• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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• pp.32-37
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• 1998

The objective of this study was to analyze lodging-related traits using different cultivars from Korea, Japan, and the U.S. in direct seeded rice on dry paddy field. Stem diameter and culm wall thickness were highest in 'Caloro' followed by 'Nongan', 'M202', and 'Calrose'. All the U.S. cultivars were higher than the others in stem diameter and culm wall thickness. These two traits were important with regard to lodging. The highest breaking strength (1442g) was observed in Caloro. 'Gancheoek', 'Dongjin', and transplanted 'Hatsuboshi' showed more than 1000g in breaking strength. Lodging index was lowest in Hatsuboshi followed by Nongan and Gancheok. Even though breaking strength of the U.S. cultivars was higher than others, their lodging index values were high. There were no statistically significant differences in starch content. However, Calrose, Caloro, Dongjin, and Koshihikari were relatively higher than others in starch content. Positive correlations were found between culm base weight, lignin and breaking strength. High contents of lignin and cellulose were observed in Nongan, transplanted Hatsuboshi, Calrose, and Caloro. Traits such as stem diameter, culm wall thickness, bending moment, culm length, breaking strength, cellulose, lignin, and culm base weight were closely related to a lodging index. According to path coefficient analysis, most important traits were culm length, stem diameter, thickness of clum wall, and top plant weight.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.230-235
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• 1999

To study the effects of an urease inhibitor, N-(n-butyl)-thiophosphoric triamide (NBPT), and a nitrification inhibitor, dicyandiamide (DCD), on nitrogen losses and nitrogen use efficiency, urea fertilizer with or without inhibitors and slowrelease fertilizer (synthetic thermoplastic resins coated urea) were applied to direct-seeded flooded rice fields in 1998. In the urea and the urea+DCD treatments, NH$_4$$^{+}$ -N concentrations reached 50 mg N L$^{-1}$ after application. Urea+NBPT and urea+ NBPT+DCD treatments maintained NH$_4$$^{+}$ -N concentrations below 10 mg N L$^{-1}$ in the floodwater, while the slow-release fertilizer application maintained the lowest concentration of NH$_4$$^{+}$ -N in floodwater. The ammonia losses of urea+NBPT and urea+NBPT+DCD treatments were lower than those of urea and urea+DCD treatments during the 30 days after fertilizer application. It was found that N loss due to ammonia volatilization was minimized in the treatments of NBPT with urea and the slow-release fertilizer. The volatile loss of urea+DCD treatment was not significantly different from that of urea surface application. It was found that NBPT delayed urea hydrolysis and then decreased losses due to ammonia volatilization. DCD, a nitrification inhibitor, had no significant effect on ammonia loss under flooded conditions. The slow-release fertilizer application reduced ammonia volatilization loss most effectively. As N0$_3$$^{[-10]}$ -N concentrations in the soil water indicated that leaching losses of N were negligible, DCD was not effective in inhibiting nitrification in the flooded soil. The amount of N in plants was especially low in the slow-release fertilizer treatment during the early growth stage for 15 days after fertilization. The amount of N in the rice plants, however, was higher in the slow-release fertilizer treatment than in other treatments at harvest. Grain yields in the treatments of slow-release fertilizer, urea+NBPT+ DCD and urea+NBPT were significantly higher than those in the treatments of urea and urea+DCD. NBPT treatment with urea and the slow-release fertilizer application were effective in both reducing nitrogen losses and increasing grain yield by improving N use efficiency in direct-seeded flooded rice field.field.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.278-288
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• 1995

Weed species occurred in dry- and water-seeded rice were 14 (2 grasses, 8 broadleaves, and 4 sedges) and 12 species (1 grasses, 7 broadleaves, and 4 sedges), respectively. Dominant weed species in dry-seeded rice were Lindernia procumbens, Cyperus difformis, Cardamine flexuosa, and Cyperus serotinus in discending order. The species in water-seeded rice were Cyperus difformis, Scirpus juncoides, and Lindernia procumbens. The number of weed species emerged in direct-seeded rice was determined at about 45 days after seeding, and dry weights of weeds were increased up to 75~90 days after seeding. Timing for great increase of plant height varied depending upon weed species. Regardless of weed number emerged, the most dominant weeds until late stage of growth were Cyperus difformis, Bidens frondosa, Digitaria ciliaris and Echinochloa crus-galli in dry- seeded rice, and Cyperus difformis, Echinochloa eras-galli and Scirpus juncoides in water-seeded rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.286-291
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• 1997

