Effect of gibberellic acid, stratification and salinity on seed germination of Echinacea purpurea cv. Magnus
This study was conducted in order to determine the appropriate treatment for breaking dormancy and the effect of salinity on seed germination of purple coneflower (Echinacea purpurea cv. Magnus), in two separate experiments. In the first experiment, five levels of gibberellic acid (GA3) (0, 250, 500, 1000, and 1500 mg×L-1) with four levels of cold moist stratification period of seeds at 5°C (0, 5, 10 and 15 days) were launched. A factorial experiment was conducted in a completely randomized design with four replications. The statistical analysis showed that concentration of 250 mg×L-1 GA3 with 10 days of cold moist chilling significantly increased the percentage of germination of normal seedlings and reduced the mean time of germination. In the second experiment, the seeds were chilled for 10 days at 5°C and half of them treated with 250 mg×L-1 GA3 for 24 hours. The seeds treated with GA3, and those non-treated were subjected to NaCl for salinity stress. The experiment was conducted using five salinity levels (0, 20, 40, 60 and 80 mM NaCl) in four replications in a completely randomized design. The results showed that purple coneflower is highly sensitive to salinity in the germination stage. The results also showed that by increasing salinity levels, the percentage of germination and normal seedlings significantly decreased and the mean time to germination increased, compared to the control treatment. But the seeds treated with GA3 showed higher viability and better performance under salinity stress condition.