“…The water content of plant stems is a major index of the physiological activity of plant water, especially in precision agriculture [ 1 , 2 , 3 ]. Methods for detecting stem water content include drying [ 4 ], gamma rays [ 5 ], nuclear magnetic resonance (NMR) [ 6 , 7 , 8 ], X-ray computed tomography [ 9 ], resistance [ 10 ], time-domain reflectometry (TDR) [ 11 ], frequency-domain (FD) capacitance [ 12 , 13 , 14 ] and infrared detection [ 15 ]. Of the above methods, drying constitutes in vitro detection, which cannot detect the dynamic changes in the stem water content.…”