AGRONOMIC PERFORMANCE OF WINTER VERSUS SPRING WHEAT

Recent advances in crop management have enabled the production of winter wheat (Triticum aestivum L.) in most of the Canadian prairies. The agronomic performance of dominant hard red winter and high-quality hard red spring wheat cultivars was compared in semiarid and dry subhumid regions of Saskatchewan. In 15 trials, winter wheat (WW) outyielded spring wheat (SW) by an average 36%, and in three trials, 'Norstar' WW yielded 26% higher than the high-yielding semidwarf SW, 'HY 320.' Protein yield was higher for WW in two of 15 trials and protein concentration was always higher for SW. Higher grain yield of WW was attributed mainly to the production of a higher kernel number per square meter (KNO). Crop development rate, aerial dry matter production, evapotranspiration (ET), and water use efficiency (WUE), were measured for Norstar WW and 'Katepwa' SW in six trials grown between 1986 and 1988. The period between Zadoks growth stage (ZGS) 21 and 65 was 4 to 14 d longer for Norstar than for Katepwa. Average daily air temperature between ZGS 21 and 65 was 2.6-degrees-C higher for katepwa, and daily air temperature during this period was negatively correlated with KNO in both cultivars. Early season dry matter production was higher for Norstar. These early season cultivar differences gradually disappeared and, with the exception of two trials, total dry matter was similar by crop maturity. Harvest index was significantly higher for Norstar in five of six trials. Seasonal ET patterns were similar for Norstar and Katepwa, except in three of six trials where ET in early May was significantly higher for the WW cultivar. The WUE for dry matter production, grain yield and grain protein yield was consistently higher for Norstar.