Dustin Wolkis1,2,3, Carol C Baskin4,5, Jerry M Baskin4, Nina Rønsted1,2. 1. National Tropical Botanical Garden Kalāheo Hawai'i 96741 USA. 2. Natural History Museum of Denmark University of Copenhagen DK-2100 Copenhagen Denmark. 3. Seed Conservation Specialist Group, Species Survival Commission International Union for Conservation of Nature Gland 281196 Switzerland. 4. Department of Biology University of Kentucky Lexington Kentucky 40506 USA. 5. Department of Plant and Soil Sciences University of Kentucky Lexington Kentucky 40546 USA.
Abstract
Premise: The Campanulaceae (Lobelioideae) is the Hawaiian plant family with the most endangered and extinct species. Although seeds of Hawaiian lobelioids are desiccation tolerant, the species are exceptional (i.e., they present challenges at various stages of the conventional ex situ conservation chain) due to their generally poor seed survival at the conventional seed-banking temperature (-18°C). Both morphological dormancy (MD) and morphophysiological dormancy (MPD) have been identified in the seeds of other Hawaiian lobelioids; however, the class of dormancy and germination requirements of the Critically Endangered genus Brighamia have not yet been determined. Methods: We measured the embryonic growth in 12-week-old seeds of B. rockii and tested their germination at three temperature regimes (15/5°C, 20/10°C, and 25/15°C) in light and at 25/15°C in darkness. Results: The embryos grew prior to radicle emergence, and the seeds germinated rapidly to high percentages in all tested conditions. Discussion: Whether fresh B. rockii seeds have MD or MPD still needs to be determined; nevertheless, 12-week-old seeds germinated well in light and darkness, and thus the seeds can be used for conservation purposes. Germination in the dark suggests that the species may not form a long-lived soil seed bank in its native habitat.
Premise: The Campanulaceae (Lobelioideae) is the Hawaiian plant family with the most endangered and extinct species. Although seeds of Hawaiian lobelioids are desiccation tolerant, the species are exceptional (i.e., they present challenges at various stages of the conventional ex situ conservation chain) due to their generally poor seed survival at the conventional seed-banking temperature (-18°C). Both morphological dormancy (MD) and morphophysiological dormancy (MPD) have been identified in the seeds of other Hawaiian lobelioids; however, the class of dormancy and germination requirements of the Critically Endangered genus Brighamia have not yet been determined. Methods: We measured the embryonic growth in 12-week-old seeds of B. rockii and tested their germination at three temperature regimes (15/5°C, 20/10°C, and 25/15°C) in light and at 25/15°C in darkness. Results: The embryos grew prior to radicle emergence, and the seeds germinated rapidly to high percentages in all tested conditions. Discussion: Whether fresh B. rockii seeds have MD or MPD still needs to be determined; nevertheless, 12-week-old seeds germinated well in light and darkness, and thus the seeds can be used for conservation purposes. Germination in the dark suggests that the species may not form a long-lived soil seed bank in its native habitat.
Authors: Thomas J Givnish; Kendra C Millam; Austin R Mast; Thomas B Paterson; Terra J Theim; Andrew L Hipp; Jillian M Henss; James F Smith; Kenneth R Wood; Kenneth J Sytsma Journal: Proc Biol Sci Date: 2009-02-07 Impact factor: 5.349
Authors: Aelys M Humphreys; Rafaël Govaerts; Sarah Z Ficinski; Eimear Nic Lughadha; Maria S Vorontsova Journal: Nat Ecol Evol Date: 2019-06-10 Impact factor: 15.460
Authors: Nina Rønsted; Seana K Walsh; Margaret Clark; Merlin Edmonds; Tim Flynn; Scott Heintzman; Alexander Loomis; David Lorence; Uma Nagendra; Ben Nyberg; Michael Opgenorth; Lauren Weisenberger; Adam Williams; Dustin Wolkis; Kenneth R Wood; Matthew Keir Journal: Conserv Biol Date: 2022-04-18 Impact factor: 7.563
Authors: Marian M Chau; Timothy Chambers; Lauren Weisenberger; Matthew Keir; Timothy I Kroessig; Dustin Wolkis; Roy Kam; Alvin Y Yoshinaga Journal: Am J Bot Date: 2019-09-09 Impact factor: 3.844