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Temperature affects the dormancy and germination of sympatric annual (Oryza meridionalis) and perennial (O. rufipogon) native Australian rices (Poaceae) and influences their emergence in introduced para grass (Urochloa mutica) swards

Bellairs, Sean M., Wurm, Penelope A. and Kernich, Beckie J. (2015). Temperature affects the dormancy and germination of sympatric annual (Oryza meridionalis) and perennial (O. rufipogon) native Australian rices (Poaceae) and influences their emergence in introduced para grass (Urochloa mutica) swards. Australian Journal of Botany,63(8):687-695.

Document type: Journal Article
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IRMA ID 84376995xPUB290
Title Temperature affects the dormancy and germination of sympatric annual (Oryza meridionalis) and perennial (O. rufipogon) native Australian rices (Poaceae) and influences their emergence in introduced para grass (Urochloa mutica) swards
Author Bellairs, Sean M.
Wurm, Penelope A.
Kernich, Beckie J.
Journal Name Australian Journal of Botany
Publication Date 2015
Volume Number 63
Issue Number 8
ISSN 0067-1924   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-84949569482
Start Page 687
End Page 695
Total Pages 9
Place of Publication Australia
Publisher C S I R O Publishing
Field of Research ENVIRONMENTAL SCIENCES
HERDC Category C1 - Journal Article (DIISR)
Abstract The seed biology of two ecologically and genetically important sympatric wild rice species from northern Australia was compared – perennial Oryza rufipogon Griff. and annual Oryza meridionalis N.Q.Ng. The aim was to determine mechanisms of dormancy exhibited at seed shed and to identify factors that trigger or inhibit germination. This information was used to investigate the ecology of in situ Oryza populations in introduced para grass swards (Urochloa mutica (Forssk.) T.Q. Nguyen) and to understand interactions between the two sympatric Oryza species. Primary dormancy in the two species is similar, namely, non-deep physiological dormancy, determined by external maternal structures and broken by warm temperature treatments equivalent to dry season soil temperatures. Light quality, smoke water, gibberellic acid and nitric acid treatments had minor influences on germination. Changes to the soil profile and aboveground biomass structure due to swards of U. mutica significantly affected emergence of O. meridionalis. Thus the influence of soil temperature explains the results of previous field studies in which biomass or litter on the soil surface prevented germination. This has implications for biodiversity management on monsoonal floodplains of northern Australia, where introduced pasture species produce greater biomass than native grasslands, reduce soil temperatures and are displacing native rices. There were differences between the Oryza species – dormancy was more quickly broken in annual O. meridionalis, reflecting the reduced need for investment in seed bank persistence for annual species in annually inundated and climatically reliable wetlands.
Keywords invasion ecology
plant conservation
seed ecology
wetlands
DOI http://dx.doi.org/10.1071/BT15092   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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