Effect of Gibberellic acid, Sulfuric acid and temperature on germination of Cycas revolute L.

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 ˚C for 4 weeks and subsequently were treated with HSO4 (5M) for 0, 5, 0 and 45 minutes followed by 00 and 00 ppm of GA for 0, 4,48 and 7 hours. Seeds then were planted in trays filled with coarse and were placed in greenhouse with 8 /0˚C (day/night) under mist system. The results indicated that 9 % of seeds survived at 5˚C, but only 4% of stored seeds at ˚C were alive after 4 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 00 mg/lit. Gibberellic acid for 48 hours and Sulfuric acid (5 M) for 0 minutes resulted in optimal germination rate of stored seeds at 5˚C for 4 weeks.