Appropriate methods for breaking seed dormancy of Iranian mountain ash (Sorbus persica Hedl.)

Iranian mountain ash (Sorbuspersica Hedl.) is a valuable shrub species which also frequently occurs in the stands located in Isfahan province in central Zagros. Mountainash seedling typically begins to germinate after winter. We investigated its seed germination by means of a completely randomized design with 15 treatments including the pre-chill, warm stratification then pre-chill, gibberellin, gibberellin then pre-chill, and control treatments, each in four replications. The highest germination rate (97.50%) was observed for two-week warm stratification (25°C) and the 4-month cold stratification (1-4°C) treatments. The success of cold stratification treatment suggests that Iranian mountain ash is associated with physiological dormancy. Since the pre-chilled treatment for 120 days at 1-4°C completely broke the seed dormancy, the seed dormancy was concluded to be substantially deep. Reducing the initial seed moisture content (17.3%) to 7% did not affect its survival. Moreover, seed viability was maintained following a 600-day storage at -20°C, suggesting an orthodox behavior of the seeds. In conclusion, the use of appropriate treatment resulted in a very high germination rate.