31 research outputs found
Influence of soil water content and atmospheric conditions on leaf water potential in cv. "Touriga Nacional" deep-rooted vineyards
Abstract In this study, the influence of soil and atmosphere
conditions on noon and basal leaf water potential of
vines ââTouriga Nacionalââ in the DaËo region submitted to
different irrigation treatments is analysed. Both indicators
showed to be dependent on environmental conditions at the
time of measurement. Leaf water potential at noon of fully
watered plants was linearly related with atmospheric conditions,
with values registered when vapour pressure deficit
(VPD) was higher than approximately 3 kPa being no
different from the values registered in stressed plants.
Therefore, this indicator cannot be reliably used to distinguish
different plant water stress levels when atmospheric
conditions induce high evaporative demands. The basal
leaf water potential (wb) was also influenced by VPD at the
time of measurement for all soil water conditions. In well
irrigated plants, it was even possible to establish a baseline
that can therefore be used to identify nonwater stressed
conditions (wb (MPa) = -0.062â0.0972 VPD (kPa),
r2 = 0.78). A good correlation was found between soil
humidity and wb. However, more than the average value of
the whole thickness of soil monitored, the wb values were dependent on the distribution of soil humidity, with the
plants responding to the presence of wet layers