China's "super" hybrid rice breeding project has developed many new varieties using a combination of the ideotype approach and intersubspecific heterosis. It is controversial whether these "super" hybrid varieties have increased the yield potential of irrigated rice. This study was conducted to compare grain yield and yield attributes among "super" hybrid, ordinary hybrid, and inbred varieties. Field experiments were done in Liuyang (moderate-yielding site) and Guidong (high-yielding site) counties, Hunan Province, China, in 2007 and 2008. Two ...