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RESEARCH ARTICLE

Differences in the distribution and seed germination behaviour of populations of Bromus rigidus and Bromus diandrus in South Australia: adaptations to habitat and implications for weed management

S. G. L. Kleemann A B and G. S. Gill A
+ Author Affiliations
- Author Affiliations

A School of Agriculture and Wine, University of Adelaide, Roseworthy, SA 5371, Australia.

B Corresponding author. Email: samuel.kleemann@adelaide.edu.au

Australian Journal of Agricultural Research 57(2) 213-219 https://doi.org/10.1071/AR05200
Submitted: 6 June 2005  Accepted: 30 September 2005   Published: 24 February 2006

Abstract

A field survey was undertaken in South Australia to determine the relative distribution of the brome grass species B. diandrus and B. rigidus. Seeds of brome grass plants were collected from locations across the Yorke (n = 10) and Eyre Peninsulas (n = 25). B. rigidus was found more frequently and at higher densities in South Australian crops than B. diandrus, which showed a distinct preference for undisturbed fence-line margins. Species identity of brome plants in each sample was initially determined by assessing morphology of the callus-scar of the caryopsis as well as the structure of the panicle. Species identity was later confirmed by counting somatic chromosome number. There was consistent agreement between the 2 approaches to identification, indicating that these morphological features can be used with confidence when identifying B. diandrus and B. rigidus in the field. Although B. diandrus and B. rigidus are morphologically very similar, they showed large differences in germination behaviour. B. diandrus seeds collected from fence-line margins were more germinable than B. rigidus from neighbouring cropped areas. Populations of B. rigidus also showed strong inhibition of seed germination when exposed to light. This inhibitory effect of light on seed germination was not seen in the B. diandrus collections. Two populations of B. rigidus from Yorke Peninsula showed little germination (<15% germination in complete darkness) until well after the start of the next growing season. These 2 populations did, however, show a large response to treatment with gibberellic acid (1 mm), indicating high seed viability but presence of deep dormancy. From a practical point of view, the germination behaviour (longer dormancy and light inhibition) exhibited by B. rigidus would allow this species to proliferate under conservation tillage systems such as no-till, where seeds only experience complete darkness after burial following the sowing operation. Germination behaviour of B. rigidus observed in this study is expected to contribute to greater seed carry-over from one season to the next, and favour its colonisation in crops, as seen in the current field survey.

Additional keywords: light inhibition, seed dormancy.


Acknowledgments

This project was funded by the Grains Research and Development Corporation. We thank Mr D. Radulovic for providing technical assistance.


References


Andersson L, Milberg P, Schutz W, Steinmetz O (2002) Germination characteristics and emergence time of annual Bromus species of differing weediness in Sweden. Weed Research 42, 135–147.
CrossRef |

Gill GS, Blacklow WM (1984) Effect of great brome (Bromus diandrus Roth.) on the growth of wheat and great brome and their uptake of nitrogen and phosphorus. Australian Journal of Agricultural Research 35, 1–8.
CrossRef |

Gill GS, Blacklow WM (1985) Variations in seed dormancy and rates of development of great brome, Bromus diandrus Roth., as adaptations to the climates of Southern Australia and implications for weed control. Australian Journal of Agricultural Research 36, 295–304.
CrossRef |

Gill GS, Carstairs SA (1988) Morphological, cytological and ecological discrimination of Bromus rigidus from Bromus diandrus. Weed Research 28, 399–405.

Gill GS, Poole ML, Holmes JE (1987) Competition between wheat and brome grass in Western Australia. Australian Journal of Experimental Agriculture 27, 291–294.
CrossRef |

Gleichsner JA, Appleby AP (1989) Effect of depth and duration of seed burial on ripgut brome (Bromus rigidus). Weed Science 37, 68–72.

Kon KF, Blacklow WM (1988) Identification, distribution and population variability of great brome (Bromus diandrus Roth.) and rigid brome (Bromus rigidus Roth.). Australian Journal of Agricultural Research 39, 1039–1050.
CrossRef |

Peters NCB (1982) The dormancy of wild oat seed (Avena fatua L.) from plants grown under various temperature and soil moisture conditions. Weed Research 22, 205–212.

Peters NCB, Atkins HA, Brain P (2000) Evidence of differences in seed dormancy among populations of Bromus sterilis. Weed Research 40, 467–478.
CrossRef |

Sexsmith JJ (1969) Dormancy of wild oat seed produced under various temperature and moisture conditions. Weed Science 17, 405–407.

Steadman KJ, Ellery AJ, Chapman R, Moore A, Turner NC (2004) Maturation temperature and rainfall influence seed dormancy characteristics of annual ryegrass (Lolium rigidum). Australian Journal of Agricultural Research 55, 1047–1057.
CrossRef |

Thomas AG (1985) Weed survey system used in Saskatchewan for cereal and oilseed crops. Weed Science 33, 34–43.








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