The effects of different seed priming agents on improving emergence, growth, yield and essential oil percentage of purple coneflower (Echinacea angustifolia DC.) under field condition

Abstract

Purple coneflower (Echinacea angustifolia DC. var. angustifolia) is an impor- tant medicinal plant in pharmacological industry. This plant is produced in commercial scale but their seeds exhibit low germination percentages under field conditions. Enhancing seed germination is thus crucial for improving the production of E. angustifolia. The influence of Ethephon, Gibberellic acid (GA3) and moringa leaf extract on emergence, growth attributes, yield at- tributing characteristics and essential oil percentage of purple coneflower (E. angustifolia) were investigated. Freshly harvested seeds of E. angustifolia were treated with 0.5, 1 and 2 mM of ethephon, 2000 2500 and 3000 mg/L of gibberellic acid (GA3) and 5, 10 and 15% of moringa leaf extract (MLE). Then, seeds were stratified at 4 °C for 4 weeks in light. All the priming treat- ments were evaluated for the emergence, growth attributes, yield attributing characteristics and essential oil percentage. Among different treatments MLE-priming at 10% could be recommended, as it was the best in terms of final emergence percentage (96%), mean emergence time (4.78 d), α-amylase activity (52.15 IU/mg), total soluble sugars (61.41 mg/g), reducing sugars (54.19 mg/g), plant height (98.82 cm), number of branches (28.36), biological yield (14.08 t/ha) and root yield dry (8.88 t/ha) and essential oil percentage (0.62%). Moringa leaf extract (10%) is recommended as a priming agent to overcome seed dormancy and improve the emergence, growth, yield and essential oil percentage of E. angustifolia.