PARENTAGE ANALYSIS OF INTERNATIONAL SPRING WHEAT YIELD NURSERIES 17 TO 27

Breeders can increase genetic diversity by selecting lines with novel parentage from international nurseries. A database program, WCOP, an a pplication of the International Center for Maize and Wheat Improvement (CIMMYT) Wheat Pedigree Management System (WPMS), calculated the coef ficient of parentage (COP) among cultivars and was used to study 169 w heats from the International Spring Wheat Yield Nurseries (ISWYN) No. 17 to 27, and a set of 27 reference cultivars. The average COP (exclud ing similarity values of cultivars with themselves) among the 196 line s was 0.14. The similarity between the ISWYN cultivar group and the re ference cultivar group was 0.08. Average internal COP values for U.S.- Canadian, Australian, and ISWYN sets were 0.18, 0.30, and 0.14, respec tively. The ISWYN cultivars were clustered by means of COP values into genealogically similar groups. The largest ISWYN dusters were diverge nt from U.S., Canadian, and Australian standard spring cultivars, The clusters highlight divergent germplasm that may broaden the genetic ba se of breeding programs in temperate zones.