Genetic variation of annual and biennial caraway (Carum carvi) germplasm offers diverse opportunities for breeding

Caraway (Carum carvi) is an important aromatic plant of the Apiaceae family. Fruits and essential oil are used as spice, pharmaceutical and for various industrial purposes. Cultivation is endangered by on-going climatic changes so that new breeding projects are necessary to secure future cultivation of caraway. However, the initialization of new breeding programs is hampered by poor availability of phenotypic data. To close this gap, 64 annual and 68 biennial caraway accessions were phenotyped under field conditions in two years. We determined the beginning of flowering, the end of flowering, maturity, plant height, thousand-grain weight, stalk attachment rate, shattering rate, limonene, carvone and total essential oil content. Best linear unbiased estimates (BLUEs) and broad sense heritability were computed using linear mixed-effects models. We observed a high variability for all traits with medium to high heritability (h2 = 0.52 – 0.95). Merely for the carvone to limonene ratio, heritability was lower (0.17–0.25). Thus, the observed phenotypic diversity is applicable to breeding. Insights into correlations between traits may ease selection processes in breeding projects. The distribution of the phenotypic variation of some traits was partially associated with the genetic substructure detected by genotyping by sequencing (GBS) data. This could be explained by selections in former breeding programs.