Cultivar diversity in Nordic spring barley breeding (1930–1991)

Abstract

A phenotypic diversity index (PDI) was calculated using 10 agronomiccharacteristics recorded in 90 accessions of 2-row spring barleys and 29accessions of 6-row spring barleys grown in the Nordic Region. The PDIranged from 0.0308 to 0.6245 in 2-row barley accessions and from0.0314 to 0.7016 in 6-row barley accessions. The average PDIs were0.2178 and 0.2438 in 2-row and 6-row barley germplasm, which confirmsthat some older cultivars were parents of newer cultivars. The lowest PDIwas between accessions with the same name, which suggest that irrespectiveof their market source, they were the same cultivars. The largest PDI rangesin 2-row barley cultivars within the same country or release decade werecorrelated to the number of accessions in the respective cluster, whichsuggests that phenotypic diversity in this germplasm depends on the numberof cultivars included in the cluster. However, this association was not alwaysobserved in 6-row barley cultivars. The most distinct 2-row cultivars wereArla and Akka from Sweden, whereas Sigur and Tampa from Iceland werethe most distinct 6-row cultivars as determined by both PDI and averagelinkage cluster analysis. This analysis also confirm that the 2-row barleyaccessions Jenny, Triumph, and Vega, which were obtained from twodistinct market sources, and the 6-row barley accessions under the nameAgneta (but from three market sources) were the same. The analysis ofvariance of the PDI indicates that 6-row germplasm may be clusteredaccording to their geographical origin or decade of release, but this was notobserved in 2-row barley germplasm. This research demonstrates theadvantage of PDI to assess variation among breeding pools.