temperature site was different depending on survey time. Urethane track and artificial turf field was hotter than other sites at 12 and 15 hours, however concrete and epoxy field was hot at 18 hours. One meter above ground temperature was the highest in artificial turf field except at 18 hours. So natural turf, zoysiagrass playground will increase the athletic performance by reduce the surface and above ground temperature.

• Korean Journal of Weed Science
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• v.6 no.2
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• pp.162-167
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• 1986

This experiment was conducted to determine the effect of light, organophosphorus compounds and plant growth regulators on phytotoxicity of pendimethalin (3,4-dimethyl-2,6-dinitro-N-1-ethyl propylamine) in rice (Oryza saliva L.). The phytotoxicity of pendimethalin on post-germination growth of rice was greatly reduced by light treatment. This effect resulted from photodecomposition of pendimethalin. Antidoting activity on phytotoxicity of pendimethalin varied with the kind of organophosphorus compounds used and the application time. The greatest antidoting effect was obtained from edifenphos (0-3thy1 S,S-diphenylphosphorothioate). However, the effect was not observed when edifenphos was applied prior to pendimethalin. There was no antidoting effect of indole acetic acid (IAA), gibberellic acid ($GA_3$) and kinetin used alone, but combinations of 3 ppmw IAA + either 3 or 5 ppmw $GA_3$ and 1 ppmw kinetin + 10 ppmw $GA_3$ reduced the phytotoxicity of pendimethalin.