Australia
July 28, 2011

Significant progress has been made in the development of a new weed management tool – wheat with superior competitiveness.

Highly vigorous wheat lines have been developed which can produce up to double the biomass of commonly grown varieties by the early tillering stage, effectively shading out weeds.

Increased root growth also enables the wheat to out-compete weeds for water and nutrients.

A standout example of high vigour wheat.

The lines have been produced by the University of Adelaide, in collaboration with CSIRO Plant Industry, under a Grains Research and Development Corporation (GRDC) funded project.

In Western Australian and South Australian field trials the competitive wheat lines suppressed weeds while producing grain yields comparable to or better than those produced from commonly grown varieties.

It is proposed these wheat lines – which could help give growers the option of keeping weedy paddocks in crop - will be provided to Australian wheat breeding programs to include in germplasm development.

Department of Agriculture and Food (DAFWA) researcher Peter Newman, who is testing three of the lines in WA as part of GRDC-funded integrated weed management research, is excited at the potential for another non-herbicide weed control option.

“These competitive wheat cultivars are capable of reducing ryegrass seed set by up to 50 per cent compared with existing commercial wheat varieties – that is almost as effective as using a chaff cart,” he said.

“Due to increasing herbicide resistance, it is important for growers to use more non-herbicide options to control weeds and there is significant potential for crop competition to be better utilised for weed control.

“WA farmers are accustomed to weeds dominating in their paddocks as they currently grow uncompetitive crop varieties at wide row spacings with low to moderate seed rates.

“The availability of competitive crop varieties could help swamp out the weeds.”

Mr Newman helped to test three competitive wheat lines at Eradu and Wongan Hills last year.

The lines, grown on yellow sandy soils, were compared with the commonly grown wheat varieties Mace , Magenta and Wyalkatchem , and Baudin barley.

Mr Newman said the WA trial sites were relatively weed free in 2010, making it difficult to assess the weed suppressive ability of the competitive lines.

“However, the competitive lines yielded almost as well as the other commercial lines and despite their big canopies, did not fall over during the dry finish to the season,” he said.

“I believe this is due to their larger root systems which can explore further into the soil for moisture.”

The best of the competitive lines grown at Eradu yielded 3.4 tonnes per hectare, compared with 3.5t/ha for Magenta , the top yielding commercial line.

At Wongan Hills the best competitive line yielded 1.5t/ha, compared with 1.6t/ha for Mace .

“In weed-free situations there is no significant yield advantage from growing these competitive lines, but the big advantage comes when they are grown in weedy paddocks,” Mr Newman said.
University of Adelaide researcher Gurjeet Gill said that in South Australian field trials where paddocks were weedier, the competitive wheat lines provided up to 50 per cent better weed suppression (weed seed production) than commercial varieties such as Wyalkatchem , while improving yields by up to 30 per cent.

Dr Gill, who led the development of the competitive wheat lines, said in areas where annual ryegrass was resistant to Group A and B herbicides, Australian wheat crops treated with pre-emergent herbicides often had unacceptable levels of weed seed set.

“The use of high early vigour and weed suppressive varieties, in conjunction with other weed management tactics, could enable farmers to keep weedy paddocks in crop if they wish to do so,” he said.
“Most of our research has focussed on the suppression of annual ryegrass, as this is the most problematic weed in southern and western grain growing areas of Australia.

“However, recent research results show that wheat varieties with superior competitive ability against ryegrass also possess superior competitive ability against other grass and broadleaf weeds.”
 

Website: http://www.grdc.com.au

Published: July 28, 2011