Background and Aims: Despite much anecdotal evidence, there has been little scientific investigation of the potential effects of a high-temperature event on grapevines during deficit irrigation. This study examined the interaction between temperature and water status on leaf physiology.
Methods and Results: Two experiments used Cabernet Sauvignon cuttings grown in a glasshouse at approximately 27–30°C before deficit irrigation treatments were imposed. When water stress was apparent, a 2-day high-temperature event with maximum daytime temperatures of approximately 40–45°C was generated. Leaf damage, stomatal conductance and water potential of deficit-irrigated vines were all affected to a greater extent than in the well-watered vines.
Conclusions: The negative effects of a high-temperature event on vine physiology were more severe in vines experiencing water stress than in well-watered vines, but recovery was rapid even without re-watering.
Significance of the Study: An increase in the use of deficit irrigation will lead to a greater likelihood of vines being water stressed on hot days, and the observed responses indicate that this will result in greater damage to the vine.