1All India Coordinated Rice Improvement Project, Hyderabad-500 030
2Rice Research Station, Tenali, Andhra Pradesh, India
1Present address: Agricultural Research Institute, Rajendranagar, Hyderabad 500 030, A.P.
2Present address: Plant Breeder (IRTP), International Rice Research Institute, P.O. Box 933, Manila, Philippines.
3Present address: International Institute of Tropical Agriculture, Oyo Road, P.M.B. 5320, Ibadan, Nigeria.
Since assessment of insect resistance under natural infestation is subject to a fluctuation in insect population, there is always a problem of erroneous classification of resistant and susceptible plants. In a study of the inheritance of resistance to rice stem borer [Tryporyza incertulas (Walker)], this problem was eliminated by adopting a special design ensuring uniform comparison with the resistant and susceptible checks. In addition, possible mis-classification of escapes as resistant was minimized by having the same F2 plants planted at two locations, namely, Tenali and Warangal, where stem borer is a serious problem. Segregation of the F2 of TKM 6 × IR 8 indicated that resistance to stem borer at heading stage is governed by a single recessive gene. Evaluation for resistance in the F3 lines confirmed the F2 data.
