• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.4
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• pp.17-27
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• 1980

All types of weed community became dominant by Monochoria vaginalis (Burm.) Presl. as the nitrogen level increased. The importance value (IV.) of M vaginalis rapidly increased with increasing nitrogen level whereas the LV. of other weed species decreased. At the 10 $\times$ 10cm plant spacing, M. vaginalis was almost totally suppressed at all nitrogen levels. At the 20 $\times$ 20cm plant spacing, the degree of suppression declined with increasing nitrogen level. At the 30 $\times$ 30cm plant spacing, there was no suppression of M vaginalis at the highest nitrogen level. The yield obtained at the 10 $\times$ 10cm plant spacing when M. vaginalis was present was not significantly different from that obtained from the weed free plot for all rice cultivars while it was significantly reduced by M vaginalis competition at the 20 $\times$ 20cm and 30 $\times$ 30cm plant spacings. The difference in yield caused by M vaginalis competition was primarily due to a reduction in the number of panicles at all nitrogen levels. There was a high negative correlation between grain yield and weed weight at heading. The yield reduction due to weed competition varied depending upon the nitrogen level.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.111-119
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• 2018

This study was carried out to investigate the differences in germination and growth of Quamoclit coccinea Moench under various temperatures, seeding depths, and levels of shading and soil moisture for effective weed management. Seed dormancy of Q. coccinea Moench was over 1 year; best results were obtained when seeds were soaked in sulfuric acid for 15 minutes in order to break the dormancy. Germination rates of Q. coccinea Moench ranged from 69 to 73% at $25-35^{\circ}C$ and 26% at $15^{\circ}C$. The germination rates ranged from 70-84% at 2, 3, 5, 7, and 8 cm of seeding depths. In addition, the germination rates were 7% and 13% at 12 cm and 15 cm of seeding depths, respectively, and showed normal growth at the both seeding depths. Q. coccinea Moench showed a high germination rate regardless of shading levels, but shoot fresh weight varied depending on the level of shading as follows: 20%>no shading=shading 35%>shading 50%>shading 75%=shading 90%. Q. coccinea Moench did not germinate when soil had a saturation rate of either 30% or 100%. However, 60-83% of seeds germinated with optimal growth when soil had saturation rates of 60% and 80%.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.78-83
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• 1981

This study was attempted to determine the major weed species occurring in Korean turfgrass, Zoysia japonica Steud. and to evaluate the most effective means for controlling them. More or less 40 weed species were determined to occur in Korean turfgrass. In terms of quantity and frequency of occurrence, Trifolium repens L., Digitaria sanguinalis (L.) Scop., Draba nemorosa var. hebecarpa Lindbl, Erigeron canadensis L., and Cyperus amuricus Max were observed to be the major weeds. Simpson's index, 0.306 was obtained to be the major weeds. Simpson's index, 0.306 was obtained in the golf course, Jinryang, Gyungsan-gun, meaning that no specific weed species were dominant, but in Kyungpook National University campus, Trifolium repense L. was a single dominant species, indicating Simpson's index, 0.776. The most effective herbicides to control Trifolium repense L. and other broad leaf weeds were MCPP [2-(2-methyl-4-chlorophenoxy) propionic acid), followed by 2,4-D (2,4-dichlolophenoxy acetic acid). Increased rates of both herbicides increased markedly their effectivity against weeds, with very slight injury against turfgrass. MCPP at 2.8 kg(a.i.)/ha gave excellent control without any injury and 2,4-D at 1.0 kg(a.i.)/ha.

• Korean Journal of Weed Science
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• v.9 no.1
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• pp.39-45
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• 1989

An experiment was conducted at the Yeongnam Crop Experiment Station for 4 years from 1985 to understand the effect of repeated use of same herbicide on weed growth. For this, the most common 6 herbicides, butachlor, bifenox, butachlor/pyrazolate, piperophos/dimethametryne, bentazon and propanil were used as single treatment or combination treatment. For non chemical plots, weed occurrence was rapidly increased with time in terms of number and weight. However no rice plot recorded the least increasing ratio. Similar trend was obtained at the herbicide plot even though the increasing ratio varied by herbicide properties. The least increasing ratio (1200 was recorded at the plot of butachlor/pyrazolate (5 days after transplanting, 5 DAT) followed by bentazon+propanil(25 DAT) while the greatest ratio (28%) was obtained from the plot of bifenox (5 DAT). In general, Scirpus hotarui, Eleocharis kuroguwai and Cyperus serotinus was gradually inereased with time by herbicide application, particularly at the butachlor/pyrazolate treatment. The community dominance and simpson index increased at the plot of bentazon and propanil due to increased of particular species while other herbicide plots exhibited reverse trend. Grain yield was curvilinearly decreased with weed weight for both times, 40 DAT and heading time eventhough the correlation coefficient of heading time was higher than 40 DAT.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.291-294
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• 1988

