Environmental degradation caused by global warming, postearthquake salt damage, and radioactive contamination and globalization of agricultural markets due to the Trans-Pacific Partnership are serious issues that call for the innovation of new cultivars to overcome the shortcomings of current crops. The results of this study showed that all tested semidwarf lines had shorter culm lengths than Koshihikari, indicating improved lodging resistance. Furthermore, the leaves were straighter (pointing upwards) in the semidwarf lines than in Koshihikari (Figure 1), indicating improved light-interception properties attributed to the introduction of semidwarf gene(s). Panicle length was solely longer by 2.5% in Koshihikari carrying Jukkoku_sd1 and shorter in lines carrying IR8_sd1 by 2.4% or d60 by 3.0%, as compared with the original cultivar Koshihikari (Table 1 and Figure 4). However, the reduction in panicle length was considerably less than that in culm length (Table 1 and Figure 3; a 22.8% decrease in lines carrying IR8_sd1 versus a 26.1% decrease in lines carrying d60), suggesting that the negative effects of the semidwarf genes sd1 and d60 on panicle length were negligible (Table 1 and Figure 4). Ogi et al.  and Murai et al.  reported that an isogenic line carrying sd1 was derived from DGWG, which was constructed with the genetic background of Norin 29 and Shiokari, respectively. However, IR8-derived sd1 did not show effects of increasing panicle length, which was also observed with the genetic background of Koshihikari in this study. On the other hand, the results showed that Jukkoku-derived sd1 solely increased panicle length by more than 2.5%, as compared to the original cultivar Koshihikari and other semidwarfing alleles.