Effect of Stratification and Its Combination with Gibberellic Acid on Seed Dormancy Breaking of Echinophora platyloba

Abstract

Extended Abstract Introduction: Seeds are a good option when it comes to propagation and protection programs of medicinal plants. Although seed dormancy is an adaptive strategy for wild medicinal plants, it is considered as an undesirable trait in their domestication and cultivation, representing a problem to be solved. Echinophora platyloba seeds have dormancy despite their remarkable medicinal properties. Materials and Methods: In order to break seed dormancy, three separate experiments, namely stratification, hormonal treatment and their combination were conducted. For stratification, 10 samples were placed in a wet bed at 5 °C for 2, 4, 6, 8, 10, 12, 14 and 16 weeks and were compared, using a completely randomized design with three replications. For hormonal treatment, the seeds were placed in GA concentrations of 0, 500 and 1000 ppm for 24 hours and were then transferred to germination conditions. However, since the dormancy breaking did not occur, this experiment was not pursued any more. For combined application of hormone and stratification, seeds were placed at above-mentioned concentrations of gibberellin for 24 hours at 20 °C and then gibberellin solutions were removed and the seeds were transmitted to 5 °C and were compared for 2, 4, 6, 8 weeks with a CRD factorial experiment with three replications. The first factor was concentration of gibberellin in three levels and the second factor was the duration of stratification in 4 levels. Results: Stratification had a positive effect on seed dormancy breake and 16-week chilling led to highest germination percentage and rate and vigor indices. The combined application of hormonal treatments accelerated dormancy release and improved seed germination characteristics, which peaked in 8 weeks. 8-week stratification treatment at 5 °C with 1000 ppm gibberellic acid was the best treatment for overcoming dormancy in Echinophora-platyloba seeds. Conclusion: It seems that seed dormancy of Echinophora seeds is physiological, which successfully broke by moist chilling and simultaneous application of stratification and gibberellin. Although Gibberellin had no effect on dormancy break, it reduced the need for stratification. Their combined application showed synergistic effects on dormancy release.