Combinational dormancy in seeds of the Western Australian endemic species Diplopeltis huegelii (Sapindaceae)
S. R. Turner A B E , D. J. Merritt A B , J. M. Baskin C , C. C. Baskin C D and K. W. Dixon A BA Kings Park and Botanic Garden, West Perth, WA 6005, Australia.
B Faculty of Natural and Agricultural Sciences, School of Plant Biology, The University of Western Australia, Crawley, WA 6009, Australia.
C Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA.
D Department of Plant and Soil Science, University of Kentucky, Lexington, KY 40546-0312, USA.
E Corresponding author. Email: sturner@bgpa.wa.gov.au
Australian Journal of Botany 54(6) 565-570 https://doi.org/10.1071/BT05156
Submitted: 13 September 2005 Accepted: 2 March 2006 Published: 15 September 2006
Abstract
Seeds of the endemic Western Australian species Diplopeltis huegelii Endl. were successfully germinated after the presence of combinational dormancy was identified, following the observation of selected seed characteristics. D. huegelii seeds were found to have large, fully developed, peripheral coiled embryos (with no endosperm) that are 7–8 mm long when uncoiled. Seed-coat dormancy was overcome by dipping seeds in hot water for ≥15 s, but seeds also required a period of after-ripening before they would germinate readily. After-ripening occurred while intact seeds were stored dry at ambient laboratory conditions for 13 months or when scarified (hot-water treated) seeds were stored at 13, 23 or 50% RH at 23°C for 6 weeks. Scarified 13-month-old seeds germinated readily at 7/18, 13/26 and 18/33°C in a 12-h photoperiod and in constant darkness, whereas scarified 1-month-old seeds germinated to ≤43%. Thus, seed dormancy in this species is caused by a water-impermeable seed coat (physical dormancy, PY) and a (non-deep) physiologically dormant embryo (PD), i.e. combinational dormancy (PY + PD). This is only the second report of combinational dormancy in seeds of Sapindaceae and the first report in this family of the PD component of (PY + PD) being broken during dry storage.
Acknowledgments
The authors acknowledge the Australian Research Council for the provision of funding to make this research possible.
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