2013 frost survivor gives researchers new target

A man in a hot house

Dr Ben Trevaskis from CSIRO is looking at the traits that contribute to frost tolerance.

PHOTO: Kerrie Ramm

In a GRDC-funded CSIRO pilot trial in Greenethorpe, New South Wales, one wheat variety held up well in the savage October 2013 frosts. Cautiously optimistic, the researchers are hoping to repeat their findings in 2014.

For many New South Wales growers such as Rob Taylor of Greenethorpe, the October 2013 frosts wiped tens of thousands of dollars of potential income from the balance sheets.

The temperatures dipped to minus 5°C over several hours on Monday 14 October, then again on Friday 18 October. 
“When the data loggers said minus 5°C, I knew I was in trouble,” Rob says. “The damage didn’t show up until seven to 10 days afterwards.”

His EGA Gregory crop, which one month earlier was on track to deliver 5.0 tonnes per hectare, ultimately yielded just 0.5t/ha, and that was in the paddocks that he took through to harvest. Much of his crop was cut for hay.

However, Rob’s property was also hosting a large GRDC-funded trial aimed at maintaining yield stability of wheat under spring frosts. In that sense, the October frost was of value to researchers.

Wheat ears

SQP Revenue following the severe frosts of 14 and 18 October 2013. The solid performance of this awnless wheat variety caught the attention of the trial researchers and further work is now underway.

PHOTO: Troy Frederiks

CSIRO’s Dr Ben Trevaskis leads the project. His research focuses on the genes controlling flowering time in cereals. Dr Trevaskis says there is strong evidence that some variants of these genes in wheat that control the time of flowering in response to cold (the vernalisation period) are also active in providing frost tolerance. So researchers are trying to identify those variants and protect the flower from common frost events.

The Greenethorpe trial consisted of 400 lines replicated twice over three sowing dates, spread to cover the various flowering times. That meant a total of 2400 plots, 800 per sowing dates; 400 lines with two replicates.

Many of these lines were developed in the CSIRO laboratory.

“Flowering is a complex trait with a lot of genes,” Dr Trevaskis says.

“We tackle this diversity in our experiments by using a powerful genetic resource called the CSIRO four-way wheat multi-parent advanced generation inter-cross (MAGIC) population, developed at CSIRO by Dr Colin Cavanagh. This population shuffles the genetic variation from four elite Australian wheats into about 1500 new lines with random combinations of the traits found in the original parents. In this population we see a wide range of flowering times.

“Each line has been assayed with high-density molecular markers, so if some lines perform well under frosty conditions we can identify genes that can be used to breed for improved frost tolerance. Frost is so difficult to predict in the field and reliable frost tolerance screening is difficult, so having molecular markers would be really useful for breeding programs.”

In the Greenethorpe trial, 350 lines were MAGIC – enough to begin to map the genes that potentially confer frost tolerance – while 50 were a mix of commercial and imported varieties, or ‘checks’.

Promising variety

A paddock showing weeds

Ripening plots in an earlier sowing block in the CSIRO Greenethorpe trial. There is little visible damage in the barley plot; however, sowing earlier than recommended is not advisable.

A paddock

CSIRO Young trial ripening plots in earlier sowing block. There is little visible damage in the barley plot (possibly frost escape).

PHOTOS: Troy Frederiks

One of these ‘checks’ was a waxy, awnless variety called SQP Revenue, and the performance of SQP Revenue caught the attention of the researchers.

“SQP Revenue was flowering late in our trial but not late enough to avoid the frost,” Dr Trevaskis says. “It should have been hit really hard but it somehow got through and made grain. At the whole-plant level, it just looked happier.”

Peter Hamblin of Kalyx, the company based in Young, NSW, that is managing the CSIRO trial, says the SQP Revenue line got through three sowing dates and the two frosts: “It looked terrific.”

Another check variety that showed a capacity to maintain yield at Greenethorpe in 2013, despite the severe late frosts, was the Australian wheat variety Bolac.

The region ran into moisture stress in September, so Dr Trevaskis and others involved in the trial are keen to see further results from this year’s trial. The GRDC is funding the trial for a further three years.

“Some of the genetic material we have is going to be useful in an average year, but won’t hold up to a season like 2013,” Dr Trevaskis says.

Mr Hamblin says the October event was the third extreme frost event in the past 15 years.

“These are frosts you can’t account for with sowing date and flowering,” he says. “In this region [NSW south-west slopes] we aim to flower from 5 to 10 October. It’s always a race between not flowering too early and running out of moisture.

“Frosts are worse than a drought because you keep spending the money. In a drought, you pull back on your inputs. With a frost, you’ve spent all your money and you just go over a cliff.”

Next steps

Dr Trevaskis will now send some of the Greenethorpe trial lines to Toowoomba, Queensland, for further testing.

“They get hard frosts there most years,” he says. “They use a series of times of sowing and artificial light to help coordinate flowering of diverse varieties. SQP Revenue does need cold to flower so we’ll need to chill the seeds for the north.”

Dr Trevaskis is optimistic that SQP Revenue could be a source of improved frost tolerance, but says there will not be overnight results: “We probably won’t get a frost solution from Australian wheat lines, at least for the type of frosts like those we saw in Greenethorpe in 2013.

“Seeking out international germplasm is the logical path and this is something that is being actively pursued in other GRDC-funded projects.”

More information:

Dr Ben Trevaskis
02 6246 5045
ben.trevaskis@csiro.au

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GRDC Project Code CSP00180

Region South, North, West