Abstract
To identify rice cultivars resistant to the brown planthopper, Nilaparvata lugens Stal., 2, 904 introductions of indigenous cultivars and breeding lines and 383 domestic, mostly old indigenous, cultivars were screened by the bulk seedling method with biotype I(wild type) of the insect. Except for the breeding lines most of the resistant indigenous cultivars were found to originate from Sri Lanka and southern India. While only a fer originated from northern India, Burma and Thailand. Tolerant but not resistant cultivars distributed rather widely within Asia, while almost no one was detected in Europe, Africa, America and Australia. Biotype groups II and III of the brown planthopper, selected through rearing on the resistant cultivars, were found to be effective folestimating the genotypes of resistant cultivars. A total of 120 cultivars were classified according to their pattern of biotype reactions. About 60 per cent of the Sri Lanka cultivars were found to possess the resistance gene bph 2, in contrast with only 10 per cent among the Indian cultivars.
