• Korean Journal of Weed Science
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• v.15 no.4
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• pp.305-312
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• 1995

Weed communities in the dry-direct seeded rice(Oryza sativa L.), soybean(Glycine max(L.) Merr.), and dry-direct seeded rice-soybean rotation system from the transplanted rice field were investigated in order to identify a change in weed species by paddy-upland rotation. Echinochloa species was the most dominant species in the dry-direct seeded rice and their great increase was observed in the continued practices of dry-direct seeded rice. Echinochloa spp., Chenopodium ficifolium, and Digitaria spp. were identified as the major weeds in soybean cultivation in paddy field. Practice of soybean rotation in the dry-seeded rice reduced weed occurrence, particularly at the soybean after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr soybean compared to the continued cultures of rice or soybean. In addition, cultivation of dry-direct seeded rice or soybean culture in the paddy rice field seemed to be helpful for suppression of perennial weeds(Eleocharis kuroguwai, Cyperus serotinus, Scirpus juncoides) and aquatic weeds(Monochoria vaginalis, Sagittaria spp. Potamogeton distinctus).

• Journal of agriculture & life science
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• v.50 no.4
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• pp.59-71
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• 2016

The occurrence and growth of grass and sedge weed species were investigated in the transplanted rice fields that have different transplanting dates from Apr. 30 to Jun 19 with 10-day interval. The growth and yield of rice plant grown without weed control examined in each plot that has different transplanting dates. Both grass and sedge weeds showed greater plant numbers in the early transplanted plots(Apr. 30 and May 10) than late transplanted plots. Based on the occurring number and dry weight of weeds, the experimental plots were classified into two groups, early group and late group. Weed occurrence and growth were not dramatically different within a group even the occurrence was enhanced as delayed transplanting. Echinochloa spp. that was the most problematic weed showed higher dry weight in early-transplanted field until July, however, the greater dry weight was observed in the late-transplanted plots after August. Sedge weeds including Eleocharis kuroguwai and Scirpus juincoides showed persistently higher value of dry weight in early-transplanted plots than late plots over the experimental period. As the puddling was conducted earlier, emergences of grass and sedge weeds were occurred early and weed growth rate became greater. Therefore, growth and yield of rice that transplanted early decreased more strongly due to the strong suppression by grass and sedge weeds showing the enhanced weed growth rates in early-transplanted plots. Based on the weed growth rate, the adverse effects of grass weeds was maintained for longer period than sedge weeds that showed higher growth rates before heading date of rice plant.

• Weed & Turfgrass Science
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• v.4 no.3
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• pp.159-175
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• 2015

Surveys of weed species on upland fields were conducted in Korea to investigate the occurrence of weed flora from April to May 2014 for winter crop fields and from July to August 2014 for summer crop fields. From the nation-wide survey, 375 weed species in 50 families were identified and classified to 162 annuals, 78 biennials and 135 perennials. Based on the occurrence ratio, the most weed species belonged to Compositae (73 species). 44 and 25 weed species belonged to Poaceae and Polygonaceae, respectively, and these 183 weed species in the most five families accounted for 49% of total weed occurrence. While 287 weed species in 45 families occurred in the winter crop fields, 339 weed species in 47 families occurred in summer crop fields. The most dominant weed species in Korean upland fields were Digitaria ciliaris, followed by Portulaca oleracea, Acalypha australis, Chenopodium album, Rorippa palustris etc. 129 weed species in 25 families were considered as exotic weeds. Based on the importance analysis, the highest value was C. album followed by Amaranthus lividus, Conyza canadensis etc. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in upland fields of Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.80-84
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• 2002

In spite of simple and cheap cultivation method, water broadcast-seeded rice demonstrates uneven and unstable seedling establishment per unit land area and requires more herbicide and labor-input for weed control. Three experiments were conducted in a phytotron at 18$^{\circ}C$ to evaluate the adaptability of seed-mat mulching cultivation technologies in water seeded rice for the uniform seedling establishment and the inhibition of weed occurrence without herbicide application. Five different kinds of mat with different mesh sizes and fabric properties were tested. The emergence of rice was the highest in Lawn-mat treatment, being comparable with the control, in which seeds were sown without mat. The Lawn-mat also exhibited the lowest mat tension. Mat tension may influence the emergence of rice. And once it was soaked in water, it didn't maintain its original shape any more. The emergence rate of rice was the lowest in Safer-mat treatment. In Lawn-mat treatment, which was the most effective for rice emergence in the first study, the differences of emergence and seedling establishment of rice depending on the seeding position (upper, beneath, and between mats) treatments were negligible, while they were higher in dry seeds than in pre-germinated seeds treatment. The emergence as affected by the kinds of mat also showed the same trend when tested using barnyard grass. Depending on the kinds of mat, the inhibition effect of weeds was the greatest in Safer-mat and the poorest in Lawn-mat. These results strongly suggest the possibility that the uniform seedling establishment and weed management without chemical could be achieved simultaneously by seed-mat mulching through the combination of effective mat for the emergence of rice and another efficient mat for the inhibition of weed occurrence. This possibility was also tested in the field.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.78-85
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• 2014

