New lucerne cultivar opens up rotation options
Paddock trials of a new grazing-tolerant dryland lucerne cultivar, developed with funding from the Grains Research and Development Corporation (GRDC), are producing encouraging results.
SARDI Grazer is a winter-active lucerne (class 6) that has been developed by the South Australian Research and Development Institute (SARDI) and the Department of Agriculture and Food Western Australia (DAFWA) over a nine year period.
SARDI lucerne breeding program leader, Alan Humphries, says the cultivar has been performing well in on-farm trials run under commercial conditions at a range of sites in southern and eastern Australia.
Mr Humphries said the new variety was an important breakthrough, especially for cereal producers who would benefit in terms of management of groundwater recharge, herbicide resistant grasses and cereal diseases, as well as improved nitrogen fixation and soil structure.
“This new variety allows farmers lacking fencing and water point infrastructure to now grow lucerne in their current farming system.
“This is particularly relevant to cereal farmers with large paddocks where it may take around 35 days to graze down a 50 hectare paddock. In large paddocks grazing pressure is seldom even, and SARDI Grazer will handle overgrazing better than our traditional lucerne varieties.”
Bred to withstand spells of persistent grazing of up to two months, Mr Humphries said SARDI Grazer offered a persistent and productive option for mixed farmers across Australia.
He said it had shown an excellent level of grazing tolerance on soils ranging from deep sands to clay in low, medium and high rainfall zones.
“Plant breeding and evaluation trials leading to the development of SARDI Grazer occurred mainly in low to medium rainfall areas such as South Australia’s Murray Mallee, as well as the cereal belt in Western Australia, so we have been pleasantly surprised to see it performing so well in high rainfall areas like Timboon in south-west Victoria,” Mr Humphries said.
Post-development, SARDI Grazer has been evaluated at 26 sites in SA, Victoria, NSW and Queensland.
Mr Humphries said these evaluations showed the cultivar was suited to a range of farming systems, it had demonstrated good levels of resistance to aphids and diseases, and was expected to be tolerant of drought conditions.
SARDI Grazer represents the first major trait improvement in winter-active dryland lucerne since Hunterfield was released in 1994, according to Mr Humphries.
The development of a grazing-tolerant lucerne variety was funded by GRDC in response to the emerging national problem of dryland salinity and the large number of studies advocating the use of lucerne to prevent recharge and mitigate the spread of salinity.
As well as improving soil structure and being a nutritious fodder source for livestock, lucerne also provides rotational benefits of increased soil nitrogen and a disease break for cereal rusts and cereal root diseases such as take-all and Rhizoctonia.
Mr Humphries said that once established, SARDI Grazer (now commercially available) could be grazed in a two-paddock rotation with six to eight weeks of grazing followed by six to eight weeks of recovery.
“The recovery period is critical for recharging the energy reserves of the plant so it maintains excellent levels of production and persistence.”
During the breeding program for the new cultivar, 120 lucerne varieties and breeding lines, many of which had previously undergone two cycles of selection under continuous sheep grazing, were evaluated in a continuous grazing trial at Roseworthy in SA.
After two years, surviving plants were dug up and replanted next to aphid and disease resistant selections for open pollination. The harvested seed resulted in the formation of 11 breeding lines that were sown along with commercial comparators in two parallel continuous grazing trials. One was at Turretfield in SA on a clay loamy soil with gravel on the surface, and the other was at Katanning in WA on an acidic light sandy soil more conducive to physical disturbance from the trampling of sheep.
Following nearly two years of continuous grazing by sheep, the breeding lines were found to maintain substantially higher plant densities than commercial varieties. Individual plants were dug from the best lines at Katanning and Turretfield and further evaluated based on their agronomic performance and yield potential.
Mr Humphries said the final parental plants used to develop SARDI Grazer were selected based on resistance to aphids and diseases, herbage yield, herbage quality and winter activity rating.
Caption: SARDI lucerne breeding program leader, Alan Humphries, pictured with SARDI lucerne breeding lines. Image SARDI.
Alan Humphries, SARDI
08 8303 9651
Sharon Watt, Porter Novelli
GRDC Project Code DAS00081, DAS347, DAS282
Region South, North, West