Indira Gandhi Agricultural University, Raipur 492012, M.P., India
We studied mode of inheritance of resistance to gallmidge in rice variety Abhaya. This variety is resistant to new biotype of gallmidge (biotype-4) which emerged in 1986 in Eastern Andhra Pradesh, India. Varieties and segregating populations were screened under field conditions at Raipur. The level of infestation was very high as the susceptible parents showed 100% infestation on single plant basis (Table 1).
The F\2\ populations from the crosses of Abhaya with susceptible varieties segregated in the ratio of 3 resistant to 1 susceptible (Table 1) indicating that Abhaya has one dominant gene for resistance. The F\2\ populations from the crosses of Abhaya with gallmidge resistant varieties Samridhi, Ruchi, and Phalguna segregated in a ratio of 15 resistant to 1 susceptible (Table 1). Samridhi and Ruchi have Gm-1 for resistance and Phalguna has Gm-2 for resistance (Choudhary et al. 1986). These results show that the gallmidge resistance gene of Abhaya is nonallelic to Gm-1 and Gm-2. This gene is probably differenet from
Table 1. Reaction of parents and F\2\ populations for gallmidge resistance ============================================================================ Reaction to Plants Parents/Cross ---------------------------- Expected ratio X2 Resistant Susceptible (R:S) (No.) (No.) ============================================================================ Kranti 0 76 - - Annda 0 71 - - Tulsi 0 75 - - Ratna 0 81 - - Cheptigurmatia 0 77 - - Abhaya 75 0 - - Samridhi 80 0 - - Ruchi 78 0 - - Phalguna 67 0 - - Abhaya/Tulsi 584 191 3:1 0.052 Abhaya/Annda 375 104 3:1 2.762 Abhaya/Kranti 449 150 3:1 0.0005 Abhaya/Cheptigurmatia 411 117 3:1 2.273 Abhaya/Samridhi 581 33 15:1 0.810 Abhaya/Ruchi 621 39 15:1 0.931 Abhaya/Phalguna 510 36 15:1 0.110 ============================================================================
References
Choudhary, B.P., P.S. Shrivastava, M.N. Shrivastava and G.S. Khush. 1986. Inheritance of resistance to gallmidge in some cultivars of rice. In Rice Genetics. p. 523-528. International Rice Research Institute, P. O. Box 933, Manila, Philippines.
Sahu, V.N., R. Mishra, B.P. Choudhary, P.S. Shrivastava and M.N. Shrivastava. 1990. Inheritance of resistance to gallmidge in rice. RGN 7: 118-121.