A La Trobe University study has found the invasive South African flower Gazania is more resilient than previously understood, with its ability to adapt to different environments making it one of the biggest weed threats to Australian native grasslands and grain production.
Weeds and invasive plant species, such as Gazania, are responsible for considerable economic losses in agriculture, estimated to cost Australia over $5 billion annually.
Due to its flexible growth requirements, Gazania is now widespread in a variety of habitats including coastal sand dunes, stream banks, wastelands, open grasslands, along roadsides and on cultivated and irrigated sites in southern Australia and parts of Western Australia.
Two varieties of Gazania were first brought to Australia as ornamental flowering plants in the 1950s and 1970s, however ended up in garden waste as lawn clippings, seeds or other live plant material which helped them proliferate along roadsides and native vegetation.
While the flower has long been considered an environmental weed in Australia, it is now infesting grain crop production fields in low rainfall regions of South Australia, with farmers finding it difficult to control with common herbicides.
Marginal sandy lands with heavy infestations of Gazania are quickly becoming unproductive with crops quickly failing to compete with the drought hardy and vigorous weed.
Muhammad Adnan, a PhD student in Dr Ali Bajwa’s Weed Science group at La Trobe Institute for Sustainable Agriculture and Food (LISAF) and the Department of Ecological, Plant and Animal Sciences collected thousands of seeds from environments across Australia and studied how they grew under various conditions.
The study, published in Frontiers in Agronomy, found the seeds had a high tolerance for a large range of environmental factors, including light levels, hot and cold temperatures, seed burial depth, salt and acidity levels in the soil, and moisture.
Mr Adnan said this showed the seeds had adapted to germinate over a wide range of environmental conditions, suggesting they could become a problematic weed across all seasons in most parts of Australia, leading to potential high infestation levels.
“While further populations should be compared for emergence response under field conditions, these preliminary findings suggest this weed has the potential to develop significant seedbank in Australian no-till grain production systems,” Mr Adnan said.
Dr Bajwa said this knowledge of seed germination triggers and emergence dynamics should help to predict potential regions of spread of Gazania and help develop and apply management strategies with respect to different environmental conditions.
“While this information is crucial for managing this highly problematic weed at the establishment stage (germination and emergence), further research is needed on growth and reproductive response of Gazania to different environmental conditions. This will help understand the invasion ecology and develop long-term management strategies for different land-use scenarios for this weed, which is rapidly spreading across Australia.” he said.
The full paper, Seeds of success: seed biology and germination response of Gazania weed in Australia, can be found here.
Muhammad Adnan and Dr Ali Bajwa are available for interview.
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