Zahra Abravesh - Research Institute of Forests and Rangelands, P.O. Box ۱۳۱۸۵-۱۱۶, Tehran, Iran
Mohammad Hassan Assareh - Research Institute of Forests and Rangelands, P.O. Box ۱۳۱۸۵-۱۱۶, Tehran, Iran
Séyed Reza Tabaei-Aghdaei - Research Institute of Forests and Rangelands, P.O. Box ۱۳۱۸۵-۱۱۶, Tehran, Iran

Damask rose (Rosa damascena Mill.) has high economic importance and commercial value. The plant essential oil is used for perfumery, food and medicinal industries. It is necessary to know much about seed germination for study of genetic variation and breeding improved varieties of R. damascena. In this study seed germination of R. damascena were evaluated, using thermal period treatments. The data were analyzed based on the Randomized Completely Design with ۳ replications. Seeds were sterilized for elimination with NaOCl. Seeds of R. damascena were subjected to five different temperature regimes. For control, the seeds were placed at ۴°C continuously. The seeds of all other treatments initially were placed at ۲۵°C for the first warm stratification. Then they were placed at ۴°Cfor ۲, ۴, ۶ and ۸ weeks for cold stratification as ۲w/۲w, ۲w/۴w, ۲w/۶w and ۲w/۸w, respectively. For the second cycle, seeds were placed at ۲۰ °C for warm stratification followed by ۲, ۴, ۶ and ۸ weeks for cold stratification. The treatments were repeated for ۳ cycles. Then the all of treatments were applied ۳۰ weeks of continuously cold stratification at ۴°C. The results of this study showed that the thermal period treatments had significantly promoted the germination percentage. The highest germination percentage and speed of germination were obtained for the ۶w/۲w treatment as (۹۲%) and (۱.۱۷ seeds per day), respectively. The lowest germination percentage was found in the control and ۸w/۲w treatments (۵۰%). In conclusion, it was observed that with application of thermal period (particularly ۶w/۲w) and ۳۰ weeks of cold stratification to Damask rose seeds, dormancy was broken and germination was also highly improved.

Rosa damascena Mill, Damask rose, Seed dormancy, germination, Thermal period