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Growing Season Weather Impacts on Breadmaking Quality of Canada Western Red Spring Wheat Grown in Producer Fields Across Western Canada

Jarvis, C. 2006. M.Sc. Thesis. Dept. Soil Science, University of Manitoba, Winnipeg, Manitoba

Abstract

A study was conducted to quantify the relationships between growing season weather conditions and end-use quality of Canada Western Red Spring (CWRS) wheat (Triticum aestivum) grown in producer fields across western Canada (Alberta, Saskatchewan and Manitoba). Samples of CWRS wheat, cultivars AC Barrie and Superb, were received from producer fields where growing season weather conditions had been monitored. Samples were collected from 2003, a hot dry season, and 2004, a cool wet growing season with late season problems of frost and excessive moisture. As a result, there was a wide range in quality in the samples collected. Grain samples received an official grade at the Canadian Grain Commission and were milled into flour using a Buhler flour mill at the University of Manitoba. Flour samples underwent an extensive analysis of flour, dough, and bread making quality. Those samples that received grades #1CWRS and #2CWRS were analyzed with the environmental data to search for relationships between growing season weather conditions and wheat quality. Single basic temperature-derived or precipitation variables accumulated over the entire growing season were simple to calculate from weather data but generally explained a low level of variance in the quality variables. The R2 values ranged from 0.02 to 0.50. When the same weather variables were accumulated over the first half of planting to anthesis, the second half of planting to anthesis, the first half of anthesis to maturity, the second half of anthesis to maturity, planting to anthesis and anthesis to maturity, the amount of variance explained in quality variables increased. The R2 values ranged from 0.06 to 0.53. If the sophistication of the environmental variables was increased to include derived crop water demand and crop water use accumulated over the same periods above, the amount of variance explained in quality variables was increased further. The R 2 values ranged from 0.06 to 0.53. Multiple regression equations using up to three environmental variables from any of the time periods explained the greatest amount of the variance in quality variables. The R2 values ranged from 0.20 to 0.75. For protein content and the protein fractions, typically, the most sensitive period to an environmental stress was the first half of anthesis to maturity. During this period, either heat or water stress had a negative effect on the synthesis of protein. However,useful heat or water use during the same period was beneficial to the synthesis of protein. Conversely, heat or water stress during the second half of the filling period or any time prior to anthesis caused an increase in final protein content. AC Barrie responded predominantly to useful heat and water use variables while Superb responded predominantly to heat and water stress variables. Superb had a higher heat stress threshold than AC Barrie. In some instances there was a significant relationship found for only one of the two cultivars for a quality parameter. In this study we also investigated the effectiveness of the Canadian grain grading system's ability to segregate wheat samples into levels of increasing quality performance and uniformity. We found that for several flour and dough quality analysis, this was often achieved for either quality performance or uniformity, but there was not an improvement in both with an improvement in grade. However, bread quality did improve in both performance quality and uniformity with an increase in grade.