Phenological characterization and thermal demand of ‘BRS Vitoria’ seedless grape grown in subtropical área

Abstract

The ‘BRS Vitoria’ is a black hybrid seedless grape with a raspberry-like taste. These characteristics meet the main demands of the grape industry in Brazil, and also this cultivar show good tolerance to downy mildew. However, there is no information available on the phenological characteristics and thermal demand of this grapevine in subtropical area. The objective of this work was to characterize the phenological behavior and determine the thermal demands in degree-days of this grapevine in the Northern region of the Paraná State. The trials were conducted during two consecutive seasons (regular crop of 2013 and off-season crop of 2014). The study verified the phenological behavior and the thermal demands of 20 representative grapevines trained in a overhead trellis system, spaced at 2.5 x 5.0 m. For the characterization of the phenological stadia, two canes of each grapevine were marked. These canes were evaluated according to the duration in number of days of the following stadia, starting from winter pruning: a) cotton swell, b) sprouting, c) inflorescence emergence, d) flowering, e) veraison f) ripening. The thermal demand was calculated by the total degree-day (DD) from pruning to ripening, as well as for each of the phenological subperiods, considering 10 °C and 12 °C as base temperatures. Results showed that the duration of the pruning to ripening was 130 days, and termal demand was 1,679.96 DD for the regular crop and 134 days and 1,831.84 DD for off-season crop, being the temperature-base of 10oC the most adequate to calculate this demand.