Diversity in Nordic spring wheat cultivars (1901–93)

Abstract

Nordic plant breeders have selected superior genotypes and released new spring wheat cultivars throughout this century. However, the extent of phenotypic diversity that exists in this improved germplasm has not been accurately investigated. This study phenotypically assessed 75 selected cultivars released to farmers in Denmark, Finland, Norway and Sweden within the last 10 decades. Grouping of cultivars was not related to their geographical origin or decade of release. The respective within‐cluster variances were always larger than the among‐cluster variances. The average phenotypic diversity for Nordic spring wheat germplasm was 0.22, which was not surprising because some newer cultivars were derived from older cultivars. There was a significant influence of geographical origin on days to heading, straw, grain and biomass weight, and kernel number. Likewise, the country × decade of release interaction was significant for all characteristics except plant height. These findings suggest that irrespective of...