Registration of NP28 Sudangrass Germplasm, A Composite of 90 Low-Dhurrin Self-Pollinated Lines

NP28 Sudangrass [Sorghum bicolor (L.) Moench] [formerly S. sudanense (Piper) Staph] (Reg. no. GP-236, PI 535772), a population developed cooperatively by the USDA-ARS and the Nebraska Agricultural Research Division, was released in April 1989. NP28 is a composite consisting of equal quantities of seed of 90 low-dhurrin, highly self-pollinated lines of sudangrass. Each of the lines was derived by seven or more generations of selfing following one or more crosses among seven sources of sudangrass germplasm. The sources included low-dhurrin selections from \u27Piper\u27; low-dhurrin breeding lines from the University of Wisconsin; two sudangrass B-lines (maintainers for A1 cytoplasm) obtained from commercial sources; and three sudangrass cultivars (Piper, \u27Greenleaf\u27, and \u27Sweet\u27) that contained the ms3 gene for genetic male-sterility. The ms3 gene was obtained from Kansas lines that were derived from an initial cross and one backcross of the above three cultivars to NP2B (2), a random-mating population of sorghum (S. bicolor). About 20% of the composite of 90 lines resulted from crosses that involved male-sterile (ms3ms3) segregates as female parents, but the frequency of the ms3 allele in the self-pollinated lines being released is unknown