RESUMO
Taking 3-year old potted 'Shuguang' nectarine (Prunus persica var. nectariana cv. Shuguang) as test material, this paper studied the effects of high temperature (50 degrees C, HT) and hydrogen cyanamide (HC) on the floral bud respiratory metabolism of the tree during its natural dormancy. Both HT and HC could break the natural dormancy of the tree, and lead to a significant decrease in the respiratory metabolism of floral buds for several hours. The main respiratory pathways, tricarboxylic acid cycle (TCA) and pentose phosphate pathway (PPP), were affected. For the buds not received dormancy-breaking treatments, both the TCA and the PPP decreased, while treating with HT and HC induced a rapid recovery of PPP after the early respiratory attenuation. HT also induced the recovery of TCA, but HC did not show this effect in 96 hours. Therefore, respiratory attenuation and the following PPP activation could be the important part in the floral bud respiratory mechanism of HT- and HC-induced dormancy release.