Rates of yield gain of hard red spring wheat in western Canada

Abstract

Thomas, J. B. and Graf, R. J. 2014. Rates of yield gain of hard red spring wheat in western Canada. Can. J. Plant Sci. 94: 1–13. The Manitoba and Saskatchewan Seed Guides dating back to 1972 represent an unused source of yield comparisons to re-examine current progress in western Canadian spring wheat cultivar yields. Adjusting for the shift in check cultivars over time showed that the yield rise due to new cultivars could be divided into two periods. Prior to the early 1990s, yields rose at a rate of about 0.33% per year; these low early rates agree with other published estimates from this period and were possibly influenced by a strong emphasis on replicating the quality of previous cultivars. From the early 1990s to 2013, yields rose by about 0.7% per year; this doubling of the earlier rate was significant based on the non-overlap of confidence intervals of comparable slopes. To compare rates published in the literature with these new rates, all slopes were adjusted to a common benchmark where mean yield = 100%. Following these adjustments, current rates in western Canada (about 0.67% per year) were comparable with a world average estimated to be about 0.62% per year. Variation in performance among Canada Western Red Spring cultivars based on the Seed Guides was significantly correlated with their on-farm yields based on Manitoba Management Plus Program (MMPP) crop insurance data (r = 0.81, n = 42). Beginning in 1991, on-farm yields rose by an average of about 1.4% per year both in Manitoba (Manitoba Management Plus Program data) and across the entire western wheat area (Statistics Canada data). This compares favorably with a world-wide rate of yield increase for wheat since 1991 of 1.16% per year. Although western Canadian on-farm yield gains were attributed to a combination of new cultivars and upgraded agronomy, the two influences were not separable in the Manitoba crop insurance data set. Opinions published in the farming press that rates of yield gain among western Canadian wheat cultivars are comparatively low were not supported by the evidence presented here.