Sunlight and red to far-red ratio impact germination of tropical montane cloud forest species

Hoyle, Gemma L., Stevens, Amelia V., Guja, Lydia K., Sommerville, Karen D., Worboys, Stuart, and Crayn, Darren M. (2023) Sunlight and red to far-red ratio impact germination of tropical montane cloud forest species. Australian Journal of Botany, 71 (7). pp. 326-339.

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Context: Australia’s tropical montane cloud forests (TMCF) exhibit exceptional species richness and endemism. Determinants of regeneration via seed of these species are next to unknown, limiting our ability to quantify and project their vulnerability to climate change. The ratio of red to far-red light (R:FR) has been shown to influence seed germination of many tropical species.Aims: We investigated germination of six previously unstudied TMCF species in relation to the presence or absence of light (light/dark) and light quality (R:FR). We hypothesised that increased R:FR would lead to increased germination and that small-seeded species would be more likely to have a light requirement and be less sensitive to R:FR compared to larger-seeded species.Methods: Sunlight and polyester filters were used to create a gradient of R:FR ranging from 0.1 to 1.14. Seeds were also sown in constant darkness.Key results: Across species we saw varying germination responses. Three of the four smallest-seeded species exhibited an absolute light requirement for germination and did not discriminate between different R:FR. Germination of the small-seeded TMCF endemic Dracophyllum increased exponentially with increasing R:FR. Germination of the largest-seeded species was inhibited by both low and high R:FR, and germination was higher in constant darkness than diurnal light/dark. All six species were able to germinate at remarkably low R:FR values.Conclusions: Light affects seed germination of Australia’s TMCF plant species in a variety of ways.Implications: The findings of this study provide insights into plant recruitment in situ, and the acclimation potential of these species under reduced R:FR predicted for the future.

Item ID: 80938
Item Type: Article (Research - C1)
ISSN: 1444-9862
Keywords: Keywords: climate change, cloud forest, light, R:FR, red to far-red ratio, seed ecology, seed germination, seed mass.
Copyright Information: © 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
Date Deposited: 04 Dec 2023 23:43
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310303 Ecological physiology @ 100%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180604 Rehabilitation or conservation of terrestrial environments @ 20%
28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 80%
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