• Korean Journal of Weed Science
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• v.15 no.2
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• pp.105-114
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• 1995

Differences in critical period of weed competition were investigated among five types of rice(Oryza sativa L.) cultivation. Increase in weed-free period resulted in 1-2 days delay of heading date in machine transplanting and direct-seeding as compared with complete weed-free plot. When weedy period increased, there was no difference in heading date in transplanting cultivations. In direct-seeding, however, weedy period of 7-10 weeks after seeding(WAS) resulted in 4-7 days delay of heading date, whereas further increase in the weedy period caused rather 5-6 days advance in heading date. Weed-free period did not significantly affect yield components in conventional hand transplanting. In machine transplanting with 30-day-old seedling decreases in percent ripening and 1,000-grain weight were caused by weeds emerged within 4 weeks after transplanting(WAT). All yield components were decreased due to weedy period in machine transplanting with 10-day-old seedling. In direct-seeding weedy periods caused to decrease in number of panicles, number of spikelets, percent ripening, and 1,000-grain weight were 8-9, 4-5, 3-4, and 8-10 WAS, respectively. The critical periods of weed competition were determined as the following. In conventional hand transplanting weed-free must be maintained for either 4 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 30-day-old seedling weed-free must keep for either 5 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 10-day-old seedling weeds must be removed for either 5 weeks after transplanting or the rest period after 7 WAT. Weed-free must be kept between 5 and 7 WAS in flood direct-seeded rice and between 6 and 9 WAS in dry direct-seeded rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.41-45
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• 2005

This experiment was carried out to identify the proper transplanting time at reclaimed saline land in the southwestern area of Korea from 2002 to 2004. The rice cultivars tested were Samcheonbyeo(Early maturing one), Nampyeongbyeo (Medium maturing one) and Hwaseongbyeo(Mid-late maturing one). The results are summarized as follows: No. of spikelet per the unit area was higher at transplanting on May 20 than those of the other transplanting time. when Samcheonbyeo was transplanted early, the ripened grain rate was high. But, Hwaseongbyeo and Nampyeongbyeo wasn't differ among transplanting time. The yield of milled and head rice(YMHR) was high transplanted May 20 in Samcheonbyeo, May 30 in Hwaseongbyeo, from May 20 to June 9 in Nampyeongbyeo. Among the varieties YMHR was higher in the order of Hwaseongbyeo, Samcheonbyeo and Nampyeongbyeo. There wasn't different of amylose and protein content among the transplanting time and varieties. But, palatability value was low transplanted early(May 20). Considering the rice growth, the rice good quality, the yield of milled and head rice, the proper transplanting time was May 20 to May 30 in Samcheonbyeo and Hwaseongbyeo, whereas Nampyeongbyeo was from May 20 to-June 9.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.2
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• pp.137-143
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• 2012

This study was conducted to investigate the yield and greenness of "Nogwonchalbyeo" on the basis of different date of transplanting and harvesting. Delay in heading was observed in the plants transplanted later but no effect on heading was observed due to different levels of nitrogen fertilizer. Percentage of green color in dehusked rice was higher in the grains of rice transplanted on 10th June. An increasing trend was observed in the yield with the delay in the date of transplanting, maximum yield was observed in the rice planted on 10th June but a decrease in yield was recorded if transplanted after 15th June. Similarly, yield also increase as the days for harvesting increased until 37 days after heading but beyond 37 days decreasing trend was observed in yield. Based on the above findings it can be suggested that 4~6 June and 9kg/10a are the optimum dates of transplanting and amount of nitrogen while 3 5~37 days after heading is the best time for harvesting of "Nogwonchalbyeo".

