The semidwarf trait has also been introduced into rice cultivars grown in other countries. In Japan, Hoyoku, Shiranui, and Reihou, which are representative main cultivars grown in the Kyushu region, were developed using the indigenous semidwarf cultivar Jukkoku . A series of cultivars, such as Akihikari and Niigata Wase, were developed in the 1970s in the Tohoku region using the semidwarf cultivar Reimei, which was induced by gamma-ray irradiation of Fujiminori . In the USA, Calrose 76 (culm length, ~90 cm) was developed in 1976 also by gamma-ray irradiation of the japonica variety Calrose (culm length, ~120 cm) [4–6]. In Korea, d47 derived from IR8 was also introduced into Tongil by japonica-indica hybridization .