The changing window of conditions that promotes germination of two fire ephemerals, Actinotus leucocephalus (Apiaceae) and Tersonia cyathiflora (Gyrostemonaceae)

Baker, K. S., Steadman, K. J., Plummer, J. A., Merritt, D. J. and Dixon, K. W. (2005) The changing window of conditions that promotes germination of two fire ephemerals, Actinotus leucocephalus (Apiaceae) and Tersonia cyathiflora (Gyrostemonaceae). Annals of Botany, 96 7: 1225-1236. doi:10.1093/aob/mci274


Author Baker, K. S.
Steadman, K. J.
Plummer, J. A.
Merritt, D. J.
Dixon, K. W.
Title The changing window of conditions that promotes germination of two fire ephemerals, Actinotus leucocephalus (Apiaceae) and Tersonia cyathiflora (Gyrostemonaceae)
Formatted title
The changing window of conditions that promotes germination of two fire ephemerals, Actinotus leucocephalus (Apiaceae) and Tersonia cyathiflora (Gyrostemonaceae)
Journal name Annals of Botany   Check publisher's open access policy
ISSN 0305-7364
1095-8290
Publication date 2005-12
Sub-type Article (original research)
DOI 10.1093/aob/mci274
Volume 96
Issue 7
Start page 1225
End page 1236
Total pages 12
Place of publication Oxford, U.K.
Publisher Oxford University Press
Language eng
Formatted abstract
Background and Aims Following a period of burial, more Actinotus leucocephalus (Apiaceae) and Tersonia cyathiflora (Gyrostemonaceae) seeds germinate in smoke water. The main aim of this study was to determine whether these fire-ephemeral seeds exhibit annual dormancy cycling during burial. This study also aimed to determine the effect of dormancy alleviation on the range of light and temperature conditions at which seeds germinate, and the possible factors driving changes in seed dormancy during burial.

Methods Seeds were collected in summer, buried in soil in mesh bags in autumn and exhumed every 6 months for 24 months. Germination of exhumed and laboratory-stored (15 °C) seeds was assessed at 20 °C in water or smoke water. Germination response to light or dark conditions, incubation temperature (10, 15, 20, 25 and 30 °C), nitrate and gibberellic acid were also examined following burial or laboratory storage for 24 months. In the laboratory seeds were also stored at various temperatures (5, 15, 37 and 20/50 °C) for 1, 2 and 3 months followed by germination testing in water or smoke water.

Key Results The two species exhibited dormancy cycling during soil burial, producing low levels of germination in response to smoke water when exhumed in spring and high levels of germination in autumn. In autumn, seeds germinated in both light and dark and at a broader range of temperatures than did laboratory-stored seeds, and some Actinotus leucocephalus seeds also germinated in water alone. Dormancy release of Actinotus leucocephalus was slow during dry storage at 15 °C and more rapid at higher temperatures (37 and 20/50 °C); weekly wet/dry cycles further accelerated the rate of dormancy release. Cold stratification (5 °C) induced secondary dormancy. By contrast, no Tersonia cyathiflora seeds germinated following any of the laboratory storage treatments.

Conclusions Temperature and moisture influence dormancy cycling in Actinotus leucocephalus seeds. These factors alone did not simulate dormancy cycling of Tersonia cyathiflora seeds under the conditions tested.
Keyword Plant Sciences
Dormancy Cycling
Fire Ephemeral
Germination Stimulants
Scarification
Smoke Water
Soil Burial
Storage Temperature
Actinotus Leucocephalus
Tersonia Cyathiflora
Lolium-rigidum Seeds
Morphophysiological Dormancy
Water-content
Smoke
Patterns
Light
Requirements
Alleviation
Temperature
Hydration
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Pharmacy Publications
 
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Created: Mon, 13 Aug 2007, 15:42:21 EST