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.282-282
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• 2009

환경오염에 대한 우려 및 안전농산물에 대한 소비자욕구 증대로 유기농산물 시장규모가 최근 3년간 2.8배 성장 추세이다. 친환경농산물 인증면적은 '00년 2,039 ha에서 '07년 122,882 ha로 급격히 증가하고 있으나 생태적 원리에 부합된 벼 재배기술이 부족하며 특히 무경운 논토양에 대한 경영분석 자료는 거의 없는 실정이다. 본 연구는 유기농업기술을 종합적으로 투입한 시범마을을 육성하기 위하여 하동군 양보면 예성마을 1ha를 대상으로 관행농업과 무경운 자운영 피복 벼 기계이앙을 실증하여 경제적인 효과를 검토하였다. 토양 관리를 위해 2007년 9월 10일에 자운영을 3 kg/10a 파종하여 겨울철 토양 생태계를 유지하였고 화학비료나 농약을 사용하지 않았다. 볍씨 소독은 마른 종자를 60 $^{\circ}C$에서 8분간 침지하는 열탕침법을 이용하였으며 논 물담기는 5월 28일경 15 cm 이상 깊게 하여 자운영이 잘 분해되도록 하였다. 기계이앙은 6월 10일경 표면 1 cm 이내의 물 깊이에서 식부장치를 최대한 깊게하고 주수는 주당 5-7주 정도로 실시하였으며 기계이앙 후에는 5일 정도 물을 담지 않고 그대로 두고 그 후 물을 10 cm 이상 깊게 하여 잡초발생을 억제하였다. 중간낙수는 7월 10일경 1회 처리하였고 수확기 낙수는 9월 23일 실시하였다. 무경운 처리구의 이앙전 토양 가밀도는 관행 1.30 g $cm^{-3}$ 비해 0.09 g $cm^{-3}$ 정도 가벼운 것으로 나타났고 공극률은 관행 50.8%에 비해 3.5% 높은 것으로 나타났으며 특히 수분률이 3.5% 높았다. 무경운 자운영 피복 기계이앙 처리구의 잡초발생 건물량은 7월 4일경 피 8.8 g $m^{-2}$, 여뀌 10.8 g $m^{-2}$ 이었으며 9월 18일에는 피 16.0 g $m^{-2}$, 여뀌 12.3 g $m^{-2}$였다. 수확기 관행처리구의 주당 이삭수는 16.7개, 수당립수는 101개, 천립중은 25.4 g, 등숙비율은 82.3%로 수량은 517 kg $10a^{-1}$ 였으며 무경운 자운영 피복 기계이앙은 주당 이삭수가 14.1개, 수당 립수는 103개, 천립중은 26.2 g, 등숙비율은 91.2%로 수량이 456 kg $10a^{-1}$였다. 무경운 자운영피복 벼 기계이앙은 기경작업이나 시비작업 등이 없으므로 노동력이 60% 절감되었으며 농가소득은 5% 증대되었다. 따라서 농업분야 저탄소 녹색성장과 관련하여 자연 생태계를 보전하면서 농가소득을 유지할 수 있는 방법으로 무경운 자운영 피복 벼 기계이앙이 효과적인 것으로 판단되었다.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.475-487
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• 2017

The aim of this study was to solve the problem of yield loss causing the lag of fertilizer efficiency after tiller stage, being originated by applying mixed expeller cake fertilizer on three day before rice transplanting in organic rice farmers. The mineralization degree of $NH_4-N$ of the mixed expeller cake fertilizer was increased until 7 weeks at flooding condition, and so did $NO_3-N$ until 5 weeks at non-flooding condition. The mineralization rate of nitrogen in paddy soil on 20 days before rice transplanting was the highest by 0.85% on 20 days before the transplanting treatment. The properties of yields during the harvest period have no difference with application time of the mixed expeller cake fertilizer, except soil organic matter. The plan length, culm length and panicle length were the longest on 20 days before rice transplanting. Also, the number of tiller, ripening rat and 1,000 grain weight were the highest on 20 days before rice transplanting, and thereby the yield of white rice were increasing by 9% on 20 days before rice transplanting compared with that of 3 days before rice transplanting. The whiteness values of the rice and amylose content made no difference, but the value of protein and palatability were the same between 20 days and 30 days treatment. In the conclusion, the relationship between rice yield, its quality and application time of the mixed expeller cake fertilizer has showed that the suitable time of applying it reveals 21.3 days before rice transplanting.

