TY - JOUR

T1 - Seed dormancy and germination of the endangered exceptional Hawaiian lobelioid Brighamia rockii

AU - Wolkis, Dustin

AU - Baskin, Carol C.

AU - Baskin, Jerry M.

AU - Rønsted, Nina

N1 - Publisher Copyright: © 2022 The Authors. Applications in Plant Sciences published by Wiley Periodicals LLC on behalf of Botanical Society of America.

PY - 2022

Y1 - 2022

N2 - 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.

AB - 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.

KW - Brighamia

KW - critically endangered plants

KW - embryo growth

KW - ex situ conservation

KW - exceptional species

KW - Hawaiian lobelioids

U2 - 10.1002/aps3.11492

DO - 10.1002/aps3.11492

M3 - Journal article

C2 - 36258791

AN - SCOPUS:85139041302

VL - 10

JO - Applications in Plant Sciences

JF - Applications in Plant Sciences

SN - 2168-0450

IS - 5

M1 - e11492

ER -