Leaf samples from each tree were collected from the fourth to the sixth fully
expanded leaves one day before water stress, the
day at the end of water stress, 1 wk after the
rewatering, and during the flushing period. Leaf
samples were dried at 65 °C for 72 h and then
ground through a 40 mesh Wiley mill. TNC was
determined using acid extraction following the
method described by Smith et al. (1964) and
Nelson’s reducing sugar procedure (Hodge and
Hofreiter, 1962). Leaf total N concentration (TN)
was measured by a combustion method using a
Nitrogen Determinator (FP-528 Leco Crop. USA).
The C/N ratio was calculated from TNC and TN
in the same period.