Trials measure frost sensitivity

The Australian National Frost Program is a five-year project funded by the Grains Research & Development Corporation which is undertaken by researchers from the University of Adelaide and Department of Agriculture and Food WA.

The project aims to deliver frost sensitivity ratings to growers for current wheat and barley varieties to help manage their risk of frost.

University of Adelaide School of Agriculture, Food & Wine senior technical officer Michael Laws, who runs and manages field trials, said reductions in grain number occurred in wheat and barley when canopy temperatures at flowering fell below 0 degrees, with no visible signs of frost damage.

"Canopy temperatures at flowering between -4C and -6C in wheat and barley respectively can cause major crop losses," he said.

"For frost events above these temperatures cultivar variation in frost sensitivity has been identified."

The experimental trials are sown on several dates between April and June to maximise the likelihood of synchronising frost events with flowering throughout the high frost-risk months of August until October.

Heads are individually tagged shortly after a frost event if they are flowering according to the protocol.

Then, after four weeks of grain growth, the heads are collected and for three months every year researchers painstakingly count the florets of 50,000 to 100,000 wheat and barley heads harvested from the 2.5-hectare trial at the SARDI-PIRSA Loxton Research Centre, as well as NSW and WA sites, to calculate the percentage of grains affected by frost.

Mr Laws, who spoke at a GRDC Grains Research Update for Growers at Lameroo last year, said the evolution of the project came after the university tested several varieties of barley obtained from targeted locations around the world.

"We initially had success with barley, in finding genetic variation between different cultivars, however previous research had documented limited success with wheat, which prompted it to be re-evaluated," he said.

Mr Laws said GRDC further invested with the university in breeding populations and exploring genetic variation.

"What we found was significant variation in Australian varieties so to further investigate the GRDC developed the ANFP, to look at both wheat and barley, and explore the variations of frost susceptibility in current Australian varieties using a standardised method," he said.

Temperature is not the only thing that affects the severity of a frost event -humidity, acclimation of the plant to its environment, diurnal temperature fluctuation and soil moisture also appear to have an effect.

Frost can cause grain heads to become sterile, head 'bleaching' and stem frost - all of which affect potential grain yield in a crop.

The five-year project will conclude in 2016. Currently, 48 barley varieties, 65 wheat varieties, including 10 long-term controls, are being monitored through the project.

* Full report in Stock Journal, January 23, 2014 issue.