Frost research intensifies
With frost damage now estimated to be costing growers $360 million a year, the Australian National Frost Program (ANFP) is broadening its assault on the issue.
The program has been stepped up to include frost rankings for wheat and barley varieties, advice on pre-emptive measures growers can take, as well as the continuing research into developing frost-tolerant varieties.
For the past three years the program’s priority has been to develop accurate and reliable field measurements, as the GRDC’s Dr Juan Juttner explains: “In 2009 we reviewed all of our frost investments from the past 10 years. Projects in agronomy, genetics and GM all met the same constraint: a capacity to reliably and accurately measure or validate in the field the performance of plants that researchers and breeders are assessing.”
Dr Juttner says methods varied across the country, so the results could not be compared. One of the difficulties is that the frost sensitivity of wheat and barley heads varies according to the stage of development. Nutrition and water stress can also affect results.
Dr Juttner says the method ANFP researchers have now developed involves staggered times of sowing, so that when a frost event hits they can tag individual heads of different wheat and barley varieties, at the same stage of development – in other words, they can compare the effect of frost on different cultivars at a synchronised developmental stage and therefore compare like with like.
He explains that different cultivars can be at the same stage of flowering development when sown at different times because they mature at different rates. For example, if you sow a main-season cultivar two to four weeks after a long-season cultivar, they will flower at the same time.
The research is a massive undertaking. Thousands of heads of wheat or barley have to be tagged after a frost event and then the level of sterility on the head has to be counted.
Dr Juttner says that as the field assessment capacity has been established, the GRDC can now build other targeted projects onto it.
From this year, wheat and barley varieties entered into the National Variety Trials program will be evaluated by the ANFP and given a frost-tolerance ranking.
The program will assess 30 varieties of wheat and 20 varieties of barley each season and generate information that growers can use to manage risk.
There is no difference in the frost tolerance of wheat varieties below minus 4°C, and barley varieties below minus 6°C, but the program is looking for genetic diversity to increase that range.
Techniques include genetic modification, understanding the biochemistry and molecular biology of flowering, and looking for better frost-tolerant germplasm from around the world.
Dr Juttner says the understanding of frost tolerance is based on a limited number of lines that Australian researchers have studied. But there are millions of wheat and wheat relatives, including wild relatives, in genetic resource centres around the world.
The plan is to use the focused identification of germplasm strategy (FIGS) to identify likely germplasm to bring to Australia for assessment. FIGS allows scientists to identify the environment in which the stored germplasm was collected so they can select varieties from those that have been exposed to sub-zero temperatures during flowering. Among these they would hope to find some that have developed a frost-tolerance mechanism.
Now that it has an accurate field‑based evaluation process, the ANFP also plans to assess the potential of GM frost‑tolerance approaches such as the use of antifreeze proteins.
On the pre-emptive management front, many growers are already implementing practices such as delayed sowing and crop grazing to push the flowering window beyond the peak frost period. Some are planning their plantings topographically, with different crop and variety selections made for rises and hollows.
Dr Juttner says there is also evidence from Western Australian research that retaining stubble has an impact on frost severity. Preliminary research indicates that reducing stubble could increase the heat stored and then radiated from the ground overnight, keeping the crop warmer.
He says there is also interest in using growth regulators for within-season management of frost risk by delaying flowering. The GRDC is also looking at any chemicals that might be used in other plant industries for protection.
The ANFP is a partnership between the GRDC, the University of Adelaide and the Department of Agriculture and Food, WA.
Dr Juan Juttner,
02 6166 4500,
GRDC Project Code UA00136, DAW00162, UA00100, UQ00052
Region National, North, South, West