ISHS Acta Horticulturae 486: II International Symposium on Ornamental Palms & other Monocots from the Tropics
PROPAGATION AND CULTURE OF CYCADS: A PRACTICAL APPROACH |
| Author: | B. Dehgan |
| Keywords: | Bowenia, Ceratozamia, Cycas, Dioon, Encephalartos, Lepidozamia, Macrozamia, Microcycas, Stangeria, Zamia, Branching, Conservation, Pollination, Germination, Root Pruning, Vegetative Propagation, Irrigation, Fertilization |
| Abstract:
Cycads are a geologically primitive group of threatened or endangered gymnosperms whose ancestors were widespread when dinosaurs were still roaming the earth. Today, the ±180 remaining species are restricted to specific tropical and subtropical regions of the Old and the New Worlds. Recent recommendations of the International Conservation Union (IUCN) include encouraging extensive propagation and culture of these magnificent ancient plants. Through our original research and publications in the past two decades, we have made long strides towards facilitating their commercial production. Methods of artificial pollination to ensure seed production and proper treatments to expedite seed germination have been reported. Mechanical removal of the fleshy seed coat (sarcotesta), scarification of the bony layer (sclerotesta) with sulfuric acid (H2SO4), and breakdown of physiological dormancy and promotion of rapid embryo development by soaking in the growth regulator gibberellic acid (GA3), collectively have increased germination of several species. Root growth and branching has been enhanced significantly by severing the original seedling tap root and dipping the cut end in Indolebutyric acid (IBA). Appropriate irrigation frequency and applications of liquid and slow-release fertilizers which contain micronutrients have resulted in exceptionally rapid growth and elimination of deficiencies. And finally, in what may be the most significant contribution towards cycad conservation, vegetative propagation has been made possible by forcing plants to branch profusely, despite absence of any lateral buds homologous to that of angiosperms and conifers. This has allowed their multiplication through division of "side shoots" or "pups". To the best of our knowledge, protocols for commercially feasible micropropagation of cycad has not been reported. | |
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