• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.7-10
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• 1985

Transplanting date, planting space and nitrogen level were evaluated for disease development of rice sheath blight using two rice cultivars, Jinheung and Yushin. Sheath blight disease was more severe in early transplanting plot (May 16), narrow planting space($27{\times}12cm$) and high nitrogen level (220kg/ha for Jinheung and 300kg/ha for Yushin) conditions than in May 26 transplanting plot, wide planting space ($27{\times}15cm$) and standard nitrogen level (110kg/ha and l50kg/ha). At the same time, cultural conditions favorable for disease development during growth stage resulted in greater damage at maturing stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.19
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• pp.25-31
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• 1975

In order to increase the rate of ripening during the grain-forming stage the partial dressing was introduced with the ordinary dressing comparatively. Two different rice varieties, Bong-kwang(early) and Nong-kwang (moderate), grown at the fine sand alluvial soil of River, Han Kimpo, were investigated. To evaluate the photosynthetic ability of these treatments assimilation rate of Carbon-14 was effectively carried out with the active leaves of rice at the maturing stage, and the inorganic constituents of leaves, stem, leaf sheath and grain were analyzed. All the data on the photosynthetic ability, inorganic constituent and yield determining were discussed with the point of continual phloem translocation between those plant organs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.4
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• pp.304-310
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• 2017

This study was conducted over a 3-year period from 2013 to 2015 in the mid-northern inland, Cheolweon, Korea, to investigate changes in flowering date, daily mean temperature during grain filling, and yield characteristics affected by transplanting date in an early-maturing rice variety, 'Joun'. Thirty-day-old seedlings were transplanted at four different dates at 15-day interval from May 5 to June 19. Flowering dates were July 16, July 21, July 31, and August 14 when transplanting was performed on May 5, May 20, June 4, and June 19, respectively. Late transplanting resulted in higher daily mean temperature before flowering but late-transplanted rice required fewer days and lower cumulative temperature to reach flowering from transplanting. As transplanting was delayed, daily mean temperature for 40 days after flowering decreased, whereas daily sunshine hours for the same period increased, with a temperature of $24.8^{\circ}C$ and sunshine for 5.8 hours being recorded at the transplanting on May 5, and with a temperature of $21.0^{\circ}C$ and sunshine for 7.7 hours at the transplanting on June 19. With late transplanting, panicles per square meter significantly decreased, whereas spikelets per panicle showed an increasing trend. Regression analysis showed that maximum head rice yield was attained from the transplanting on May 18, for which the flowering date was July 21, and daily mean temperature for 40 days from that flowering date was $24.6^{\circ}C$. A decrease in head rice yield by 5% and 10% of the maximum was observed for rice transplanted on June 6 and June 15, which resulted in flowering dates of August 2 and August 11, respectively, and the daily mean temperatures for 40 days from flowering were 23.2 and $21.7^{\circ}C$, respectively. Therefore, in mid-northern inland, it is recommended to transplant 'Joun' on May 18 to induce flowering on July 21, when grain filling is subjected to a daily mean temperature of $24.6^{\circ}C$ during active filling stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.323-335
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• 2019

Rice is sensitive to day-length and short-day plants. It has a characteristic that the photosensitivity response required for flower bud differentiation decreases under long-day conditions. To identify critical photoperiod required for flower bud differentiation of major cultivation rice varieties, the average temperature was fixed at 28 ℃, and the day length was set at 12 hours and 10 minutes intervals from 13 hours to 14 hours 30 minutes. The critical photoperiod for each cultivar was set to day-length, where the daily cumulative response [(X_{(Critical Photoperiod)}-Y_{(Set day-length)})/(X_{(Critical Photoperiod)}-12:00_{(Optimal Day-length)}) × (28.0_{(Set Temperature)}-10_{(Minimum Temperature)})/(29.2_{(Maximum Temperature)}-10_{(Minimum Temperature)})] was the same for each day-length conditions. The flower bud differentiation time of all varieties was 32 days before heading at the average temperature of 28 ℃ conditions. The critical photoperiod of the early maturing type, such as Woonkwang, Odae, Koshihikari, Jopyeong, were 19:20, 18:14, 18:58, 17:30, respectively. Medium maturing type, such as Daebo, Haiami, Samdeok, were 16:08, 16:15, 16:55, respectively. Mid-late maturing type, such as Saenuri, Sindongjin, Chucheong, Samkwang, Ilpum, Saeilmi, Hwangkeumnuri, Dongjinchal, Ilmi, Hopum, Yeonghojinmi, were 15:58, 15:56, 16:36, 16:44, 15:35, 16:26, 15:33, 16:20, 16:29, 16:13, 15:41.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.284-293
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• 2020

