Breeding efforts have been important in addressing the challenges of wheat production in western Canada. We studied the effect of breeding on grain yield and other important traits of 100 wheat cultivars released in Canada from 1885 to 2012. The cultivars were grown in seven environments during 2011 to 2013. Grain yield was positively correlated with days to maturity and kernel weight but negatively correlated with plant height, lodging, and grain protein content. Results indicate that grain yield increased at a rate of 0.28% year–1 in 62 cultivars of Canada western red spring (CWRS) class, 1.2% year–1 in 9 cultivars of Canada prairie spring (CPS) class, but not in 14 studied cultivars of Canada western amber durum (CWAD) class due to breeding efforts. Grain protein content exhibited an increasing trend in cultivars of CWRS (0.05% year–1) and CPS (0.79% year–1) classes, and a decreasing trend in those of CWAD (0.23% year–1). Days to maturity decreased in CWRS (0.02% year‐1) and CWAD (0.09% year‐1) classes but remained unchanged in CPS class. Plant height exhibited a gradual decline in cultivars of CWRS (0.16% year–1) and CWAD class (0.44% year–1), but an increase in those of CPS class (0.50% year–1). Test weights showed an increasing trend in CWRS (0.04% year–1) and CPS (0.17% year–1) classes but not in CWAD class. Grain weight also increased over time in CWRS (0.06% year–1) and in CPS (0.41% year–1), but not in CWAD class. These results suggest that breeding efforts have improved yield, quality and other attributes in wheat cultivars of different Canadian wheat classes over the last 100 years.

Navabi, A., Iqbal, M., Strenzke, K. and Spaner, D. 2006. The relationship between lodging and plant height in a diverse wheat population. Can. J. Plant Sci. 86: 723-726. We examined the genetic variation for lodging tolerance in different plant height groups, within a diverse population of wheat (Triticum aestivum L.) genotypes (n = 140). Lodging was artificially induced by dragging a weighted apparatus across plots twice during the season at early and late milk stages. Grain yield was negatively correlated with lodging, while lodging scores were positively correlated with plant height. Although plant height appeared to be the major contributor to lodging tolerance, some variation was also observed in taller plants. This suggests that genetic gain in lodging tolerance can be obtained, to some extent, independent of plant height.Key words: Plant height, lodging tolerance, Triticum aestivum L., CIMMYT, Canada Navabi, A., Iqbal, M., Strenzke, K. et Spaner, D. 2006. Lien entre la verse et la taille du plant dans un peuplement de blé mixte. Can. J. Plant Sci. 86: 723-726. Les auteurs ont examiné la variation génétique de la tolérance à la verse dans des groupes de taille différente au sein d'un peuplement de plusieurs génotypes (n = 140) de blé (Triticum aestivum L.). Ils ont induit artificiellement la verse en traînant un dispositif lesté de poids à deux reprises sur la parcelle, au début et à la fin du stade du grain laiteux. Le rendement grainier présente une corrélation négative avec la verse tandis que le degré de verse est positivement corrélé à la hauteur du plant. Bien que la taille du plant semble être le principal facteur concourant à la tolérance à la verse, on observe une certaine variation chez les plants les plus grands. On en déduit que la résistance à la verse pourrait être améliorée dans une certaine mesure par la génétique, peu importe la taille du plant. Mots clés:Taille du plant, tolérance à la verse, Triticum aestivum L., CIMMYT, Canada Lodging in cereals refers to the displacement of culms from an upright position. Lodging is often associated with yield loss, with the magnitude of loss dependent on cultivar, growth stage, and the severity of lodging (Fischer and Stapper 1987;Jedel and Helm 1991;Kelbert et al. 2004a). Height reducing (Rht) genes are the major sources of lodging tolerance in wheat (Triticum aestivum L.). However, reduced plant height may not always be suitable for all agro-econiches. For example, in organically managed wheat systems, a relatively taller plant with greater tillering capacity may potentially confer increased competitive ability (Spaner, unpublished data). Sources of lodging tolerance independent of height reducing genes may be of interest to plant breeders selecting for competitive ability within taller genotypes.In previous studies (Kelbert et al. 2004a) we reported the artificial induction of lodging by dragging a weighted plywood apparatus over experimental wheat plots. This technique was originally proposed by Briggs (1990) as a screening tool for lodging tol...

