• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.1
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• pp.1-8
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• 2000

The objectives of this study were to investigate weather conditions which induced discolored grains and viviparous germination, and to evaluate yield responses following viviparous germination during mid- and late- ripening stage, the submergence during reproductive growth stage, and lodging in the yellow ripe stage. Weather conditions which caused glume discoloration at heading stage were 21.3-26.4$^{\circ}C$ in average temperature, 75.2-98.4% in relative humidity, 19.3 in transpiration coefficient and 10.8-13.8 m/sec. in wind speed. Yield reduction was 26-27% and 10~17%, respectively, when the glume discoloration rates were 63.2-65.7% and 38.3-45.2%, obviously due to the decrease in percent of fertile grain and ripening ratio. Weather conditions during continuous rain for 7 days were 96% in relative humidity, 18.9$^{\circ}C$ in average temperature, 21.9$^{\circ}C$ in maximum temperature, and 16.8$^{\circ}C$ in minimum temperature, causing the most viviparous germination in Juanbyeo(45.5%), followed by Jinbubyeo(14.5%), Bongkwangbyeo(14.2%), and Obongbyeo(12.6%). Lateral tillers started to occur when the submergence at the depth of 1.5-2 m lasted one day during the reproductive growth stage. The submergence for 2-3 days at 3-4 m of water depth induced 269-571 lateral tillers/m$^2$, supporting 32-52% of the total yield. The rice yield in the paddy fields which were left under the lodging conditions until harvesting was not different compared to that of the paddy fields which were kept upright by tieing them together after lodging, but perfect grain ratio decreased about 9.1% in the transplanting culture and 12.5% in the direct seeding culture on dry paddy field because of the increase in immature grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.233-243
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• 2011

This experiment was conducted to investigate the effect of future climate change on growing period and temperature in different rice maturity types as global warming progressed, where Odaebyeo, Hwaseongbyeo, Ilpumbyeo were used as a representative cultivar of early, medium, and medium-late rice maturity type, respectively, and A1B scenario was applied to weather data for future climate change at 57 sites in Korea. When cropping season was not adjusted to climate change, entire growing period and growing temperature were shorten and risen, respectively, as global warming progressed. On the other side, when cropping season was adjusted to climate change, growing period and temperature after heading date were not changed in contrast to growing period and growing temperature before heading which were more seriously shortened and risen as global warming progressed than in not adjusted cropping season. It is supposed that adjusting cropping season to climate change can alleviate rice yield reduction and quality deterioration to some degree by improving growing temperature condition during grain-filling period, but also still have a limit such as seriously shortened growing period indicating that there need to develope actively new rice cultivation methods and varieties for future climate change.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.619-624
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• 1996

An experiment was carried out to find out the effects of water foxtail on weed control and rice yield as well as on the reduction of nitrogen application in no tillage transplanted paddy field. Paddy field was dominated by water foxtail whose soil covering degree was adjusted from 8 to 6 by treatment of paraquat (70 l /10a of solution diluted by 1, 000 times). Thirty five-day old seedling was mechanically transplanted and reduced nitrogen, 80% of conventional application was applied at the paddy field. The higher failure in seedling stand was observed at higher degree of soil covering by water foxtail. The failure of seedling stand with covering degree of 8(no paraquat) was 37.4%, while that of covering degree of 6(paraquat-treated) was 12.3%. However, the seedling stand failure was completely recovered at covering degree of six at two weeks after transplanting. The mechanical transplanting made water foxtail in the paddy field fall on the ground whose panicle part was recovered from falling sometimes after transplanting and whole plant died with slow scenesence untill the late of June. But the water foxtail affected by paraquat produced the new panicle from uppernode of stem with dead leaves at early of June and it become die slowly untill the early of July. Though several rice field weeds were observed in the order of Echinochloa crusgallis, Cyperus serotinus, Lemma paucicostata during the active tillering stage of rice, the value of weed control due to the dominance of water foxtail was 77~78%. The death and subsequent decay of water foxtail during the active tillering stage of rice induced the soil reduction which again defect the growth of rice root. The more vigerous rice growth was observed in the plot dominated with water foxtails, than control plot. The yields of rice in the water foxtail (degree 6) plot was 629kg per l0a as brown rice, the same as that of control plot. In conclusion, the no-tillage transplanting with control of covering degree of water foxtail (to degree 6) was effective in reduction of input cost such as herbicide and nitrogen fertilizer, as well as weed control without reduction of rice yield.

• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.156-162
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• 1995

This study was carried out to select the useful mutants among 20 lines treated with mutagen, gamma ray. These materials were treated with 15, 20, 25 and 30Krads, respectively and sowed at experimental field of College of Agriculture on 27th May, 1995. Items surveyed were germination rate and loss of chlorophyll at seedling stages, abnormal reproductive organs, discordance of flowering times and stem and ear height at ripening stages. The germination rate of lines treated with 15 Krad was different. The germination rate of the IK1, IK2 and Sinki lines were high, while the IK3, A632 and FR140 lines were very low. At same dose level, the germination rate of both IK1/H26 and Puyo synthetic variety were different; the germination rate of the IK1/H26 was high as above 70% at all treatments, while that of the Puyo synthetic variety was very poor at above 20 Krad. Generally stem adn ear height of the IK1/H26 were gradually decreased as the dose of mutagen increased, but there was no difference in stem and ear height of the IK1/H26 when this line was treated with 20Krad. The stem and ear height of lines treated with 15 Krad were shown to be decreased than those of check with non-treatment. The number of tiller of tillering lines were not greatly affected by ${\gamma}$-ray treatment.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.336-341
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• 2008

The objective of this research was to investigate the suitable cultivar for organic strawberry (Fragaria ananassa Duch.) cultivation in Korea. The six strawberry cultivars which were bred and commonly cultivated in Korea as forcing and semi-forcing culture were tested in this experiment. To achieve the objectives, various characteristics of these cultivars were investigated for two consecutive years such as growth habit, yield, fruit quality and occurrence rate of disease/pest. As results of this research, the total yield of 'Seolhyang' was the highest among cultivars tested in both forcing and semi-forcing cultivation. The average of soluble solid contents (SSC) in 'Seolhyang' was $12.0^{\circ}Bx$ that is lower than other cultivars and especially below $10^{\circ}Bx$ after March (high temperature period). But there was not much difference in SSC among 6 cultivars until the end of February. The average of hardness in 'Seolhyang' was 279g/${\phi}5\;mm$ which was a little higher than that of 'Akihime'. Titration acidity (TA) in 'Maehyang' was 0.69% which was the highest value among 6 cultivars. Total fresh/root weight of 'Seonhong' and leaf area of 'Seolhyang' were significant among other cultivars' ones in forcing culture. Growth habits (fresh weight, root weight, leaf area, etc.) showed no significant difference among cultivars in semi-forcing culture. The lowest occurrence rate for powdery mildew and aphids was found in 'Seolhyang', but gray mold was severer than other cultivars. The density of two spider mites was the lowest in 'Redpearl'. We have concluded that 'Seolhyang' is the most suitable cultivar for organic strawberry cultivation by the result of yield, fruit quality and resistance of disease/pest.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.3
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• pp.151-158
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• 2002

In Korean high yielding varieties developed by crosses between indica and japonica rice, the most limiting factor for yield increase may be attributed to the less number of tillers per unit area. The goal of this study is to find out the effect of the environmental factors as well as cultivation practice on the development and increase of tillers of Dasanbyeo, the high yielding indica / japonica hybrid cultivar. The effect of temperature was examined with 3 different light intensity, 220,600, and 1220 $\mu$㏖/s/$m^2$, respectively. For all the experiments, the leading japonica variety in Korea, Hwaseongbyeo, was used fur the check cultivar for the comparison with Dasanbyeo. The increase of the tillers was more prominent in Dasanbyeo than in Hwaseongbyeo at 220 $\mu$㏖/s/$m^2$ of light intensity, while the similar increase of tiller no. was found at 600 $\mu$㏖/s/$m^2$ of light intensity treatment. However, Hwaseongbyeo showed more rapid increase of tiller at 1220 $\mu$㏖/s/$m^2$ of light intensity. The mean number of the primary tiller ranged 5 to 7 in Dasanbyeo, and 2 to 7 in Hwaseongbyeo, showing greater variation in the latter case. However, the secondary tiller number ranged from 2 to 13 for the former, and 2 to 12 for the latter. The earliest initiation of tiller node of Dasanbyeo and Hwaseongbyeo was observed on 6 and 4 days after transplanting(DAT), respectively, at 600 $\mu$㏖/s/$m^2$ of light intensity, while 10, and 7 DAT, respectively, at 1,220 $\mu$㏖/s/$m^2$. No cultivar difference was observed at 600 $\mu$㏖/s/$m^2$ with the 18 DAT. The ratio of effective tiller was lower in Dasanbyeo, ranging from 47 to 55% than in Hwaseongbyeo, ranging from 72 to 100%.

