REST COMPLETION AND GROWTH OF 'THOMPSON SEEDLESS' GRAPES AS A FUNCTION OF TEMPERATURES

Abstract

Research was carried out over four seasons, from 2000 to 2003, in order to establish the effect of temperature on phenological development of 'Thompson Seedless' grapevine in the Aconcagua Valley, Chile (32°45S, 600 m a.s.l.). Winter chilling requirement to break dormancy was determined by different models, which were compared according to Ashcroft et al. methodology (1977). Grapevine development since dormancy breaking was characterized based on growing degree-hours (GDH) and degree-days (DD). It was concluded that the Utah model was the least variable model for rest estimation, with 430 chilling units up to dormancy break, which would have occurred between June 6 and June 17 for the years between 2000 and 2003. Heat requirement from rest completion up to full bloom were 9,451 GDH, 252 DD and 145 days, and 16,101 GDH, 713 DD or 77 days were required from 4 mm berry up to harvest. In order to validate heat requirements for berry growth, phenological stages were estimated for the season 2003-2004, the most accurate estimation was obtained when GDH were used.