• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.113-117
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• 2014

This study was conducted to evaluate the efficacy of benzobicyclon mixtures by using Remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field. Eight annual weed species including Echinochloa crus-galli L. and three perennial weeds were dominated in the experimental field. Application of benzobicyclon mixtures using RCAA was highly effective to control both annual and perennial weed species. When compared with untreated control, no visual injuries were detected at single and double dosage of benzobicyclon mixtures. Finally, rice yield in the benzobicyclon mixtures was as much as that in the hand weeding. This study indicates that benzobicyclon mixtures using RCAA can be applied to control both annual and perennial weed species in rice paddy field.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.473-476
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• 2012

The experiment was conducted to investigate the herbicidal efficacy of imazosulfuron mefenacet by using remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field. Eight annual weed species including Echinochloa crus-galli L. and three perennial weeds were dominated in the experimental field. Application of imazosulfuron mefenacet using RCAA was highly effective to control both annual and perennial weed species. No phytotoxic effect was observed in the rice based on the plant height and the number of tillers. Finally, rice yield in the imazosulfuron mefenacet treatment was as much as that in the hand weeding. This study indicates that imazosulfuron mefenacet using RCAA can be applied to control both annual and perennial weed species in rice paddy field.

• Spatial Information Research
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• v.3 no.1
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• pp.47-53
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• 1995

The weed survey in lowland rice fields through Korea was conducted in 1992 to determine a change of the weed communities based on different regions, soil types, planting methods, and cultural practices. GIS was applied to identify a spatial analysis of predominant weed species in specific region. On behalf of vegetatine analysis such as absolute and relative density, absolute and relative frequency, importance value, and summed dominance ratio(SDR), there was highly dominant with a perennial weed species, Eleocharis kuroguwai Ohwi over whole country. However, in particular it was most predominant at southem area of Gyunggi province in Korea. Thus, rice farmers of this area have to introduce a specific comperhensive control strategy against this predominant weed species.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.319-322
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• 1983

Species-area and species-quadrat number curves were used to determine the minimum sampling size and the minimum quadrat number for weed data collection in transplanted rice. In both cases, characteristic curves that first increased abruptly and then leveled off as fewer species were added with increased sampling size or quadrat number were obtained. Using these techniques, it was determined that three quadrats each 0.3㎡ (0.5m ${\times}$0.6m) in area were needed to adequately represent the weed community when it was sampled at rice heading.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.41-48
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• 2011

This survey of weed population by different soil moisture with paddy-upland rotation was conducted to investigate information on weed flora and its ecology between two years. Weed species were assessed in April : 2009, 2010. Soil samples were taken from each study plot to assess the impact soil moisture on the occurrence and abundance of dominance weed species. Soil water of poorly drained field ranged from 10.2~18.2% more than 11.8~14.3% of somewhat poorly drained field. Weeds of fields composed of 19 species belonging to 12 families. Among 12 families, 6 weed species belonged to Compositae (31.6%) were the biggest family, Cruciferae were 2 species (10.5%), and Rubiaceae were 2 species (10.5%), respectively. Youngia japonica had the highest summed dominance ratio(SDR) (97.0%) and followed by Conyza canadensis (92.1%), Galium spurium (35.3%) and Hemistepta lyrata (28.4%) of somewhat poorly drainage in 2009. Artemisia princeps the highest SDR (100%) and followed by Stellaria alsine(55.2%), Y. japonica (38.3%) and Nasturtium officinale (28.5%) of poorly drainage in 2009. And, Stellaria alsine had the highest SDR (86.8%) and followed by Alopecurus aequalis (77.7%), Astragalus sinicus (68.7%) and Y. japonica (46.3%) of somewhat poorly drainage in 2010. S. alsine the highest SDR (93.7%) and followed by A. aequalis (78.6%), Nasturtium officinale (31.3%) and Y. japonica (30.4%) of poorly drainage in 2010. Simpson's index was calculated to 0.12~0.23, which showed that weed occurrence with different soil moisture in paddy-upland rotation and between years was various. Similarity coefficient between years was 43.0% (2009) and 74.2% (2010), which indicate a low diversity because of the moisture in the agro-ecosystem.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.295-303
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• 1998

The seed dormancy is one of the peculiar characteristics of a number of weed species and it makes difficulties in weed control. To clarify the mechanism of seed dormancy, several chemicals such as $KNO_3$, KOH, thiourea, and $H_2O_2$ and phytohormone($GA_3$) were treated to dormant seeds. Among the species treated with several chemicals, the germination percentages of Setaria glauca, Ambrosia trifida and Ranunculus sceleratus were increased with $KNO_3$ and those of S. glauca, R sceleratus were increased with thiourea. Hydrogen peroxide promoted the germination of Setaria viridis and S. glauca. Germination percentages of S. viridis, S. glauca and Cyperus saraguinolentus were increased with enzyme treatment using pectinase. GA treatment enhanced the geim.ination of Eleusine indica and R sceleratus but the other species were affected slightly. Especially. E. indica showed linearity in the relationship between germination percentage and GA concentration. So, It seemed that E. indica can be used as a bioassy material for GA. Considering the phenological habits of weed species, the seeds were buried under soil for long time(more than 1 month) over winter. When seeds were buried in soil, the degree of dormancy was drastically decreased. Especially, germination of seeds buried were increased under alternating temperature. The germination rates of Persicaria ssp. and Chenopodium ssp. were increased by 50% order alternating temperature after burial for seven weeks.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.285-294
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• 1994

