Canadian Spring Wheat Research Articles

Analysis of deoxynivalenol and deoxynivalenol-3-glucosides content in Canadian spring wheat cultivars inoculated with Fusarium graminearum

ABSTRACTContamination of wheat grains with Fusarium mycotoxins and their modified forms is an important issue in wheat industry. The objective of this study was to analyse the deoxynivalenol (DON) and deoxynivalenol-3-glucosides (D3G) content in Canadian spring wheat cultivars grown in two locations, inoculated with a mixture of 3-acetyldeoxynivalenol (3-ADON)-producing Fusarium graminearum strains and a mixture of 15-acetlyldeoxynivalenol (15-ADON)-producing F. graminearum strains. According to the analysis of variance, significant differences were observed among the cultivars for Fusarium head blight (FHB) disease index, Fusarium-damaged kernel percentage (%FDK), DON content and D3G content. When the effect of chemotype was considered, significant differences were observed for FHB disease index, FDK percentage and DON content. The D3G content and D3G/DON ratio were not significantly different between the chemotypes, except for D3G content at the Winnipeg location. The Pearson correlation coefficient between DON and D3G was 0.84 and 0.77 at Winnipeg and Carman respectively. The highest D3G/DON ratio was observed in cultivars Carberry (44%) in Carman and CDC Kernen (63.8%) in Winnipeg. The susceptible cultivars showed lower D3G/DON ratio compared with the cultivars rated as moderately resistant and intermediate. The current study indicated that Canadian spring cultivars produce D3G upon Fusarium infection.

Quantitative Trait Loci Associated with Phenological Development, Low-Temperature Tolerance, Grain Quality, and Agronomic Characters in Wheat (Triticum aestivum L.).

Plants must respond to environmental cues and schedule their development in order to react to periods of abiotic stress and commit fully to growth and reproduction under favorable conditions. This study was initiated to identify SNP markers for characters expressed from the seedling stage to plant maturity in spring and winter wheat (Triticum aestivum L.) genotypes adapted to western Canada. Three doubled haploid populations with the winter cultivar ‘Norstar’ as a common parent were developed and genotyped with a 90K Illumina iSelect SNP assay and a 2,998.9 cM consensus map with 17,541 markers constructed. High heritability’s reflected large differences among the parents and relatively low genotype by environment interactions for all characters considered. Significant QTL were detected for the 15 traits examined. However, different QTL for days to heading in controlled environments and the field provided a strong reminder that growth and development are being orchestrated by environmental cues and caution should be exercised when extrapolating conclusions from different experiments. A QTL on chromosome 6A for minimum final leaf number, which determines the rate of phenological development in the seedling stage, was closely linked to QTL for low-temperature tolerance, grain quality, and agronomic characters expressed up to the time of maturity. This suggests phenological development plays a critical role in programming subsequent outcomes for many traits. Transgressive segregation was observed for the lines in each population and QTL with additive effects were identified suggesting that genes for desirable traits could be stacked using Marker Assisted Selection. QTL were identified for characters that could be transferred between the largely isolated western Canadian spring and winter wheat gene pools demonstrating the opportunities offered by Marker Assisted Selection to act as bridges in the identification and transfer of useful genes among related genetic islands while minimizing the drag created by less desirable genes.

Genetic variation for flowering time and height reducing genes and important traits in western Canadian spring wheat

Genetic variation is prerequisite for wheat improvement. High grain yield and protein content and early maturity are some of the major objectives in global as well as Canadian wheat breeding programs. We investigated genetic diversity for earliness related and plant height reducing (Rht) genes in 82 spring wheat cultivars, registered in western Canada, through eight diagnostic DNA markers. Allelic variation was observed at the Vrn-A1, Vrn-B1, Vrn-D1 and Ppd-D1 loci but not at Ppd-A1 and Ppd-B1 loci in the 82 cultivars. Spring type allele of Vrn-A1 was present in 94 % cultivars, whereas only two cultivars carried spring allele of Vrn-D1. Among the four earliness related genes, the most frequent combination was Vrn-A1a, Vrn-B1, vrn-D1 and Ppd-D1b, which was found in 32 cultivars. As for the Rht genes, eight cultivars had Rht-B1b and 13 cultivars had Rht-D1b. All cultivars carrying dominant allele of Vrn-B1, photoperiod-insensitive allele of Ppd-D1 and height reducing allele of Rht-1 had shorter plants and higher grain yield but lower grain protein content. Days to heading and maturity showed positive genetic (rg = 0.65) and phenotypic (rp = 0.44) correlation, and were also positively correlated with grain yield and kernel weight but negatively correlated with test weight and protein content. Plant height was positively correlated with grain protein content (rg = 0.53; rp = 0.42), but negatively correlated with grain yield (rg = −0.47; rp = −0.14). Grain yield and protein content showed negative genetic correlation (rg = −0.57). Among the sixty cultivars from Canada Western Red Spring Class released over 100 years, the newest cultivar yielded 23 % more grain and had 15 % higher grain protein than the oldest cultivar ‘Red Fife’. Breeders in western Canada have incorporated vernalization and photoperiod insensitive and Rht genes in modern cultivars to promote early maturity, to make use of off-season nurseries abroad, and to improve lodging tolerance.

