HIGH TEMPERATURES DURING DORMANCY INFLUENCED BUDBREAK OF TABLE GRAPES CV. FLAME SEEDLESS.

Abstract

Table grape production on desert regions present a narrow period of low temperatures during dormancy, with a high oscillation between day and night temperature. Under this situations chilling accumulation and budbreak are influenced on early cultivars. Treatments consisted on continuous (100, 200 and 300) or interrupted chilling hours (CH) at 4°C, with and without 0.1M cyanamide application. The interruptions were at 100 or 200 CH for 2,4 or 6 day at temperatures of 20 or 25°C. High temperatures intervals after 100 CH affected more negatively budbreak on cyanamide treated plants than no treated, regardless of temperature. Budbreak was earlier and higher when chilling was interrupted after 200 CH for 2 days at 20°C or 4 and 6 days at 25°C and no cyanamide was applied. With cyanamide application, 200 CH interruption for 2, 4, or 6 days at 20°C reduced and delayed budbreak. At 25°C, and non cyanamide application, only 2 days interruption after 200 CH affected negatively budbreak, while 4 and 6 days intervals at this temperature stimulated budbreak. When cyanamide was applied on this treatment, no differences were found with respect to continuous CH.