• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.310-318
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• 1983

Four methods of vegetation analysis were compared to determine the most suitable method to use in transplanted rice. The highest number of weed species, 14 was obtained with the list quadrat method while the least number, 8 was obtained with the line intercept method. The clip quadrat method tended to overestimate weed species with a low moisture content such as Sagittaria trifolia L. and Ludwigia prostrata Roxb while for the list quadrat method, weed species with a high moisture content such as Sagittaria pygmaea Miq. and Monochoria vaginalis (Burm. f) Pres 1 were overestimated. With the line intercept method, weed species having conspicuous leaf blades such as S. trifolia and Potamogeton distinctus Benn. were dominant. Of the methods tested, the line intercept method was the least desirable because it accounted for the least number of weed species. Any of the others could be use for vegetation analysis without any significant problems arising. However, preference was given to the point quadrat method because of the ease of measurement. It was also less tedious and less time consuming than the other methods.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.159-166
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• 1991

Seven oxyfluorfen formulations were tested for control of 8 weed species and rice injury under four different water depths with various ages of rice seedlings. Among formulations tested, rice injury was slight by formulations of Elvan, Coal Slag, Chitosan and Bentonite B under 0 cm or shallow water depths, and by those of Elvan and Coal Slag under deep water conditions. Weed control was high by Bentonite A and B, and Chitosan, and was low by Elvan. Coal Slag and Sand coated oxyfluorfen, if the target weeds of oxyfluorfen are annual species, further development of Elvan, coal slag, chitosan and Bentonite A would be controlled to increase control efficacy or to decrease rice injury.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.311-316
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• 2013

This study was conducted to evaluate the efficacy of two different formulations and application timings of benzobicyclon+penoxsulam+pyrzaosulfuron-ethyl (BPP) in rice field. BPP granule (GR) and tablet (TB) controlled more than 90% of four weed species 10 and 15 days after sowing in direct seeding when compared with untreated control. BPP TB was highly effective to control herbicide resistant Scirpus juncoides and Monochoria vaginalis both 10 and 15 days after transplanting (DAT). BPP GR controlled 94.0 and 96.5% of S. juncoides and M. vaginalis, respectively 10 DAT, but its efficacy decreased to 88.5 and 49.8% respectively 15 DAT. When compared with untreated control, no visual injuries were detected at 255 and 510 g a.i./ha of BPP. The yield of rice increased in both BPP GR and TB in transplanting and direct seeding rice cultivation when compared with untreated control. Based on these data, early application (10 DAT) of BPP GR and TB can be applied to provide effective weed control, especially in the field infested with herbicide resistant weed species.

• The Plant Pathology Journal
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• v.21 no.1
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• pp.77-82
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• 2005

A summer annual weed of monochoria (Monochoria vaginalis) grows in the edges of rice paddies, ditches, and moist upland throughout Korea. It is very difficult to control with herbicide because of its sulfonylurea resistance. It is very competitive with fast growing pattern, that can cause reducing yields of rice. Brown leaf blight of monochoria (Monochoria vaginalis) occurred naturally in rice paddy, is first reported in Korea. The fungal isolate BWC01-54 was successfully isolated from the diseased leaves of monochoria. The fungus BWC 01-54 was grown well at $25-28^{\circ}C$, conidia of the greysh black brown mycelia were abundant produced on PDA at 15 days. The fungus was grown well in potato dextrose broth at $28^{\circ}C$ and fully grown within 10 days in 250 ml of flask. In host and pathogenicity test, conidia suspension of BWC01-54 was the most effective to control of monochoria compare to others isolates. Typical symptoms having pin point brown lesions were formed on stem and leaf and which severely affected the whole plants ware blighted within two weeks, respectively. Under paddies field condition, conidial suspension of the fungus BWC01-54 gave around 90% control. Therefore, we conclude that the fungus may have a potential as a biological control agent against sulfonylurea resistance weed in rice paddy.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.375-381
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• 1997

When the rice straw mulched, the inhibition of weed growth was observed in the paddy field. If we use these allelopathic effect of decreased weed establishment, we can save labor, and protect environment. Aqueous extract of rice straw were bioassayed using water foxtail seeds to investigate chair effects on the germination and the growth, and to identify allelopathic compounds. The major results obtained were summarized as follows : Aqueous extract was fractioned by solvent, among various fractions, II-3, II-4 fractions inhibited the coleoptile and the radical of water foxtail, by 100%, respectively. There were fumaric acid and 4 unknown organic acids. Seven organic acids including fumaric acid inhibited the growth and germination of water foxtail in $10^{-2}$M solution. One of the most effective allelopathic compounds in rice straw was identified the unknown organic acid, as molecular weight 253, by GC/MS.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.28-35
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• 1998

Cyhalofop/bentazon ME and pyribenzoxim EC herbicides were originally developed as foliarapplied herbicides to control weeds at 4-5 leaf stages of barnyard grass 20-25 days after seeding (DAS) in direct-seeding culture but further possible utilization of these two herbicides earlier than 3-4 leaf stages of rice were evaluated for a field where early weed infestations might be severe. The application of cyhalofop/bentazon ME and pyribenzoxim EC at right after rice emergence and the 2-3 leaf stages of rice had an excellent weed control efficacy with above 90% up to 30 DAS without a phytotoxicity of rice plant and the control efficacy of over 80% was maintained until 60 DAS. However, these two herbicides controlled Echinochloa crus-galli very effectively above 97% but Aneilema keisak and Aeschynomene indica were not controlled by cyhalofop/bentazon ME and Cyperus serotinus by pyribenzoxim EC. Therefore, to control those problem weeds, second systematic application of pyribenzoxim EC and pyrazosulfuron/mefenacet G for A. keisak and A. indica, and pyrazosulfuron/molinate G, cyhalofap/ azimsulfuron/molinate G, pyrazosulfuron/mefenacet G and bentazon SL for C. serotinus at 30 DAS was found to be very efficient herbicide systems.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.7-12
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• 1982

