• Korean Journal of Plant Resources
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• v.10 no.4
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• pp.386-391
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• 1997

A study was carried out to investigate the variation of heading date and related yield components at Honam Agricultural Experiment Station in Korea. The treatments were consisted of five transplanting time: from May 5 to July 5 at 15-day intervals, and six cultivars: two early-maturing, two mid-maturing and two late-maturing cultivars. The results showed that variation of heading at different transplanting time was not significant at transplanting after June 5 in early-maturing cultivars, and days of heading from seeding for all tested cultivars were shorter in later transplanting times. The yield components such as numher of spikelcts, percentage of ripened grain and 1.000 grain weight were found to he great on May 5 in early-maturing cultivars and on June 5 in mid-and late-maturing cultivars. Yield was maximized at transplanting of May 20 in early maturing and on June 5 in mid-and late-maturing cultivars. When transplanting time was late, the yield difference hetween early maturing cultivars and late nldtunng ones showed 44 to 77kg/10a in the transplanting of June 20, and 26~30kg/10a in the transplanting of July 5 indicating that the late-maturing cultivars take more advantage than early-maturing ones.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.191-199
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• 2003

Optimum transplanting time for extremely early rice cultivation as an after-crop of fruit and vegetables under greenhouse conditions in the southern area was determined. Rice was transplanted on March 10, March 20, March 30, April 10 and April 20 far three years from 1998 to 2000. Meteorological computations for rice production were high for heading between early May and early July, but they were too low for heading between late July and early August. Especially the expected yield predicted with 35,000 spikelets, the average spikelets per $m^2$ for extremely early transplanting. Computation for heading between late July and early August was low by 106 kg/10a compared with that yield at heading during the same period in the field. As the transplanting date in extremely early rice cultivation was earlier) rice growth at early stages was more retarded by low temperature. Rice growth at heading stage recovered with high temperature, showing less difference for the transplanting date. Abnormal tillers occurred by 15.5∼22.2%. The contribution of 1,000 grain weight${\times}$ripened grain ratio to yield of the extremely early rice cultivation in the greenhouse was 50.6%, indicating 16% hi일or than the degree of panicle per $m^2$ on yield. The estimated optimum transplanting time on the basis of yield for the extremely early greenhouse rice cultivation ranged from March 19 to April 28, and the estimated critical transplanting date on the basis of accumulated effective temperature was March 12. Rice reduced the amount of NO$_3$-N by 97.1% and EC by 90.5% in greenhouse soil with continuous fruit/vegetables fer more than a 10-year period, and completely removed the root-knot nematodes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.1
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• pp.6-11
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• 2001

In this lysimeter experiment, temporal changes of water percolation rate, irrigation requirement and ${No}_3$－-N leaching were investigated under different cultural practices that were no-till direct seeding on flooded paddy (NTDSF), till direct seeding on flooded paddy (TDSF), and transplanting. The highest water percolation rate of 3,001 l/$m^2$ was measured in NTDSF. Others were 2,551 l/$m^2$ and 2,210 l/$m^2$ in TDSF and transplanting. Water percolation rate in NTDSF and TDSF was increased by 36% and 15% compared to transplanting. Water percolation rates in all cultural practices were increased remarkably from the reproductive growth stage and relatively large amount of water loss through percolation was measured even after the reproductive growth stage. A total irrigation requirement was 3,469 l/$m^2$ in NTDSF and 2,898 l/$m^2$ in TDSF. That was equivalent to 45% and 21 % of increase compared to 2,389 l/$m^2$ in transplanting. The largest ${No}_3$－-N leaching through the entire rice growing period was 701 mg/$m^2$ in NTDSF and was followed by 494 mg/$m^2$ in TDSF and 465 mg/$m^2$ in transplanting. The ratios to the total amount of ${No}_3$－-N leaching at the vegetative growth stage, reproductive growth stage and ripening stage were 31 %, 41 % and 28% in NTDSF; 21 %, 48% and 31 % in TDSF; and 18%, 48% and 35 % in transplanting.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.3
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• pp.259-267
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• 2010

