In rice, heading date is a key determinant for adaptation to different cultivation areas and cropping seasons.Heading date is a complex trait in rice and is controlled by many endogenous genetic factors (genes) and environmental conditions, such as temperature and day length.In this research, a set of 66 chromosome segment substitution lines (CSSLs) with the genetic background of Asominori, a japonica variety and harboring the IR24 insert section was used.