Document Type : Research Paper
Authors
1 1Department of Cultivation & Development, Institute of Medicinal Plants, ACECR, Tehran
2 Islamic Azad University, Shushtar, Iran
3 Department of Cultivation & Development, Institute of Medicinal Plants, ACECR.Tehran
4 Agriculture of Jahad Organization, Gilan, Iran
Abstract
This study has been conducted to overcoming seed dormancy of Rubia tinctourum L., Echinacea angustifolia D.C. and Myrtus communis L.. Treatments to break seed dormancy in Rubia tinctourum included: untreated seed (control), mechanical scarification with sandpaper, imbibitions in hot water at 70°C and 90°C for 5 and 10 minutes, chemical scarification with concentrated sulfuric acid for 10, 15 or 20 minutes, pre-chilling (4°C) for 2, 4 or 6 weeks, soaking in gibberellic acid (500ppm) and continuous light. Treatments to break seed dormancy in Echinacea angustifolia included: untreated seed (control), soaking in gibberellic acid (250 and 500 ppm), continuous light, Potassium Nitrate (0/3%), pre-chilling (4°C) for 4, 7 or 10 weeks, continuous light and combined treatment (soaking in gibberellic acid (250ppm) and pre-chilling for 4 week). Treatments to break seed dormancy in Myrtus communis included: untreated seed (control), mechanical scarification with blade and sandpaper, chemical scarification with concentrated sulfuric acid for 3 minutes, pre-chilling (4°C) for 7 or 10 weeks and soaking in gibberellic acid (250 and 500ppm). According to results in R. tinctourum, sulfuric acid for 15 minutes was significantly efficient in promoting germination. From the above one can infer that dormancy of the seeds of R. tinctourum was probably associated with the seeds coat, since the treatment that induce germination were those that can effect disruption of the seed coat. This experiment also showed that combined treatment significantly increased E. angustifolia seed germination. As stratification and GA3 had main role on breaking of seed dormancy so it is known that dormancy is physiological and it is related to embryo and inhibitor factor or both of them. Results indicated that germination of M. communis seeds mechanically scratched with blade significantly increased. So, reason of seed dormancy is hard coated seeds. The seed coat is as one physical barrier against growth of embryo or radicle that inhibits in absorption of water and gas-exchanges. Therefore, type of dormancy is initial dormancy (induced dormancy).
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