Research

Objectives

1. Develop a thorough understanding of genotype, growing environment and select management practices on gluten strength for breadmaking.
2. Develop and/or refine and validate methods for efficient evaluation and prediction of gluten strength.

Sub Project 1

This study was conducted on the influence of genotype and the growing environment on Canadian wheat gluten strength and various aspects of wheat processing quality. Canadian Western Red Spring (CWRS) wheat was the focus. The project stemmed from concerns of deficient and variable gluten strength in shipments of CWRS wheat that were raised by many domestic and international customers as reported in 2013. Sub project 1 (SP1) - Effects of genotype and growing environment on the gluten strength and end-use quality of CWRS wheat. The study amassed results for 27 site-years encompassing three years of replicated field trials (2015, 2016, 2017) in nine growing locations across the Prairie region (three each in Manitoba, Saskatchewan and Alberta) for nine CWRS wheat varieties including AAC Brandon, Carberry, Cardale, Glenn, Harvest, Stettler, Unity, CDC Stanley, Unity, and Utmost. Near real-time weather data encompassing many parameters of precipitation and temperature were acquired for all sites. doi.org/10.1016/j.jcs.2021.103410 "Exploring the influence of weather on gluten strength of hard red spring wheat (Triticum aestivum L.) on the Canadian Prairies" Manasah Mkhabela, Paul Bullock, Harry Sapirstein, Janelle Courcelles, Soleiman Abbasi, Filiz Koksel

SP 1: Key Takeaways

• Gluten strength related parameters (e.g. dough mixing work at peak (WAP), and proportion of high molecular weight glutenin in flour protein) were distinct as a group by having considerably larger contribution of genotype variance compared to environment variance. This means that compared to other wheat quality factors, gluten strength differences among the nine genotypes in the SP1 study were less sensitive to site-year effects caused mainly by growing season weather.
• The point above notwithstanding, dough mixing properties related to gluten strength of individual genotypes, as with most other quality parameters, varied considerably across growing sites.
• The range in flour protein contents for samples of individual genotypes across the 27 site-years was remarkable (11-17%) and was mainly attributed to weather variation.
• Among the grading factors that were assessed (test weight, FDK, ergot, midge and sprout damage), FDK stood out as the principal grading factor that influenced grade.
• Variation in gluten strength was unrelated to variation in protein content, whether for individual crop years or across the 27 site-years. This means that protein content is not a proxy for gluten strength as is often believed. It follows that gluten strength cannot be controlled via the grading system or inferred from the protein content of milling grade samples.
• Going beyond mean differences, when considering population distributions of gluten strength by genotype for all varieties except Glenn, there was considerable overlap in gluten strength arising from environmental variation.
• The results compiled for gluten strength based on mixograph WAP indicated consistently, the relative strength of varieties Glenn and Carberry, and weakness of Harvest regardless of the growing season. However, in at least two of the three study years, the varieties Brandon, Stanley, Stettler and Unity had significantly lower gluten strength than Carberry

Sub Project 2

Effects of FHB fungicide and pre-harvest glyphosate on wheat quality and gluten strength for breadmaking. This study acquired data for 10 site-years and included six wheat varieties (Carberry, Cardale, Glenn, Harvest, Stanley and Stettler) and four growing locations (two in Manitoba, and one each in Saskatchewan and Alberta) in 2015, 2016 and 2017. Each genotype at each location received four treatments including a no treatment control: fungicide (F) (Prothioconazole/Tebuconazole, i.e. Prosaro® EC) applied at anthesis for Fusarium head blight, glyphosate (G) (Roundup Weathermax® with Transorb2) applied at physiological maturity, and both F and G combined. Pesticide applications were according to label recommendations for rate and timing.

SP 2: Key Takeaways

• Application of fungicide at anthesis to mitigate effects of Fusarium head blight had no effect on gluten strength. Similarly, this treatment had no effect on the underlying protein composition of gluten proteins.
• Preharvest application of glyphosate at label timing and rate had no effect on gluten strength or protein composition.

Sub Project 6

Effects of delayed harvest on wheat gluten strength. In this study, four genotypes (Glenn, Carberry, Brandon and Harvest) were grown in replicated field trials at four different Manitoba locations (Brandon, Carberry, Grosse Isle and Kelburn) in 2017. At each location there were four harvest dates: H1 at physiological maturity, H2 at normal harvest period (grain moisture content between 13-15%), H3 at four weeks after physiological maturity and H4 at six weeks past physiological maturity.

SP 6: Key Takeaways

• Delayed harvest while adversely affecting wheat grade, had no negative effect on gluten strength. Interestingly, both mixograph and protein composition results showed that gluten strength was slightly increased for wheat samples from the two most delayed harvest dates.

Project Key Findings

• Gluten strength related parameters (e.g. dough mixing work at peak (WAP), and proportion of high molecular weight glutenin in flour protein) had considerably larger contribution by variety compared to environment variance. This means that compared to other wheat quality factors, gluten strength differences among the nine varieties in the study were less sensitive to site-year effects caused by growing season weather, however, the dough mixing properties related to gluten strength of individual varieties varied considerably across growing sites.
• The results compiled for gluten strength indicated consistently, the relative strength of varieties Glenn and Carberry, and weakness of Harvest regardless of the growing season. However, in at least two of the three study years, the varieties Brandon, Stanley, Stettler and Unity had significantly lower gluten strength than Carberry.
• Despite optimal fertility at field sites, the range in flour protein contents for samples of individual varieties across the 27 site-years was remarkable (11-17%) and was mainly attributed to weather variation.
• Variation in gluten strength was unrelated to variation in protein content, whether for individual crop years or across the 27 site-years. This means that protein content is not a proxy for gluten strength as is often believed.
• Gluten strength cannot be controlled via the grading system or inferred from the protein content of milling grade samples.
• During the study period Fusarium Damaged Kernels (FDK) was the principal grading factor that influenced grade.
• Gluten strength was unrelated to the physical location in which the crop was grown, although a negative influence of FHB in affected sites was observed between FDK and gluten strength. This result was in line with published research indicating a relationship between FDK and degradation of polymeric glutenin protein.
• We observed a consistent, albeit weak, negative relationship between FDK content and wheat protein content which was reflected in protein contents of gliadin and glutenin fractions.
• When considering population distributions of gluten strength by variety for all varieties except Glenn, there was considerable overlap in gluten strength arising from environmental variation.
• An accurate and efficient protein fractionation procedure was developed to distinguish the two main constituents of gluten (gliadin and glutenin proteins).
• Soluble prolamin was the predominant fraction of flour protein averaging 73% over all samples, and its content was highly correlated with flour protein (r = 0.95). In contrast, HMW glutenin did not vary appreciably with flour protein content.
• Application of fungicide at anthesis to mitigate effects of Fusarium head blight had no effect on gluten strength. Similarly, this treatment had no effect on the underlying protein composition of gluten proteins.
• Preharvest application of glyphosate at label timing and rate had no effect on gluten strength or protein composition.
• Delayed harvest while adversely affecting wheat grade, had no negative affect on gluten strength.
• A novel method was developed to study relationships between growing season weather and wheat quality in the absence of detailed phenological data. The method specifically addressed the problem of large variation in days to maturity across growing sites.
• Many site-years of data are required to accurately establish the processing quality of wheat varieties. In this regard, the current protocol for quality evaluation of bread wheat lines in wheat registration trials is deficient (no results are generated from individual trial locations) and could be improved significantly by adopting a G x E approach, even on a limited basis for a few key quality traits, most notably gluten strength.