The xylem cavitation diagnosis technology based on ultrasonic acoustic emission

Studies have shown that ultrasonic acoustic emission (UAE) is associated with the phenomenon of cavitation diagnosis in plant conduit. The UAE signals can be acquired between 100 KHz and 1 MHz, which is the indicator of xylem cavitation. The UAE diagnosis system is established by PCI-2, PCI-8333 data acquisition card (DAQ), transducers and virtual instrument platform to realize the functions of data acquisition and transmission, data storage and information query, data output and report generation. From the experiment data, the 30 days cumulative UAEs curve is like inverted “V”, and the transpiration rate reaches the peak is earlier than cumulative UAEs. The both trends are very similar, the correlation coefficient is 0.89. Through the 24 time phase transpiration rate and cumulative UAEs proportion analysis, the conclusions can be got, the cumulative UAEs proportion is less than the transpiration rate during 00:00 - 11:59 phase, while reverse during 12:00 - 23:59 phase, and the 12:00 is an inflection point. In any case, the difference between both is not more than 10%, and the both have a better coordination and consistency. The UAE signal characteristics indicate that it is possible to use UAE as the plant body water status diagnosis index to estimate the water stress degree and guide the irrigation.