Agroscope, ETH Zurich

European Red Clover Exhibits High Diversity and Local Adaptation

Red clover is one of the most important legumes in European forage production. In a multi-year field trial, researchers tested Europe’s largest collection of different red clover accessions at five European locations.

The high amount of genetic diversity present in red clover provides an invaluable resource for improving important traits such as yield, quality, and resistance to biotic and abiotic stress factors. Unfortunately, these traits are often poorly described. As part of the Horizon Project EUCLEG (, the genetic and phenotypic diversity of 395 diploid red clover accessions was studied, among others in Switzerland at Agroscope’s Tänikon site. The results have now been published.

Local breeding leads to high genetic diversity

The genetic similarity of the red clover accessions largely reflects their geographic origins, with the Northern European and Swiss accessions clearly differing genetically from the remaining European ones. In addition, the results show that the current breeding material originated from local landraces or naturally occurring populations (ecotypes). Interestingly, some accessions show genetic similarities to accessions from foreign breeding programmes. This suggests that red clover breeders made use of the right to use foreign breeders’ varieties to incorporate desired traits into their own breeding programmes.

Agronomic performance is location-dependent

The agronomic performance of red clover accessions was tested in field trials at five European locations. The average dry-matter yield in the first main harvesting year ranged from 0.74 kg/m2 in Serbia and Norway to 1.34 kg/m2 in Switzerland. Many accessions exhibited decreasing plant densities over the duration of the trial under selective experimental conditions, viz., hot summers in Serbia, cold winters in Norway and high disease pressure in Switzerland and the Czech Republic. Furthermore, the performance of the accessions was highly location-dependent. As a rule, their performance and persistence were good under the climate and management conditions in which they had been bred. This local adaptation is particularly noticeable in the Northern European accessions, which exhibited the highest yields and survival rates in the Norwegian field trial, but performed less well at all other locations.


  • European red clover varieties have been bred from local ecotypes and landraces and show specific adaptation to regional conditions.
  • Locally bred red clover cultivars were generally the most productive and persistent in their region of origin. This local adaptation was most pronounced in Northern European accessions.
  • Varieties that achieved a similar or better performance than local varieties represent interesting genetic resources for breeding.
  • The study provides important data on the so-called “genetics x environment” interaction of red clover and allows a first assessment of the adaptation potential in future climate scenarios.
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