Effects of Electromagnetic Field and Ultrasonic Waves on Seed Germination, Seedling Characteristics and Essence Percent of Thymes (Thymus vulgaris L.)

Abstract

The effect of electromagnetic field and ultrasonic waves on the seed germination, seedling characteristics and essence percent of thymes investigated by using two separate factorial experiments, based on completely randomized design with three replications, at the Seed Science and Technology Laboratory of Faculty Agricultural Sciences of Islamic Azad University of Mahabad in 2017. In the first experiment, the seeds were exposed to electromagnetic field with 5, 50 and 100 milli tesla for 5, 15 and 30 minutes, and in the second experiment, the seeds were exposed to ultrasound intensity of 20, 40 and 60 kHz for 4, 8 and 12 minutes. Results of analysis of variance showed that the effects of electromagnetic field intensity by ultrasound intensity interactions were significant on all traits and indices. In this research, the highest germination percentage (97.66%), speed of germination (0.20), root length (8.70 cm), stem length (9.67 cm), root dry weight (41.5 mg), stem dry weight (44.75 mg), seedling dry weight (86.21 mg), plant dry weight (0.82g), and lowest mean germination time (4.84 days) belonged to the seeds treated with electromagnetic field intensity of 50 milli tesla for 15 minutes. The results also revealed that highest germination percentage (90.66%), germination speed (0.21), root length (7.78 cm), stem length (6.65 cm), root dry weight (41.21 mg), stem dry weight (53.60 mg), seedling dry weight (94.80 mg) and plant dry weight (0.55 g) and the lowest mean germination time (4.96 days) were related to 60 KHz ultrasound intensity for 16 minutes. The highest essence percent was produced from seeds treated with electromagnetic fields of 5 milli tesla for 30 minutes (3.44 percent) and 60 KHz ultrasound waves for 16 minutes (2.95 percent). Thus, these treatments are recommended to improve thyme germination and its seedling properties.