Table of contents; List of tables; List of figures; List of abbreviations; 1 General introduction; 2 Evaluation of cauliflower genebank accessions under organic and conventional cultivation in Southern Germany; 3 Evidence for strong population structure caused by germplasm regeneration in ex situ genebank collections of cauliflower (Brassica oleracea var. botrytis); 4 Genome-wide association and genomic prediction of curd-related traits in genebank accessions of cauliflower (Brassica oleracea var botrytis L.); 5 General discussion; 6 General summary; 7 Zusammenfassung; 8 References