Research has generated findings and genetic material that could help produce future barley varieties that are less susceptible to ‘head loss’ – an issue that significantly reduces barley crop yields in some areas and seasons.

Led by Murdoch University Professor Chengdao Li, the work has also highlighted the importance of growers comparing the risk for different varieties and ensuring barley crops at critical growth stages have adequate access to potassium and copper, as crops deficient in these nutrients were found to be much more prone to the issue.

Barley crops in areas such as Western Australia’s south coastal districts and South Australia’s Lower Eyre and Yorke Peninsulas are especially susceptible to head loss, which is caused by straw under the head breaking and results in in yield losses of 5 to 9 per cent in typical seasons in these areas.

The research findings are from a project with Grains Research and Development Corporation (GRDC) investment, led by Professor Li, director of the Western Barley Genetics Alliance. This collaborative project involved work by the Department of Primary Industries and Regional Development WA, Murdoch University and the University of Adelaide.

Advanced breeding lines

Professor Li said the laboratory work and field trials at Esperance, Katanning and Geraldton had revealed information and developed advanced breeding lines, new germplasm and molecular markers which had the potential to be used in breeding programs.

“Our research suggests barley varieties will be less susceptible to head loss if the barley ‘peduncle’ – the straw beneath the barley head – is bred to have greater flexibility and strength,” he said.

“A significant finding from this project is the relationship between straw strength and straw flexibility, and some varieties are significantly more flexible and are less prone to breakage.

“We identified quantitative trait loci (QTL) associated with straw strength on three chromosomes and these could be used as selection targets by barley breeders.”

Straw strength

Professor Li said seasonal conditions were shown to have a significant effect on straw strength, with some varieties demonstrating a significant variation in straw strength in different years of the trials.

He said the head loss risk of barley varieties varied significantly and several high yielding, new varieties and advanced breeding lines had an even greater head loss risk than current susceptible varieties.

“The research also demonstrated that varieties respond differently to low levels of potassium, suggesting that genetically improving potassium use efficiency in barley varieties will not only enhance yields and reduce the need for fertiliser, but also improve straw strength and reduce head loss,” he said.

Professor Li said the project showed that the same variety sown at the same trial could have head loss levels up to two to three times greater if copper and potassium were deficient during the stem elongation and head formation stage of the crop.

“This shows the importance of providing adequate levels of these nutrients, particularly during this growth stage,” he said.

“Up to 30 per cent of soils in WA’s cropping regions are deficient in potassium and this can be exacerbated on sandy soils in the south coastal region where nutrients are prone to leaching.”

Varietal head loss risk information is available in sowing guides such as the Barley Sowing Guide for WA.