Agronomic and chemical characterization of 39 Hypericum perforatum accessions between 1998 and 2000

Thirty‐nine accessions of St John's Wort were studied over a 3‐year period. The percentage of diseased plants ranged from 0 to 100%. After 3 years of cultivation, 18% of the accessions presented a dieback rate of <10%. Hypericins and hyperforins in flowering tops (top 30 cm of plants at full bloom) and flowers were assayed using high‐performance liquid chromatography (HPLC‐DAD Diode Array Detector) (one to three cuttings a year). The hypericin contents in flowering tops ranged from 0.7 to 3%. These levels were, on average, 2.8‐fold lower than those recorded in flowers. Hyperforin levels varied in the different accessions, ranging from 0.65 to 3% in flowering tops and 2 to 5.7% in the flowers. In line with present industrial needs, a minimum content of one or more of the active components, it will therefore be necessary to select accessions in terms of the dry weight yield and the contents of flowering tops and flowers. Dry weight depends on cutting height, which also affects the quality of the plant material harvested. Because of the plant to plant variability, the performance of the accessions selected would be improved.