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Factors Affecting Germination of Coolatai Grass (Hyparrhenia hirta)

Published online by Cambridge University Press:  20 January 2017

Vinod K. Chejara*
Affiliation:
School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
Paul Kristiansen
Affiliation:
School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
Ralph D. B. Whalley
Affiliation:
School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
Brian M. Sindel
Affiliation:
School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
Christopher Nadolny
Affiliation:
Department of Environment and Climate Change, P.O. Box U245, Armidale, NSW 2351, Australia
*
Corresponding author's E-mail: vinod_chejara@yahoo.com

Abstract

Coolatai grass is an invasive, perennial grass from Africa and the Middle East that has infested large areas of northern New South Wales, Australia, and also occurs in other Australian states. An understanding of the seed germination ecology of Coolatai grass can assist in predicting its potential distribution and developing effective management strategies. The effects of various environmental factors on Coolatai grass seed germination were investigated in a series of laboratory experiments. The effect of diurnal alternating temperatures (5–45 C) with a 12-h photoperiod were examined on a thermogradient plate. Seed germination occurred at almost all temperature combinations from 5 to 45 C. At moderate temperatures the speed of seed germination was very high; at 30/20 C more than 80% of seeds were germinated within 12 h. Germination was slightly enhanced by the presence of light, but length of photoperiod did not affect germination. Germination at neutral pH was over 90%, and declined to 65% at acidic (pH 4) and alkaline (pH 10) pH levels. Germination was completely inhibited at an osmotic stress of −0.55 MPa or greater and was reduced by 50% at −0.37 MPa. Greater germination in relatively dry soil conditions compared with native species may contribute to the establishment of this species in the field. Results indicate that Coolatai grass seeds can germinate over a wide range of diurnal temperatures, light regimes, pH levels, and under marginal water stress. These characteristics help explain the successful invasion of Coolatai grass and provide evidence that this species is capable of establishing in many parts of Australia.

Type
Weed Biology and Ecology
Copyright
Copyright © Weed Science Society of America 

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