Figure 2.

The diurnal variation in the NMR signal (black line) is apparent for the entire 2 months of data acquisition. The temperature model (red line) of Equation 2 visually accounts for the vast majority of the signal variation during the water limited epoch, but not for the well watered or drying epochs, since the water content was not constant. To encourage water loss, the tree was manipulated in several ways: (a) watering was stopped; (b) the crown was removed 1 m above the detector coil, with the cut sealed with an impermeable barrier; (c) the crown was removed 10 cm from the detector coil and the cut left unsealed; (d) strips of phloem were removed above and below the detector coil to cease carbohydrate transport. Epochs were determined based on NMR signal response to the manipulations.