The Northwest region of São Paulo State presents winter with mild temperatures, that allows grape crops between June and October, outside of harvest time from traditional grape-growing areas. In these conditions vine sprouting is irregular and low, requiring budbreak with chemical compounds. In this context, a trial was conducted in a commercial Centennial Seedless (Vitis vinifera L.) vineyard, where it was studied the effects of hydrogen cyanamide applied at different epochs. Vinegrapes were pruned at three different times (03-23, 04-05 and 04-20-2002) and the following doses of hydrogen cyanamide were used: 0, 0.75, 1.50, 2.25, 3.00 and 3.75%. The following variables were evaluated: percentage of sprouting, percentage of growing shoots, number of clusters, cluster weight and total yield. Independently of the hydrogen cyanamide dose, vines pruned earlier showed a lower percentage of sprouting. Hydrogen cyanamide applications presented a quadratic effect for percentage of sprouting, and number of clusters. Additionally, it was verified quadratic effects of hydrogen cyanamide applications for the variables percentage of growing shoots, cluster weight and total yield; in the prune carried out on April 20th . In the prune done on April 5th, it was observed linear increase for these variables. The estimated dose of hydrogen cyanamide for the highest sprouting was 2,89%.
Vitis vinifera; grapes; growth regulator; dormancy; prune dates
