Inheritance of bacterial blight resistance in rice.

The inheritance of resistance to bacterial leaf blight was studied in 12 rice cultivars: BR51-91-6, KMP 242, KMP240, AD 3488, CNM 31, CR 138–1040, RP 633-76-1, ADT 30, IR 13240-10-1, IR 1545-339, UPRD 79–79 and RTN 68. These test cultivars were crossecl with a highly susceptible parent T(N)1. The F1, F2 and F3 generations were raised and inoculated with the ‘Ranchi Isolate’ at the maximum tillering stage of vegetative phase by the clipping technique. The resistance in BR 51-91-6, KMP 242, KMP 240, AD 3488, CNM 31, CR 138–1040, RP 633-76-1, and ADT 30 was found to be governed by a single dominant gene. The resistance in IR 13240-10-1 and IR 1545-399 was conditioned by a single recessive gene and in UPR 79–79 and RTN 68 by a pair of complementary genes. Six test cultivars were also crossed with IR 22, a cultivar homozygous for Xa 4 gene and found to have resistance genes nonallelic to Xa 4 and segregated independently of it.