Statistical assessment of the late marginal heading date for normal maturation of temperate japonica rice in South Korea
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J. Crop Sci. Biotech. 2014 (December) 17 (4) : 247 ~ 253 DOI No. 10.1007/s12892-014-0115-0 RESEARCH ARTICLE
Statistical Assessment of the Late Marginal Heading Date for Normal Maturation of Temperate Japonica Rice in South Korea Junhwan Kim1, Jiyoung Shon1, Hanyong Jeong1, Woonho Yang1, Chung Kuen Lee2, Kwang Soo Kim3, * Rice Research Division, National Institute of Crop Science, Rural Development Administration, Suwon 441-857, Korea Planning and Coordination division, National Institute of Crop Science, Rural Development Administration, Suwon 441-857, Korea 3 Department of Plant Science, College of Agriculture and Life Science, Seoul National University, Gwanakro 1, Gwanakgu, Seoul 151-921, Korea
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Received : November 17, 2014 / Accepted: November 27, 2014 Ⓒ Korean Society of Crop Science and Springer 2014
Abstract The late marginal heading date (LMHD) for normal maturation has been assessed to infer the range of late transplanting date and applicability of a new cropping system. A minimum threshold temperature for grain filling can be used to determine the late marginal heading date that would allow normal maturation. In this study, a statistical procedure was developed to determine the threshold temperature for 40 days of the grain-filling period. The threshold temperature was chosen to be the minimum temperature at which grain-filling ratio and weight are minimally affected. To identify the threshold temperature, grain-filling ratio and weight, which were observed at two sites for 2 years in Korea, were compared with a range of cumulative temperature during 40 days in the late season. As a result, cumulative temperature of 800℃, which is equivalent to, on average, 20℃ during 40 days of grain-filling period, was determined to be the threshold temperature for normal grain filling in the late season. The LMHD for normal maturation was also determined from cumulative probability density function of dates from which the threshold temperature of 800℃ was met during the last 15 years as well as 33 years. Our results suggested that it would be better to use the cumulative density function of those dates derived from the last 15 years rather than 33 years because current climate conditions could be better represented by the density function derived from recent years. Key words : grain-filling ratio, lower threshold of optimum temperature, rice, the latest heading date for normal maturation, 1000grain weight
Introduction It would helpful to assess the range of late planting date for rice cultivation in major production areas as well as marginal croplands. For example, growers could miss the optimum timing for transplanting of rice because they were not able to irrigate their paddy field due to drought, e.g., which occurred in the Taean region during the spring period in 2012. For machine transplanting, it would be difficult to use old Kwang Soo Kim ( ) Department of Plant Science, Seoul National University Gawnakro 1, Gawankgu Seoul 151-921, Korea E-mail: [email protected] The Korean Society of Crop Science
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