The apple culture is a fruit tree of temperate climate which is characterized by the bud dormancy, requiring a certain amount of hours of chilling (< 7.2ºC) for bud opening. In Brazil, São Joaquim Country is the region that presents the best climatic conditions for the cultivation of this specie. However, it is not correct to affirm that it always present sufficient chilling requirement to content the cultivars exigency. Two years of experiments in 1998 and 1999 the trial in specific micro-climates from 900 to 1.400 m in São Joaquim Country lead to afirm except for Gala cultivar adult plant, in years were the number of chilling units exceed 2.300, there is no need to carry out chemical bud break with hydrogen cyanamide.
breaking dormancy; hydrogen cyanamide; mineral oil
