Articles
Vapour pressure deficit as a means of scheduling irrigation in Vitis vinifera subsp. vinifera ‘Shiraz’
Article number
1468_34
Pages
261 – 268
Language
English
Abstract
Evapotranspiration (ET0 and ETc) has long been used in winegrape culture to aid in managing irrigation requirements of the crop.
Advances in data collection and storage have made it easier for growers to recall and analyze current and historic data sets to more fully understand trends below and above the ground.
Vapour Pressure Deficit (VPD) measurements essentially measure surrogates of the ETc in the immediate environment.
The application of VPD measurements from within and above the canopies of growing plants has become more commonplace as growers seek to gain competitive advantage in the marketplace.
By combining this with soil Volumetric Water Content (VWC) data, it is possible to link trends in plant water use with changes in the local microclimate.
Management of the plant environment within the canopy can improve the timing of temperature and humidity intervention strategies in conditions of heat stress and frost.
Such interventions can also counter the negative effects of common fungal, bacterial and insect pathogens.
This study brings soil water sensors together with above-ground instrumentation to show links between VWC and VPD within the different layers of the canopy of Vitis vinifera (subsp. vinifera ‘Shiraz’). These links were found to be particularly relevant within the fruiting canopy of the vines.
Interventions previously imposed on the basis of soil water trending data alone are shown to be also indicated by changes observed in VPD. Capacitance soil water sensors were installed adjacent to temperature and relative humidity (RH) sensors in the canopy and managed via the internet using Sentek’s IrriMAX Live® software.
Regression analyses found significant relationships between reference evapotranspiration (ET0) vs.
VPD (r2=0.6431) and VPD vs. daily water use (DWU) (r2=0.6427). A relationship was also found to exist between VPD and dew point, which can be used to predict the incidence of frost (r2=0.9575). Advance knowledge of these relationships is proposed as additional tools to help growers in the scheduling of irrigations to optimise their water and pumping costs, as well as to reduce their total crop pathogen loads and manage their frost risk.
Historic data was reanalysed to demonstrate the potential optimisations that can be made with the benefit of these new findings.
Advances in data collection and storage have made it easier for growers to recall and analyze current and historic data sets to more fully understand trends below and above the ground.
Vapour Pressure Deficit (VPD) measurements essentially measure surrogates of the ETc in the immediate environment.
The application of VPD measurements from within and above the canopies of growing plants has become more commonplace as growers seek to gain competitive advantage in the marketplace.
By combining this with soil Volumetric Water Content (VWC) data, it is possible to link trends in plant water use with changes in the local microclimate.
Management of the plant environment within the canopy can improve the timing of temperature and humidity intervention strategies in conditions of heat stress and frost.
Such interventions can also counter the negative effects of common fungal, bacterial and insect pathogens.
This study brings soil water sensors together with above-ground instrumentation to show links between VWC and VPD within the different layers of the canopy of Vitis vinifera (subsp. vinifera ‘Shiraz’). These links were found to be particularly relevant within the fruiting canopy of the vines.
Interventions previously imposed on the basis of soil water trending data alone are shown to be also indicated by changes observed in VPD. Capacitance soil water sensors were installed adjacent to temperature and relative humidity (RH) sensors in the canopy and managed via the internet using Sentek’s IrriMAX Live® software.
Regression analyses found significant relationships between reference evapotranspiration (ET0) vs.
VPD (r2=0.6431) and VPD vs. daily water use (DWU) (r2=0.6427). A relationship was also found to exist between VPD and dew point, which can be used to predict the incidence of frost (r2=0.9575). Advance knowledge of these relationships is proposed as additional tools to help growers in the scheduling of irrigations to optimise their water and pumping costs, as well as to reduce their total crop pathogen loads and manage their frost risk.
Historic data was reanalysed to demonstrate the potential optimisations that can be made with the benefit of these new findings.
Authors
G. Dridan, M. Dalton, M. Intervera
Keywords
capacitance, evapotranspiration, frost, grapevine, soil, vapour, VPD, water
Groups involved
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