COMPARISONS OF METHODS FOR INTROGRESSING EXOTIC GERM PLASM INTO ADAPTED SORGHUM

The incorporation of exotic germ plasm into breeding populations can b roaden and diversify the genetic base of adapted genotypes. To more ef fectively utilize the genetic resources existing in Sorghum bicolor (L .) Moench, a rapid and efficient method of incorporating exotic genoty pes into adapted populations is needed. Therefore, this study was cond ucted to compare the effectiveness of backcrossing to a broad-based po pulation versus backcrossing to an inbred line for developing improved lines from adapted x exotic crosses. A wild sorghum, a cultivated lan drace, and a converted sorghum line were crossed to an inbred line (CK 60) and a broad-based population (KP9B). After two generations of back crossing to the respective adapted parent, 50 F-2 lines were derived f rom each of the backcross generations of every mating and evaluated at three test environments. Backcrossing to an inbred line (CK60) gave f ewer high-yielding segregates and generated less genetic variation tha n backcrossing to a population (KP9B). Also, the number of agronomical ly acceptable lines derived from each CK60 mating was fewer than that derived from the corresponding mating with KP9B. Overall, the use of a broad-based population as an adapted recurrent parent for introgressi ng exotic genotypes may provide good opportunities for developing suit able inbred lines from adapted x exotic backcrosses.