Effect of growing site, moisture stress and seed size on viability and dormancy of Sporobolus pyramidalis (giant rats tail grass) seed
W. D. Vogler A C and L. M. Bahnisch BA Tropical Weeds Research Centre, Queensland Department of Natural Resources and Mines, PO Box 187, Charters Towers, Qld 4820, Australia.
B School of Agronomy and Horticulture, The University of Queensland Gatton Campus, Gatton, Qld 4343, Australia.
C Corresponding author. Email: wayne.vogler@nrm.qld.gov.au
Australian Journal of Experimental Agriculture 46(11) 1473-1479 https://doi.org/10.1071/EA04191
Submitted: 7 September 2004 Accepted: 15 June 2005 Published: 9 October 2006
Abstract
Sporobolus pyramidalis P. Beauv (giant rats tail grass) is a serious agricultural and environmental weed in tropical and subtropical areas of Australia. Infestations of this unpalatable plant reduce the productivity of pastures and the profitability of industries dependent on grazing animals. This paper reports a series of studies undertaken to assist in the development of control strategies for this species. In particular, these studies measured the viability and dormancy status of fresh seed of S. pyramidalis and the decline of dormancy with time. Variability in these characteristics was determined in seeds collected from several sites within south-east Queensland. The effect of moisture availability during the inflorescence and seed production phases on seed viability and dormancy was also determined. The dormancy of freshly collected seed from several sites ranged from 15 to 95%, but decreased to negligible levels after 4–6 months. Seeds that matured under conditions of high moisture availability were initially more dormant than seeds matured where moisture was less readily available. The proportion of viable seeds was significantly lower in smaller than larger seeds even though viability for all seed sizes exceeded 90%. This study has shown that seed of S. pyramidalis generally has high viability with a large proportion of the seed germinable soon after maturity.
Acknowledgments
The editorial assistance of Drs Shane Campbell, David Orr and Dane Panetta is gratefully acknowledged. We are also grateful for the assistance and resources supplied by Brian Pastures Research Station, The University of Queensland, Gatton Campus and Meat and Livestock Australia.
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