Australia
December 14, 2009

Break crops with greatly improved herbicide tolerance are a step closer to reality following recent breakthroughs by WA researchers.

Pre-breeding research at the University of WA (UWA), funded by the Grains Research and Development Corporation (GRDC), has produced lupin and chickpea material with significantly increased tolerance to the important broad-leaf herbicide metribuzin.

A lupin line produced in 2009 is estimated to have about 10 times the tolerance to metribuzin compared with the anthracnose-resistant lupin variety Tanjil.

The new lupin and chickpea lines will be used as breeding material in GRDC-funded national and state pulse breeding programs.

Increased tolerance to post-emergent herbicides will result in improved crop safety and reduce the risk of weeds developing herbicide resistance.

The ability to adequately control weeds is a significant reason why many WA growers have increased their production of triazine tolerant (TT) canola in the past decade, at the expense of other break crops such as lupins.

Centre for Legumes in Mediterranean Agriculture (CLIMA) director Willie Erskine, said the GRDC-funded, three-year research project also involves the WA Herbicide Resistance Initiative and ties in with plant breeding by Pulse Breeding Australia and the Department of Agriculture and Food (DAFWA).

It followed previous work at UWA which aimed specifically to improve lupin tolerance to metribuzin while retaining the trait of resistance to anthracnose disease.

“The current project is also looking beyond metribuzin, to which small populations of wild radish are resistant, and looking for new herbicides which can be used for break crops,” Dr Erskine said.

CLIMA researcher Ping Si said the previous pre-breeding work had in 2005 produced two new lines of lupin, each containing a gene conferring a high level of metribuzin tolerance.
These lines, which have already been used in lupin breeding programs, have six times the tolerance to metribuzin compared with Tanjil.

In 2009, these two lines were crossed to produce a new strain of lupin with about 10 times the metribuzin tolerance of Tanjil.

In trials conducted by Dr Gang Pan (Endeavour Post-Doc Fellow from Zhejiang University, China) the 2009 strain showed no herbicide damage when sprayed with metribuzin at a high rate that killed the two lines produced in 2005.

The three-year pre-breeding project had also recently produced two lines of chickpeas tolerant to metribuzin.

Dr Si said this was significant as currently there were very limited options for the use of post-emergent herbicides in chickpeas, making weed control very difficult.

If it was proven that metribuzin could be used safely in chickpeas, it could be registered for use as a post-emergent herbicide in the crop.

Dr Erskine said the main limiting factor in the uptake in chickpeas in WA had been the disease ascochyta blight.

“However, you have to have a good weed management system in addition to tolerance to the disease,” he said.

“Ascochyta blight-resistant chickpea cultivars are expected to be released in two or three years, but it is also increasingly important to find herbicides that will work on chickpeas for broadleaf weeds.”

Dr Si expected WA growers would be quick to adopt new pulse varieties with better herbicide tolerance.

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

Published: December 14, 2009