• Korean Journal of Weed Science
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• v.16 no.2
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• pp.81-87
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• 1996

Seeds of rice, cv. Ilpoom, and barnyardgrasses(Echinochloa crus-galli, vars. oryzicola, crux-galli, and praticola) were sown for a characterization of their responses to temperature during emergence under a dry direct-seeded condition. A laboratory-made aluminum block apparatus for emergence-temperature control conferred a linear continuous temperature gradient from 10 to $30^{\circ}C$ to the seeds from cooling to heating ends of the apparatus. The lowest temperature for emergence was $12.3^{\circ}C$ for rice cv. Ilpoom, and $11.0^{\circ}C$ for the three varieties of Echinochloa spp.. Percent emergence of rice increased sharply with an increase in temperature by ca. $20^{\circ}C$, then leveled-off, while those of barnyardgrasses increased almost linearly with temperatures up to $30^{\circ}C$. In rice the time required for emergence after seeding was shortened exponentially with increased temperature while those for barnyardgrasses were shortened almost linearly from 11 to $30^{\circ}C$. The temperature-response characteristic of rice in emergence-speed was almost the same among those for the 1st emergence, emergence by 25, 50, 75%, or average emergence time. At $13^{\circ}C$, $346.7^{\circ}C$ days of accummulated temperature(26.67 days) were required for the 1st emergence in rice while 131.7, 136.0, and $138.7^{\circ}C$ days(10.13, 10.46, and 10.67 days) were required for the 1st emergence in E. spp., vars. crus-galli, praticola, and oryzicola, respectively. Greater cold tolerance and increasingly faster emergence of barnyardgrasses than rice below $20^{\circ}C$ seem to render the barnyardgrasses as much more competitive than rice at lower temperatures.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.116-122
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• 1989

An experiment was carried out at the International Rice Research Institute in 1987 to understand the seed dormancy and germination habit of rice and several weed species. The germinability of the weed seeds just after harvest was variable depending on the species and ranged from 0 to 72%. Two rice cultivars, IR64(lowland type) and UPLRi-5(upland type) had higher than 95% in germination ability throughout the experimental period due to the fact that the rice seeds came from the harvest of the previous season and dormancy had already been overcome. The length of the storage period needed to overcome dormancy at room temperature($25{\pm}2^{\circ}C$) was about 50 days for Echinochloa glabrescens Munro ex Hook, f., more than 60 days for E. crus-galli ssp. hispidula (Retz.) Honda and 20 days for Ludwigia octovalvis(Jacq.) Raven. Seeds of E. colona(L.) Link, Monochoria vaginalis(Burm. f.) Presl, Fimbristylis miliacea(L.) Vahl and Cyperus difformis L. appeared to have no dormancy. Among the nine species M. vaginalis had the lowest germination of less than 1% throughout the experimental period. However, its seed germinated easily when planted in soil. The low germinability of E. glabrescens, E. crus-galli ssp. hispidula and L. octovalvis just after harvest could be overcome through pretreatment of seeds either by soaking in nitric acid(0.1N) for 1 day or removal of the hull in the grass species, the nitric acid treatment being superior. The results imply that germination habit of weed species varied depending on the species through their differential dormancy period or differential germination strategy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.134-139
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• 2011

This study was conducted to evaluate the weed suppressing effects of two winter cover crops, hairy vetch and rye in foxtail millet and sorghum fields in 2010. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In hairy vetch treated plots, heading of minor cereals occurred early. The heading date was earlier by 1 day and 2 days in sorghum and foxtail millet, respectively. However, rye treatment delayed heading by 12 days and 8 days in sorghum and foxtail millet, respectively. Besides he effect of cover crop on ear emergence of crops, the Besides changed growth-related characteristics. Plant height, chlorophyll content and chlorophyll fluorescence of sorghum ere increased in hairy vetch treatment by 46.4% 88.7% and 7.9%, respectively. In foxtail millet, the characteristics ere also increased by 45.6%, 50.9% and 37.8%, respectively, s compared to control. Yields of sorghum and foxtail millet were increased by 105.1% and 135% as compared o control by hairy vetch treatment, respectively. However, he yields of cereal crops were decreased by rye cover crop treatment, the yields of sorghum and foxtail millet were decreased by 25.8% and 119.1%, respectively. Rye cover crop treatment inhibited crop growth suggesting nitrogen starvation in rye treated plots. In rye treatment, plant height, chlorophyll contents and chlorophyll fluorescence of sorghum ere slightly decreased by 7.1%, 10.8% and 10.8%, respectively, as compared to control whereas the inhibitory effects were greater in foxtail millet. Weed occurrences based n weed number in hairy vetch and rye plots were reduced n weed number in hairy vetch and rye plots were reduced y 27% and 20%, respectively. The smothering effect was weakened or disappeared after heading of crops. Weed number and dry weight in hairy vetch plot were increased by 159% and 55.2%, respectively, as compared to control. The results implied that weed suppressing of cover crops could be reduced drastically after heading of crops.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.489-495
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• 1996

