This study was performed to determine the optimum transplanting dates of ‘Bbareumi’ in the Chungnam Plain area. ‘Bbareumi’ was transplanted into a rice research field of Chungnam Agricultural Research and Extension Services at intervals of approximately 15 days from April 17^th to August 1^st in 2019 and 2020. The heading dates of ‘Bbareumi’ were June 23^rd to September 2^nd depending on transplanting dates. The highest milled-rice yield was 5.61 MT/ha on May 1^st and the lowest was 3.65 MT/ha on August 1^st. As the transplanting date was delayed, protein content increased; however, the number of days from transplanting to heading decreased. Protein content and the number of days from transplanting to heading showed a highly significant correlation (R² = 0.802^**). Therefore, it was found that early transplanting was beneficial to produce lower protein content because head rice percentage was 84-87% for early (April 17^th to May 16^th), 74-80% normal (June 1^st to June 16^th), and 86-95% for the late transplanting date (July 1^st to August 1^st). The mean temperature during the ripening stage differed according to the transplanting dates, and early transplanting showed a lower temperature than the normal one (May 16^th to June 15^th) and a higher head rice percentage. Therefore, extremely early maturing rice cultivars should be transplanted between late April and early May to obtain lower protein content and higher head rice percentage. These results will be useful for rice breeding programs, as it is generally recognized that early transplanting results in poor rice quality; however, this study revealed contrasting results.

‘Bbareumi’ is an extremely early maturing rice cultivar with the fastest harvesting time in Korea. To develop ‘Bbareumi’, ‘Joami’ with good quality in Chungnam plain area and ‘Hokuto’ originating from Japan with the fastest heading date among genetic resources were used as breeding materials. After crossing them in 2010, the ‘Bbareumi’ cultivar was developed using the pedigree method. A yield trial was conducted from 2015 to 2016, and a local adaptability test was conducted from 2016 to 2018. The heading date of ‘Bbareumi’ was seven days earlier than ‘Jinbuolbyeo’, showing an average of June 23^rd, and it could be harvested from the end of July to the beginning of August when transplanted early in Chungnam plain area. ‘Bbareumi’ had a short culm length of 63.3 cm and panicle length of 19.3 cm. Milled rice yield was approximately 4.87 MT/ha and the percentage of head rice was 89.2% under normal fertilizer condition. ‘Bbareumi’ will be used as a premium rice brand with newly harvested rice before ‘Chooseok’, Korean Thanksgiving Day and is expected to contribute to the revitalization of double-cropping in the Chungnam plain area (Registration No. 8130).