Long-term research needed to tackle weed seed persistence
26 Apr 2012
Weed research has confirmed the potential for a Seed Persistence Tool Kit to help farmers and land managers control invasive plant species, but longer term research is needed to deliver on the promising start.
Seeds can persist in the soil long after weeds are removed, and act as a reservoir for re-invasion into crucial agricultural land and environmentally sensitive areas.
To counter this problem, the Seed Persistence Tool Kit research project was conducted by a team at The University of Western Australia with a long-term view to enabling land managers to predict how long weed seeds will persist in soils.
“Inaccurate estimates of seed persistence are costly: when seed persistence is underestimated, eradication programmes end prematurely and weeds reinvade,” lead researcher Rowena Long states in the project’s final report.
“Conversely, when seed persistence is overestimated, time, money and labour are wasted in pursuing a problem that no longer exists.”
During the laboratory work conducted over the past year, seeds of 22 weed species (six environmental, 12 agricultural and four roadside weeds) were collected from south-west Western Australia for use in laboratory and field experiments.
Seeds were tested for a range of persistence-related properties in the laboratory, including germination responses, response to accelerated ageing and the antimicrobial content of seed coats.
Dr Long said some species could now be ranked according to how resistant their seeds were to being eaten by insects or decayed by microbes, with seeds from a weed such as gorse much more likely to survive in the ground than seeds from buffel grass.
“This is just one of about 30 factors that need to be considered in forecasting weed seed persistence, and much more work is needed to understand how weed seeds respond to their environment,” Dr Long said.
To support longer term view of the problem, the research team also established two five-year seed burial trials to verify the accuracy of persistence predictions made from the laboratory studies.
The research project was funded by the National Weeds and Productivity Research Program, which has been managed by the Rural Industries Research and Development Corporation (RIRDC) for the Australian Government.
The Australian Government provided up to $12.4 million to RIRDC to support more than 50 research projects, with the program due to end on 30 June 2012. The funding covered the first two years the National Weeds and Productivity Research Program R&D Plan, which covers the period 2010-2015.
Dr Long said further research into seed persistence was needed to identify which of the many seed, species, soil, site and climate characteristics are the key drivers of seed persistence for different weed types and habitats.
“Long-term field trials are needed to verify the accuracy of predictive models to ensure they are robust and informative for policy makers and land managers,” she said.
Researchers hope the study will allow land managers to collect seed and soil samples, send them to a laboratory with climatic and other data, and run tests to determine how long those weed seeds are likely to persist at that site.
Damon Whittock – RIRDC Public Affairs Manager – 02 6271 4175