Development of primary dormancy in seeds of Prunus avium during maturation

The development of primary dormancy in seeds of Prunus avium during maturat ion was studied in selected trees in two consecutive years. Seeds without e ndocarp were prechilled and germinated at 4 degreesC and the mean time to c omplete germination was recorded as a relative, quantitative measure of dor mancy level. Corresponding levels of germination capacity, dry weight and m oisture content of the seeds were determined. Changes in dry weight and moi sture content followed the behaviour of general seed development. Seed acqu ired maximum ability to germinate 4-6 weeks before full maturity, at which point they began to germinate after a few weeks at 4 degreesC, thus display ing a shallow dormancy. Generally, dormancy levels increased with increasin g maturity at rates of up to 4 weeks deeper dormancy per week during matura tion. Dormancy levels are suggested to reach a final plateau. Both inductio n rate and final level depend on the tree and year. The levels of dormancy were different in the two years for the same dry weight and moisture conten t of seeds, which suggests that other factors affect dormancy induction sig nificantly. Environmental factors, especially high temperatures, are hypoth esised to be important for dormancy induction.