The behaviour of the averaged normalized sensor response parameter (NR) used to monitor the drought response of cv. Red Setter plants subjected to two cycles of drought stress (DSI and DSII) interrupted by a rewatering recovery phase (RE). Arrows show the timing of the initiation of each treatment. The data represent the mean of three well-watered (control) and four stressed plants. The various phases have been highlighted by grey boxing: PI—sensor insertion, PII—drought stress, and PIII—post-rewatering recovery.