Rice consumption in Korea has been decreasing as the eating habits of the Korean people have diversified with rapid economic growth. Recently, floury endosperm rice cultivars were developed to boost rice consumption and replace wheat flour consumption with rice flour, which is vulnerable to viviparity under wet weather during the grain-filling stage because of its loosely packed starch granule structures. To overcome this limitation, it is necessary to find a suitable rice transplanting date to produce high-quality rice flour by altering the heading ecology type and changing the cultivation time by region. We examined four floury endosperm rice cultivars (FERC) in the Cheongju (central plain area) and Boeun (mid-mountainous area) regions of Korea from 2017 to 2019. Of the FERCs, the mid-late maturing types (MMT) Seolgaeng (SG), Hangaru (HGR), and Shingil (SGL) exhibited high yield and yield components after transplanting May 30 in both regions; the early maturing type (EMT) Garumi 2 (GRM2) also exhibited high yield after transplanting June 20 in Cheongju. In addition, MMTs showed the same tendency as the characteristics shown in Cheongju when grown in the Boeun region, and EMT displayed high yield and yield components after transplanting June 10. The FERCs could easily present pre-harvest sprouting in the rainy season during the grain-filling stage after 20 days post-heading because the mean temperature and frequency of more three-day rainfalls have increased over the last 5 years from the previous annual averages. Viviparity of HGR and GRM2 decreased as the transplanting date was delayed, with decreases of 2.3%-4.6% in HGR and 11.9%-23.1% in GRM2 according to the region. SGL was generally resistant to viviparity because of the Tongil type. To minimize pre-harvest sprouting and produce high yield of rice flour in the Chungbuk province, the most suitable transplanting time was the end of May in MMT and the middle and end of June in EMT.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.4
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• pp.229-241
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• 2006

Global air temperature has risen by $0.6^{\circ}C$ over the last one hundred years due to increased atmospheric greenhouse gases. Moreover, this global warming trend is projected to continue in the future. This study was carried out to evaluate spatial variations in rice production areas by simulating rice-growth and development with projected high resolution climate data in Korea far 2011-2100, which was geospatially interpolated from the 25 km gridded data based on the IPCC SRES A2 emission scenario. Satellite remote sensing data were used to pinpoint the rice-growing areas, and corresponding climate data were aggregated to represent the official 'crop reporting county'. For the simulation experiment, we used a CERES-Rice model modified by introducing two equations to calculate the leaf appearance rate based on the effective temperature and existing leaf number and the final number of leaves based on day-length in the photoperiod sensitive phase of rice. We tested the performance of this model using data-sets obtained from transplanting dates and nitrogen fertilization rates experiments over three years (2002 to 2004). The simulation results showed a good performance of this model in heading date prediction [$R^2$=0.9586 for early (Odaebyeo), $R^2$=0.9681 for medium (Hwasungbyeo), and $R^2$=0.9477 for late (Dongjinbyeo) maturity cultivars]. A modified version of CERES-Rice was used to simulate the growth and development of three Japonica varieties, representing early, medium, and late maturity classes, to project crop status for climatological normal years between 2011 and 2100. In order to compare the temporal changes, three sets of data representing 3 climatological years (2011-2040, 2041-2070, and 2071-2100) were successively used to run the model. Simulated growth and yield data of the three Japonica cultivars under the observed climate for 1971-2000 was set as a reference. Compared with the current normal, heading date was accelerated by 7 days for 2011-2040 and 20 days for 2071-2100. Physiological maturity was accelerated by 15 days for 2011-2040 and 30 days for 2071-2100. Rice yield was in general reduced by 6-25%, 3-26%, and 3-25% per 10a in early, medium, and late maturity classes, respectively. However, mid to late maturing varieties showed an increased yield in northern Gyeonggi Province and in most of Kwangwon Province in 2071-2100.

