• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.666-672
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• 1997

Twenty years' daily mean air temperature data was used to calculate the critical early seeding date(CESD), the optimum heading date(OHD), the critical late heading date for stable ripening(CHDR) and the critical late ripening date(CLRD) for rice seeded on dry paddy in different agroclimatic zones in Korea. The CESD was defined as the first day with mean air temperature of 13$^{\circ}C$, and the OHD as the first day of the 40 consecutive days with mean air temperature of 22$^{\circ}C$ or above after heading. The CHDR was defined as the date after which the cumulative daily mean air temperature would be at least 76$0^{\circ}C$. Lastly, the CLRD was defined as the last day when daily mean air temperature remains above 15$^{\circ}C$. This information was used for the estimation of periods from the earliest date of seeding to optimum heading date, the latest possible date of heading and the latest possible date of ripening in respective regions. For instance, in Suwon, those respective periods mentioned were found to be 104days, 124days, and 165days.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.285-290
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• 1983

Two methods were tested to establish the cropping period for rice cultivation using the meteorological data. The Hanyu-Uchijima method was based on the normal average temperature to select the earliest possible transplanting date (ETD), the earliest heading date (EHD), the optimum heading date (OHD) and the latest maturing date (LMD). The probability method was based on the temperature occurrence probability. The cropping period based on the probability method gave higher stability than H-U method for year variability. The ETD by the probability of 75 to 90 percents was May 12 to 22 for northern part of Korea, May 15 to 25 for east coastal area and May 4 to 16 for southern part, respectively. In Chuncheon area, the rice varieties requiring more than 1700 degree-days from transplanting to heading might not be appropriate due to low temperature condition and those requiring 1900 degree days were not allowable in Kangreung area. The OHD was July 30 to August 8 in northern part of the country and August 11 to 16 in southern part for Tongil varieties which demand higher temperature than common Japonica varieties. The OHD for Japonica varieties were 5 to 7 days later than Tongil varieties. The LMD was September 30 to October 2 in northern part, October 13 to 14 in east costal area and October 7 to 14 in southern part, and was earlier than the first frost date.

• 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.