This experiment was carried out to improve seedling emergence and establishment in paddy rice sown into puddled soil. Rice seed were coated with CaO$_2$, KNO$_3$ and acid sulphate soil. When coated seeds with CaO$_2$, KNO$_3$ and acid sulphate soil were sown into puddled soil, soil redox potential was increased and the period of oxidizing was longer in KNO$_3$ than that of any other soils. pH was higher in control than that of coated seeds with CaO$_2$, KNO$_3$ and acid sulphate soil. It seems that the coated seeds oxidize soil locally, thus prohibit soil reduction. Seedling emergence was improved by seed coating materials. Emergence date was 8 days after seeding(DAS) in CaO$_2$, 14 DAS in acid sulphate soil, 21 DAS in KNO$_3$ coated seed and 20 DAS in uncoated seed, respectively. Emergence rate was highest in CaO$_2$ coated seed(80％) followed by acid sulphate soil coated seed(61％), while control(46％) and KNO$_3$(42％) were very poor. This result would be interpreted as the difference in oxidizing power among coating agents ; CaO$_2$ and acid sulphate soil may oxidize weakly and shortly while KNO$_3$ may oxidize soil strongly and persistantly. Our results suggested that local oxidizing around rice seed sown into puddled soil enhanced seedling emergence and also found a possibility to promote seedling emergence with acid soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.221-224
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• 1999

A field experiment was carried out to observe the weed control effects of vetch and to evaluate vetch characteristics on clay loam soil in no-till direct-sown rice-vetch cropping systems. The effects of weed control, forage productivity, and N content of vetch plants were investigated. With the progress of plant growth, density of Chinese milk vetch (Astragalus sinicus L.) gradually decreased, but densities of foxtail and other weeds decreased steeply due to the depression by the over-shaded vetch canopy in a no-till direct-sown rice-vetch cropping paddy field. The vetch density in tillage systems was lower than in notillage cropping systems. Lower vetch density occurred with an increase in foxtail density and other weeds. Weed control effect increased by the progress of vetch growth, which indicated that the vetch canopy over-shaded the weeds. Vetch straw was degraded rapidly submergence after with water at the time of wet sowing of rice. Early harvesting of vetch seed resulted in lower seed germination. To acquire enough seedlings without re-sowing, the harvesting of seed should be delayed at least 28 days after the flowering stage in order to ensure the vetch population is sustainable in a no-till direct-sown rice-vetch cropping system. In order to improve the survival of vetch plants, vetch seeds should germinate from the heading .stage to before the full-ripening stage of rice plants. To enhance the percent of over-wintering survival, vetch seeds should germinate no later than the end of October in southern Korea. The dry weight of vetch plants increased with the progress of vetch growth until the flowering stage but N content decreased for 30 days from before the flowering stage (2.9%) until the ripening stage (1.8%). We concluded that Chinese milk vetch could have an effect on weed control before the flowering stage, sustainability without re-sowing of seed annually, and effective green manure for rice pre-crop in no-till direct-sown rice-vetch relay cropping systems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.352-356
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• 1997

In order to trace the survival route of weedy rice in Korean farmer's field, occurrence rate and position of weedy rice, number of weedy rice plants per $m^2$, in transplanted and direct seeded field were investigated. The highest occurrence rate of weedy rice in transplanted field was 5.5％. Number of weedy rice plants in direct seeded field was higher than that in transplanted field. In transplanted field, most of the weedy rice were grown within hills of cultivated rice and only a few was grown between hills of the cultivated rice, however in direct seeded field the number of weedy rice occurred between hills or rows of cultivated rice was higher than that occurred within hills or rows. Weedy rice occurrence rate in the field of .non-recommended rice variety was higher than that in the field of recommended variety. The main survival route of weedy rice in transplanted field was supposed to be mixture of weedy rice seeds with cultivated rice, and that in direct seeded field to be natural survival.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.178-186
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• 1991

