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Research gives insight into how stubble influences frost risk

frost risk

The latest findings to come from breakthrough research on the influence of stubble and rainfall on the incidence of frost will be profiled at WA’s premier grains conference.

Last year (2020) research by the Department of Primary Industries and Regional Development, funded by the Council of Grain Growers Organisations, found a type of bacteria present on some stubbles could elevate the frost risk, particularly after rain.

Department field trials revealed wheat grown on stubbles with ice nucleation active (INA) bacteria froze from the ground up at temperatures four to five degrees warmer than without stubble.

Further research on the main sources of ice nucleation activity on wheat will be discussed at the Grains Research and Development Corporation’s (GRDC) Grains Research Updates 2021 in Perth.

Department research scientist Ben Biddulph said followup research explored the cause-effect relationship between stubble and crops to determine the temporal variation from head emergence to grain filling under varied stubble management.

“The results indicated that flag-4 leaves and older ones had the highest INA, freezing at between -4.7 and -6.3 degrees centigrade, followed by stubble, where freezing was triggered at between -5.7 and -6.7,” Dr Biddulph said.

“With stubble, the peak ice nucleation activity period coincided with heading and flowering, the most frost susceptible stages.

“Even with the low rate of stubble residue of two tonnes per hectare, there seems to be an increased risk of frost damage in the infected stubble plots compared with the blanket burn plots.”

A key result was that a blanket burn of the stubble had little influence on completely protecting the flag-4 and older wheat leaves from INA, rather it just delayed the peak activity until after the crops’ most susceptible stages.

“The field trial data suggests stubble removal doesn’t guarantee frost protection but might offer a slight advantage by delaying the onset of high INA activity until after flowering, when crops are most at risk,” Dr Biddulph said.

Additional research across frost prone areas of the Grainbelt and seasons are required to further validate the trial findings.

Dr Biddulph said cereal growers are encouraged to manage paddock stubble loads according to the department’s recommendations, found on its website.

“Evidence is mounting to implicate the role of ice nucleating bacteria on the increase in INA, which will lead to a greater understanding to how best to manage stubbles and the older leaves of wheat crops to reduce the frost risk,” he said.

“In the mean time, growers should continue to consider a range of a strategies to reduce the frost exposure to the crops, including zoning, enterprise, crop type, variety maturity and sowing date.”

For more information on frost management, tools and support visit agric.wa.gov.au.

Dr Biddulph and his colleague Dr Amanuel Bekuma will speak on the first day of the GRDC’s Grains Research Updates 2021 in Perth on Monday, 22 to Tuesday, 23 February. For more details or to register visit the GRDC Upcoming Updates and Events webpage.

The webpage also has information about Regional Updates to be held in each port zone following the Perth update, as well as advice should COVID emergency measures be in place.

Picture caption: DPIRD research scientists Dr Ben Biddulph (pictured) and Dr Amanuel Bekuma will provide an update on research on the frost risk to wheat grown on stubbles at the Grains Research Updates 2021 in Perth.

Source: WA DPIRD

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