Two new lines from the Lethbridge Research Centre's winter wheat breeding program appear to be showing better drought tolerance than check varieties, says a wheat breeder.

AC Bellatrix and Radiant show improved drought tolerance over the half dozen new Western Canadian winter wheat varieties registered in recent years, says Dr. Rob Graf, wheat breeder at the Agriculture and Agri-Food Canada research station. AC Bellatrix was registered in 1999, while Radiant is expected to be registered this year with seed available for the 2005 crop.

"AC Bellatrix looks very good for drought tolerance and Radiant looks better than average winter wheat varieties," says Graf. "Farmers should expect both varieties to produce higher yields under drought conditions compared to other varieties. And we also have more promising lines coming along." The drought tolerance breeding effort is funded in part by the Wheat Check-off Fund administered by Western Grains Research Foundation (WGRF).

Improving drought tolerance in winter wheat is no easy task, points out Graf. The challenge is about equal if not more difficult than improving another important trait - cold tolerance. "Both characteristics are influenced by complex sets of interacting genes, which have to be expressed in the new lines," he says. "The more genes involved, the more difficult it is to get the whole package transferred through conventional breeding."

While the two varieties show as good as or better drought resistance compared to older varieties such as Norstar, their disease resistance is tailored more for the western Prairies. AC Bellatrix has resistance to common bunt, while Radiant is resistant to the wheat curl mite, which carries wheat streak mosaic. Neither variety has rust resistance.

The drier southern Alberta growing conditions may be more conducive to development of drought tolerant winter wheat varieties than higher moisture growing conditions in parts of the central and eastern Prairie, says Dr. Brian Fowler, a long time winter wheat breeder with the Crop Development Centre in Saskatoon.

Varieties from the CDC breeding program, such as CDC Raptor, CDC Buteo and CDC Falcon, tend to fit better with the cooler climate and higher moisture regimes outside of southern Alberta and southwest Saskatchewan.

"Our successes are not in the area of getting adaptation to the lower moisture environments," says Fowler. "Varieties developed through the Lethbridge program appear to perform better under dry conditions."

Depending on the timing and severity of drought winter wheat reacts differently to stress. With early-season drought the crop's first reaction is to shut down tillers. With drought at flowering the crop will produce fewer fertile florets with fewer seeds per spikelet. Winter wheat's last defense against drought is to reduce seed size.

"What we're looking for is a plant that will maintain maximum yield potential through different forms and stages of drought stress," says Fowler. Graf agrees, stating that a stable yield advantage across all environments, regardless of growing season moisture, is the ultimate goal that will benefit producers over the long term.

The Wheat Check-off Fund, administered by WGRF, allocates more than $3 million annually to wheat breeding programs.