RELATIONSHIPS AMONG 70 NORTH-AMERICAN OAT GERMPLASMS .2. CLUSTER-ANALYSIS USING QUALITATIVE CHARACTERS

Analysis of genetic relationships in crop species can provide a relative measure of genetic diversity, an index for parental selection, and structure for stratified sampling of populations. This research was to study the genetic relationships among 70 recent and historical North American oat cultivars using an estimate of the similarity of alleles for polymorphic allozymes, prolamine seed proteins (avenins), and simply inherited morphological characters. Clusters were formed by sequentially dividing groups of cultivars using factor analysis. The first division split cultivars into fall and spring-planted groups. A modified Shannon-Weaver information statistic (I'), which is inversely related to genetic diversity, was estimated for each of the six large clusters formed. The I' value for cultivars in the fall-planted clusters was 0.35, while the spring clusters' value was 0.37. The two clusters representing most of the cultivars from Canada and the midseason spring oat region had a collective I' value of 0.50. This study of qualitative characters indicated that fall- and spring-planted oat cultivars are genetically divergent groups. The fall-planted oat cultivars are more genetically diverse than the spring-planted cultivars adapted to the economically important growing regions of the upper North American central plains.