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Frost Nurseries Identify Tolerant Grain Varieties

29 February 2012

AUSTRALIA - Breeding new wheat and barley varieties with improved frost tolerance is the ultimate solution to minimise economic losses due to frost.

Pre-breeding research funded by the Grains Research and Development Corporation (GRDC) has identified improved genetic sources of frost tolerance, and these genes are already part of barley breeding programs and under evaluation for wheat.

Department of Agriculture and Food (DAFWA) research officer Ben Biddulph will present the latest results on projects screening for varietal differences in frost tolerance at the 2012 Agribusiness Crop Updates in Perth in February.

The Updates are supported by DAFWA and the GRDC, and convened by the Grains Industry Association of WA (GIWA). Registrations are now open.

Dr Biddulph says it’s tough to measure damage from frost events in the field.

“Because it’s impossible to know in advance where a frost will occur, the equipment is not always set up to measure temperatures. Often, damage is not immediately visible, and there are many other factors which may influence ultimate yield.

“This has led to an assumption for many years that there was little variation amongst wheat and barley varieties in terms of frost tolerance,” Dr Biddulph said.

“However, successive GRDC funded projects have enabled dedicated frost screening nurseries to be developed in South Australia, Western Australia and now New South Wales to measure frost tolerance with greater accuracy and repeatability.

“The research has shown that under severe frost (<-2° for wheat and <-6°C for barley) all varieties are equally susceptible.

“However genetic variation does exist for frost under milder conditions, with Keel, Sloop and Schooner having lower levels of damage than other barley varieties, for instance.

“Tolerance has also been identified in Japanese barley varieties, although this is still comparable to Keel.

“The tolerance genes from the Japanese material have been introduced into Australian barley breeding programs and in adapted backgrounds this tolerance has been validated in the field in WA and SA,” Dr Biddulph said.

The frost nurseries are set up with multiple times of sowing at each site to increase the probability that the test lines are at the flowering stage when a natural frost event occurs.

On-site weather stations monitor the temperature at the crop canopy. Following a frost event, heads at flowering are tagged and then assessed later for frost induced sterility at mid grain fill.

This approach minimises confounding effects due to maturity and enables repeatable results over successive seasons and sites.

The research has found that reductions in the number of grains in the head start to occur in wheat and barley when temperatures are around 0 and -2°C respectively with no visible signs of frost damage.

Temperatures below -2°C in wheat and -6°C in barley lead to substantial reductions in the number of grains in the head.

“Future work will continue refining screening methods, searching for sources of tolerance, work towards developing frost sensitivity ratings of new varieties and validate the impact of frost induced sterility from mild frosts on yield in wheat and barley,” Dr Biddulph said.

“This includes a new project working towards developing frost susceptibility ratings for new varieties to assist growers in managing frost risk.”

TheCropSite News Desk

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