This study was performed at Rice and Winter Cereal Crops Department of NICS during 2007 and 2008 to investigate the characteristics of rice leaf emergence and to obtain basic data which can be used for rice growth simulation model by which we can forecast rice growth stage and heading date accurately under different cultivars, transplanting date, and climatic conditions. To confirm leaf emergence rate according to rice maturing ecotype, we surveyed the leaf emergence rate and heading date of Unkwangbyeo, Hwayoungbyeo and Nampyeongbyeo which are early maturing, medium maturing and medium-late maturing cultivars, respectively, according to seedling raising duration and transplanting time. When seedling duration was 15 days, the growth duration between transplanting time and completion of flag leaf emergence on main culm were 51.5~78.3 days in Unkwangbyeo, 55.3~87.9 days in Hwayoungbyeo and 58.4~98.4 days in Nampyeongbyeo, respectively. When seedling duration was 30 days, they were 50.1~75.5 days in Unkwangbyeo, 52.4~84.7 days in Hwayoungbyeo and 56.4~93.8 days in Nampyeongbyeo, respectively. As transplanting time delayed, the emerged leaf number after transplanting decreased in all rice cultivars. The cumulative temperature between transplanting time to completion of flag leaf elongation on main culm were $1,281^{\circ}C{\sim}1,650^{\circ}C$ in Unkwangbyeo, $1,344^{\circ}C{\sim}1,891^{\circ}C$ in Hwayoungbyeo and $1,454^{\circ}C{\sim}2,173^{\circ}C$ in Nampyeongbyeo, respectively. Leaf emergence rate on main culm were precisely represented by equation, y = $y_0$ + a / [1 + exp( - (x - $x_0$) / b)]^c, when we used daily mean temperature as variable.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.28-35
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• 2013

Anthocyanin pigments from three pigmented rice varieties, Hongjinju, Sintoheugmi and Josaengheugchal pigmented by black color, were quantified to evaluate effects of transplanting and harvesting time during seed development. Hongjinju, a rice variety of grains pigmented by red color, contains only two kinds of anthocyanins, delphinidin and cyanidin. Meanwhile, delphinidin, cyanidin, and pelargonidin were identified in Sintoheugmi and Josaengheugchal. Anthocyanidin contents in pigmented rice variety Hongjinju under different planting times were decreased with prolonged harvesting times. The Sintoheukmi showed that cyanidin content was the highest among analyzed pigments during seed development. Two anthocyanins (cyanidin and pelargonidin) in Josaengheugchal recorded highest contents at 20 days after heading in three transplanting times. Cyanidin content was also slightly increased with prolonged transplanting time. Total anthocyanidin contents in Hongjinju were always lower than that of Sintoheukmi and Josaengheukchal. In two rice varieties, Sintoheugmi and Josaengheugchal, $a^*$ values were commonly slightly decreased by late transplanting and harvesting times. Changes of $a^*$ and $b^*$ values in waxy rice varieties, Sintoheugmi and Josaengheugchal varied more than those in Hongjinju. In Josaengheugchal, early harvesting before maturity showed lower brown rice yield and late harvesting in the each transplanting times resulted in highest brown rice yield.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.171-171
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• 2022

Effect of temperature during the period of 10 days from transplanting (10 DFT) on the growth and development of rice plants was investigated by transplanting semi-adult seedlings six times from 5 April to 15 May at 10-day interval in the field conditions of 2020 and 2021, with aims to investigate the critical temperature for early transplanting of temperate rice. In the two experimental years, mean temperature for 10 DFT appeared 9.1, 10.5, 11.6, 13.8, 13.9, 16.2, 16.4, 16.7, 17.1, 17.8℃ depending on the transplanting date. Mean temperature of 9.1℃ and 10.5℃ for 10 DFT appeared in the April 5 and April 15 transplants in 2020 showed negative or no effect on the increase of rice growth and acceleration of heading date when compared to those of right after transplanting treatments in the same year. Mean temperature of 11.6℃ for 10 DFT appeared in the April 5 transplant in 2021 demonstrated greater biomass from early to heading stage but the same heading date compared to April 15 transplant, indicating that 11.6℃ for 10 DFT had a positive effect on rice growth but no effect on advanced heading. Both more biomass and advanced heading stage were observed when the mean temperature for 10 DFT was 13.8℃ or higher, compared to those of right after transplanting treatments. These findings indicate that effective 10-DFT mean temperature for rice growth exists between 10.5 and 11.6℃, and that for rice development in terms of heading stage lies between 11.6 and 13.8℃ in natural condition. Further field and indoor studies are suggested to narrow down the critical temperature for early transplanting of temperate rice, which will enable to maximize the crop period in high altitude regions with low temperature.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.198-198
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• 2017