The likelihood of success in developing modern cultivars depend on multiple factors, including the identification of suitable parents to initiate new crosses, and characterizations of genomic regions associated with target traits. The objectives of the present study were to (a) determine the best economic weights of four major wheat diseases (leaf spot, common bunt, leaf rust, and stripe rust) and grain yield for multi-trait restrictive linear phenotypic selection index (RLPSI), (b) select the top 10% cultivars and lines (hereafter referred as genotypes) with better resistance to combinations of the four diseases and acceptable grain yield as potential parents, and (c) map genomic regions associated with resistance to each disease using genome-wide association study (GWAS). A diversity panel of 196 spring wheat genotypes was evaluated for their reaction to stripe rust at eight environments, leaf rust at four environments, leaf spot at three environments, common bunt at two environments, and grain yield at five environments. The panel was genotyped with the Wheat 90K SNP array and a few KASP SNPs of which we used 23,342 markers for statistical analyses. The RLPSI analysis performed by restricting the expected genetic gain for yield displayed significant (p < 0.05) differences among the 3125 economic weights. Using the best four economic weights, a subset of 22 of the 196 genotypes were selected as potential parents with resistance to the four diseases and acceptable grain yield. GWAS identified 37 genomic regions, which included 12 for common bunt, 13 for leaf rust, 5 for stripe rust, and 7 for leaf spot. Each genomic region explained from 6.6 to 16.9% and together accounted for 39.4% of the stripe rust, 49.1% of the leaf spot, 94.0% of the leaf rust, and 97.9% of the common bunt phenotypic variance combined across all environments. Results from this study provide valuable information for wheat breeders selecting parental combinations for new crosses to develop improved germplasm with enhanced resistance to the four diseases as well as the physical positions of genomic regions that confer resistance, which facilitates direct comparisons for independent mapping studies in the future.

Zealand hard red spring wheat (Triticum aestivum L.) was developed using a modified bulk breeding method at the University of Alberta in Edmonton, AB. Zealand is an apically awn-letted, hollow-stemmed cultivar with a combination of high yield potential, tall plant type, large leaves, and early maturity. In three years of testing in the Western Bread Wheat Cooperative Registration Test during 2013–2015, Zealand exhibited grain yield similar to Glenn and Carberry and 5%–6% lower than Unity and AAC Viewfield, though this difference was not significant (p > 0.05). Zealand yielded 37% greater than the highest-yielding Canada Western Red Spring (CWRS) check, CDC Osler, in A-level testing at a certified organic farm. Zealand matured 1–4 d earlier and was taller than all the check cultivars, but exhibited lodging resistance better than Unity and similar to the other checks. The test weight of Zealand (79.1 kg hL−1) was lower than Glenn and similar to the other checks, while its seed mass was in the range of the check cultivars. Overall, Zealand was rated as resistant (R) to the prevalent races of leaf rust, moderately resistant (MR) to stripe rust and loose smut, intermediate (I) to stem rust and leaf spot, and moderately susceptible (MS) to common bunt and Fusarium head blight. Three years of end-use quality evaluation indicated that Zealand is acceptable for the CWRS class, with relatively few weaknesses. The tall plant type, large leaves, and early maturity render Zealand suitable for organic/high weed environments.

Both the Linear Phenotypic Selection Index (LPSI) and the Restrictive Linear Phenotypic Selection Index (RLPSI) have been widely used to select parents and progenies, but the effect of economic weights on the selection parameters (the expected genetic gain, response to selection, and the correlation between the indices and genetic merits) have not been investigated in detail. Here, we (i) assessed combinations of 2304 economic weights using four traits (maturity, plant height, grain yield and grain protein content) recorded under four organically (low nitrogen) and five conventionally (high nitrogen) managed environments, (ii) compared single-trait and multi-trait selection indices (LPSI vs. RLPSI by imposing restrictions to the expected genetic gain of either yield or grain protein content), and (iii) selected a subset of about 10% spring wheat cultivars that performed very well under organic and/or conventional management systems. The multi-trait selection indices, with and without imposing restrictions, were superior to single trait selection. However, the selection parameters differed quite a lot depending on the economic weights, which suggests the need for optimizing the weights. Twenty-two of the 196 cultivars that showed superior performance under organic and/or conventional management systems were consistently selected using all five of the selected economic weights, and at least two of the selection scenarios. The selected cultivars belonged to the Canada Western Red Spring (16 cultivars), the Canada Northern Hard Red (3), and the Canada Prairie Spring Red (3), and required 83–93 days to maturity, were 72–100 cm tall, and produced from 4.0 to 6.2 t ha−1 grain yield with 14.6–17.7% GPC. The selected cultivars would be highly useful, not only as potential trait donors for breeding under an organic management system, but also for other studies, including nitrogen use efficiency.

