The effect of different treatments on dormancy break and seed germination of Sumac (Rhus coriaria L.), a shrub species in semi-arid regions

Background and purpose: The Sumac shrub, a commonly used species for afforestation in arid and semiarid regions, plays a crucial role in land reclamation.Additionally, the economic importance of Sumac is evident through the use of its fruits to support local communities.This study aims to analyze the type of dormancy exhibited by Sumac seeds and evaluate the effects of various dormancy-breaking treatments.The treatments include seed scratching, exposure to boiling water, sulfuric acid, cold stratification, and gibberellic acid (GA3) to enhance the germination rate. Materials and methods:The study was conducted with four replicates of 50 seeds each, utilizing a completely randomized design.The first step involved measuring the survival percentage of the seeds using the tetrazolium test.The designated treatments for the Sumac seeds included boiling water treatment, with three cold stratification durations of 2, 4, and 6 months.Additionally, a chemical scraping treatment was applied using 96% sulfuric acid at three exposure times: 40, 80, and 120 minutes, along with the same three cold stratification durations.A combined treatment of chemical scraping with 96% sulfuric acid (at the aforementioned exposure times) and boiling water treatment was also implemented, each with the same cold stratification durations.All treatments incorporated gibberellic acid at three concentrations (250, 500, and 1000 mg per liter), and a control group was established without the addition of gibberellic acid. Results:The survival rate for seeds was 85.5%.Data analysis reveals significant differences in seed germination percentage and speed among the treatments.The highest germination percentage was observed with gibberellic acid.Specifically, the treatment of 500 mg/liter gibberellic acid combined with boiling water and a cold stratification period of 6 months resulted in the highest germination percentage, which was 77.5%.Additionally, the results indicated that increasing the duration of cold stratification allowed for a reduced amount of gibberellic acid to be effective in overcoming seed dormancy.Among the treatments that did not include gibberellic acid, the boiling water treatment proved to be the most effective.Conversely, the results showed that sulfuric acid treatment alone had the least impact on enhancing the germination of sumac seeds. Conclusion:The results indicate that sumac seeds exhibit both physical and physiological dormancy.The treatment involving scraping with sulfuric acid followed by a cold stratification did not significantly affect the breaking of dormancy or the germination process.However, the application of gibberellic acid enhanced both the percentage and speed of germination.The most effective results were achieved with a treatment of 500 mg/L gibberellic acid, combined with boiling water and six months of cold storage, resulting in the highest germination rate of 18.79%.