| چکیده انگلیسی مقاله |
Extended Abstract Introduction: Seed dormancy as a way to escape from environmental stress is important in preserving plant species that have physiological, physical, morphological and morph-physiological types. Seed testa hardness is one of the important reasons of dormancy in leguminous family plants. One principal mechanism to seed dormancy breaking in leguminous plants is the use of scarification treatments. Since, oxygen deficiency is a factor that induces dormancy, scarification treatments may accelerate gas exchanges, in particular oxygen and carbon dioxide, can cause reducing seed dormancy and increasing germination percentages. In addition, priming with gibberellic acid can help dormancy breaking in plant species that have physiological dormancy, and lead to germination. Therefore, the purpose of this study was to investigate seed dormancy, germination and find the most appropriate treatment for elimination seed dormancy in three ecotypes of Astragalus cyclophyllus. Materials and Methods: This research was done in 2013 at laboratory agriculture of Lorestan University in a factorial experiment based on a completely randomized design with three replications. The first factor was three ecotypes of Astragalus Semirom, Damavand and Zanjan, and the second factor was seed dormancy breaking treatments. The applied treatments were as: control, (mechanical scarification plus chilling time with 10, 20 and 30 days prechilling at 4°C, mechanical scarification + gibberellic acid at concentrations of 400 and 500 ppm for 48 hours, scarification with sulfuric acid 96% for 2 and 4 min, mechanical scarification and 2% potassium nitrate for 72 h, mechanical scarification and gibberellic acid 400 ppm for 48 h with 20 days prechilling. The measured indices included germination percentage, mean germination time, seedling length, seedling fresh weight, seedling dry weight and alpha-amylase activity. Results: Results showed that interaction of seed dormancy breaking treatments and ecotype were significant for all traits. Based on the results of mean comparison, Damavand ecotype was better in most of the studied traits compare to Semirom and Zanjan ecotypes. Compared to the treatments applied, mechanical scarification plus gibberellic acid 400 ppm had more effective for germination parameters and Seedling vigor index. Mechanical scarification and gibberellic acid 400 ppm for 48 h along with 20 days prechilling increased total germination percentage in Semirom ecotype with an average of 67.68% and was more effective on increase activity of α-amylase enzyme. Conclusion: Seed dormancy Astragalus cyclophyllus seems not be physiological and increasing germination can be due to mechanical scarification in physical dormancy breaking, in addition to tpriming effect of prechilling and gibberellic acid. Highlights: The effect of different dormancy breaking treatments on seed germination was investigated. Alpha-amylase activity Astragalus Seed was increased under dormancy breaking treatments. |