Seedling emergences of four rice varieties (Dongjinbyeo, Dadajo, Galsaekggarak-sharebyeo, and Italiconaverneco) and three barnyardgrass species(Echjnochloa oryzjcola, E. crus-gali var. crus gali E. crus-gali var. praticola) were evaluated in relation to soil strength. Soil strength was varied by compressing the entire volume of soil with a hydraulic jack so as to be 0.5, 1, 2, 3, 6kg /$\textrm{cm}^2$. Soil strength was measured with a penetrometer (Yamanaka type) and soil covering above the seed was 4cm deep. Experiments were conducted at two air temperature conditions of 17 and $25^{\circ}C$. At a soil strength of up to 2kg/$\textrm{cm}^2$, little or no decrease in seedling emergence occurred in all rice varieties and barnyardgrasses tested. Above that value, seedling emergence decreased progressively as the soil strength increased. The degree of decrease was greatest in Dongjinbyeo and smallest in Dadajo among tested rice varieties, and greatest in Echinochloa oryzicola among barnyardgrasses, being greater in barnyardgrasses than rice. Seedling emergence was delayed almost linearly as the soil strength increased. The delay was greatest in Dongjinbyeo among rice varieties and in Echinochloa oryzicola among barnyardgrasses. Mesocotyl length increased as soil strength increased up to 2 to 3kg / $\textrm{cm}^2$ in Dongjinbyeo and Dadajo in 17$^{\circ}C$ and $25^{\circ}C$, and up to 6kg/$\textrm{cm}^2$ in Galsaekggaraksharebyeo and Italiconaverneco in $25^{\circ}C$. Dongjinbyeo showed the least elongation of mesocotyl among rice varieties in any soil strength. The total length of mesotyl, first internode and incomplete leaf showed little variation with soil strength. The total length was longer than the 4cm covering depth in other varieties except Dongjinbyeo. This might have caused the lower emergence rate in Dongjinbyeo than other varieties in higher soil strength.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.88-99
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• 1996

In recent years dry direct-seeding of rice has been encouraged by the government and increasingly practiced by farmers in Korea. This has been bringing up an increased occurrence of weedy rites. Some farmers in the southern region dare to sow the rice before winter after harvest, while most farmers wish to sow as early as possible in the spring to secure the growing period, and to disperse the intensive labor in early May. The purpose of this study was to determine the feasibility of moving the sowing of rice to an earlier date under dry direct-seeding, and to elucidate the nature of emergence of an old strain of rice, weedy rites, and barnyardgrasses tinder this farming practice and their adaptive competence over present cultivate. The presently recommended rice cultivar, Dongjinbyo and an old rice strain, Dadajo which prevailed in early 1900s, almost could not emerge from soil deeper than 6cm and could emerge to only 5.3% at best from 1cm deep loamy soil field when the seeds were sown on Nov. 28. However, two strains of weedy rites being weedy for over 200 years emerged by 17.0 to 63.0% from the loamy and sandy clay loam field 1 to 6cm deep. Emergence of the weedy rites was greater in the loamy soil and at a shallow depth, and negligible from the soil depth of 9cm. Barnyardgrasses sown on Nov. 28 emerged by 13.4 to 51 % from the 1 to 3cm deep loamy soil, and 8.6 to 46.7% from the 1cm deep sandy clay loam. Echinochloa crus-galli var. crus-galli emerged more than var. praticola, and var. oryzicola least. Most of the non-emerged barnyardgrasses seem to have entered secondary dormancy. Seeding rice a month earlier than the season lowered the emergence of Dongjinbyo by ca. 10, 18, and 26%, respectively at 1, 3, and 6cm soil depths, indicating that moving the seeding date a month earlier is impractical. The old strain, Dadajo sown in the soil at a depth of 6cm responded similarly. However, the strain has shown a significantly higher ability in emergence from 9cm deep soil. Weedy rices sown a month earlier A month earlier sown weedy rices have shown very similar emergence rates at various soil depths to those sown on May 1. Barnyardgrasses have also shown similar emergence rates when sown between April 3 and May 1. Like barnyardgrasses, the old strain and weedy rices apparantly posessed a greater adaptability to emerge under lower temperatures, and from deeper soil ; Dongjinbyo${\leq}$ Echinochloa species in that order. However, emergence- speed under lower temperature(sown on April 3) was faster in the order of weedy rice

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.276-283
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• 2014

This study was conducted in order to investigate the distribution pattern of weeds on upland crop field in northern Gyeonggi-do. The weeds were summarized as 201 taxa including 42 families, 129 genera, 178 species, 1 subspecies, 21 varieties and 1 form. One hundred and thirty one species were classified to annual plants, accounting for 65.1% and 70 species were classified to perennials, accounting for the rest of 34.9%. Compositae was dominant family (21%), followed by Gramineae (12%), Polygonaceae (7%) and Brassicaceae (5%). Among the weeds appearing in the fields of northern Gyeonggi-do, the invasive weeds were classified to 62 species in18 families. The most dominant weed species in the fields were Portulaca oleracea, followed by Echinochloa crus-galli, Amaranthus lividus. Detrended correspondence analysis for investigation of occurrence pattern of weeds by crops revealed the occurrence pattern of weed species in adlay field were different from those in other crop fields. This information could be useful for establishment of weed control methods in northern Gyeonggi-do.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.407-414
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• 1999

