The effect of irradiation ofVicia fabaroots with 1·5 MHz ultrasound

Abstract

Roots of Vicia faba seedlings have been exposed to 1·5 MHz ultrasound at intensities in the range 1–4 W/cm² for periods of two to 60 minutes. The subsequent average growth in eight days expressed as a fraction of the corresponding average growth for control roots, decreased with increasing exposure time and radiation intensity. The response was not changed if the exposure was split into two fractions separated by 24 hours. In contrast to results following exposure to ionizing radiation, the growth rate fell to a minimum in the first day after exposure, recovering gradually to the control value over eight days. This may indicate damage to both the dividing cells of the meristem and to the differentiated elongating cells in the root.