• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.442-448
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• 1992

In order to determine the critical seeding date in dry paddy field at southern plain area of Gyeongbug province, dry seeds of three different rice cultivars was sown April 25 to June 20 at 15 or 10-day intervals. The number of days from seeding to emergence decreased in late seeding date : from 32 days at April 25 to 7 days at June 10 sowing. The number of seedlings showed 121-154 plants per square meter were not much differed among the varieties and seeding dates. Culm length, panicle length and ripened grain ratio decreased in late seeding date, but number of panicles per square meter, 1,000 grain weight and spikelets number per panicle were similar among the seeding dates. The cumulative effective temperature(mean air temperature-15$^{\circ}C$) from emergence to heading was very constant having 655$\pm$9$^{\circ}C$ in Keomhobyeo, 771$\pm$9$^{\circ}C$ in Donghaebyeo and 801$\pm$3$^{\circ}C$ in Milyang 95, respectively. Grain yield of Dong Haebyeo seeded in June 20 and Milyang 95 seeded in June 10 were much lower compared with other seeding dates and increased green kernel in late seeding date of Donghaebyeo and Milyang 95.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.3
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• pp.319-323
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• 2013

Red rice (Oryza sativa L.) is one of the most important weeds in most of rice cultivating area. Seed germination related experiments were done to evaluate germination percentage, emerging speed, and initial growth by seeding depth and soil moisture level. The four experiments, 1) temperature, 2) seeding depth, 3) soil moisture level, and 4) seeding position, were done with combination each other on phytotron for germination and seedling growth related experiments of redrice. The treatments levels were: 1) Temperatures were 20/15(Low), 25/20 (Mid.), $30/25{\circ}C$ (High), (day/night), 2) seeding depths were 0, 3, 6 cm, 3) soil moisture levels were 25, 35, 45, 55, 65% (VWC, %), and seeding position were furrow, ridge, ridge-top. The germination percentage and germination speed of red rice were higher and faster than Daeanbyeo in low temperature. Yoeongcheon redrice of seed germination percentage and seedling length was more vigor than Hapcheon red rice. Red rice was not germinated on 6 cm seeding depth until 11 days after seeding except high temperature treatment. Germination percentage increased with increasing soil water percentage in low temperature, however it was greatest in 45% in high soil moisture level between 25% to 65% in low temperature. Seed germination percentage and seedling length were not significantly different among the soil water level in mid- and high temperature levels. In conclusion, red rice could germinate in top soil (<6 cm) in mid- and high temperature range, so we might be control red rice by spraying herbicide after germination of red rice combined with delayed rotary cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.143-158
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• 2009

This experiment was carried out to examine ecological response and soybean quality as affected by environmental cultivation for producing high seed quality in domestic soybean variety. The results are as follows: Under equal cumulative temperature condition, soybean plants grown in Muju showed longer days to flowering, which was an effect of the long day-length on high latitudes, and longer duration of reproductive stage as a result of low temperature within that period. Considering apparent seed quality, 100 seed weight of soybeans grown in Muju was heavier than Miryang. Ratio of seed crack and disease-damaged seeds was lower in Muju, and these parameters decreases as planting was delayed. The protein contents did not show significant difference in terms of altitude and planting date, however, crude oil contents were higher in Miryang. An opposite trend was observed in C18:1 and C18:3. In the fatty acid composition, the proportion of C18:1 decreased as seeding date was delayed, and was higher in Miryang. Opposite observations were obtained from C18:3. The anthocyanin contents were highest on June 10 planting and higher in Muju than in Miryang. Isoflavone content was higher as seeding date was delayed and is similar accross seeding dates in Muju. As a summary, for high seed quality production the optimum planting date was June 10, and Muju was more suitable region than Miryang.