Dried top and root extracts of seven different weed species, fresh top and root extracts, and various concentrations of extract (0, 5, 10 and 15%, W/V) and residue rate (0.0, 0.25. 0.5, 0.75 and 1.0%) of velvetleaf (Abutilon theophrasti Medic.) were used to study their allelopathic effects on alfalfa in the laboratory and greenhouse. Top and root aqueous extracts of common lambsquarter (Chenopodium album L.), giant foxtail (Setaria faberii Herrm), redroot pig-weed (Amaranthus retroflexus L), velvetleaf, large crabgrass (Digitaria sanguinalis L), canada thistle (Cirsium arvense L.) and prostrate knotweed (Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, and vigor in alfalfa. Top growth extracts of weeds exhibited greater allelopathic effects than root extracts. Alfalfa test species, WL-320, responded significantly different to the various weed species extracts in terms of allelopathic effect. The regression slopes of various top extracts showed significant variation with respect to germination percentage. Velvetleaf (b=3.69) extracts were the most inhibitory, while large crabgrass (b=2.39) extracts had the least allelopathic effect on alfalfa. When compared the activity of fresh velvetleaf extract to that of dry velvetleaf extract, dry extract was more inhibitory to alfalfa germination and seedling growth. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Seedling emergence and survival percentage was inhibited by velvetleaf residue mixture treatment. Also, more of the toxic effects were observed from the dried top extracts, as compared to extracts from fresh top and root. These results demonstrate the allelopathic activity of different weed species extracts and suggest that weeds may affect crop growth and development due to the inhibitory effects of allelochemicals present in weed tissue.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.147-156
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• 1997

The survey of weed population in apple orchard was conducted to investigate basic information on weed flora and its ecology at 27 locations in 1996. The weed species observed include 7 species of grasses, 60 species of broadleaves and 2 species of sedges, and the ratio of annual weed vs perennial weed was 64 : 36. Major dominant weed species by frequence were Chenopodium album, Capsella bursa-pastoris, Digitaria sanguinalis, Rorippa islandica, Alopecurus aequalis and Erigeron canadensis. While, on the basis of dry weight, the most dominant weeds were C. album followed by E. canadensis, A. aequalis, R islandica and R indica. The dominant weed species in middle-north Kyeongbuk region were C. bursa-pastoris, C. album, R indica and R islandica, were E. canadensis, Persicaria hydropiper, A. aequalis and Arenaria serpylliforia in Chungbuk region and were A. aequalis, E. canadenris and R islandica in Honam region.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.120-128
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• 1983

The nationwide survey of weed population covering 1,800 wheat and barley fields in 60 Cities and Guns all around Korea was conducted in December of 1982 and March-April of 1983. In this survey result, two species of gresses and 35 species of broadleaves were identified, and among them 36 and 29 species were found in the wheat and barley fields of upland and paddy, respectively. In the scope of weed life cycle, biennials were more dominant than perennials and annuals in these fields. The most dominant weed species in upland fields were Stellaria media, Cyrillus and Alopecurus aequalis Sobol var. amurensis Ohwi while those in paddy fields were Stellaria alsine Grimm. var. undulata Ohwi and Alopecurus aequalis Sobol var. amurensis Ohwi. In addition, the more weeds were observed in the conventional row seeding method than in other seeding methods including drill seeding and also in no-tillage than in tillage method. In the other hand, the successive use of herbicide for several years greatly influenced the pattern of weed occurrence; broadleaved weeds increased and grasses decreased with the successive use of herbicides.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.3
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• pp.245-250
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• 1991

Analysis of the characteristics and the grouping of the species of sown and weeds in artificial pastures was studied applying the principal component analysis method. Presency and coverage of six sown species and fifteen weed species which occurred in pastures of under-grazing and optimumgrazing were subject to analysis. From field survey, species were divided into three groups: the group A included five species such as Festuca arundinacea, Lolium perenne and Dactylis glomerata, etc., the group B included eleven species such as Polygonum longisetum, Agrostis alba and Rumex obtusifolius, etc., and the group C included five species such as Miscanthus sinensis, Rubus palmatus and Artemisia princeps, etc. The group A species corresponded to good pasture conditions and management. On the contrary, the group C species occurred in poor pasture conditions with inadequate management. The group B species corresponded to intermediate pasture conditions and management. Interrelated pair species co-existing and species non-co-existing were discovered. Factor loading as negative for the group A species. positive for the group C species and positive but lower than the group C species for the group B species. From these results it is concluded that the principal component analysis seems to one of the useful tools for the analysis of characteristics of species and the diagnosis of sown pasture vegetation, although further studies are required to get more general information about species characteristics.