Effect of cold stratification and gibberellic acid on seed germination of wild pear (Pyrus glabra L.) from two different provenances

Seed dormancy is one of the most complex processes in response to adverse environmental conditions that has been reported in wild pear seeds. This research was conducted to investigate stratification and gibberellic acid treatments on wild pear seed germination from two intermediate and high altitude origins (2150 and 2450 m above sea level, respectively) located in the southeastern forests of Yasuj, Iran. For this purpose, seeds of wild pear were collected from two different provenances and then treated with gibberellic acid (0 and 1500 mg/l) for 48 hours followed by stratification treatment (at zero, 30, 60 and 90 days) at 4°C. The germination test was performed through a factorial experiment with two factors of seed origin at two levels and dormancy treatments at eight levels in completely randomized design with four replications in the seed laboratory of Yasouj University. The highest germination percentage (100%), germination rate (49.75 seed/day) and seed vigor index (17.9) were observed in seeds collected from high altitude and treated with cold-stratification (90 days) + gibberellic acid (1500 ppm). The results showed that the germination percentage of intermediate seeds with gibberellic acid + cold stratification treatment for 90 days (88%) was lower than the germination percentage of high altitude seeds treated with gibberellic acid + stratification for 60 days (93%) and the high altitude seeds were reached the maximum germination percentage in shorter period of time. According to the obtained results, seed dormancy of wild pear is of physiological type. In addition, for the production of seedlings in the nursery, as well as for sowing to reforestation and enrich the degraded stands in Zagros forests; the use of high altitude seeds is suggested.