Genetic analysis of resistance to whitebacked planthopper, Sogatella furcifera (Horvath), in some rice varieties

For genetic analysis of resistance to the whitebacked planthopper, Sogatella furcifera (Horvath) (Homoptera: Delphacidae), in 13 rice varieties, seedlings at the one-leaf stage were artificially infested in the greenhouse with second; and third-instar nymphs of this planthopper. Reactions of the seedlings were recorded 7–10 days after infestation when the susceptible check (control variety) TN1 was completely killed. The reactions of the F<SUB>1</SUB>, F<SUB>2</SUB>, and F<SUB>3</SUB> populations from the crosses of resistant varieties with TN1 revealed that single dominant genes condition resistance in the varieties Sinnanayam, ARC 13349, MGL 1, Sukhwel 20, Bam 3, Hornamawee, Senawee, A1, T1432, W128, and Chuvanna Kumbolum. The resistance in NP130 and CI-5662-2 was conditioned by two independent dominant genes. The allelic relationships of the latter genes for resistance in the test varieties to resistance genes Wbph 1 and Wbph 2 were determined. Reactions of the F<SUB>2</SUB> and F<SUB>3</SUB> progenies from the crosses of test varieties with IR13475-7-3-2 which is homozygous for Wbph 1, and with IR30659-2-165, which is homozygous for Wbph 2, showed that the resistance genes in Sukhwel 20, Senawee, T1432, and W128 are allelic to Wbph 1. The resistance genes in Sinnanayam, ARC 13349, MGL 1, Bam 3, A1, and Chuvanna Kumbolum are allelic to Wbph 2. The two independent dominant genes for resistance in NP130 and CI-5662-2 are Wpbh 1 and Wbph 2. However, there is a single dominant gene for resistance in Hornamawee which is independent and non-allelic to Wbph 1 and Wpbh 2