CSIRO news release

CSIRO is breeding new 'high-vigour' wheats so fast-growing they can out-compete weeds while maintaining high yields.

Weeds cost Australian farmers over $4 billion annually in chemical and mechanical control and yield losses.

"High-vigour wheats have the potential to provide significant economic savings and environmental benefits for Australian agriculture," says Dr Greg Rebetzke, CSIRO Plant Industry.

"In field trials where wheat crops have to compete with weeds, the high-vigour wheat yielded double the grain of current varieties."

The new wheats shade the soil surface, suppressing weeds and saving water by reducing soil evaporation.

They also have more robust root systems than current varieties, enabling them to starve weeds and access water and nutrients deep in the soil.

The high-vigour conventional breeding program follows a three-year study by CSIRO and the University of Adelaide that evaluated the competitiveness of over 200 wheat lines from Australia and around the world.

The study found that competitiveness in Australian wheat has been largely bred out over the last 100 years, as breeders focused on better grain quality and disease resistance.

"We measured a range of traits including wheat and weed seed yield, rate of leaf area development and the ability to suppress or tolerate weeds, selecting the most vigorous wheat lines for further breeding," says Dr Gurjeet Gill of the University of Adelaide.

"The program is now breeding the high-vigour traits into commercial wheat varieties for release to growers. Varieties are expected to be available in four to five years."

Further CSIRO research is aimed at understanding genetic control of early vigour and developing breeding strategies to improve the efficiency of selection.

Weed-beating wheats

Source: CSIRO Newsletter Issue 6 Winter 2004

CSIRO is breeding highly vigorous wheat varieties that maintain high yields while shading the soil surface to suppress weeds and reduce soil evaporation.

The new wheats also have more vigorous root systems that can starve weeds of nutrients, reach previously unavailable water and nutrients and perform well in hard soils.

The high-vigour breeding program follows a three-year study by CSIRO and the University of Adelaide that evaluated the competitiveness of over 200 wheat lines from Australia and overseas.

The study found that competitiveness in Australian wheat has been largely bred out over the last 100 years as breeders focused on better grain quality and disease resistance.

By measuring a range of traits such as wheat and weed seed yield, rate of leaf area development, and the ability to suppress or tolerate weeds, researchers were able to select the most vigorous lines for further breeding.

Current CSIRO research is aimed at understanding genetic control of early vigour and developing breeding strategies to improve the efficiency of selection.

The high-vigour trait is now being bred into commercial lines.

Research is supported by funding from the Grains Research and Development Corporation.

INFORMATION SHEET

High vigour wheat for Australia

Highly vigorous wheat has the potential to benefit growers through better weed control and higher yields. Environmental benefits will include reduced herbicide use and larger root systems to reduce deep drainage and capture water and nutrients more effectively.

CSIRO Plant Industry is collaborating with researchers at the University of Adelaide to breed high-vigour wheat cultivars with prospects for better control and management of weeds, greater water use efficiency and improved late sowing options.

Chemical and mechanical control of weeds currently costs Australian farmers $80 per hectare. Even where weeds are controlled, herbicide resistance and late weed emergence can result in a vast seed bank in following crops. Wheats that develop leaf area quickly early in the season compete well against weeds, sometimes completely suppressing them without the need for chemical or mechanical control.

A three-year study by CSIRO and the University of Adelaide has evaluated the competitiveness of over 200 wheat varieties from Australia and overseas. Wheats were evaluated for early vigour and the ability to tolerate or suppress weed growth. Wheat lines were identified as weed-tolerant if they produced high yields in the presence of weeds while a number of breeding lines were also found to suppress weed growth. By measuring aspects of wheat and weed growth, researchers found plants that produced greater leaf area faster intercepted more sunlight to shade out weeds.

Commercial lines (left) and high vigour wheat

If greater leaf area could be achieved from seedling emergence, then the wheat crop slowed weed growth and maintained more vigorous growth throughout the season.

The study found that current Australian wheat varieties performed poorly in terms of competitiveness. Vigour has been largely bred out of wheat over the last 100 years as breeders focused on better grain quality and disease resistance.

Investigations of overseas wheat varieties identified several genes that could be used to breed for greater vigour. These genes increase the size of the embryo, reduce leaf thickness and promote earlier tillering.

Preliminary research also shows that greater early vigour is associated with increased root growth, which can starve weeds of nutrients and water.

Even where weeds are not a problem, a larger root system can intercept water and nutrients that would otherwise be leached beyond the roots. Leaching of nitrogen is a major problem in some countries and on sandier soils in parts of Australia.

 The use of molecular markers can hasten the process of conventional breeding and the release of a commercial variety by two to three years.

Research is supported by funding from the Grains Research and Development Corporation.