The experiment was studied to know the competitive ability of rice against weeds as affected by rice maturity and plant spacing. For both cultivars, Tongil (12 days later) and Yeongnamjosaeng, the least amount of weed was obtained from the 10 ${\times}$ 10cm plant spacing while no difference between 40 ${\times}$ (10 ${\times}$ 10cm) and 30 ${\times}$ 15cm plant spacings was observed. When weed was nor pulled out by hand, significant yield loss was resulted in 30 ${\times}$ 15cm and 40 ${\times}$ (10 ${\times}$ 10cm) plant spacings while no difference between weeding regime was observed at the 10 ${\times}$ 10cm plant spacing in both cultivars. Rice grain yield was unaffected by plant spacing for hand weeded plot in both rice cultivars. For noweeding plot, however, the highest grain yield was obtained from 10 ${\times}$10cm plant spacing and also this yield was not significantly different from the yield of hand weeded plot while significant yield loss was recognized at the 30 ${\times}$ 15cm and 40 ${\times}$ (10 ${\times}$ 10cm) plant spacings in noweeding plot. There was also a good relationship between weed weight and grain yield for both cultivars (Tongil; Y = 5.68 - 0.0127 X, r = -0.814$^*$; Yeongnamjosaengv Y = 5.04 - 0.0314 X, r =-0.9704$^{**}$). Based on these relationship, weed weight of 188.2g/sq.m for Yeongnamjosaeng and 223.6g/sq.m for Tongil was needed to reduce rice yield by 50%, respectively. This result implied that Tongil compete more efficiently against weed than Yeongnamjosaeng and hence, could be concluded that late maturing cultivar was more competitive against weed compared to early maturing cultivar.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.360-367
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• 2011

The use of green manure crop is one of the methods for alternative of chemical fertilizer as well as maintain of soil sustainability, therefore we evaluated the effect of green manure crops on rice growth and weed occurrence in rice-green manure crop double cropping system. The treatments consisted of incorporation of hairy vetch, barley or combined hairy vetch and barley without any agrochemical or fertilizer. In hand weeding, rice yield in hairy vetch only or hairy vetch and barley incorporated fields was attained by 90% and 93% of the conventional practice, respectively, while the value in barley incorporated fields was just 79%. Although the rice yields were lower than the hand weed control, similar trends in non-weed control were observed among all treatments. At maximum tillering stage, occurred weeds in hairy vetch, barley or hairy vetch and barley incorporated fields were five, five and two species, respectively, while those in conventional practice were six species. Also, the dry weight of weeds in hairy vetch and barley incorporated fields was decreased by 33% and 53% compared to it of conventional practice, while the value in hairy vetch and barley incorporated field was increased by 34%. Among all treatments, although occurrence density of Echinochloa crus-galli was lower than another weed species, the dry weight of it significantly increased. These results suggested that although continuous incorporation of proper amount of legume green manure crops was possible to productivity insurance of crop, but to attain it was essential to the effective management of weeds.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.310-313
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• 1997

The seedling of barley and weed would be generally inhibited by rice straw residues in the field. This experiment was carried out to investigate the allelopathic effects of rice straw and environmental conditions of germination such as osmotic potential, pH on the seedling of barley and water foxtail. The pH did not affect the germination of barley and water foxtail. Osmotic potential to -2.9bar, -0.6bar did not affect the germination of barley and water foxtail, respectively. Rice straw mixed with soil at the concentration of 4%(w/w) reduced the dry weight of shoot and root, and volume of barley root, as compared to the untreated control. Dry weight of water foxtail by rice straw mulching was decreased by 87.1%, 86.2%, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.185-185
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• 2017

In previously study, we evaluated seed germination for longevity derived from a cross between 'Ilmi' and 'Dharial', a weed rice collected in Bangladesh. The strong germination trait originated from 'Dharial' was incorporated into 'Ilmi', through backcross method. The germination ratio was evaluated after two years of room temperature storage conditions. A high germination ratio of 80.5% in donor plant of 'Dharial' and 77.3% in an introgression lines was observed based on the two years of storage while the recurrent japonica cultivars, 'Ilmi' was failed in germination. In this study, we investigate changes in physicochemical properties of 'Ilmi' and introgression lines (ILs) stored at room temperature. We analyzed germination rate, texture of cooked rice, toyo glossiness value, pasting properties, amylose content, protein content and ${\alpha}-amylase$ content of 'Ilmi' and 5 introgressions every 4 months on the room temperature condition. Seed germinations were decreased by storage periods. Three ILs germination rate was slowly decreased more than 'Ilmi' and 2 another ILs after 4 months. Toyo glossiness value of 'Ilmi' and three ILs were no difference, but, 2 ILs gradually decreased every 4 months at storage periods. Pasting properties were affected by storage temperatures and periods of 'Ilmi' and ILs. The increase at breakdown was observed but setback was decreased by storage periods. Amylose content and protein content were no significant difference at storage periods, respectively. The ${\alpha}-amylase$ content was gradually increased during the storage periods. The introgression line could be useful to increase longevity and maintain quality during storage of japonica rice seed.