A Diversity Analysis of a World Collection of Barley1

Abstract

Data on more than 17,000 accessions of the barley (Hordeum vulgare L.) world collection maintained by the USDA, SEA, were analyzed for variation of five morphological characters (growth habit, caryopsis type, awn type, kernel row number, and kernel color). Phenotypic frequencies within the accessions from each of 48 countries, grouped in 14 regions, were tabulated. Polymorphism was widespread in most countries for different sets of characters. Very weak east‐west clinal patterns were observed and this analysis only partially supported the earlier reported patterns of variation in the postulated centers of diversity. This result may be due to an inadequate sample of characters available for analysis and/or an inadequate number of geographic regions in the world collection.The H' diversity index was computed for each country and region, for individual characters, and after pooling all five characters. Analyses indicated the between‐regions component of diversity to be relatively smaller than the variation in H' among characters and among countries within regions. This analysis shows no distinct geographical patterns in these data, but its use with additional data is warranted.