Distribution of biota and removal efficiency of organic matter in natural wetland systems were examined from June to October 1998. The aquatic macrophyte communities were consisted of 13 families and 22 species. The composition of occurrence species were as follows: Phragmites communis Trinius are 35%, Persicaria thunbergii Nakai are 19%, Typha angustifolia L. are 17%, Bidens tripartita L. are 16%, Echinochloa crus-galli (L.) Beauv. are 12% and others are l％. The fauna collected from 5 sites consisted of total 6 classes of macroinvertebrates. The composition of occurrence classes were as follows: Insecta are 76%, O1igochaeta are 19%, Gastrapoda are 4％ and others are 1%. These included 18 families, 7 orders of Insects. The larve and mosquito and midges were found in wetlands. Preventive strategies are needed for the suppression of mosquito at the stage of wetland planning and design. In wetland, removal efficiency of dissolved organic carbon is low because of primary production and the background level of DOC in the wetland discharge seems to be 5 mgC/1, but those of BOD was ca. 50%. Wetlands receiving water of low concentration can not work as purification field.

• The Korean Journal of Ecology
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• v.28 no.5
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• pp.271-279
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• 2005

Soil seed banks at ecological preservation areas in Seoul, Jinkwannae-dong, Bangi-dong and Bam-sum, were studied by seedling emergence method from May to October 2004. Total number of species and individuals in seed banks were 42 and 5,190 at Jinkwannae-dong, 39 and 2,290 at Bangi-dong, and 39 and 1,047 at Bamsum. Salix koreensis community at Jinkwannae-dong has the highest number of seedlings among all sites. The most abundant species were Lindernia procumbens in Jinkwannae-dong and Bam-sum and Typha spp. in Bangi-dong. The dominant species of seed banks were different from that of plant communities such as Phragmites communis community, Salix koreensis community, Persicaria thunbergii community, Phragmites japonica community, and Populus tomentiglandulosa community. However the dominant species of seed banks in Typha community was Typha spp. Total 63 species emerged in either the wet or submerged conditions. Fifty six species appeared in the wet condition and 25 in the submerged condition. Eighteen species appeared in both conditions. Numbers of species and individuals were much less in the submerged condition than in the wet condition but free-floating hydrophytes including Rorippa islandica and floating-leaved hydrophytes including Monochoria vaginalis appeared only in the submerged condition. In the investigation of soil seed bank by distance from water edge (Bamsum), water side 3 ($300\sim350m$ from water) edge, where water level is fluctuating frequently, has the highest number of seedlings.

• Korean Journal of Plant Taxonomy
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• v.37 no.4
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• pp.545-563
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• 2007

The investigated vascular plants of Dok-do island were confirmed that consisted of 46 species, 1 subspecies, 1 varieties in total of 48 taxa growing spontaneously. 1 taxa of Pteridophyta, 36 taxa of Dicotyledon and 11 taxa of Monocotyledon identified. In 48 identified taxa in this study, total 13 taxa included Orobanche coerulescens Stephan, Fallopia sachalinensis (F. Schmidt) Rouse Decr., Lonicera insularis Nakai identified according to the Korean plant taxa for environmental assessment. Planting species were about 10 taxa included Pinus thunbergii Parl., Hibiscus syriacus L. and etc. Four species confirmed in this study such as between Chenopodium virgatum Thunb. and Chenopodium album L., Echinochloa crusgalli (L.) P.Beauv. and Echinochloa crusgalli var. oryzicola (Vasinger) Ohwi. were doubt on identification in taxonomic entity due to morphological characteristics. The dispersion type of Do-kdo plants were anemochore 31 taxa, zoodchore 8 taxa, hydrochore 2 taxa and the others by artificial means.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.52-58
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• 1997

Rice (Oryza sativa L.) contains water-soluble substances that inhibit the germination of Echinochloa crus-galli. This study investigated the allelopathic potential of rice in which rice had been grown with E. crus-galli in the field. Extracts of forty-seven rice varieties were screened for allelopathic potential in the laboratory. Double distilled water was used as a control. Based on the germination percentage, the varieties may be classified in the following order of decreasing inhibition : Namweon(36%) and Gyehwa(38%) hulls extracts and Sambaeg(43%) and Seoan(46%) leaves extracts. In the comparison of allelopathic activity test between leaves and hulls extracts, hulls extracts contain more allelopathic toxic substances. In the effect of concentration treatment on the six levels of extract solutions(3, 6, 12, 25, 50, 100%, v/v) germination percentage was significantly inhibited as the extract concentration increased. The highest concentration(100%) caused the greatest reduction in E. crus-galli. Allelopathic potential effects were significantly different among the various varieties and between '94 and '95 year extracts. The results indicate that there are genetic differences among varieties for allelopathic potentiality on E. crus-galli. Allelopathic potential in the ecological aspects can be decided through variety selection.