The objective of this work was to test the value of the meiosis method as biological marker for peach endodormancy end in sub-tropical regions. The number of GDHºC (Growing Degree Hour Celsius) and the chilling hours (temperature £ 7,2 ºC) from May 1st until the end of meiotic division (80 % of tetrads), and from this phase until 10 and 50 % of budbreak, in field trees, were determined. The correlation between tetrads + pollen versus GDHºC, and tetrads + pollen versus number of chilling hours, were determined in different dates from May 1st to the end of meiosis. The results, obtained in two years of observation, showed a heat requirement for pollen mother cells to reach the tetrads stage. Therefore, the tetrads formation was not a good index for estimating the end of endodormancy phase in peach.
heat requirement; pollen; Prunus persica; ecodormancy; tetrads
