Determination of natural populations to be included in breeding program in St. John’s wort species (<i>Hypericum perforatum</i> L.)

St. John's wort (<i>Hypericum perforatum</i> L.) is a medicinal and aromatic plant of rapidly increasing importance. The cultural production of this species, which is of economic importance due to its medicinal properties, is limited. One of the main ways to increase production is to develop cultivars. Thus, the homogeneous raw material required for a standard product will be provided. This study aimed to determine the characteristics of natural populations to obtain productive cultivars with high hypericin and hyperforin that can meet market demands. In addition to yield and quality values, other characteristic features of the plant such as flower diameter, petal length and petal width, which directly affect productivity, were revealed in the study. The study was conducted under field conditions for two years with three replications. Fresh flower weight among the populations varied between 30.15 and 240.28 g/plant, while the hypericin ratio varied between 51.32 and 105.31 (mg/100 g). The study determined a wide variation among the populations, and the populations with superior characteristics were included in the breeding program.