Effect of Plant Height on Fusarium Head Blight in Spring Wheat

Fusarium Head Blight (FHB), caused by the fungal species Fusarium graminearum, is a disease affecting wheat cultivars across Canada. Recent and severe outbreaks have spurred research in developing FHB-resistant cultivars and evaluating the underlying causes of FHB susceptibility. In this study, the effect of plant height on Fusarium Head Blight in Canadian spring wheat was evaluated over a two-year period. Cultivars of spring wheat varying in origin, height, and disease susceptibility were artificially inoculated with FHB, and the subsequent disease symptoms and height data was collected. It was found that plant height is negatively correlated with FHB incidence and severity. However, varieties originating from Eastern Canada had a much stronger negative correlation between plant height and FHB, whereas the trials with Western Canada origins had a weaker correlation.

The effect of weeds on soil arbuscular mycorrhizal fungi and agronomic traits in spring wheat (Triticum aestivumL.) under organic management in Canada

Kubota, H., Quideau, S. A., Hucl, P. J. and Spaner, D. M. 2015. The effect of weeds on soil arbuscular mycorrhizal fungi and agronomic traits in spring wheat (Triticum aestivum L.) under organic management in Canada. Can. J. Plant Sci. 95: 615–627. Understanding the influence of weeds in agroecosystems may aid in developing efficient and sustainable organic wheat production systems. We examined the effect of weeds on soil microbial communities and the performance of spring wheat (Triticum aestivum L.) under organic management in Edmonton, AB, Canada. We grew 13 Canadian spring wheat cultivars in organically managed hand-weeded less-weedy and weedy treatments in 2010 and 2011. The less-weedy treatment exhibited greater grain yield and tillers per square meter, while kernel weight, test weight, days to maturity, plant height, grain P and protein content were not altered by weed treatment. Canada Western Red Spring (CWRS) wheat cultivars CDC Go and CDC Kernen were the most yield-stable because they minimized fertile tiller reduction in response to weed pressure (10 and 13% reduction, respectively, compared with the average reduction of 20%). Other cultivars exhibited yield stability through increased kernel weight. The contribution of arbuscular mycorrhizal fungi (AMF) to the total phospholipid fatty acid increased in both treatments; however, the rate of this increase was greater in the weedy treatment than the less-weedy treatment (from 2.9 to 3.9%, from 2.8 to 3.1%, respectively). Weed dry biomass was positively correlated with AMF% in the less-weedy treatment only. Organic systems tend to be weedier than conventional systems. We found that weeds are important determinants of AMF proliferation in soil. In addition, choosing wheat cultivars that maintain important yield components under severe weed stress is one strategy to maximize yields in organic systems.

Evaluation of Wheat Cultivars to Test Indirect Selection for Organic Conditions

There is debate regarding direct or indirect selection for organic conditions. Our objective was to evaluate the progress of indirectly selecting organic cultivars in conventional environments. Canadian spring wheat (Triticum aestivum L.) cultivars, developed for conventional environments from 1885 to 1999 and from 1975 to 2009, respectively, were grown in two separate experiments to assess progress of yield and associated agronomic traits due to breeding. The first experiment evaluated 27 cultivars in organic and conventional conditions for 3 yr (2002, 2003, and 2004), on three sites in western Canada. In the second experiment, eight cultivars were evaluated in organic conditions in 2010 and 2011 at the University of Alberta, Canada. The first experiment showed that breeding had improved yield and most associated traits only in conventional systems and a few associated traits in organic conditions. The second experiment showed that breeding had made significant improvements in yield and test weight in organic conditions. This study suggests that with sufficient quality and disease resistance criteria in place for the breeding of wheat in conventional environments, it may be possible to concomitantly improve wheat yield destined for organic growing conditions. However, fewer associated traits showed significant improvement in organic conditions and improvement rates were lower than in conventional conditions. This suggests that optimizing trait performance in organic conditions should include organic conditions during breeding and selection.

