Plant material and temperature treatments
The experiment was conducted using four 11-year-old potted
grapevines of V. vinifera L. cv. Cabernet Sauvignon grafted on
SO4 (Selection Oppenheim No. 4) grown in a phytotron. Vines
were trained on a Guyot trellising system and each vine carried
4–10 clusters of grapes. The experiment started approximately
1 week before veraison, when berry softening started, and continued
to fruit maturity. The two temperature regimes consisted of a high
day (06.00–20.00 h) temperature (max. 35 C) and a control (max.
25 C). Under both conditions, the night-time (20.00–06.00 h)
temperature was 20 C. The photoperiod corresponded to natural
day length. Twenty-five per cent of the berries (15–20 berries) in