Seed dormancy and germination of the endangered exceptional Hawaiian lobelioid Brighamia rockii

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 ch...

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Bibliographic Details
Published in:	Applications in plant sciences 2022-09, Vol.10 (5), p.e11492-n/a
Main Authors:	Wolkis, Dustin, Baskin, Carol C., Baskin, Jerry M., Rønsted, Nina
Format:	Article
Language:	eng
Subjects:	Application Brighamia Conservation critically endangered plants Desiccation Dormancy embryo growth Embryos Endangered & extinct species Endangered species ex situ conservation exceptional species Extinct species Flowers & plants Germination Hawaiian lobelioids Plant sciences Seed banks Seeds Wildlife conservation
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Summary:	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.
ISSN:	2168-0450 2168-0450