Influence of temperature on the dynamics of ATP, ADP and non-adenylic triphosphate nucleotides in vegetative and floral peach buds during dormancy.

The nucleotides test of endodormancy, which is based on the capacity of tissues to synthesize ATP and non-adenylic triphosphate nucleotides (NTP), cannot be used for floral buds, and it is of questionable use for vegetative buds. In an attempt to find an alternative test, we examined whether the dormancy state of vegetative and floral buds of trees exposed to different temperature conditions during the rest period is directly related to their ATP, ADP and NTP concentrations and ATP/ADP ratio. Once the buds had entered endo- or paradormancy, the nucleotide concentrations and the ATP/ADP ratio were low in the vegetative primordia and very low in the floral primordia. Only after the action of chilling, when the buds were considered to have completed the endodormancy and paradormancy phases, did the nucleotide concentrations increase, accompanied by a steep rise in ATP/ADP ratio. We conclude that the ATP/ADP ratio could be used to characterize the bud dormancy state by comparison with critical values of 1.5 for vegetative primordia and 1.0 for floral primordia.