• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.2
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• pp.73-79
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• 2020

This study was conducted to develop a technique for the stable production of Italian ryegrass(IRG) seeds in reclamation sites. Harvesting 35 days after heading in Autumn resulted in the highest production, an average of 2,232kg/ha. The production yield decreased due to seed loss as harvesting was delayed to 45 and 55 days post-heading. For the harvested 35 days post-heading, under growing rice sowing resulted in 80% seed yield of after rice sowing's; spring sowing resulted in 40%. After rice sowing using the domestic IRG seeds of 30kg/ha produced the highest seed yield of 2,507kg/ha. The highest straw yield has resulted when using the imported IRG seeds of 20kg/ha for after rice sowing 35 days post-heading fresh weight 36,667kg/ha, dry weight 14,500kg/ha, and TDN weight 7,895kg/ha.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1090-1097
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• 2001

Nine tons of fresh rice straw from early-maturing varieties was ensiled with 50 g urea $kg^{-1}$ DM straw in plastic bags immediately after threshing. Five months after storage, preserved straw was used to partially replace elephant grass (Pennisetum purpureum, Schumach) for lactating cows. Eight crossbred Holstein lactating cows (75% of Holstein blood) in their second to fourth lactation and in mid-lactation were arranged in a balanced design with two squares consisting of $4\;periods{\times}4\;treatments$ (100% grass ad lib. as a control; 75% grass+urea treated fresh rice straw (UTrFRS) ad lib.; 50% grass+UTrFRS ad lib.; 25% grass+UTrFRS ad libitum) in one square. A concentrate supplement was given at a rate of 400 g per day per kg of milk produced. Samples of fresh straw taken in the field and UTrFRS and elephant grass taken at feeding time were evaluated in a degradation trial with 3 fistulated heifers (undefined blood ratio of crossbred of Sindhi and local yellow cattle). Straw preserved for 5-9 months was in nearly all cases of good quality. Crude protein (CP) content was increased 2.1 fold and 48 h dry matter loss (DML) was 20% higher compared to dry straw. Elephant grass cultivated intensively was low in DM content and 10% higher in 48 h DML compared to UTrFRS. Dry matter intake (DMI) was higher for the mixture of UtrFRS and Elephant grass, and highest when one-third of the roughage was UTrFRS. Higher DMI of mixed roughage diets was probably due to the low DM content of elephant grass in the sole grass roughage diet. Increasing substitution of elephant grass with UTrFRS up to 75% of the roughage component increased milk fat content and had no effect on milk yield and other milk composition parameters. Feeding UTrFRS, partially replacing elephant grass in the diets of lactating cows in the dry season can reduce the cost of roughage.

• Korean Journal of Weed Science
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• v.12 no.3
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• pp.230-260
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• 1992

The paper was reviewed the research results on weed dynamics and effective control methods in direct-seeded rice crop. Direct seeding method resulted in drastic increment of weed growth compared to transplanting method and also changed in troublesome weed flora. Two to three fold more weeds were harvested at the direct seeded rice and weed flora of dominant species shifted toward $C_4$type grass weeds. Some of the important troublesome weeds in direct seeded rice were Echinochloa crus-galle, Oryza saliva ssp spontanea, Leptochloa chinensis. Setaria viridus. Digitaria adsendens, Sesbania exaltata, Aeschynomene indica, Algae, etc. Yield loss due to weed competiton was about 40-60% for water-seeded and about 70-100% for dry-seeded rice while these for transplanted rice were about 25-35% for mechanical transplanting and about 10-20% for manual transplanting, respectively. Integrated weed management concept was neede to approach weed control effectively. Several cultural technologies were very effective to suppress the weed growth. These were tillage operation, water management, seeding date and seeding rate. Crop residues of barley, rice, wheat, oat and italian ryegrass were also effectivly suppressed the paddy weeds particularly to Potamogeton distiuctus, a perennial broadleaf weed. A pathogen of Epicoccosorus nematosporus identified from Eleocharis kuroguwai was an excellent potential bioagent to control the most troublesome perennial sedge weed of E. Kuroguwai without arising any detrimental effect. The herbicidal efficacy of this pathogen was as high as bentazon herbicide. Plant growth regulator of paclobutrazol (pp-333) was another possible alternative to reduce the herbicide use. In current, herbicide exhibited the most conspicuous results to control weeds in direct-seeded rice even though the application technologies were not fully established. Recommendations for herbicide application were suggested for in both water-and dry-seeded rice in USA, Japan and Korea, respectively. To make better and comprehensive recommendations further studies on weed ecology and herbicide development were emphasized.

