Drip irrigation was initiated for the well-watered plants when stem water potentials reached -0.6 MPa and for the water-deficit vines when stem water potentials reached -1.2 MPa, the target levels for the treatments.
The stem water potential differences between well-watered plants and water-deficit plants were monitored as a comprehensive indication of water-deficit in the vines [ 29].
Mid-day stem water potentials were monitored weekly for well-watered (WW)- and water-deficit (WD -treated vines to assess plant WD -treateds and to determine the amount of water to be applied to maintain stem water potentials ovineshe season (toble 1; assessonal file 2).
In well-watered plants, the photosynthesis rate, transpiration rate, stomatal conductance, and stem water potential of control and rd29A LeNCED1 plants were very similar.
Stem water potentials were significantly more negative for water-deficit treated than for well-watered vines at the time of harvest (Table 1).
Higher water deficits on NE-facing slope were partially compensated by a higher leaf and stem water storage.
We also observed a significant decrease in plant hydraulic conductance with decreasing soil and stem water potential under drought stress.
The differences in the recovery of leaf conductance and mid-day stem water potential are probably related to root flow.
Nocturnal flow activity was observed throughout the year and reflected ambient conditions on some occasions, and stem water storage recovery on others.
Water storage in tree trunks may enable maintenance of high stem water potential and flowering during the dry season (Schongart et al. 2002).
Species can also postpone declines in leaf water potential during drought through stem water storage and greater rooting depth (Abrams 1990).