• Korean Journal of Weed Science
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• v.12 no.2
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• pp.89-101
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• 1992

In this study, various physiological and biochemical experiments were conducted to know whether the selectivity between rice and barnyardgrass treated with bleaching herbicides containing diphenyl ether compounds was also partly based on their basic physiological proterties such as peroxidation ability, membrane stability or antioxidant system. It seemed to be partly based on the differences of their physiological characteristics that barnyardgrass was commonly more susceptible to most of the bleaching herbicides than rice. The scenescence of intact leaf segment was more rapid in barnyardgrass than in rice, indicating that barnyardgrass is weak at early stage. Also pigment metabolic ability, antioxidant enzyme activities(peroxidase, catalase, superoxide dismutase, glutathione reductase) and antioxidant content (tocopherol, ascorbic acid, glutathione, carotenoids) were lower in barnyardgrass on the basic of fresh weight. However, lipoxygenase activity and the content of unsaturated fatty acid which is vulnerable to oxygen radicals were higher in barnyardgrass, suggesting that barnyardgrass seedling bave a properties easy to be peroxidized. The differences of PPIX (protoporphyrin IX) or carotenoid content, which are the primary substances inducing herbicide activity, were not related to the selectivity between rice and barnyardgrass.

• Journal of Gifted/Talented Education
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• v.10 no.2
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• pp.71-86
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• 2000

According to Torrance, it is said that about 30% of feeble-headed children are bearing potential brilliant quality. Such potential gifted children exist really much more than children who appear to show their own brilliant quality. Nevertheless, research activity to reveal children's potential giftedness has not been relatively actively progressed. Renzulli, Smith and so on progresses research activity to reveal children's potential giftedness and strategies developed by them are being used widely all over the world, but these strategies show the defect that children can not overcome by themselves the interfered factors influenced negatively on their gift revelation. Russian scholar Babaeva made the effective education program to develop children's potential giftedness. Her program includes various activity methods or mental correct activity and psychological training activity and such training activity is realized through some steps and each step has it's own purpose and realization method. With the result that children discriminated as common children by the experimental study which is progressed by the present program participate, their standard of intelligence and originality showed the improved effect of the similar standard to children factors not a little influencing on children's giftedness development process but she also developed the leading concrete study method for the children to overcome this by themselves. In this paper, the present writer will examine potential giftedness development program researched in Russia and discuss their theoretic background and concrete activity course, activity result. Through this, children's have the excellent abilities in various spheres, this writer will obtain significant suggestions to educate the potential gifted children who do not display their own potentialities and do not receive a favor from gifted children program.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.324-327
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• 2008

'Onnuri' is a japonica rice cultivar developed from the cross between 'Milyang 165' and HR14732-B-67-2-3 at Honam Agricultural Research Institute (HARI), NICS, RDA, in 2005. This cultivar has a short grain shape and about 121 days growth duration from transplanting to harvesting in Korean climate condition. In reaction to biotic and abiotic stresses, it shows resistance to blast, bacterial blight pathogen from $K_1$ to $K_3$ and stripe virus, but susceptible to other major diseases and insect pests. The milled kernel of 'Onnuri' is translucent with non-glutinous endosperm. It has about 18.6% of amylose content and better palatability of cooked rice compared with 'Chucheongbyeo' cultivated in Kyunggi province. The milled rice yield of 'Onnuri' is about 5.94 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. 'Onnuri' would be adaptable to southern plain of Cheonan, middle-northern plain, and southern mid-mountainous of Korea.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.352-355
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• 2008

"Unmi" is a new japonica rice variety developed by the rice breeding team of Honam Agricultural Research Institute, NICS, RDA in 2007. This variety was developed from a across between Samcheonbyeo with lodging and cold tolerance and HR17870 derived from the cross of Iksan435 (Sobibyeo) and Sangju17 with resistance to diseases and good quality. This variety has about 110 days of growth duration from transplanting to harvesting in northern plain, northern and southern mid-mountainous areas of South Korea. It is about 68 cm in culm length and tolerant to lodging. In reaction to biotic and abiotic stresses, it shows moderate resistance to blast, and to bacterial blight pathogen races from $K_1$ to $K_3$, but susceptible to other major diseases and insect pests. The milled rice of "Unmi" is translucent and has relatively clear non-glutinous endosperm and medium short grain. It has about 17.3% amylose content and 6.3% of protein and similar palatability of cooked rice compared with Odaebyeo. The milled rice yield performance of this variety is about 5.16 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. "Unmi" would be adaptable for ordinary transplanting in the northern plain, northern and southern mid-mountainous area of South Korea.