Changes in Growth and Quality Traits According to Transplanting Dates using ‘Bbareumi’, an Extremely Early Maturing Rice Cultivar, in the Chungnam Plain Area

Abstract

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 (R 2 = 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.