عنوان مقاله [English]
Purple coneflower [Echinacea purpurea (L.) Moench] is one of the most well-known medicinal plant species with high economic value throughout the world. In Iran, the roots and shoots of this species are used in the production of herbal medicines. In order to evaluate the best seedling transplanting date in field as well as plant density, an experiment was carried out with six dates (April 9, May 9 and June 8, June 30, July 30 and August 29) and three planting densities (7, 10, and 16 plant/m2). The highest quantitative (dry matter) and qualitative (caffeic acid derivatives) yield were achieved in coneflowers transplanted in April 9 to May 9 and in higher density (16 plant/m2). In summer time planting dates, the highest amount of all caffeic acid derivatives and dry matter yield were related to early transplanting date (June 30) and higher density. Among the caffeic acid compounds measured, the highest amount was related to cichoric acid with 26.1 mg/ g dry matter in flower. In roots, echinacoside with 5.8 mg/ g dry matter showed the highest compound concentration. Overall, the early cultivation of the crop with higher plant density (15-plant/m2) could be more suitable for caffeic acid derivatives and dry matter production compared with delayed planting.