About 136 weed species belonging to 44 families occurring in summer observed in Cheju island. The Compositae was the most widely occurring family covering 29 weed species, followed by 16 species in Graminae, 14 in Leguminosae, 13 in Rosaceae, 10 in Polygonaceae etc., The dominant weed species detected in range areas of Cheju island were Trifolium repens, Botrychium virginianum, Rosa multiflora, Miscanthus sinensis, Imperata cylindrica. The range areas of Cheju island consisted of the communities of Artemisia princeps-Botrychium virginianum, Artemisia princeps-Erigeron borariensis and Dianthus sinensis, and Artemisia-Lespedeza bicolor and Miscanthus sinensis and then the differential species of their communities were Botrychium virginianum, Erigeron boriensis, and Lespedeza bicolor and Miscanthus sinensis, respectively. The species of the high frequencies occurring in investigated sites were Artemisia princeps, Cirsium rhinoceros, Hydrocotyle ramijlora, Rosa multiflora, Sanguisorba officinalis, Rubus crataegifolius, Potentilla fragariodes, Erigeron annus, Plantago asiatica, Oxalis corniculata, Mosla dianthera in order.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.151-155
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• 1983

Photosynthetic activity of two rice varieties "Suweon 318, Nagdongbyeo" and two species of grass weeds, two species of sedge weeds, and four species of broadleaf weeds was measured at 5, 10, 20, 30, 40, 50 Klux light intensity. Relative photosynthetic activity of weed species was high in the decreasing order in Cyperus serotinus, Echinochloa grusgalli var caudata, Bidens tripartita, Monochoria vaginalis, and Ludwigia prostrata, while respiration rate was high in Bidens tripartite, Monochoria vaginalis and Cyperus serotinus. Light saturation point of Monochoria vaginalis and Sagittaria pygrnaea may be considered as at 30 klux and photosynthetic rate of other weed species increased with increasing light intensity. Photosynthetic activity of weed species was generally two times higher than rice at the light intensity of 50 klux and increased more than rice as light intensity increased. Photosynthetic activity per leaf dry weight and specific leaf area was higher in broadleaf weeds than in grass and sedge weed species.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.196-202
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• 2017

This study was conducted to investigate the change of yield and quality according to seeding time and planting density and to determine effective weed control method in wet-hill-seeding use black colored rice. The most effective weed control system was application of bromobutide thiobencarb five days before seeding followed by bensulfuron mefenacet thiobencarb 12 days after seeding (barnyardgrass at 2.5-3.0 leaf stage). The seedling stand by seeding time and planting density increased with the delay seeding time and high planting density. The heading dates were delayed as the seeding time became late but no difference was found between planting density. The anthocyanin content of black colored rice was higher at late seeding time and lower planting density. The yield of full colored rice was high 80 plants per $3.3m^2$ in seeding on May 30 and June 10. This information could be useful for spreading rice direct seeding by inducing stabilization of wet-hill-seeding use black colored rice.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.99-104
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• 1995

This experiment was conducted to evaluate effective weed control in direct-seeded rice under dry fields. The results obtained are as follows. Cyhalofop/bentazone EW and cyhalofop/pendimethalin EC were very effective for the weed control but cyhalofop/cinosulfuron WP and cyhalofop/azimsulfuron SC were tended to exhibit the lower weeding effect. The plant height and the tiller number of rice were not greatly affected by herbicides, but rice yield was greatly influenced by them. The control efficacy was observed the extend of 94% until 60days after seeding under the treatment of systematic herbicides such as foliar applied pendimethalin propanil EC at 15days after seeding mowed by pyrazosulfuron molinate GR at 5days after irrigation. Irrigation at 25days after seeding was able to control annual weeds by the extent of 25% and exhibited control effect of 94% on systematic treatment of herbicides compared with that of 35days after seeding.

• 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.

• 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.