• Plant Resources
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• v.3 no.3
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• pp.194-199
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• 2000

The result of this experiment which are conducted, to improve the cultivation technology of Alisma plantago, to increase its quantity and to contribute for stable production with Yongiun local group by examining the optimal planting density and transplanting period of double cropping of Alisma plantago in the southern region. The characters of plant height, leaf width and length tend to be reduced as the seeding period is later by the order of the 10th, 20th and 30th of July. The period required for flowering is reduced as the transplanting period is later and dense planting is applied. Plant height, the number of leaves and yield of dry root have much quantity at the dense planting density of 20$\times$ 15cm as they are transplanted later in the 30th of August or the 10th of September, but they are rather less in sparse planting density of 20$\times$25cm or 20$\times$35cm.

• 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 CROP SCIENCE
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• v.67 no.1
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• pp.17-26
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• 2022

Rice is one of the three major grains globally, and has been used as a staple food in Asian countries for a long time. In recent years, with the increase in the use of processed rice, the development and distribution of rice flour varieties have become a research focus. However, rice flour varieties are susceptible to pre-harvest sprouting (PHS). In this study, the optimal transplanting date for rice flour varieties for maximum yield production with PHS avoidance was examined. Four rice flour varieties with different maturity types (early maturing type, Garumi2 and medium-late maturing type, Seolgaeng, Hangaru, and Singil) were selected. The field experiment was conducted in Chuncheon (Central Plain area) and Cheorwon (Northern Plain area), Gangwon Province, Republic of Korea, from 2017 to 2019. The transplanting dates used were May 10, May 20, May 30, June 10, and June 20 in Chuncheon and April 30, May 10, May 20, May 30, and June 10 in Cheorwon. In Chuncheon, late transplantation decreased PHS in Garumi2. In Cheorwon, PHS in Garumi2 decreased with transplantation dates after May 20. The PHS decreased in Seolgaeng, Hangaru, and Singil with late transplantation in Chuncheon and Cheorwon. The optimal transplanting date for maximum yield production while avoiding PHS for Garumi2 was estimated to be June 10 in Chuncheon and May 25 in Cheorwon; for Seolgaeng, the optimal transplanting dates were May 20 in Chuncheon and May 15 in Cheorwon; for Hangaru, it was estimated to be May 30 in Chuncheon and May 15 in Cheorwon; and for Singil, the optimal dates were May 25 in Chuncheon and May 15 in Cheorwon.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.242-252
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• 1985

In order to get information on the ecology of rice false smut, germination ability and pathogenicity of sclerotia and chlamydospores of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. The degree of outbreak of rice false smut was higher in the upland rice in comparison with the paddy field rice in respect to the number of affected grains per ear, the size and weight of smut balls formed on affected grains as well as the ratio of sclerotial formation produced on smut balls. 2. Germination percentage and days required for germination of overwintered sclerotia placed on the soil surface in July were 81% and 19 days, respectively, while those of overwintered sclerotia treated in May were 60-70% and 41 days. Sclerotia placed on the soil surface or under 1 cm depth of the soil surface and incubated at $25-30^{\circ}C$ were germinated well, whereas those placed under 3 cm or 5 cm depth of the soil surface were not germinated at all. Germinability and stroma productivity of sclerotia were reduced when the sclerotia were cutted into small pieces. 3. The average number of stroma formed on a sclerotium was six and that of perithecia formed in a stroma was about 50 to 140. 4. Percentage of germination of chlamydospores on the yellow balls was very high and was decreased as the color of the balls being darken with maturation. 5. Panicle of rice plants were successfully infected by injection inoculation with suspention of ascospores and chlamydospores of the pathogen to the sheaths at the booting stages, while seeding infection by spraying with suspensions of chlamydospores was unsuccessful. 6. More number of infected grains was distributed on basal parts of an affected ear than that of infected ones distributed upper parts of the ear, when the affected ear was divided into five parts from its basal portion to the apical of the ear. 7. The occurrence of the disease was more severe in the late maturing varieties of rice in comparison with the early maturing varieties. 8. When the level of nitrogen applied was increased, the incidence of disease increased, and the infection percentage of the disease was increased as the transplanting date was delayed. 9. The weight of panicles and 1000 kernels and the ratio of ripenness were reduced, and the contamination degree of grains with chlamydospores were increased as the number of smut balls per panicle were increased.