Gene helps growth in acidic soils

Jo FulwoodCountryman

Researchers have isolated a gene that allows common barley varieties to compete with wheat yields when planted into acidic soils.

Barley is the most sensitive of all the cereal crops to acid soils, with some farmers reporting up to 30 per cent yield losses on crops planted into soils with a low pH.

With a large percentage of WA soils well known for being acidic coupled with high levels of aluminium toxicity, this finding will be good news for many growers.

Trails at the Department of Agriculture and Food (DAFWA) Merredin Research Station compared yield results of Baudin and Hamelin barley varieties that had been bred with an aluminium-tolerant gene against the same varieties without the tolerant gene.

Both yield results were then compared with the wheat varieties of Wyalkatchem, Calingiri and Tamarin Rock.

DAFWA senior research officer Blakely Paynter said results from the three-year trial showed the barley varieties that included this aluminium-tolerant gene yielded as well, if not better, as the three wheat varieties grown during the trials.

"The aluminium-tolerant Baudin was 94 per cent of wheat yields, whereas the normal Baudin was 74 per cent of wheat, so we had a 20 per cent increase in yield due to that single gene," Mr Paynter said.

"Hamelin, without the gene, was only 76 per cent of wheat, but the aluminium-tolerant Hamelin was 103 per cent of wheat yields, so we had a 27 per cent increase in yield just due to that gene being incorporated."

Mr Paynter said despite the findings, growers would still need to apply lime, since the application of lime was the only long-term way to ameliorate acidic soils.

"In the future, the incorporation of this gene into common barley varieties will provide another rotation option on farms with acidic soils," he said.

"In most paddocks the soil types vary significantly, so one part could be alkaline, and one could be slightly acidic, so what this gene will do will stabilise some of the yield variability that might occur where pockets of the paddocks are low in soil pH."

DAFWA principal research officer Chengdao Li said the ALT gene increased the exudation of citric acid from the roots.

"The citrate reduces the level of aluminium in the area surrounding the roots, and allows the roots to increase their proliferation in the soil," he said.

"The aluminium-tolerant gene increases the exudation of citrate by 10-fold, relative to barley that is sensitive to aluminium, hence we get more root extension."

Mr Paynter said the aim of the trial was to ultimately breed the gene into a commercially available barley variety.

"If we want to make barley really competitive, we need to make it as tolerant as the best wheat," Mr Paynter said.

Breeding company Intergrain has incorporated the ALT gene into its WABAR 2625 barley variety, which, while not yet commercially available, is part of the 2012 National Variety Trails.

Yield results will be available after harvest.

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