A gronomy J our n al • Volume 102 , I s sue 2 • 2 010 649 1985-1986(StatsCan, 2007. Th e development of agronomic practices compatible with the new practice of direct seeding and reduced tillage was the main reason for the increased popularity of winter wheat. Research during the 1980s that identifi ed optimum seeding dates (Fowler, 1982(Fowler, ,1983a(Fowler, ,1986 and depth (Fowler, 1983b) encouraged the northward expansion of winter wheat production outside the traditional area of the Chinook belt in southern Alberta.Even though practices for the successful production of winter wheat were adopted, winter wheat cultivar choice for the prairies was limited mainly to two varieties, Sundance (Grant, 1972) and Norstar (Grant, 1980). Norstar, the newest cultivar at the time, had excellent winter hardiness but very weak straw strength. Th e lack of genetic improvements, limited market potential, and two successive years of severe winter kill led to a signifi cant decline in winter wheat acreage in the late 1980s.One agronomic practice not fully explored in studies during this time period for western Canada was the determination of optimum plant density for Canada Western Red Winter (CWRW) wheat or hard red winter wheat production. Early seeding rate recommendations paralleled those for spring wheat. Th e seeding rate recommended in a mid-1970s production guide specifi ed 67 to 78 kg ha -1 (< 200 seeds m -2 ) (Grant et al., 1974). Studies by Entz and Fowler (1991) and Fowler (1986) also used plant densities similar to or slightly less than these recommendations. Smid and Jenkinson (1979) recommended a higher seed rate during this period, but it was for a class of wheat (soft red winter wheat) in Ontario that possesses higher yield potential than hard red. A study conducted in the Netherlands reported that winter wheat grain yield was optimized with a plant density of 100 plants m -2 (Darwinkel, 1978).Th e potential for winter wheat to compensate for lower seeding rates or large reductions in plant density (Holen et al., 2001;Whaley et al., 2000) through increased tillering capacity may explain a reluctance to alter seeding rates. However, newer studies suggested that these rates did not fully exploit the yield potential of winter wheat. Lafond and Gan (1999) observed optimal yields at a seeding rate of 134 kg ha -1 . Although their results were reported on a volume basis, which can vary significantly with kernel size, shape, and weight, the rate was approximately twice that of earlier recommendations. McKenzie et al. (2007) reported that increasing seeding rates to achieve a plant density of 350 plants m -2 was ideal for conditions in southern Alberta, particularly if seeding dates were delayed past the optimal window of sowing; that is, early-to mid-September. Th e greatest response to seeding rate was observed in conditions where moisture was not a limiting factor (Tompkins et al., 1991). In an irrigated environment in Spain, Lloveras et al. (2004) observed a positive response in yield to seeding rates as high as ...