Environmental factors determining the yield and quality of winter wheat in Saskatchewan
Effects of prevailing environmental conditions, N fertilization and crop cultivar on winter wheat productivity were investigated independently in field experiments in Saskatchewan between 1984 and 1986. The relationship between grain yield and grain protein with weather and soil water parameters indicated that "critical" stress periods exist for these parameters. The critical stress period for grain and protein yield was found to occur between June 9 and June 24 while environmental conditions both before and after anthesis were critical for grain protein content. Evaporation during the two weeks before heading followed by root zone available water at anthesis and precipitation were the most important environmental factors. Addition of N fertilizer increased crop growth, rate of water use, and water use efficiency. Despite the higher tiller mortality and lower amount of available soil water after anthesis associated with high N levels, N additions significantly increased grain yield. In dry environments, the tall cultivar 'Norstar' significantly out-yielded the semi-dwarf 'Norwin'. The superior performance of Norstar under high stress conditions was attributed to its higher growth rate, especially before anthesis. In wet environments, Norwin out-yielded Norstar and the superior performance of the semi-dwarf under these conditions was attributed to a greater harvest index and better water economy.
Soils and Crops Workshop