Removal of distal part of cotyledons or soaking in BAP overcomes embryonic dormancy in sour cherry.

摘要

Dormant seeds of sour cherries (Prunus cerasus) normally require warm stratification for 2 weeks followed by cold stratification for 15-18 weeks to germinate. Seed treatments that reduce time to germination and increase germination percentages are important in breeding programmes and different experimental approaches to speed up germination were therefore investigated in this study. Removal of endocarps from dry or moist seeds resulted in high germination percentages after 2-4 months of chilling and normal seedling growth. Dormant seeds with testa did not germinate at all at 20 degrees C. Up to half of dormant excised embryos germinated at 20 degrees C, but these showed abnormal seedling growth. Removal of the distal two-thirds of the cotyledons from dormant embryos gave 50-60% germination after 2 weeks at 20 degrees C and seedlings grew normally. Excised dormant embryos soaked in 10 or 200 mg benzyladenine/litre for 30 minutes gave 70-80% germination at 20 degrees C and seedlings grew normally, except for more lateral branches than in seedlings from chilled seeds. Soaking seeds with testa in the same concentrations of benzyladenine for 24 h only improved germination slightly. The study showed that both endocarp, testa and embryo contributed to seed dormancy in sour cherry and that embryonic dormancy was caused by inhibitors in the cotyledons. Removal of part of the cotyledons or external application of benzyladenine to excised embryos eliminated the block to germination and allowed normal growth of seedlings. High germination percentage and normal seedling growth may thus be achieved after only few weeks compared to traditional stratification and germination after 4-6 months.