THE POTENTIAL of a naturally occurring fungus to influence wheat establishment, growth and yields is being demonstrated from glasshouse to paddock in research underway across Australia.
The fungus is Penicillium radicum, first discovered in a paddock near Wagga Wagga, NSW, in 1989 in a joint project between Charles Sturt University and Australian Seed Inoculants (ASI), Wodonga.
Researchers believe the uptake of phosphorus in certain soils is improved when P. radicum is present in the wheat roots.
Now marketed a s PR70 Release, the seed inoculum underwent limited commercial release two years ago. In 2002 sufficient inoculum to treat about 3,000 tonnes of wheat seed was produced.
ASI site manager, Peter Grieve, said the effect of the inoculum on wheat was being further assessed this year in trials being conducted by Agriculture Victoria, NSW Agriculture, the SA Research and Development Institute, Australian Fodder Industry Association, WA Department of Agriculture and WA No-Till Farmers Association.
"As well, a number offarmers are using it and we are monitoring the results," Mr Grieve said.
"Common observations in field trials have been visual improvements in plant establishment and increased vigour and growth. Yield responses have been varied, ranging from marginal improvements to gains as high as 25 per cent - the collective average in trials to date being 8 per cent throughout Australia.
"We are not making claims that it is the cure for phosphorus tie-up in all soils but results in specific soils are promising and demand for the product has been excellent."
Soils where inoculant shows advantage
Mr Grieve said situations where PR70 Release showed positive results included in low pH soils where phosphate was immobilised; in paddocks returning to wheat after a pasture phase; and where wheat had been sown into paddocks that had been waterlogged. This year the effect of the inoculum on a wide range of crops was being assessed.
Meanwhile P. radicum is being further investigated in related GRDC-supported research being conducted at CSIRO Land and Water, Adelaide. Project leader, Maarten Ryder, said the field trial data compiled by ASI had been studied and they contained a "a lot more positives than neutral or negative results".
He said there were several aspects to the CSIRO work including determining the distribution of the fungus, testing its effects on plants grown in the glasshouse and developing a DNA probe so that the fungus could be speedily identified in soil samples. As well, Simon Anstis of the University of Adelaide, supported by the Australian Research Council and ASI, was trying to determine "how the fungus works".
Effect of P. radicum in soils from three states
Much of the CSIRO research is the province of Steven Wakelin who has discovered a second population of P. radicum - this time near The Rock in southern NSW.
The discovery was made following comprehensive sampling of soils from three states.
"While Pencillium fungi are common in soils, this is just the second time that the species P. radicum has been identified," Dr Wakelin said.
"In our (glasshouse) pot trials we are testing responses to wheat following inoculation with P. radicum in a range of soils and so far have seen responses in three soil types - one in an acidic sand from WA, another from an acid red soil around Wagga Wagga, and the third from a neutral loam near Tarlee in SA's lower north.
"The responses show out in height and dry matter responses - to date, we have not taken them through to yields."
DNA probe sounds like a good idea
The development of a DNA probe would enable the presence of the fungus to be determined in soil. A farmer who inoculated the seed could find out, for example, if the fungus was present in following years, or if re-inoculation of seed was needed.
Dr Ryder said wheat plant response and DNA development work would continue but, as well, there would be research into the interaction between P. radicum and different phosphatic fertilisers and soil moisture levels, along with its effect on a range of wheat varieties and other crop types.
THE GRDC-supported P. radicum research is part of a Soil Biology Strategic Initiative led by Sustainable Farming System program consultant Greg Bender.
The GRDC has committed $10 million over five years to this initiative which is aimed at overcoming limits to crop performance and thus increasing profit margins for growers.
Outcomes sought from the investments include the development of practical methods and cost-effective products resulting from a better understanding of crop root/soil/microorganism interactions.
Dr Bender was one of the original discoverers of P. radicum at Wagga Wagga.
See also p25 where we feature new forestry research indicating that a natural soil ecology, including friendly fungi, may be a major booster for re-establishing native vegetation.
Program 4 Contact: Mr Peter Grieve 02 6024 5595; Dr Maarten Ryder, Dr Steven Wakelin 08 8303 8400; Dr Greg Bender 02 6248 0165
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