Endodormancy of peach and plum tree buds in a region of low chill occurrence/Endodormencia de gemas de pessegueiro e ameixieira em regiao de baixa ocorrencia de frio

The objective of this research was to evaluate the dormancy dynamic of peach tree 'Chimarrita' and plum tree 'Poli Rosa' buds in a region of low chill occurrence. The stems were collected in an orchard in Fazenda Rio Grande, State of Parana, Brazil, from April to August of 2007 and 2008. In the last date, an additional group of stems was collected and maintained in a refrigerator (4 to 7[degrees]C) by 672 hours. The evaluation of dormancy was observed by the biological test of single node cuttings under controlled conditions of temperature (25[degrees]C) and photoperiod (16 h). The quantification of chilling hours (CH) and the chilling units (CU) occurred in the region were performed. The two species were evaluated separately, as two separate experiments. The experimental design was completely randomized, with 9 treatments for peach tree buds and 11 treatments for plum tree buds, both with four replications. The two years were analyzed individually. The more intense endodormancy period of peach tree buds occurred in May 2007 and 2008. The more intense endodormancy period of plum tree buds occurred in May 2007, and it was extended until June 2008.