In most parts of Iran, particularly in arid and semi-arid regions, severe water shortages have become one of the most significant limiting factors for maintaining and developing green spaces. These shortages have been made worse by climate change, rising temperatures, and excessive water extraction from industrial, agricultural, and urban activities in recent years. The use of adaptable and native plants is one of the important strategies for reducing water consumption and maintenance costs of green spaces to achieve sustainable landscape. Caucasian Hackberry (Celtis caucasica Willd.) is one of the important native species of the genus Celtis, which is distributed in the Zagros mountain range. This tree species is drought-resistant and has a long lifespan, making it noteworthy not only for industrial uses and afforestation but also as an urban green space tree. In any case, there is limited information regarding the production and propagation of this valuable species. Therefore, this research was conducted with the aim of eva‎luating the effects of various physical and physiological pretreatments on breaking the seed dormancy of different populations of this species under laboratory and greenhouse conditions at Isfahan University of Technology. In this study, fruits were collected from three different seed sources (Shahre-Kord, Dehaghan, and Vaneshan) from the Zagros region. After recording the characteristics of the fruit and seeds of all three populations, the seeds were subjected to treatments of scarification with concentrated sulfuric acid for 10 and 20 minutes and mechanical scarification. Then, the treated seeds underwent treatments to break their physiological dormancy, including soaking in 100 mg/liter gibberellic acid for 24 hours and cold stratification for 2 and 4 months. In total, 16 treatment levels were obtained, which were executed as a factorial experiment in a completely randomized design with 4 replications. The characteristics of germination percentage, various germination indices, and seedling growth were eva‎luated. The results showed that there was significant variation in fruit and seed characteristics among the three studied populations, with the Vanshan population having greater flesh thickness and fruit diameter, and smaller seed length compared to the other two populations. Among the treatments examined, the mechanical scarification treatment had the highest germination percentage (61%) in all three populations, and the Vaneshan population had the highest seed germination rate (67%). Mechanical scarification combined with gibberellic acid had a positive effect on the seed germination rate in the Vaneshan population. Increasing the duration of cold stratification from 2 months to 4 months led to an increase in germination percentage and seed germination indices in all three populations. Other treatment levels did not show any effect on seed dormancy breaking in this species. The results also showed that the seed origin had a significant impact on the height, diameter, and growth rate of the seedlings, with the seedlings from the Shahrekord population showing superiority in these indices. In general, based on the results obtained in this study, the type of dormancy in the seeds of Caucasian Hackberry is mainly attributed to the presence of a hard seed coat, which prevents seed germination and causes physical dormancy in the seeds. The best method for breaking seed dormancy is the use of mechanical methods and rapid seed planting. Additionally, the use of a 4-month cold stratification was effective in breaking the seed dormancy of Caucasian Hackberry. Therefore, in order to break the seed dormancy in Caucasian Hackberry, the use of mechanical scarification or a 4-month cold stratification is recommended.

نعمت اله اعتمادي شلمزاري , مهديه غلامي

رحيم اميري خواه

حميدرضا عشقي زاده , مهدي رحيم ملك