عنوان مقاله [English]
Cycas revolute is one of the most primitive living seed plants of subtropical landscapes. There is substantial demand for ornamental leaf trade due to their attractive shape and long shelf life. Seeds of most commonly cultivated Cycas species is now available. Fast and uniform seed germination is essential because of relatively rapid loss of seed viability of Cycas duo to delayed seed germination. Some dormancy mechanisms contribute to delayed seed germination including: inhibitors, thick and very hard sclerotesta, and immature embryo at the time of seed abscission. An experiment was conducted as a factorial in compeletely randomized design in order to study the effect of growth regulators and temperature storage on embryo development and germination of Cycas seeds. Seeds were stored at 5 and 22˚C for 24 weeks and subsequently were treated with H2SO4 (15M) for 0, 15, 30 and 45 minutes followed by 100 and 200 ppm of GA3 for 0, 24,48 and 72 hours. Seeds then were planted in trays filled with coarse and were placed in greenhouse with 28 /20˚C (day/night) under mist system. The results indicated that 92 % of seeds survived at 5˚C, but only 42% of stored seeds at 22˚C were alive after 24 weeks. Gibberellic acid and Sulfuric acid treatments had showed considerable effect on seed germination and their higher concentrations and longer exposure time increased germination rate and speed. Seed treatment with 200 mg/lit. Gibberellic acid for 48 hours and Sulfuric acid (15 M) for 30 minutes resulted in optimal germination rate of stored seeds at 5˚C for 24 weeks.