Cultivated varieties of sweet potato were from dry texture type to tender texture type on the basis of consumer preferences. There are many differences in the quantity of sweet potato, starch content, pigment, and sugar content depending on the cultivation season and area, even in the same variety. Therefore, in this study, we attempted to establish optimum time of harvesting through growth characteristics and variation in component like starch, sugar, polyphenol and flavonoid. Four sweet potato varieties were used in this experiment. Among them, Jinhongmi (JHM) & Yulmi (YM) were as dry texture type and Pungwonmi (PWM) & Hogammi (HGM) were as tender texture type. Sweet potatoes were transplanted on 23 May, 2016 and were investigated storage root weight and component contents every 20 days from 60 days to 120 days and surveyed yield at 110, 120, 130 days after transplantation. Result revealed that storage root weight of YM, JHM, and HGM were 30.1, 38.9, 20.8 g respectively in 60 days after transplanting. Storage roots of PWM gerw faster with the weight of 88.2 g. In 120 days after transplanting, storage root weight varied from 88.3 to 118.7 g, HGM was the smallest, and PWM was the largest. Sugar contents of sweet potato ranged from 21.0 to $23.8Brix^{\circ}$ in 60 days after transplanting and from 27.5 to $30.78Brix^{\circ}$ in 120 days after transplanting. In particular, the sugar content of HGM was the highest over $30Brix^{\circ}$ after 80 days. The starch content of dry texture type (YM, JHM) increased from 15.5% to 20.4% and tender texture type (PWM, HGM) increased from 11.0% to 17.3%. Starch content tended to be high in dry type sweet potatoes. The content of polyphenol and flavonoid were highest in 60 days after transplanting and was reduced according to cultivation period. The total yield of PWM was high as 3,154 kg/10a and large storage root of over 250 g accounted for 47.4% in 110 days after transplanting. Storage root (YM, JHM, HGM) of 81~150 g accounted for 34.9% ~ 43.2% in 120 days after transplanting. These are the most marketable. Because consumer in Korea prefers small, round and about 100g size sweet potato. The ratio of large storage root (over 250 g) were increased in all varieties at 130 days after transplanting. Therefore, it is considered appropriate to harvest PWM at 110 days and YM, JHM, HGM at 120 days after transplanting, which planted in late May.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.114-121
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• 1993

Differences in need occurrence and competition were investigated among five types of rice(Oryza sativa L.) cultivation. Dry weights of weeds in between transplanting and/or seeding and heading date showed in the decreasing order of dry direct-seeded, flood direct-seeded, machine transplanting with 10-day-old seedling, machine transplanting with 30-day-old seedling, and conventional hand transplanting. A similar trend was obtained with application of weedy followed by weed-free. Weed-free periods allowed to decrease by 20% dry weight of rice were 3 weeks after transplanting(WAT) in transplanting cultivations, 5 weeks after seeding(WAS) in wet direct-seeded rice, and 7-8 WAS in dry direct-seeded rice. On the other hand, weedy periods as determined by the same criterion were 9 WAT in conventional hand transplanting and machine transplanting with 30-day-old seedling, 7 WAT in machine transplanting with 10-day-old seedling, 8 WAS in dry direct-seeded rice, and 6 WAS in flood direct-seeded rice.

• Korean Journal of Plant Resources
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• v.12 no.2
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• pp.145-151
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• 1999

This study was conducted to know the influence of transplanting dates on yield and chemical component of colored rice varieties at Taejon area in middle part in Korea. The late transplanting led to late heading in which the latest transplanting on June 18 headed on August 9 in Heugiinjubyeo and on August 24 in Heugnambyeo, respectively, which in the safe latest heading date at Taejon area. The highest yield was attained by middle of June transplanting in Heugjinjubyeo, while that for the Heugnambyeo was transplanting from end of May to beginning of June. The relative optical density(ROD) of the pigment measured at 530 nm was higher in Heugjinjubyeo than that of Heugnambyeo. The late transplanting increased the ROD in Heugnambyeo, while later than May 28 decreased the ROD in Heugjinjubyeo. There was a varietal difference in cation contents such as K, Ca, Mg and Fe. The Contents of the former three was not influenced by different transplanting dates, while the Fe content was increased by early transplanting.

• Korean Journal of Organic Agriculture
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• v.7 no.2
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• pp.169-177
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• 1999

This experiment were performed on rice dignity during 1998 at paddy field of Dong-a Univ., Pusan, Korea. Depression effect of weed occurrence by pasture of 2kg of the Ampullarius insularus per 10a was 80.4% at the 7th day after transplanting, 69.7% at the 14th day after transplanting pasture plot and 51.8% at the 21th day after transplanting. Deperssion effect of weed occurrence by pasture of 5kg of the Ampullarius insularus per 10a was 97.9% at the 7th day after transplanting, 79.2% at the 14th day after transplanting pasture plot and 64.1% at the 21th day after transplanting. Depression effect of weed occurrence by pasture of 8kg of the Ampullarius insularus per 10a was 97.9% at the 7the day after transplanting, 87.1% at the 14th day after transplanting pasture plot and 71.4% at the 21th day after transplanting. Weeds ingestied by the Ampullarius insularus were in the order of perennial weed, annual weed.