The effects of ultrasonic irradiation on germination

An attempt to investigate the biological action of ultrasound on germinating vegetable seeds is presented. Specimens were irradiated with weak and continuous wave radiation of an intensity below 15 W/cm² and a frequency of 1 MHz. The experimental data showed that the weight increase of seeds due to absorption of water and the growth of roots were accelerated by some effects other than the ultrasonic thermal action. The effects were a function of the temperature and the sound intensity. A quantity in terms of thermal equivalent is suggested for the accelerated growth, instead of the appearance temperature under water in an experimental bath