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.229-235
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• 1999

To identify the differences on plant growth and yield of two rice cultivars among direct water-seeding methods broadcasting on flooded paddy surface(BF), drilling on flooded paddy surface(DF), and puddled-soil drill seeding(PD) under markedly different weather condition between 1995 and 1996. The mean air temperature for duration from May to June, early growth stage of rice in 1995 was lower $1{\sim}3^{\circ}C$ than that in normal or 1996. In 1995 the respiratory consumption index during panicle formation stage and early ripening stage was higher than those of in 1996 or normal year. Number of seedling stand among the methods of direct seeding rice appeared slightly higher in order of BF>DF>PD. Properly in Nonganbyeo, the number of seedling stand was much low in 1995 compared with in 1996. The leaf area index and shoot dry weight at early growth stage of rice plant and culm length at mature in 1995 were larger in direct water seeding rice than those of machanical transplanting rice, but in 1996. Faster ripening speed and shorter ripening period of rice crop appeared in 1996 compared to in 1995. It was due to higher growing degree-days, sunshine hours and solar radiation during rice growing season in 1996. Dongjinbyeo rice showed higher yield than Nonganbyeo which had lower ripened grains especially in 1995.

• 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 CROP SCIENCE
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• v.64 no.3
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• pp.185-192
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• 2019

Early-maturing rice type is cultivated to produce rice before the Korean Thanksgiving Day. We investigated the flowering and ripening characteristics of major breeding lines in early maturing rice type. In Jeonju, field growth days (FGD) from transplanting to heading changed about 3.3 days by 10 days of transplanting days and about 2.5 days by the change of mean temperature during growth period. As the temperature during ripening stage, 1000 brown rice weight was changed 0.2 g, the rice quality of brown and milled rice was changed 5% and 6.5%, respectively. Baegilmi and Kittake showed early heading habit suitable for harvesting before Korean Thanksgiving. Joun and Pecos showed good ripening characteristics under high temperature during the ripening stage. We expect that these characteristics might be useful for breeding new rice cultivars for harvesting before Korean Thanksgiving.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.289-296
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• 2021

This study aimed to analyze the optimal transplanting date of the floury endosperm rice varieties Hangaru, Seolgeang, Singil, and Baromi2 allowing to reduce the viviparity rate. The viviparity rate rapidly increased with the mean temperature during the ripening stage. Therefore, to reduce the viviparity rate, we calculated the optimum heading date based on the safe heading date limit in each area so that the ripening stage occurred at lower temperatures. hen, the effects of changes in heading date were monitored by recording the transplanting date and the temperature during the growth period. The transplanting date was highly correlated with the number of heading days in the field. Therefore, the optimum transplanting date was calculated according to the transplanting date in each area. When the accumulated temperature was 700℃, if floury rice was transplanted at the optimum transplanting date, the mean temperature was approximately 20℃. When the accumulated temperature was 900℃, the mean temperature was approximately 18℃. Under these conditions, the viviparity rates of Hangaru, Seolgeang, and Singil rice were lower than 10%. However, Baromi2 showed a high viviparity rate. These results suggest that the viviparity rate of Hangaru, Seolgeang, and Singil rice can be reduced by transplanting at the optimum transplanting date. However, further research is required for pinpointing the optimum transplanting date of Baromi2 rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.273-281
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• 1990

Two rice varieties, Samkangbyeo and Sangpungbyeo, were transplanted on 1/2000a pots at 6 different dates beginning on May 11 with 10 day interval in 1987 and at 4 different dates beginning on May 21 with 10 day interval in a paddy field at the Chungbuk Provincial Rural Development Administration. Dry matter distributions to stem and leaf sheath, leaves and ear at different growth stages were analyzed to provide basic informations neccessary for the development of dynamic growth model. Dry matter production was reduced as transplanting was delayed and the degree of reduction was greater at the transplanting later than June 1. Dry matter distribution to stem and leaf sheath was increased up to 60-70 days after transplanting with the maximum ratio between 60-70%, which were decreased to 37-43% in pots and 27-33% in field at the end of ripening stage. On the other hand, dry matter distribution to leaf blade was decreased from 40-50% at transplanting to 11-17% at harvesting. Ear dry matter distribution increased rapidly after heading and the distribution ratio was 42-49% in pots and 52-62% in field. Although regression equations to predict dry matter distribution to different parts of rice plant were satisfactory for individual experiment, the application to different experiment was not appropriate.