RELATIONSHIPS AMONG TETRAPLOID WHEAT (TRITICUM-TURGIDUM L) LANDRACE POPULATIONS REVEALED BY ISOZYME MARKERS AND AGRONOMIC TRAITS

Diversity and relationships among ten tetraploid wheat landrace popula tions, collected from different localities in the central highlands of Ethiopia, were studied using isozyme markers and agronomic traits. Th is type of analysis in crop species is fundamental for designing optim al germ plasm collection, management practices and for developing an i ndex for parental selection, The populations differed in allelic frequ encies. Gene-diversity estimates showed that the populations encompass an appreciate amount of variation. However, differentiation between t hem was low, as was also confirmed by the presence of gene flow. Much of the diversity (85%), was attributable to the within-population leve l. The genetic distances were mostly small with the exception of those between a few pairs of populations. Thus, the relationships discerned among the populations were more of a similarity nature which could be ascribed to sharing a common ancestral population and/or adaptation t o similar climatic conditions, The pattern of genetic divergence appea red to be independent of geographic distance. Considerable divergence in the agronomic traits was observed for certain populations. Cluster analyses of the isozyme and agronomic data produced different patterns and memberships of groupings. This lack of agreement could be ascribe d to the different forces of evolution acting on isozyme markers and a gronomic baits since agronomic traits, are the prime target of artific ial selection. The clustering based on agronomic traits resulted in gr ouping together populations with similar agronomic performance. The re sults of this study suggest that taking more samples within a locality or population would be a better approach to capture the range of vari ation in the landrace populations of the central highlands of Ethiopia .