Influence of three contrasted climatic conditions on endodormant vegetative and floral peach buds: analyses of their intrinsic growth capacity and their potential sink strength compared with adjacent tissues

Three treatments with various temperature-photoperiod combinations (LDW: long-day warm; SDW: short-day warm; SDC: short-day cold) were applied to endodormant vegetative and floral peach buds. In order to analyze the effect of these factors on their dormancy state, the following complementary methods were used: (1) for vegetative buds, the 'single-node cutting' test that measures the growth capacity of the buds connected to the shoot and integrates endo- and short-distance paradormancy; (2) for floral buds, growth rate of the primordia that integrates endo- and all paradormancy. For both kinds of buds: (3) the 'nucleotides' test that reveals the intrinsic growth capacity of the isolated bud, i.e. endodormancy, by measuring the potential of converting adenosine to non-adenylic nucleotides; (4) the intracellular pH measurement of primordia and adjacent tissues (cushion and shoot) which is supposed to reflect their relative sink strength for nutrients and the competition between them. This is a possible element of short-distance paradormancy. Temperature, and not photoperiod, strongly determined the evolution of dormancy in vegetative and floral buds. Exposure to temperatures >20 degrees C, prevented the buds recovering any intrinsic growth capacity, but they did it with notable rapidity under 10-18 degrees C temperature regime (SDC).