Abstract

                                Four sodic soil tolerant rice cultures received from the International Rice Research Institute (IRRI), Philippines were evaluated for their host-plant resistance to brown planthopper. Nilaparvata lugens in screen house and leafholder, Chaphalorrocis medinalis and yellow stem borer. Scirpophaga incertulas under field conditions. The level of antixenosis and antibiosis mechanisins found in the four cultures viz., IRRI 2011, 2028, 2030. 2122 were measured in comparison with the local check CO43. In seedling box screening test, all the cultures showed lower damage rating and nymphal settling response against the check. Further, the cultures delayed the nymphal growth (13.60 16.20 days) compared with CO 43 (13.0 days). Similarly, low fecundity (136.0-163.0 nos) ad shortened female adult longevity (6.09.60 days) were recorded on sodic soil tolerant cultures than CO43 (203.0 nos. and 12.4 days). Significant differences were observet among the test cultures/variety in the nymphal survival rate and their emergence. In the field, the culture IRRI 2028 was found to be highly susceptible to both pests.

Key words : Nilaparvata lugens, Scirpophaga incertulas. Cnaphalocrocis medinalis, Sodic soil, Tolerant cultures