Abstract: In order to develop an effective analytical and monitoring method in b reeding rice varieties with higher resistance stability to brown planthopper (BP H), Tai’s method (1971) was employed to estimate the resistance stability of tw elve rice varieties to different biotypes of BPH. It was shown that light intens ity, seedling age, and nitrogen application rate had significant effects on the resistance performance and stability of rice varieties to different BPH biotypes . Among the varieties with resistance to BPH biotype Ⅱ, the RHT, RP1976-18-6 -4- 2, and Ptb33 showed stable, IR56 showed unstable, while IR36 and ASD7 showed the most unstable resistance; whereas among the varieties susceptible to BPH biotyp e Ⅱ, the TN1 showed stable, Guihuazhan, Foshanyouzhan and IR26 showed relativel y stable, while Guojing No.4 and Mudgo showed unstable susceptibility. For the r ice varieties resistant to BPH biotype Bangladesh, the RHT, RP1976-18-6-4-2 and Ptb33 presented unstable, and IR56 presented very unstable resistance; whereas f or the varieties susceptible to BPH biotype Bangladesh, the Guihuazhan, Foshanyo uzhan and IR26 performed stable, TN1 and IR36 performed unstable, and Guojing No .4, Mudgo and ASD7 performed the most unstable susceptibility.

Key words: Pinus koraiensisdominated broadleaved mixed forest, forest gap size, relative light intensity, herbaceous plant.