• Research in Plant Disease
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• v.12 no.1
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• pp.5-9
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• 2006

Grain discoloration, caused by several microorganisms, is a minor disease, but it is gaining importance in almost all rice growing areas of the world in recent years. Such grains are of low market value and consumption appeal in addition to their abnormal performance as seed of source of nutrient value. When the casual agents were inoculated on rice plant,'Ilmi-byeo'(at right before heading time and on heading time), the incidence of rice ear blight caused by Alternaria alternate and Nigrospora oryzae was higher in a plot inoculated at right before heading time than (in n plot inoculated) on heading time. Meanwhile, the incidence of rice ear blight caused by Bipolaris oryzae and Curvularia lunate was higher in a plot inoculated on heading time than in a plot inoculated at right before heading time. In rice quality, the ratio of imperfect grains was increased at right before heading time or on heading time by Nigrospora oryzae or Alternaria alternata, respectively. As discoloration rate of rice grains increased on 'Ilmi-byeo', the percentage of perfect grains decreased proportionally and the percentage of damaged rice grains increased remarkably.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.265-265
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• 2022

Increased temperature caused by global warming has become a significant problem for the growth and production of crops. A high temperature has a direct or an indirect effect on crops, leading to a significant yield loss. The damage of a high temperature stress to rice depends on its developmental stage. In present study, we performed evaluate the heading date in different location, Yeoju and Miryang, during growth of Korean rice core set. The heading date for the 223 rice accession were evaluated in Yeoju City (37°23' 127°57') and Miryang City (35°50', 128°72') located on middle and southern part of Korea, respectively. The average temperature of a day was higher in Miryang during entire growth stage. Here, total 222 KRICE-Core set was analyzed by GWAS for the high temperature effect. GWAS results revealed the Chr07_26954556, a lead SNPs were significantly associated with delaying heading date of KRICE-Core set. Significance threshold was set with 6.0 > -log10(P), and Cross-Validation (CV) error suggested an optimal K value of 5 for the population based on the lowest cross-validation error K = 5.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.319-319
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• 2017

Methane is the main greenhouse gas released from rice paddy field. Methane from paddy fields accounts for 11 % of the global total methane emission. The global warming potential (GWP) of methane is 25 times more than that of carbon dioxide on a mass basis. It is well known that most effective practice to mitigate methane in paddy is related to the water management during rice growing season and the use of organic matters. This study was conducted to investigate the effects of tillage and cultivation method on methane emission in paddy. Tillage (tillage and no-tillage) and cultivation methods (transplanting and direct seeding) were combined tillage-transplanting (T-T), tillage-wet hill seeding (T-W), tillage-dry seeding (T-D) and no-till dry seeding (NT-D) to evaluate methane mitigation efficiency. Daily methane emission was decreased on seeding treatments (T-W, T-D, NT-D) than transplanting treatment (T-T). Amount of methane emission during rice growing season is highest in T-T ($411.7CH_4\;kg\;ha^{-1}y^{-1}$) and lowest in NT-D treatment (89.7). In T-W and T-D treatments, methane emissions were significantly decreased by 36 and 51 % respectively compared with T-T. Methane emissions were highly correlated with the dry weight of whole rice plant ($R^2=0.62{\sim}0.93$). T-T treatment showed highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that direct seeding practice in rice production could mitigate the methane emissions without loss in grain yield.

• Journal of Biosystems Engineering
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• v.16 no.1
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• pp.37-48
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• 1991

Rice plants are subjected to various forces such as natural force of wind and mechanical force of cultivating machines. Rheological behavior of the rice stem can be expressed in terms of three variables : stress, relaxation and time. The objectives of this study are to examine stress relaxation, creep and recovery characteristics on the rice stem in case of axial and radial loading. Stress relaxation with time was studied on three levels of loading rate and on four levels of applied stress. The results were summarized as follows : 1. The hysterisis losses of the rice stem distinctly observed at the radial compression in comparison with axial compression. The hysterisis loss implied that the stem to absorbed energy without being deformed beyond the yield point. 2. Ageneralized Maxwell model consisting of three elements gave a good description of the relaxation behavior of the rice stem. Rate of loading was more significant on the observed relaxation behavior within the short relaxation time, but there were little influences of rate of loading on the relaxation time. 3. The stress relaxation intensity and the residual stress increased in magnitude as the applied stress increased, but the relaxation time was little affected by the applied stress. 4. The coefficients of the stress relaxation model showed much differences in the radial compression and the axial compression, especially the higher relaxation stress of the third element was observed in the radial compression. 5. The behaviors of rice stem in creep and recovery test also might be represented by a four element Burger's model. But the coefficients of the creep model were different from those of the recovery model. 6. The steady-state phenomena of creep appeared at the stress larger than 20 MPa in Samkang and 1.8 MPa in Whajin. 7. The elastic modulus of the stem showed the range from 40 to 60 MPa. It could be considered, as a result, the rice stems had viscoelastic properties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.201-201
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• 2022

