Gardenia (Rubiaceae) seed conservation physiology with emphasis on rare Hawaiian species
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Background and aims – Gardenia species are ecologically, culturally, and economically significant but the three native species of Gardenia in Hawai‘i are assessed as Critically Endangered. Seed banking is the most cost effective and efficient means of conserving plant material ex situ. To better understand the conservation physiology of Hawaiian and South Pacific Gardenia spp. and support their conservation, we asked 1) How do seeds respond to different temperatures and light and dark regimes? 2) What class of dormancy, if any, do seeds exhibit? 3) How does seed germinability respond over time in a seed bank? and 4) What is the conservation status and level of ex situ representation of Gardenia globally? Material and methods – To answer these questions, we used 19 accessions of fresh seeds and seeds stored for varying periods of time in the National Tropical Botanical Garden’s Conservation Seed Bank and Laboratory of Hawaiian (G. brighamii, G. remyi), New Caledonian (G. aubryi, G. oudiepe), and Tahitian (G. taitensis) species. Seeds were incubated at varying temperatures and in light, and in dark. Key results – We found that (1) seeds of all species tested germinated slowly and only at higher temperatures in the light and dark, (2) seeds have non-deep physiological dormancy, (3) seeds of the Hawaiian species are short lived at conventional seed bank conditions, and (4) only 40% of Gardenia spp. are represented in ex situ facilities, and 66% of the species have not been evaluated for the IUCN Red List. Conclusion – Seeds of Hawaiian Gardenia spp. are short lived in storage. Since seeds germinate in darkness, they are unlikely to form a persistent soil seedbank. Although seeds of all species tested are physiologically dormant, they can be easily propagated from seed at warmer temperatures, giving some hope to the conservation and restoration of the Critically Endangered Hawaiian species. Since our dataset was limited by a lack of continuous viability monitoring, we emphasize the need for initial germination testing and ongoing viability tests to better understand seed longevity. Lastly, we discuss the ecological relevance of our results in the context of the Hawaiian archipelago.
Originalsprog | Engelsk |
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Tidsskrift | Plant Ecology and Evolution |
Vol/bind | 157 |
Udgave nummer | 2 |
Sider (fra-til) | 220-235 |
Antal sider | 16 |
ISSN | 2032-3913 |
DOI | |
Status | Udgivet - 2024 |
Bibliografisk note
Funding Information:
This project is the result of \u2018laulima\u2019 (lit. many hands). We thank Ben Nyberg for creating Figure 3. We are grateful to Ane Bakutis, Patti Pali, Kristin Coelho, Kawaila Purdy of the Moloka\u2018i Plant Extinction Prevention Program for guiding us to plants and support in new fruit collections; Matt Kier and the team at Hawai\u2018i State Department of Land and Natural Resources (DLNR) for providing permit guidance on Hawaiian Gardenia and providing data related to their conservation status and updated distribution. We are also appreciative of Devon Gordon and Nellie Sugii at the Harold Lyon Arboretum at the University of Hawai\u2018i at M\u0101noa for their efforts and shared knowledge about the propagation of Hawaiian plants, including Gardenia, which contributed to how the experiment was designed. We thank Ken Wood and Tim Flynn for support in conducting field work and providing ecological data related to Hawaiian Gardenia. Dave Lorence provided the seeds of G. taitensis and for incredible insight related to Rubiaceae and assisting to resolve Gardenia taxonomy questions. Thanks to Margaret Clark for assistance with the pathogen abatement and maturity experiments. We thank National Tropical Botanical Garden (NTBG) Seed Lab volunteers Jeffrey Frelinger and Leslie Ridpath for assistance in monitoring germination experiments; NTBG Nursery personnel Rhian Campbell and Hayley Walcher for continuing to propagate seedlings; and Kupu/ AmeriCorps for the opportunity for ES to study within the Conservation Leadership Development Program. NTBG provided institutional support. This research received no specific grant from any funding agency, or commercial or not-for-profit sectors. This research was conducted under DLNR Permit numbers I5389, I5371, and I5124.
Publisher Copyright:
© Mike Opgenorth, Emily Sailing, Nina Rønsted, Dustin Wolkis.
ID: 402487446