Comparative yield, disease resistance and response to fungicide for forty-five historic Canadian wheat cultivars

Martens, G., Lamari, L., Grieger, A., Gulden, R. H. and McCallum, B. 2014. Comparative yield, disease resistance and response to fungicide for forty-five historic Canadian wheat cultivars. Can. J. Plant Sci. 94: 371–381. Forty-five historic Canadian spring wheat cultivars, ranging from Red Fife (1870) to modern cultivars, were compared for yield and disease resistance in field trials from 2007 to 2010. A split-plot design was used to test yield, leaf rust and Fusarium head blight resistance, with or without a fungicide application. Older cultivars were generally lower yielding and more leaf rust susceptible than modern cultivars; this difference was greatest in 2007 and 2010 under heavier leaf rust. Response to fungicide application was highest in 2007 and 2010. In 2008, leaf rust was very low, and fungicide application had a slightly negative effect on yield overall. Cultivars that have good leaf rust resistance, such as Pasqua, AC Minto, and 5600 HR, had a negligible response to fungicide, whereas older, susceptible cultivars had a larger response. Fusarium head blight levels were too low to compare the cultivars. The highest-yielding cultivars in the untreated plots were AC Domain, 5500HR, AC Cora, Roblin and Barrie, whereas AC Cora, AC Domain, McKenzie, Roblin and AC Intrepid were the highest yielding in the fungicide-treated plots. AC Domain, AC Barrie and Roblin were among the most popular wheat cultivars in Manitoba, in terms of seeded area from the early 1990s to 2009.

Comparative yield, disease resistance and response to fungicide for forty-five historic Canadian wheat cultivars

Martens, G., Lamari, L., Grieger, A., Gulden, R. H. and McCallum, B. 2014. Comparative yield, disease resistance and response to fungicide for forty-five historic Canadian wheat cultivars. Can. J. Plant Sci. 94: 371-381. Forty-five historic Canadian spring wheat cultivars, ranging from Red Fife (1870) to modern cultivars, were compared for yield and disease resistance in field trials from 2007 to 2010. A split-plot design was used to test yield, leaf rust and Fusarium head blight resistance, with or without a fungicide application. Older cultivars were generally lower yielding and more leaf rust susceptible than modern cultivars; this difference was greatest in 2007 and 2010 under heavier leaf rust. Response to fungicide application was highest in 2007 and 2010. In 2008, leaf rust was very low, and fungicide application had a slightly negative effect on yield overall. Cultivars that have good leaf rust resistance, such as Pasqua, AC Minto, and 5600 HR, had a negligible response to fungicide, whereas older...

The effect of VRN1 genes on important agronomic traits in high‐yielding Canadian soft white spring wheat

AbstractFor reproductive success, flowering time must synchronize with favourable environmental conditions. Vernalization genes play a major role in accelerating or delaying the time to flowering. We studied how different vernalization (VRN1) gene combinations alter days to flowering and maturity and consequently the effect on grain yield and other agronomic traits. The study focussed on the effect of the VRN1 gene series (Vrn‐A1, Vrn‐B1 and Vrn‐D1) and their combinations. The Vrn gene group Vrn‐A1a, Vrn‐B1, vrn‐D1 was the earliest to flower and mature, while Vrn‐A1b, Vrn‐B1, vrn‐D1 was the latest to flower. Spring wheat lines with vrn‐A1, Vrn‐B1, Vrn‐D1 were the highest yielding and matured at a similar time as those having vernalization genes Vrn‐A1a, Vrn‐B1 and Vrn‐D1. The findings of this study suggest that the presence of Vrn‐D1 has a direct or indirect role in producing higher grain yield. We therefore suggest the introduction of Vrn‐D1 allele into higher‐yielding classes within Canadian spring wheat germplasm.

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

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.

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

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 yie...

