Effect of drought stress on some morphological and physiological characteristics of Echinacea spp.

Drought stress is one of the most important environmental stress of plants in arid and semi-arid regions that limit productivity. To evaluate the effects of drought stress on two-year-old seedlings of Echinacea purpurea and Echinacea angustifolia, an experiment was conducted with four levels of irrigation: 25, 50, 75, and 100% of field capacity (FC) as a completely randomized factorial. Several morphological, biochemical, and developmental traits were measured after three months of treatment. Growth indices such as plant height, shoot weight, root weight, shoot dry weight, and root dry weight, were reduced at lower FC in both species. Flowering was not observed in E. angustifolia under 50 and 25% FC treatments, and the best flowering quality and longevity was observed in E. purpurea under 75% FC. Protein content decreased in both species when plants were exposed to lower irrigation levels. The lowest protein content was seen in E. angustifolia under 25% FC. Reducing radical scavenging activity was observed in both species during drought stress, while the highest antioxidant capacity was found in E. purpurea under 75% FC. Proline content was highest in E. angustifolia under 25% FC. Based on flower quality, longevity, and antioxidant capacity, it seems that E. purpurea is more tolerant than E. angustifolia to drought stress.