Abstract
Two bacterial blight resistant varieties/strains of cotton viz., C-2 (67) 577 and C2 (69) 1455 both of each used as male and female parents were crossed with the susceptible variety DPL-7344424, to study the inheritance response of resistance genes for bacterial blight. The cross C2 (67) 577 x DPL-7340-424 (resistant x susceptible) indicated a single gene difference with complete dominance for resistance to the race-18 in the resistant parent C, (67) 577. Single gene inheritance of resistance to the race-18 was also indicated in C2 (67) 577 when crossed as male with susceptible DPL-7340-424. Both seedling and adult plant growth stages, F, and back cross disease grade distributions clearly indicated a monogenic type of inheritance of resistance in resistant x susceptible and susceptible x resistant crosses. The monogenic inheritance of resistance indicates that pedigree breeding would be adequate for transferring the resistance in the susceptible genotypes. All the plants were resistant in F-1, F-2 and back cross progenies in cross between resistant x resistant showings that the gene for resistance is the same in both the parents. Seedling and adult disease grade in the present study were positively correlated as monogenic inheritance was observed in both seedling and in the adult stage of growth. These results support the concept of common basic mechanism controlling the resistance in the two different stages of plant growth and suggest that selection for resistance can be accomplished in either growth stage.