This study was conducted to evaluate the major weeds occurred in direct seeded rice and their compition with rice, and to establish the effective weed control method. The important weeds occurring in dry direct seeded rice were Echinochloa crusgalli, Cyperus amuricus, Rorippa islandica, etc. Among them, Echinochloa crusgalli was the most dominant weed species. In view of the Simpson's dominance index, the maximum number of the weeds was observed at 30 days after seeding, showing 0.26, but decreased as the time passed. In other hand, Simpson's dominance index of weed dry weight increased from 0.09 at 15DAS(days after seeding) to 0.28 at 60DAS indicating that particular weed such as barnyardgrass was dominating the fields. The plant height and the tiller number of rice in the dry direct seeded rice were not greatly affected by the time and duration of competition with weeds, but rice yield was greatly influenced by them. The yield reduction was observed when compition between rice and weeds were initiated at 20 to 40 DAS till the harvesting time. The highest weed control efficacy was observed at the treatment of systematic herbicide application such as soil applied Butachlor followed by Mefenacet/Bensulfuron-methyl/Dymron at 30 DAS after seeding, and soil applied Dimepiperate/Bensulfuron-methyl mixture as a preemergence type gave also an excellent control.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.270-274
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• 1996

To estimate the suitable method of phosphorus application in puddled-soil drill seeding of rice, available phosphorus, appearance of algal water bloom, and rice yield were investigated in paddy soil of Honam area from 1994 to 1995. Available phosphorus content with different regions was the highest in the east-west inland region of Noryeong mountain range and the inland region of Honam area and it was the lowest in the Charyeong south plains region. Available phosphorus content was the highest in the alluvial plains. and it was the lowest in dilluvial terrace. Frations of phosphorus in Jeonbug series were high in the order of Ca-P, Fe-P, and Al-P, respectively. Algal water bloom occurred highly in 100% and 70% basal applications before seeding, and slightly in no-fertilizer and 100% application of 3-leaf stage in puddled-soil drill seeding of rice. Suitable amount of phosphorus application was 21kg/ha in the single cropping paddy field of Fluvio-marine plain, and rice yield was increased 6% at 50% basal application.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.239-244
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• 2014

Barnyard grasses are dominant weed that are not eliminated easily in the direct water seeding cultivation. So, deep water treatment can reduce their growth at the early growing stage of submerged paddy. This study was carried out to investigate the reducing growth of the barnyard grasses through flooding at seedling stages of rice plant in the green house. Under the normal condition, the plant height of rice variety, Samgwangbyeo, and 3 species of barnyard grass, E. caudata, E. pratocola and E. utilis were not showed the difference up to 10 days after seeding while the plant height of 3 barnyard grass species, especially E. utilis, was more elongated than the rice at 25 days after seeding. Plant height of the 3 barnyard grasses were not elongated largely during 3, 5 and 7 days of flooding treatment at 10 days after seeding. Interestingly, the rice seedlings was grown over 20 cm, and the flooding tolerance of rice seedling was higher than the 3 barnyard grass varieties. However, after flooding treatment for 3, 5 and 7 days, the elongation of plant height of 3 barnyard grasses, especially E. utilis was more speedy compared to rice seedlings as 6 to 9 days passes. And the protein spots from barnyard grasses were also reduced and eliminated more than the spots of rice seedling after flooding treatment.

• Korean Journal of Radiology
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• v.19 no.6
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• pp.1099-1109
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• 2018

Objective: In a proof of concept study, we compared no-touch radiofrequency ablation (NtRFA) in bipolar mode with conventional direct tumor puncture (DTP) in terms of local tumor control (LTC), peritoneal seeding, and tumorigenic factors, in the rabbit VX2 subcapsular hepatic tumor model. Materials and Methods: Sixty-two rabbits with VX2 subcapsular hepatic tumors were divided into three groups according to the procedure: DTP-RFA (n = 25); NtRFA (n = 25); and control (n = 12). Each of the three groups was subdivided into two sets for pathologic analysis (n = 24) or computed tomography (CT) follow-up for 6 weeks after RFA (n = 38). Ultrasonography-guided DTP-RFA and NtRFA were performed nine days after tumor implantation. LTC was defined by either achievement of complete tumor necrosis on histopathology or absence of local tumor progression on follow-up CT and autopsy. Development of peritoneal seeding was also compared among the groups. Serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) were measured via ELISA (Elabscience Biotechnology Co.) after RFA for tumorigenic factor evaluation. Results: Regarding LTC, there was a trend in NtRFA (80%, 20/25) toward better ablation than in DTP-RFA (56%, 14/25) (p = 0.069). Complete tumor necrosis was achieved in 54.5% of DTP-RFA (6/11) and 90.9% of NtRFA (10/11). Peritoneal seeding was significantly more common in DTP-RFA (71.4%, 10/14) than in NtRFA (21.4%, 3/14) (p = 0.021) or control (0%). Elevations of HGF, VEGF or IL-6 were not detected in any group. Conclusion: No-touch radiofrequency ablation led to lower rates of peritoneal seeding and showed a tendency toward better LTC than DTP-RFA.