Lucerne breeders now have for the first time the capacity to apply high selection pressure for performance under aluminium toxicity, an important aspect of acid soil conditions.

Researchers are confident that there is much room for improvement on acid soil and preliminary results suggest that seedling root growth has been increased by at least 15 per cent.

Lucerne is a key pasture species for local grain and livestock enterprises, with about half of all lucerne seed sold in Australia ending up in NSW.

However, the prevalence of acid soils is a major constraint to broader adoption in NSW and elsewhere, commonly reducing yields to a fraction of their potential.

A recent breakthrough by Australian researchers was the technique to enable screening of a large number of lucerne seedlings for their ability to regrow after the stress of high aluminium conditions.

"The research team has now focussed its attention on the nodulation of lucerne," NSW Department of Primary Industries’ Richard Hayes, said.

Mr Hayes, a farming systems research agronomist at Wagga Wagga Agricultural Institute, says nodulation is critical in maximising the nitrogen fixation capacity of lucerne.

"This is an issue only likely to become more important with the increased cost of nitrogen fertiliser," he said.

"Nodulation has also been shown to be an important aspect of lucerne survival, as unnodulated plants appear to be less persistent than nodulated plants.

"Nodulation of conventional lucerne using the current commercial rhizobia has been shown to be very poor in acid soils, with only about 20pc of plants forming nodules."

A promising development in the current research has stemmed from a collection of naturalised lucerne rhizobia.

Mr Hayes and Nigel Charman from the South Australian Research and Development Institute (SARDI) made the collection from southern NSW in November 2007.

The objective was to isolate lucerne rhizobia which had naturally adapted to acid soils.

Samples were taken from roadsides and paddocks containing established lucerne growing on acid soils down to pH 4.2.

In some cases the stands of lucerne were up to 15 years old and were from the Bookham, Bowning, Yass, Bredalbane, Goulburn, Crookwell, Ladysmith, Book Book and Tarcutta districts, on a range of soil types.

In total, 229 new strains were collected and isolated.

Screening of the new rhizobial strains is just about to begin but the diverse morphology of the material has already surprised researchers.

Previous research in North America had delivered little tangible outcome to growers.

The success in Australia comes after a five year collaboration between the Future Farm Industries CRC, Grains Research and Development Corporation, the state Departments of Primary Industries in NSW and Victoria and SARDI.

Contact Richard Hayes, Wagga Wagga, (02) 6938 1615, richard.hayes@dpi.nsw.gov.au