The survey of weed occurrence was conducted to identify dominant weed species in the paddy field. Total 346 sites of the 12 regions in Chungbuk Province in Korea were investigated in July, 2013. Weed flora was composed of 43 species belonged to 15 families. The compositions of major plant families, Cyperaces, Poaceae, Pontederiaceae and Asteraceae, were 21.5, 17.4, 15.5 and 12.7%, respectively. Based on life cycle, weed species was grouped into annuals of 71.3 and perennials of 28.1%. The most dominant weed species in paddy fields of Chungbuk Province were Monochoria vaginalis (14.5%), followed by Scirpus juncoides (10.5%), Echinochloa oryzoides (9.3%), Eleocharis kuroguwai (7.0%), Aeschynomene indica (6.2%) et al. The similarity of paddy weeds in 12 regions observed through TWINSPAN analysis was distinguished by Persicaria longiseta, Aneilema keisak, Persicaria thunbergii, Fimbristylis millacea, Blyxa japonica, Digitaria ciliaris, Potamogeton distinctus, Cyperus nipponicus. This information could be useful for estimation of future weed occurrence and establishment of weed control methods in chungbuk province in Korea.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.139-146
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• 1997

The experiment was conducted at Gyeongbuk Provincial Rural Development Administration in 1996 to obtain basic information on weed ecology and effective weed control in direct-seeded rice fields under different seeding types and seeding times. A large number of upland weeds such as Echinochloa crus-galli, Digitaria sanguinalis, Capsella bursa-pastoris and Stetaria viridis etc occurred at early growth stage, while Eleocharis kuroguwai, Aneilema keisak and Cyperus serotinus dominated at late stage in dry seeded rice field. In wet seeded rice field, the dominance of E. crus-galli was lower and the occurrence of M. vaginalis and A. keisak were higher than in dry seeded field. Amount of weed occurrence in dry seeded field was 1.8 to 2.4 times greater than in wet seeded field and it increased with delaying seeding time. Increasing rate of weed occurrence through whole life cycle was the highest at 20 days after seeding (DAS) to 40 DAS, regardless of seeding types and seeding times. Simpson index in wet seeded field was higher than in dry seeded field and it gradually increased as growing of dominant species. For F-value test, it was recognized as statistical significant in seeding types, seeding times and interaction of two factors.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.114-121
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• 1993

Differences in need occurrence and competition were investigated among five types of rice(Oryza sativa L.) cultivation. Dry weights of weeds in between transplanting and/or seeding and heading date showed in the decreasing order of dry direct-seeded, flood direct-seeded, machine transplanting with 10-day-old seedling, machine transplanting with 30-day-old seedling, and conventional hand transplanting. A similar trend was obtained with application of weedy followed by weed-free. Weed-free periods allowed to decrease by 20% dry weight of rice were 3 weeks after transplanting(WAT) in transplanting cultivations, 5 weeks after seeding(WAS) in wet direct-seeded rice, and 7-8 WAS in dry direct-seeded rice. On the other hand, weedy periods as determined by the same criterion were 9 WAT in conventional hand transplanting and machine transplanting with 30-day-old seedling, 7 WAT in machine transplanting with 10-day-old seedling, 8 WAS in dry direct-seeded rice, and 6 WAS in flood direct-seeded rice.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.313-320
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• 1995

The major weeds observed in soybean(Glycine max(L.) Merr.) culture at the paddy field where transplanted rice was cultivated in previous year were Digitaria spp., Echinochloa spp., Chenopodium ficifolium, Rorippa islandica and Stellaria alsine. C. ficifolium and R. islandica increased as soybean was cultivated for two years in the same field. Weed biomass decreased by 84.8% as the seeding date was delayed from April 26 to May 20. Most of weeds started to emerge from 20 days after seeding(DAS) until 40 DAS, and higher seed yield was obtained by eliminating the weeds emerged until 40 DAS. The development of soybean branches, pods stem diameter was severely injured by weed interference, and thus soybean seed yield was reduced by 70% in comparison with a full season weed free plot. Herbicides such as pendimethalin, metolachlor, metolachlor+prometryn and alachlor controlled very effectively weeds present in soybean culture in rice-soybean rotated paddy field.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.356-363
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• 1998

In general weed vegetation analysis has been applied to the study of weed population shift. However, it is a limited tool for understanding a problem region and a specific weed species in a certain area. Recently GIS may be used as an important tool to solve this target or to conduct specific field analysis which enables to introduce a reasonable management strategy. Thus, the GIS study was carried out to understand an integrated weed population changes between 1981 and 1992 in Korea. The nationwide weed survey was performed through the whole rice paddy fields in 1981 and 1992. Weed occurrence was totally different over whole country based on these data. In 1981 a region with high weed occurrence was at western and central areas of Korea in terms of weed population density but this was changed into western and southern area in 1992. In both years there were high weed population density at Taean, Seosan county of Chungnam province in Korea. Thus, this particular area may be needed to introduce a special strategy to reduce weed population density and/or to control problem weed species.

• Weed & Turfgrass Science
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• v.4 no.3
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• pp.199-208
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• 2015

This study was conducted to provide basic information for weed control by surveying the occurrence of weed species in upland crop fields in Gyeongnam province of Korea. The result of this survey, 55 weed species 21 families in barley fields, 56 weed species 22 families in garlic fields, 47 weed species 19 families in onion fields, 68 weed species 26 families in Chinese cabbage fields, 54 weed species 22 families in potato fields, 62 weed species 25 families in sweet potato fields, 87 weed species 29 families in red pepper fields, 79 weed species 28 families in corn fields, 84 weed species 29 families in soybean fields. The most dominant weed species in upland crop fields of Gyeongnam province were Alopecurus aequalis var. amurensis 20.7% (barley fields), Cardamine flexuosa 12.3% (garlic fields), Chenopodium ficifolium 18.7% (onion fields), Portulaca oleracea 8.1% (Chinese cabbage fields), Chenopodium ficifolium 13% (potato fields), Digitaria ciliaris 12.6% (sweet potato fields and red pepper fields) and Digitaria ciliaris 11.3% (corn fields), 13.2% (soybean fields). This information could be useful for establishment of future weed control methods in Gyeongnam province.