The time when the tip of the panicle first emerged from the flag leaf sheath was recorded as the heading time for all plants. Ten plants typical of each line were selected. The sampling procedure was performed twice. Sampled plants were air-dried and the following phenotypic traits were assessed or measured: (1) culm length (the length between the ground surface and the panicle end of the main culm), (2) internode length (the lengths between two neighboring internodes of the upper five internodes), and (3) panicle length (the length between the panicle base and the tip of the panicle). Differences in phenotypic traits between each line carrying a semidwarf gene (or genes) and Koshihikari were obtained using the following equation: percent difference = [(measurements of each line) − (measurements of Koshihikari)]/(measurements of Koshihikari) × 100.