Relative performance of Canadian spring wheat cultivars under organic and conventional field conditions

Producing higher yields under organic conditions is generally hampered by weeds and lesser nutrient supply. In wheat certain adaptive traits like early season vigour, taller plants, and shorter life cycle have been reported to help plants compete with weeds and produce satisfactory yields. In this experiment we tested the hypothesis ‘that early flowering and maturity conferred by insensitive vernalization alleles Vrn-A1a and/or Vrn-B1 has a yield advantage under organic conditions’ in Canadian spring wheat germplasm. We genotyped 32 cultivars for their vernalization gene composition (Vrn-A1a, Vrn-B1 and Vrn-D1) and studied these cultivars in organic and conventional management systems. We found 88 % of the cultivars possessed vernalization (Vrn) insensitive allele Vrn-A1a either alone or in combination with Vrn-B1. There were no differential affects between the cultivars having insensitive Vrn allele at either single locus (Vrn-A1a) or two (Vrn-A1a, Vrn-B1) under organic and conventional field conditions; except for days to maturity, where cultivars having only Vrn-A1a allele matured earlier. This earlier maturity did not translate to any yield advantage under organic field conditions. Overall, the cultivars grown under organic conditions were earlier flowering, lower yielding with lower test weight compared to the conventional management system. Significant cultivar × environment interactions were found for grain yield, grain protein content and grain fill rate. For grain protein content, cross-over interactions of the cultivars between the management systems were observed. Three cultivars (Marquis, Unity and Minnedosa) exhibited minimal comparative loss in grain yield and grain protein content under organic field conditions, and hence could potentially serve as parents for organic wheat breeding programs.

Phenotypic Effects of the Flowering Gene Complex in Canadian Spring Wheat Germplasm

Wheat (Triticum aestivum L.) has inherent genetic potential to synchronize its flowering and maturity to a broad growing period and is therefore one of the most widely adapted and grown food crops. Vernalization and photoperiod response genes are of primary importance to this adaptability. We screened 102 Canadian spring wheat cultivars and/or lines, developed between 1885 and 2008, from the Canada Western Red Spring (CWRS), Canada Prairie Spring Red (CPSR), and Canada Western Soft White Spring (CWSWS) classes and studied their phenotypic response both in the field and the greenhouse. Almost all the hard red cultivars possessed the Vrn‐A1a gene either alone or in combination with the dominant Vrn‐B1 while 74% of the higher yielding soft white lines possessed the Vrn‐B1 gene alone or in combination with other Vrn genes. The Vrn‐A1a alone or in combination with the Vrn‐B1 gene was the most potent gene conferring early maturity. Ppd‐D1a did not alter flowering and maturity in the hard red cultivars tested in the field but did in the greenhouse. Ppd‐D1a reduced days to flowering for soft white spring wheat but did not alter maturity. The photoperiod sensitive gene (Ppd‐D1b) is being replaced with the insensitive gene, Ppd‐D1a, in most modern Canadian germplasm, suggesting its adaptive advantages in the prairies. An overall analysis of the data for the hard red class revealed a declining trend of 0.04 d yr−1 in days to maturity in cultivars released from 1885 to 2008 and an increase of 8 kg ha−1 yr−1 in grain yield. The findings of this study may aid wheat breeders selecting parents with appropriate vernalization and photoperiod gene complexes.

Stripe rust resistance among western Canadian spring wheat and triticale varieties

Randhawa, H., Puchalski, B. J., Frick, M., Goyal, A., Despins, T., Graf, R. J., Laroche, A. and Gaudet, D. A. 2012. Stripe rust resistance among western Canadian spring wheat and triticale varieties. Can. J. Plant Sci. 92: 713–722. Stripe rust (Puccinia striiformis Westend.) is an important pathogen of wheat in western Canada and worldwide. One hundred and four spring wheat and triticale varieties and cultivars were evaluated for resistance to stripe rust in nurseries at Lethbridge and Creston, BC, during 2009 and 2010. In the Canada Prairie Spring Red (CPSR) wheat class, newer varieties were more resistant compared with many of the older varieties. Among the white Canada Prairie Spring White (CPSW) wheats, Vista was moderately resistant, whereas Snowhite475 and Snowhite476 were susceptible. Little useful resistance was observed within the Canada Western Hard White Spring (CWHWS) class. Sixty percent of the Canada Western Red Spring (CWRS) wheats, including the currently popular varieties Lillian, Harvest and Kane, were resistant. Susceptible CWRS varieties that are extensively seeded in western Canada include AC Barrie, Superb and McKenzie, but also include the recently registered CDC Kernen and Vesper. The varieties were tested for the presence of the stripe rust genes Yr10, Yr17, Yr18 and Yr36 using molecular markers. Much of the stripe rust resistance, particularly in the CWRS, Canada Western Extra Strong (CWES), and CPSR wheat classes was attributed to the presence of adult plant resistance gene Yr18. Yr17 and Yr36 were also detected among CWRS and CWES varieties. However, the absence of markers for known genes in several resistant varieties indicated that uncharacterized genes for stripe rust occur among hexaploid wheats. Durum wheat and triticale varieties were universally resistant with the absence of tested markers. Therefore, there appear to be numerous sources of stripe rust resistance, both characterized and uncharacterized, among western Canadian spring wheat and triticale varieties.

