Ultrasonic Assisted Seed Priming to Alleviate Aging Damages to Milk Thistle (Silybum marianum) Seeds

Milk thistle is a medicinal plant with high pharmaceutical properties to help relief of liver diseases. In this study, the effects of ultrasonic assisted seeds priming (20, 40, 80 and 160 s) with a frequency of 24 kHz and Power of 400 W was investigated on seed enhancement of aged seeds of Milk thistle. Results of the study, showed that as the aging damages increased, the longer sonication results in the better germination. Root growth was significantly improved using ultrasonic energy. Seeds aged for 24 hours, were exposed to ultrasonic produced for 20 seconds exhibited root length of 10.39 cm which was 5.48 cm with no ultrasonic treatment with the same aging duration. The maximum malondialdehyde activity was observed at the 96-hour aging treatment (87.83 nmol/grFW) while the lowest activity was observed at no aged and 24-hour aged seeds (7.28 nmol/grFW). It is suggested that there is a negative correlation between seedling vigor and MAD activity. It was revealed that fatty acid composition of Silybum marianum seed oil is highly influenced by the aging treatment. The variations of unsaturated fatty acids significantly increased in aged seeds. Our results showed that under accelerated aging conditions, ultrasonic assisted seed priming could not provide satisfactory enhancement to seed germination while no aged seeds germination was significantly improved using ultrasonic assisted seed priming