ISHS Acta Horticulturae 493: I ISHS Workshop on Water Relations of Grapevines
THE INFLUENCE OF THE SOIL WATER BALANCE ON THE WATER FLUXES IN THE SOIL-PLANT-ATMOSPHERE CONTINUUM. FIELD STUDIES IN A VINEYARD AT SANTARÉM, PORTUGAL |
| Authors: | J. Michaelsen, J. Silvestre, M.I. Ferreira |
| Keywords: | grapevine, soil water potential, soil water content, hydraulic lift, sap flow, radiation |
| Abstract:
Soil water status was measured in the root zone of single plants of cultivar Trincadeira Preta using TDR-probes and tensiometers in summer 1996 (see also Silvestre et al. 1998). Changes of soil water potential were described by differences in water tension (dT=  1-2) over a 30 minutes period (Gruler, 1998). At the onset of transpiration, dT decreased and during night dT increased, indicating periods of drying and wetting.
Higher amplitudes of the oscillation were observed at lower soil water content.
A decrease in dT in the morning began at the same time with the onset of sap flow.
The increase in dT during the afternoon showed, at lower soil water content, a time lag in comparison to start of decrease of transpiration.
Short-term changes of solar radiation were immediately detected by changes of sapflow velocity and dT. The course of the soil water potential is discussed in relation to root water uptake and transpiration.
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