Development and evaluation of a new Canadian spring wheat sub-model for DNDC

Krobel, R., Smith, W. N., Grant, B. B., Desjardins, R. L., Campbell, C. A., Tremblay, N., Li, C. S., Zentner, R. P. and McConkey, B. G. 2011. Development and evaluation of a new Canadian spring wheat sub-model for DNDC. Can. J. Soil Sci. 91: 503-520. In this paper, the ability of the DNDC model (version 93) to predict biomass production, grain yield and plant nitrogen content was assessed using data from experiments at Swift Current, Saskatchewan, and St-Blaise, Quebec, Canada. While predicting wheat grain yields reasonably well, the model overestimated the growth of above-ground plant biomass and nitrogen uptake during the first half of the growing season. A new spring wheat sub-model (DNDC-CSW) was introduced with a modified plant biomass growth curve, dynamic plant C/N ratios and modified plant biomass fractioning curves. DNDC-CSW performed considerably better in simulating plant biomass [modeling efficiency (EF): 0.75, average relative error (ARE): 6.0%] and plant nitrogen content (EF: 0.61, ARE: -2.7...

Development and evaluation of a new Canadian spring wheat sub-model for DNDC

Kröbel, R., Smith, W. N., Grant, B. B., Desjardins, R. L., Campbell, C. A., Tremblay, N., Li, C. S., Zentner, R. P. and McConkey, B. G. 2011. Development and evaluation of a new Canadian spring wheat sub-model for DNDC. Can. J. Soil Sci. 91: 503–520. In this paper, the ability of the DNDC model (version 93) to predict biomass production, grain yield and plant nitrogen content was assessed using data from experiments at Swift Current, Saskatchewan, and St-Blaise, Quebec, Canada. While predicting wheat grain yields reasonably well, the model overestimated the growth of above-ground plant biomass and nitrogen uptake during the first half of the growing season. A new spring wheat sub-model (DNDC-CSW) was introduced with a modified plant biomass growth curve, dynamic plant C/N ratios and modified plant biomass fractioning curves. DNDC-CSW performed considerably better in simulating plant biomass [modeling efficiency (EF): 0.75, average relative error (ARE): 6.0%] and plant nitrogen content (EF: 0.61, ARE: −2.7%) at Swift Current and St-Blaise (EF of 0.75 and ARE of 2.3%), compared with DNDC 93 (biomass SC: EF 0.49, ARE 17.1%, SB: EF 0.02 ARE 33.4%). In comparison with DNDC 93, DNDC-CSW better captured inter-annual variations in crop growth for a range of wheat rotations, increasing the EF from 0.32 to 0.52 for grain and from 0.35 to 0.39 for straw yields. DNDC-CSW also performed considerably better than DNDC 93 in estimating soil carbon changes at Swift Current. Hence, DNDC-CSW has the potential to improve the performance of DNDC 93 in simulating wheat biomass, plant nitrogen, yield and soil carbon at various Canadian sites.

Spring wheat genotypes differentially alter soil microbial communities and wheat breadmaking quality in organic and conventional systems

Nelson, A. G., Quideau, S., Frick, B., Niziol, D., Clapperton, J. and Spaner, D. 2011. Spring wheat genotypes differentially alter soil microbial communities and wheat breadmaking quality in organic and conventional systems. Can. J. Plant Sci. 91: 485–495. Wheat (Triticum aestivum L.) cultivars may have differential effects on soil microbial communities and the breadmaking quality of harvested grain. We conducted a field study comparing five Canadian spring wheat cultivars grown under organic and conventional management systems for yield, breadmaking quality and soil phospholipid fatty acid (PLFA) profile. Organic yields (2.74 t ha−1) were roughly half of conventional yields (5.02 t ha−1), but protein levels were higher in the organic system than the conventional system (16.6 vs. 15.3%, respectively). Soil microbial diversity measures were significantly higher in the organic system compared with the conventional system, including PLFA richness (31 vs. 27 unique PLFAs per sample, respectively) and PLFA div...

