Non-Destructive Measurement of Vascular Tissue Development in Stems of Miniature Tomato Using Acoustic Method

Abstract

The guided wave effect resembling that of annual rings found in woods and the cortical region of bones is believed to be observable in vascular tissues of herbaceous plants. The properties of acoustic waves traveling through the vascular tissue in the stem of a miniature tomato were measured using a piezoelectric pulser and receiver. The thickness of the vascular tissues and the stem's water content were measured. The detected acoustic waves showed a guided wave effect. The apparent sound velocity, v_a, was related to the vascular tissue thickness, t_v. These results reveal that the detected acoustic waves traveled along the vascular tissues in stems. The maximum peak intensity of the detected acoustic waves, I_max was also related to t. Furthermore, wilting of the examined plants decreased the I_max, although v_a was not changed. The decrease in I_max might result from cavitations and embolisms with a subsequent increase in air pores in xylem tissues. These results demonstrate that the measurement of acoustic waves traveling through vascular tissue is a useful tool for the non-destructive evaluation of vascular tissue development and embolism density in xylem tissues.