Effects of Genotype, Weather and FHB Fungicide/Pre-harvest Glyphosate on Wheat Quality and Gluten Strength for Breadmaking
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Canada Western Red Spring (CWRS) wheat is composed of genotypes that have relatively uniform instrinsic quality characteristics. Variation in growing season weather strongly affects CWRS quality, including its gluten strength, but relatively little is known about the effects of pesticide applications. The first study examined effects of genotype, growing location weather and two common pesticides on the grade and quality, including gluten strength of six CWRS wheat genotypes with a wide range of gluten strength characteristics in plot trials across Manitoba, Saskatchewan and Alberta in 2015, 2016 and 2017. Pesticide treatments were fungicide (Prothioconazole/Tebuconazole) applied at anthesis (F) for Fusarium head blight (FHB) mitigation, glyphosate applied pre-harvest (G), both F and G combined (FG) and an untreated control (C). Gluten strength was evaluated using dough mixing and gluten protein composition. Precipitation from seeding to anthesis was closely related to Fusarium damaged kernels (FDK). Site-year and genotype were the most significant factors affecting all quality parameters. In contrast, pesticide treatments had a small impact on the parameters associated with gluten strength. The second study examined the effects of delayed harvest on the grade and quality, including gluten strength, of four CWRS wheat genotypes with a wide range of gluten strength characteristics in plot trials at four locations in Manitoba in 2017. At each location, there were four different harvest dates including harvest at physiological maturity or two weeks prior to normal harvest (H1), normal harvest date at optimal moisture content of 13 to 15% (H2), four weeks after maturity (H3) and six weeks after maturity (H4). Substantial rainfall following H2 significantly and negatively affected grain quality and grades for H3 and H4. However, gluten strength increased slightly for H3 and H4. While harvest date was statistically significant for many wheat quality parameters including gluten strength, contributions to total variance were very small and often lower than residual error. It was concluded that neither pesticide treatment when used as recommended, nor delayed harvest, were significant sources of variation of gluten strength for CWRS wheat.