Leaf photosynthetic properties and biomass accumulation of selected western Canadian spring wheat cultivars

Chytyk, C. J., Hucl, P. J. and Gray, G. R. 2011. Leaf photosynthetic properties and biomass accumulation of selected western Canadian spring wheat cultivars. Can. J. Plant Sci. 91: 305–314. Current studies indicate wheat straw as a viable source for the production of cellulosic ethanol. Since photosynthetic performance impacts the overall success of the mature plant, this study aimed to measure the photosynthetic vigour of 11 spring wheat cultivars during field development as well as their biomass composition at maturity to determine which would be optimum for ethanol production. All cultivars had similar maximal quantum yields of photosystem II photochemistry (FV/FM), normalized difference vegetation index and biomass composition in the field. However, differences were observed in photosynthetic rate, with McKenzie having the highest light-saturated maximal rate of CO2 uptake (A max) and apparent quantum yield of CO2 uptake (Φapp CO2), while also having the best water use efficiency. Snowbird was found to have the lowest CO2-compensation point (Γ*) and A max. Upon subjecting wheat samples to photoinhibitory conditions, McKenzie and Kyle were found to be the most resistant and susceptible, respectively, with a difference of 11% in FV/FM. Abundance of xanthophyll pigments were not found to be a contributing cause to differential photoinhibitory resistance as there was not a noticeable difference between cultivars. Although some cultivars were found to have enhanced photosynthetic traits over others, these were slight and did not contribute to changes in plant biomass. However, McKenzie did present a higher cellulose content, which would be favourable for ethanol production.

Relative aggressiveness and production of 3- or 15-acetyl deoxynivalenol and deoxynivalenol by Fusarium graminearum in spring wheat

Fusarium graminearum is the principal cause of fusarium head blight in North America, a disease that has caused severe losses in yield and quality of cereals. In North America, the vast majority of F. graminearum isolates produce 3- or 15-acetyl deoxynivalenol (ADON) in addition to DON. Until recently, 15-ADON isolates predominated, but a rapid shift from 15-ADON to 3-ADON producers in Canada and north central USA has been documented. In order to better understand the effect of this population shift on relative aggressiveness of isolates and mycotoxin accumulation, we tested a total of 58 isolates for 3- and 15-ADON production on two Canadian spring wheat cultivars, ‘Roblin’ (susceptible) and ‘5602 HR’ (moderately resistant). In Experiment 1, three isolates from the Canadian provinces of Manitoba, Saskatchewan and Alberta, each of which produced either 15-ADON or 3-ADON, were tested using spray inoculation. In Experiment 2, 20 isolates which produced 15-ADON and 20 which produced 3-ADON from Manitoba, were tested using point inoculation. There were no significant differences in aggressiveness among isolates based either on geographic origin or mycotoxin type. Analysis of seeds from inoculated heads by gas chromatography/mass spectrometry indicated that the 3-ADON producing isolates had significantly higher DON levels than the 15-ADON isolates in ‘Roblin’ after both spray and point inoculation and in ‘5602HR’ after point inoculation. DON levels following point inoculation by 15-ADON isolates were similar in the two cultivars. The 15-ADON isolates from Alberta produced less DON than 15-ADON isolates from Manitoba and Saskatchewan. Consistently, more ADON was produced by 15-ADON isolates than by 3-ADON isolates. The results of the study suggest that if the percentage of 3-ADON isolates in Canada increases, DON levels in cereals are likely to increase in epidemic years.

Effect of Waxy Wheat Flour Blends on the Quality of Fresh and Stale Bread

Starch is the major component in the wheat kernel, which is mainly composed of amylose and amylopectin. The wheat without amylose in its endosperm was called “waxy wheat”. Waxy wheat can be used to adjust the amylose content and improve the wheat-based food quality by adding to non-waxy wheat flour. In order to investigate the effect of waxy wheat flour on the quality of fresh and stale bread, waxy wheat flour was added into the flour of Canadian Spring Wheat 2 at 0.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, and 35.0% to make breads. The physicochemical properties were adjusted to suitability by adding Yangmai 158 flour, and breads were evaluated for sensory quality, crumb firmness, loaf volume and weight loss over a period of 0, 2, 4, and 6 days. The result showed that the best total score of fresh bread was 82.9 by adding waxy flour at 7.0%, though no significant difference was found among blends with 0.0-15.0% of waxy flour. Breads with the addition of 22.0% waxy flour had lower firmness, and decreasing loss of weight. Waxy wheat flour blend at 15.0% was optimal in retarding staling without significant decreasing fresh bread quality in comparison to the control.