ISHS Acta Horticulturae 449: II International Symposium on Irrigation of Horticultural Crops
TRANSPIRATION OF GRAPEVINES IN THE FIELD |
| Authors: | J. Schmid, P. Braun |
| Keywords: | Sap flow, Granier method, water relations |
| Abstract:
The transpiration of grapevines was measured using the Granier (1985) method. This method allows a continuous measurement of sap flow through the stem under natural conditions in the field. Thus the reactions of the plants to different environmental variables could be followed. When expressing water loss on a per unit leaf area basis, differences between plants could basically be eliminated. Considerable water loss could be observed during the night (up to 30% of the peak flow rate during the day), when conditions of high water vapour pressure deficit (VPD) prevailed. When summarizing data to hourly values, a clear relationship for light and VPD could be shown. For VPD it was useful to separate into day and night values. A prolonged period of drought in the grapevine experiment resulted in a shift to lower values for both, the light and VPD curves. | |
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