Screening for resistance to rice bakanae disease has been underway since 1990s. A few lines were reported to have high resistance to bakanae in the studies of Li et al. (1994), Lv (1994) and Khokhar and Jaffrey (2002). According to our results, no matter whether other semidwarf genes or the recessive tall gene eui were present, rice lines carrying sd1 were sensitive to GA3 and susceptive to bakanae disease. This may be the main reason why it is difficult to identify rice lines highly resistant to bakanae disease from germplasms
with the sd1 gene because this allele is present in most of the modern indica rice varieties, indica hybrid rice as well as half of the japonica varieties (Zhu and Li, 1984). For the same reason, Lv (1994) found that japonica rice showed higher resistance than indica rice, and Li et al. (1994) also found that half of japonica materials displayed moderate resistance when evaluated during the budding stage and the flowering stage. Therefore, screening and characterization of the disease resistant resources from rice germplasm carrying dwarf or
semidwarf genes rather than sd1 may be an efficient way to breed for bakanae resistance.
 The present study indicated that the rice accessions carrying d29, sd6 and sdq (t) genes display resistance to bakanae disease. We also found that there is no linkage between the three dwarf genes and other negative characters such as small grain and sterility (Mackill and
Rutger, 1979; Ma et al., 2003). Thus, these materials might be useful resources in rice breeding program for the improvement of resistance to bakanae.