Effects of delayed harvest on wheat quality, gluten strength, and protein composition of hard red spring wheat

Background and Objectives Delayed harvest of spring wheat is a common occurrence in the Northern Great Plains region of North America, especially western Canada, as a result of inclement weather. This can have negative impacts on the yield, grade, and quality of wheat leading to financial loss for farmers and processing complications along the value chain. The objective of this study was to investigate the effects of delayed harvest on wheat quality, gluten strength, and gluten protein composition about which little is known. Four leading varieties of Western Canadian hard red spring bread wheat were grown in replicated trials at four locations, involving four harvest dates from physiological maturity to 6 weeks thereafter. Findings Delayed harvest had a statistically significant effect on Fusarium damaged kernels (increased), grain test weight (decreased), flour ash (decreased), gluten strength (increased) measured by mixograph development time and work input to peak development, and two protein compositional factors: HMW glutenin in flour protein and ratio of HMW glutenin to soluble prolamins (both increased). Conclusions Considering the totality of results, apart from grade and test weight, the effects of delayed harvest on wheat quality on gluten strength, while significant, were relatively minor compared to the much larger effects of growing location and genotype. Expanding the study to include more growing locations and seasons to capture a wider range of weather conditions may be required to reveal more pronounced effects caused by harvest delays. Results emphasize the importance of harvesting wheat as soon as is practical after physiological maturity to limit degradation of grade and economic loss. Significance and Novelty Results clarify the limited understanding of the effects of delayed harvest on wheat quality and related properties. There appear to be no previous studies specifically evaluating the effects of delayed harvest on gluten strength and protein composition of hard spring wheat, especially considering that the time frame in the present study begins at physiological maturity. Reduced grades and deterioration of grain quality as a result of post‐growing season precipitation and cooler temperatures, and weathering in general, did not result in reduced gluten strength as might be expected when harvest was delayed. The small but significant improvement in gluten strength and highly correlated increase in glutenin per unit protein for the latter two harvest dates appear to be in‐line with postharvest effects of wheat maturation.