Fig. 4From: Methodology: non-invasive monitoring system based on standing wave ratio for detecting water content variations in plantsStanding wave ratio (SWR) changes for Radermachera sinica prior to and 3–72 h post-watering. A narrow frequency range of 1.600–1.630 GHz was set. The plant remained without water for 7 d prior to the experiment. Triangle indicates the frequency of 1.611 GHzBack to article page