• Korean journal of applied entomology
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• v.33 no.3
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• pp.173-177
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• 1994

his study was conducted to Investigate the occurrence of small brown planthopper (SBPH), LaodeIpahx striatellus Fallen, and the ind~cence 01 rice virus diseases by d~fferent seeding dates in dryseeded rice. The occurrerlce of SBPH was the highest an nce seeded in May 11, followed byMay 1, May 21 and May 31. However. SBPH dld not occur on the rice seeded in June 10 duelo the rice was emerged after peak occurrence of first generailon adult of SBPH. The occurrenceof the first generation adult of SBPH was May 11 and it was 3-day earlier than that of infantnce transplanting. The ~nd~cencofe rice vlrus diseases, rice stripe vilus (RSV) and rice black-streakeddwarf virus (RBSDV), was the most severe at seeding date May 11. and then followed by May1, May 21 and May 31 Thus the incidence of "ce virus diseases was closely related with thedensity of the first generat~on adult of SBPH Rice yield was decreased by later seeding dates, although rice yield from May 1 to May 21 was relatively stable and hqii compared with laterseeding dates. Accordingly, there was slgniilcant relatlonsh~p between rice yield and seeding datesice yield and seeding dates

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.3
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• pp.238-246
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• 1994

This experiment was carried out to determine the effects of seeding date and fall harvest method on the growth characteristics, forage yield and quality of winter rye(Seca1e cereale L.) at the forage experimental field, College of Agriculture and Life Sciences, SNU, Suweon from 5 September 1992 to 21 May 1993. The experiment was arranged in a split plot design with three replications. Main plots consisted of three harvests, no defoliation, cutting and grazing. Sub-plots consisted of seeding dates, early(5 September), mid(25 September) and late(l0 October). The results obtained are summari7d as follows; I . A 3-day difference in the first heading of rye was observed between no defoliation and fall grazing, while there was a 6day difference between early and late seeding dates. Therefore, the effect of seeding dates on the fist heading date of rye was larger than that of fall harvest methods. 2. CP content of rye with fall grazing was slightly higher averaged 16.5% compared with both fall cutting and no defoliated 1ye(15.6%). Mean CP content of rye at the early, mid and late seeding dates was 14.2, 14.5 and 19.1 %, respectively. 3. ADF content of rye was slightly higher with both fall cutting(29.99) and no defoliation(29.5%) than that of fall grazing(28.0%). ADF content of rye at the early, mid and late seeding dates was 30.7, 29.1 and 27.7%, respectively. Effect of fall harvest methods and seeding dates on NDF content of rye were similar to the observations made on ADF. 4. RFV and IVDMD of rye were lower with both no defoliation and fall cutting than fall grazing. but those of rye slightly increased with seeding dates progressed. 5. Dry matter yield of rye was the highest of 6,779 kg/ha with fall cutting, while the lowest yield of 6,240 kg/ha was obtained from no defoliation But no significant difference was found among the harvest methods. Dry matter yield of rye was significantly declined with later seedings. It is concluded that the highest forage yield of rye be possible from two harvest systems of fall and spring with earlier seeding rather than from one harvest system of spring.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.72-80
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• 1999

The study was conducted to establish the safe cropping season for direct- seeding on flooded paddy by the analysis of meteorological data(l973~1992, 20 years) from Korea Meteorological Administration. The critical date for early seeding(CDES) at direct- seeding culture on flooded paddy was decided by the appearance date of daily mean air temperature(DMAT) of 15$^{\circ}C$. The optimum heading date(OHD) was the first day when 22$^{\circ}C$ of daily mean air temperature could be kept for 40 days of ripening period after heading, and the critical date of late heading for safe ripening(CDHR) was the last day when 19$^{\circ}C$ of daily mean air temperature could be kept for 40 days after heading. The optimum seeding date(OSD) and the critical date for late seeding(CDLS) could be decided by the accumulated temperature from OHD and CDHR to the appearance dates of necessary temperatures for early, intermediate, and intermediately late maturing varieties. This results can be used for the determination of the safe cropping season of direct-seeding on flooded paddy in each agroclimatic zone. For instance, the OSD appearance date for early maturing variety in Suwon region appeared to be May 11~20 and the CDLS appearance date was May 31~June 7.

• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.133-138
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• 1981

Effect of the seeding rate and nursery period on the growth and characteristics of seedling suitable for rice transplanter was analyzed and the following results were obtained. The optimum seeding rate were about 100 to 150g in the 30 day old seedling, and 150g per nursery box in the 25day old seedling, respectively, as having adequate leaf number, plant height, dry weight, hardiness and crop growth rate for transplanting. Excessively low and high seeding rate resulted in excessive aging and weakness of the seedling at the later growth stages.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.132-132
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• 2022

The application of direct seeding cultivation reduces time, labor, and cost. However, this application often has poor seedling establishment and leads to lower yield as compared to transplanting system. The tolerance to anaerobic and low temperature germination is important to improve seedling establishment and the wide-spread application of direct seeding method. This study was carried out to evaluate the responses of three japonica cultivars to different temperatures (15℃, 18℃, 21℃, 24℃, and 27℃) and different flooding levels (1 cm, 4 cm, 7 cm, 10 cm) during germination and seedling development. The mean survival percentage significantly increased (P<0.05) when the flooding level decreased and when temperature increased. There were significant effects of the interaction between temperature and water depth on survival percentage and seedling height. When temperature decreased from 27℃ to 15℃, the germination duration significantly increased from 6.4 days to 16.3 days while the germination speed, survival percentage, and seedling height decreased from 5.3 seeds day^-1, 61.9% and 190.6 cm to 2.2 seeds day^-1, 33.2%, and 47 cm, respectively. The increase in temperature under submergence condition was associated with the increased expression of Amy3D and ALDH2a but the decreased expression of ADH1 and PDC1. The results of this research would be used for further studies and breeding programs to improve rice seedling establishment and the application of direct seeding cultivation.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.331-339
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• 1975

This experiment was carried out to obtain some imformations about the ecological variations of the heading time of the newly breeded Indica x Japonica varieties/pedigrees according to the seasonal changes of the seeding date. day length and temperature. The results obtained are summarized as follows; 1) At all varieties. days to heading showed a straight reduction according as the seeding time was delayed. 2) At the group of Japonica varieties. the days to heading of early maturing varieties were much shortened and that of medium or late maturing varieties were little or not shortened under high temperature condition but at the group of Indica ${\times}$ Japonica va rieties/pedigrees. days to heading were significantly elongated under high temerature condition. 3) At the group of Japonica varieties. the effect of the short day condition on the days to heading was significantly high at the medium and the late maturing varieties than at the early maturing varieties. however. the short day effect on the reduction of days to heading was not related with the earlyness of each varieties at the group of Indica ${\times}$ Japonica varieties/pedigrees. 4) Days to heading of all varieties under the high temperature condition were longer than that under the ordinary culture. On the other hand, the days to heading of Japonica varieties under the short day treatment were shorter than the days to heading of ordinary culture but at the group of Indica x Japonica varieties/pedigrees. the days to heading under the short day treatment were longer than ordinary culture. 5) At both varieties groups. the days to heading at each seeding time were significantly correlated with days to heading at ordinary cultivation. fl) At the group of Japonica varieties. relatively high correlation(p=0.1) was recognized between the days to heading by delay of seeding time, but at the group of Indica ${\times}$ Japonicava rieties/pedigrees, correlation between the ordinary heading date and the shortening rate of days to heading was very low.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.407-415
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• 2009

To investigate the effects of seeding date, nursery days and plug cell size on seedling growth and quality of waxy corn. This study was carried out in the field of the National Institute of Crop Science in 2007. Varieties used were two waxy corn hybrids cvs. Chalok# 1 and Chalok# 4. The plant height, number of leaves and dry weight of waxy corn seedlings were significantly affected by seeding dates and plug cell size, while no differences between varieties. The growth of seedlings was faster in March 14 seeding than in May 8 and July 4 seedings. Based on plant height, March 14 seeding, May 8 seeding and July 3 seeding reached suitable size for transplanting after 30 days (21.6cm), 15 days (25.5~26.9cm) and 10 days (21.6~24.0cm) in the nursery, respectively. Seedlings of March 14 seedling and May 8 and July 3 seeding reached suitable number of leaves i,e. 2~3 leaves, 15~20 days after seeding on March 14 and 10 days after seeding on May 8 and July 3. Dry weights of 30 days seedling for March 14 seeding, 20 days seedling for May 8 seeding and 15 days seedling for July 3 seeding were 0.43g, 0.57~0.67g and 0.53g, respectively, and the dry weight of seedlings increased by 2~3 folds at the later nursery days. The suitable nursery days of waxy corn were 20 days on March 14 seeding and 10~15 days on May 8 or July 3 seeding.