Genetic variability available for the improvement of fiber strength and length within Pima cotton often occurs in genetic backgrounds that are unimproved or unadapted. The objectives of this project were to develop agronomically improved germplasm lines possessing high strength and long length fiber, and document the performance of these lines. Crossing was performed among germplasm lines possessing superior fiber strength or length in 1993 and 1994, followed by selection within the F _2, F3, and F4 generations. Ten selected progeny lines were evaluated for performance and fiber quality in replicated tests at Maricopa and Safford, AZ in 1999, and Shafter, CA in 2000. Among the five lines identified for germplasm release, four lines (93252, 94218, 94220, and 94217-19) produced yields not differing from the check cultivar Pima S-7 at Safford, AZ and Shafter, CA. Two of the five candidate lines (93252 and 94218) exceeded Pima S-7 in yield at Maricopa, AZ. Plant heights of candidate lines for release either did not differ from Pima S-7 or were slightly shorter than Pima S-7 at Maricopa, AZ (93252 and 93260-5). All lines tested produced greater fiber lengths than the Pima S-7 check at both the Maricopa and Safford, AZ locations. Across locations, fiber lengths of test lines ranged from 1.49 to
1.56 inches. All test lines had significantly stronger fiber than Pima S-7 at both Maricopa and Safford, AZ. Fiber strength improvement over Pima S-7 among lines identified for release ranged from 3.5 g/tex to 8.5 g/tex, depending upon line and location. All test lines produced lower lint percent and micronaire values than did Pima S-7 at both Maricopa and Safford, AZ. A release notice and formal release of 94220, 93252, 94218, 94217-19, and 93260-5 is scheduled for 2001.