Rice bakanae disease is a serious global threat in major rice-cultivating regions worldwide causing high yield loss. It is caused by the fungal pathogen Fusarium fujikuroi. Varying degree of resistance or susceptibility to bakanae disease had been reported among Korean japonica rice varieties. We developed a modified in vitro bakanae disease bioassay method and tested 31 Korean japonica rice varieties. Nampyeong and Samgwang varieties showed highest resistance while 14 varieties including Junam and Hopum were highly susceptible with 100% mortality rate. We carried out mapping QTLs for bakanae disease resistance with four F2:F3 populations derived from the crosses between Korean japonica rice varieties. The Kompetitive Allele-Specific PCR (KASP) markers developed in our laboratory based on the SNPs detected in Korean japonica rice varieties were used in genotyping F2 plants in the populations. We found four major QTLs on chromosome 1, 4, 6, and 9 with LOD scores of 21.4, 6.9, 6.0, and 60.3, respectively. In addition, we are doing map-based cloning of the QTLs on chromosome 1 and 9 which were found with Junam/Nampyeong F2:F3 population and Junam/Samgwang F2:F3 population, respectively. These QTLs will be very useful in developing bakanae disease resistant high quality rice varieties.

• Mycobiology
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• v.51 no.4
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• pp.195-209
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• 2023

The seed borne disease such as bakanae is difficult to control. Crop yield loss caused by bakanae depending on the regions and varieties grown, ranging from 3.0% to 95.4%. Bakanae is an important disease of rice worldwide and the pathogen was identified as Fusarium fujikuroi Nirenberg (teleomorph: Gibberella fujikuroi Sawada). Currently, four Fusaria (F. fujikuroi, F. proliferatum, F. verticillioides and F. andiyazi) belonging to F. fujikuroi species complex are generally known as the pathogens of bakanae. The infection occurs through both seed and soil-borne transmission. When infection occurs during the heading stage, rice seeds become contaminated. Molecular detection of pathogens of bakanae is important because identification based on morphological and biological characters could lead to incorrect species designation and time-consuming. Seed disinfection has been studied for a long time in Korea for the management of the bakanae disease of rice. As seed disinfectants have been studied to control bakanae, resistance studies to chemicals have been also conducted. Presently biological control and resistant varieties are not widely used. The detection of this pathogen is critical for seed certification and for preventing field infections. In South Korea, bakanae is designated as a regulated pathogen. To provide highly qualified rice seeds to farms, Korea Seed & Variety Service (KSVS) has been producing and distributing certified rice seeds for producing healthy rice in fields. Therefore, the objective of the study is to summarize the recent progress in molecular identification, fungicide resistance, and the management strategy of bakanae.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.93-101
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• 2010

For the study of possibility of practical use as an organic farm materials of the mixtures with lignite and amino acid solution, this experiment was carried out to investigate the effects of the mixtures on the growth and the yield of rice plant, chinese cabbage, and red pepper, and the effects of the mixtures on chemical properties of soil. Also, when the mixtures of the lignite plus amino acid solution and the chemical fertilizer were applied to these three crop cultivation area, authors want to know how can the loss in quantity of chemical fertilizer affects the growth and the yield of these crops. As the results, growth of rice plant applied with the mixtures of lignite and amino acid solution was better than that applied with the recommended rate of chemical fertilizer. Especially, the growth of rice plant appeared to be good at the treatment of 150 kg/ha of the mixed lignite with amino acid solution and at that of its mixtures and standard fertilization. Growth of chinese cabbage and red pepper was good at the application of 600 kg/ha of the mixed lignite with amino acid solution and at that of its mixtures and standard fertilization. Yield of rice and chinese cabbage was good at the treatment of 150 kg/ha of the mixed lignite with amino acid solution and at that of its mixtures and standard fertilization, and yield of red pepper was good at the application of 600 kg/ha of the mixed lignite with amino acid solution and at that of its mixtures and standard fertilization. The organic matter content increased and while the exchangeable cation decreased when the lignite mixed with amino acid solution and the loss in quantity of chemical fertilizer applied at paddy field. Incase of these treatments, pH and available phosphorus increase at upland field, but did not change at paddy field.