RESEARCHERS from the University of Sydney have developed a standard method to test how different wheat varieties cope with heat stress.
This could lead to a standardised, easy to use ratings system for farmers that will help them with their varietal choices.
Heat shock is one of the major causes of yield loss in Australia and experts expect it to only get worse due to climate change.
Rebecca Thistlethwaite, lead researcher on the heat stress test project at the University of Sydney's Agriculture Institute, based at Narrabri, said giving farmers easy to interpret data about varietal performance under heat stress could boost underlying farm profitability.
"It would help with varietal choice and also with time of sowing, to allow farmers to sequence plantings to minimise the risk of heat shock," Dr Thistlethwaite, who was the lead author of a study on the project published recently in Field Crops Research, said.
The research found that heat shock was a particular risk to plants at flowering, as is widely known, but also during the meiosis phase, a biological process where cells divide.
Dr Thistlethwaite said it was difficult to pick up meiosis in the field but added it usually took place just before flowering.
She said it had been difficult to come up with a test that took into account the various factors that contributed to heat stress.
"While much has been published on wheat responses to high temperature, the techniques that are often used to assess complex plant traits lack relevance to farming conditions or rely too heavily on a single screening strategy," she said.
"For this reason, a three-tiered screening approach was developed and validated over a three year period to screen large numbers of materials, primarily in the field."
She said some of Australia's most popular commercial varieties had shown reasonable resistance to heat stress, while new genetic material put up by leading wheat breeders such as Intergrain, AGT and LongReach was also very promising in terms of its ability to handle hot conditions at critical periods of its phenology.
Co-author Richard Trethowan said a repeatable test on heat shock performance would be a key cornerstone in getting varieties better suited to coping with extreme temperature.
"Without reliable, repeatable and relevant ways of assessing plant response to high temperature we cannot provide farmers with the heat tolerant wheat cultivars so desperately needed in our increasingly variable environment," Professor Trethowan said.