Tuesday, November 6, 2007
152-3

Influence of Seeding Rate and Cultivar on Winter Wheat Yield and Weed Competitiveness in Southern and Central Alberta, Canada.

Brian Beres, George Clayton, K. Neil Harker, Robert Blackshaw, and Robert Graf. Agriculture and Agri-Food Canada, Agriculture and Agri-Food Canada, 5403-1st Avenue S, Lethbridge, AB T1J 4B1, CANADA

Advances in cultivar development and the demand for winter wheat as an ethanol feedstock renewed interest in winter wheat (Triticum aestivum L.) across the Canadian prairie leading to an increase in acreage not observed since 1987. A sustainable production package is required to maintain this level of production. This study was conducted to determine the effect of cultivar and seeding rate on weed management and crop yield. Study sites were located at Lethbridge, Alberta (dark brown soil zone) and Lacombe, Alberta (black soil zone). From 2001 to 2004, four cultivars AC Radiant, CDC Osprey, CDC Falcon, and CDC Ptarmigan, each with contrasting quality, growth type, and end-use marketability, were sown at rates of 300, 450, and 600 seeds m-2. Plots received one of two herbicide treatments, 1)fall applied 2,4-D, or 2) fall applied 2,4-D plus a spring in-crop tank mix of Refine Extra/Horizon. Yield of CDC Ptarmigan (under contract for ethanol market) was significantly higher than the other winter wheat cultivars. This was not a surprise as CDC Ptarmigan is a soft white wheat, a class that is generally higher yielding than red wheats. CDC Falcon (feed wheat) and AC Radiant (milling wheat) were similar in terms of yield performance. CDC Osprey (milling wheat) was significantly lower yielding than the other cultivars. There was no significant yield difference between the seed rates at Lethbridge, but yield was significantly lower at the 600 seeds m-2 rate in Lacombe. Weed biomass diminished with higher seed rates and was significantly lower at the 600 seeds m-2 rate. Although weed biomass was significantly reduced when the spring in-crop Horizon+Refine Extra herbicide application was performed, this practice did not result in increased grain yield. Our results suggest winter wheat can be productive without added inputs of spring herbicides, particularly at higher seed rates.