Marker-assisted selection requires the identification of molecular markers associated with major genes and quantitative trait loci (QTL). In this study, we used 167 doubled haploid (DH) lines derived from two unregistered spring wheat (Triticum aestivum L.) parental lines that belong to the Canada Western Special Purpose (CWSP) class to map QTLs associated with five traits using inclusive composite interval mapping (ICIM). Using ICIM, the least square means phenotype data across 3-4 environments, and a genetic map of 2,676 SNPs out of the wheat 90K SNP array, we identified ten QTLs associated with days to maturity (4A and 5B), plant lodging (4B, 5A, 5D, and 7D), grain yield (2D), leaf rust (4A) and stem rust (1A and 2B). Each QTL individually explained 6.0-22.3% of the phenotypic variance and together accounted for 8.6-38.2% of the total variance per trait. Two of the QTLs associated with rusts (QLr.dms-4A and QSr.dms-1A) had a minor effect (6.0-9.0%) whereas the second QTL for stem rust (QSr.dms-2B) had a major effect (22.3%). Although chromosome 2B harbors multiple disease resistance QTLs, the physical location of QSr.dms-2B has not been reported in previous studies. Results from this study provide additional valuable information to wheat researchers, in particular, the area on chromosome 2B should be considered for future analyses.

Hundreds of quantitative trait loci (QTLs) have been reported in diverse types of hexaploid wheat (Triticum aestivum L.) populations, but direct comparisons of QTLs in different studies and populations are still challenging due to the lack of physical positions for most QTLs. Here, we used the International Wheat Genome Sequencing Consortium (IWGSC) RefSeq v2.0 physical map of all markers to map QTLs associated with leaf spot (Ls), leaf rust (Lr), stripe rust (Yr), and common bunt (Cbt) resistance in two recombinant inbred line populations. QTL mapping was conducted using the IWGSC physical map of 3158 and 5732 markers and disease severity data of Peace/Carberry and Attila/CDC Go populations evaluated in three to eight environments. We uncovered a total of 82 QTLs associated with Yr (36), Ls (18), Lr (15), and Cbt (13) resistance in the individual and overall means of all combined environments. Among them, 29 were associated with all combined environments, which accounted for 0.5%–20.9% individually and 12.4%–41.2% of the total disease severity per trait. Three (QLr.dms‐2D.2, QLs.dms‐5B, and QYr.dms‐5B.2) of the 29 QTLs were common in both populations. Fourteen out of the 29 QTLs were stable as they were identified both in the overall means and most of the individual environments. Ten chromosome arms harbored a cluster of QTLs associated with resistance to two to four diseases. This methodology would serve as one of the resources to compare QTLs identified in different populations and studies based on the improved physical information of all markers instead of population‐specific and consensus linkage maps.

Jake hard red spring wheat (Triticum aestivum L.) was developed using a modified bulk breeding method at the University of Alberta, Edmonton, AB. Jake is an awned, hollow-stemmed line with high yield potential, medium tall plants, and medium maturity. During the three years (2015–2017) of evaluation in the Parkland Wheat Cooperative test, Jake yielded 6% higher than the mean of all of the checks, and matured 0.7 and 1.7 d later than Parata and Splendor but 2.9 d earlier than Glenn. Jake was 91.2 cm tall, shorter than AC Splendor (95.8 cm), but similar in height to Glenn (91.8 cm) and Parata (92 cm). The lodging score of Jake (2.2) was lower than Parata (3.1) and AC Splendor (3.1), but similar to Glenn. The test weight of Jake (80.8) was higher than AC Splendor (78.3), similar to Parata (80.5), but lower than Glenn (82.5). The grain weight of Jake (35.6 g) was similar to Parata (35.6 g), but lower than Glenn (36.7 g) and AC Splendor (37.4 g), while the NIR Protein of Jake (15.9%) was higher than Glenn (15.5%) and similar to the other checks. Jake was moderately resistant to resistant to leaf, stem, and stripe rusts, and moderately resistant to common bunt during the 3 yr of testing. The reaction of Jake to Fusarium head blight was variable and ranged from moderately susceptible to moderately resistant, with DON values similar to Carberry and Glenn. Three years of end-use quality evaluation has indicated that Jake is acceptable for the CWRS class.