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Ultra-early wheat growing systems based on soil temperature triggers for planting instead of arbitrary calendar dates can increase grain yield and overall growing system stability of spring wheat (Triticum aestivum L.) on the northern Great Plains. We conducted field trials at three sites in western Canada from 2017 to 2019 to evaluate the suitability of Canadian spring hexaploid wheat cultivars and market classes for use within ultra-early spring wheat growing systems. All cultivars and classes exhibited improved grain yield stability (lower adjusted coefficient of variation values) and optimal grain yield when planted ultra-early at 2 °C soil temperature rather than delaying planting to 8 °C.

AAC Oravena is a white-hulled spring oat (Avena sativa L.) cultivar selected and developed under organic management. AAC Oravena yields well under organic and conventional production systems, compared with check cultivars. AAC Oravena has good milling quality. AAC Oravena was registered (Reg. No. 7561) by the Variety Registration Office, Canada Food Inspection Agency, on 3 July 2014.

Stripe rust, caused by Puccinia striiformis Westend. f.sp. tritici Erikss. (Pst), is one of the most devastating diseases of wheat (Triticum aestivum L.) globally. Exploring and utilizing new sourc...

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.

Pyrenophora tritici-repentis (Ptr), the cause of tan spot of wheat, is a foliar pathogen of economic importance worldwide. Tan spot development is associated with the production of necrotrophic effectors (Ptr ToxA, Ptr ToxB and Ptr ToxC) that serve as fungal pathogenicity and/or virulence factors. The objective of this study was to investigate the sensitivity to each of these effectors in a collection of 100 Canadian wheat cultivars representing all wheat classes and developed over a century by various Canadian breeding programmes. Heterologously expressed, His-tagged Ptr ToxA and Ptr ToxB, and spore germination fluids possessing putative Ptr ToxC activity, were produced and used to screen the cultivars for sensitivity. Of the 100 wheat cultivars tested, 92 were sensitive to at least one effector, 68 were sensitive to Ptr ToxA, 63 were sensitive to Ptr ToxC and 24 were sensitive to Ptr ToxB. Only eight cultivars were insensitive to all three effectors. These results reflect the widespread sensitiv...

Growing resistant wheat (Triticum aestivum L) varieties is an important strategy for the control of leaf rust, caused by Puccinia triticina Eriks. This study sought to identify the chromosomal location and effects of leaf rust resistance loci in five Canadian spring wheat cultivars. The parents and doubled haploid lines of crosses Carberry/AC Cadillac, Carberry/Vesper, Vesper/Lillian, Vesper/Stettler and Stettler/Red Fife were assessed for leaf rust severity and infection response in field nurseries in Canada near Swift Current, SK from 2013 to 2015, Morden, MB from 2015 to 2017 and Brandon, MB in 2016, and in New Zealand near Lincoln in 2014. The populations were genotyped with the 90K Infinium iSelect assay and quantitative trait loci (QTL) analysis was performed. A high density consensus map generated based on 14 doubled haploid populations and integrating SNP and SSR markers was used to compare QTL identified in different populations. AC Cadillac contributed QTL on chromosomes 2A, 3B and 7B (2 loci), Carberry on 1A, 2B (2 loci), 2D, 4B (2 loci), 5A, 6A, 7A and 7D, Lillian on 4A and 7D, Stettler on 2D and 6B, Vesper on 1B, 1D, 2A, 6B and 7B (2 loci), and Red Fife on 7A and 7B. Lillian contributed to a novel locus QLr.spa-4A, and similarly Carberry at QLr.spa-5A. The discovery of novel leaf rust resistance QTL QLr.spa-4A and QLr.spa-5A, and several others in contemporary Canada Western Red Spring wheat varieties is a tremendous addition to our present knowledge of resistance gene deployment in breeding. Carberry demonstrated substantial stacking of genes which could be supplemented with the genes identified in other cultivars with the expectation of increasing efficacy of resistance to leaf rust and longevity with little risk of linkage drag.

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.

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.

A randomly derived recombinant inbred line (RIL) population (n = 163) from a cross between CIMMYT spring wheat ‘Attila’ and the Canadian ‘CDC Go’ was used to map quantitative trait loci (QTL) affecting various agronomic and quality traits. The experiment was also designed to investigate the feasibility of organic wheat breeding by determining selection differentials and the effect of Rht-B1 in paired organic and conventional management systems. Heritability estimates differed between systems for five of nine traits measured; including grain yield, number of tillers, plant height, kernel weight, and grain protein content. Direct selection in each management system resulted in 50% or fewer selected individuals in common between the two systems, for eight of the nine (except for flowering time) studied traits. Most QTL were specific to either the organic or the conventional management system. However, consistent QTL for grain yield, grain volume weight, kernel weight, and days to flowering were mapped in both systems on chromosomes 6A, 1B, 3A, and 5B, respectively. The effect of Rht-B1 was more pronounced in organic systems, where RILs carrying the wild-type allele were taller, produced more grain yield with higher grain protein content, and suppressed weed biomass to a greater extent than those carrying dwarfing alleles. Results of the present study suggest that differences exist between the two management systems for QTL effects. Indirect selection of superior genotypes from one system to another will not result in the advancement of the best possible genotypes. Therefore, selection of spring wheat cultivars for organic systems should be conducted on organically managed lands.

Recently, we mapped genomic regions associated with resistance to wheat diseases and insensitivity to Pyrenophora tritici-repentis (Ptr) toxins using 81 historical and modern Canadian western spring wheat cultivars genotyped with genome-wide single nucleotide polymorphic (SNP) markers. Here, we investigate the frequency and effects of allelic variants of 50 markers associated with 16 candidate genes that regulate resistance to leaf rust (Puccinia triticina), yellow or stripe rust (P. striiformis f. sp. tritici), tan spot (P. tritici-repentis), and Ptr ToxA reaction in a subset of 70 of the 81 spring wheat cultivars. We evaluated the 70 cultivars in the field for all diseases except Ptr ToxA, which was evaluated in a greenhouse. Using Spearman rank correlation, stepwise discriminant analysis, and partial least squares regression, we identified between 4 and 11 markers as best predictors of each phenotypic trait. Overall, 23 of the 50 markers were associated with one or more of the phenotypic traits of which analysis of variance showed significant differences between allelic variants of 19 markers. In most analyses, markers for Lr34/Yr18 and Tsn1 loci were identified consistently as the best predictor of disease resistance and Ptr ToxA sensitivity, respectively. The same alleles from two Lr34/Yr18 diagnostic SNP markers (wMAS000003 and wMAS000004) not only decreased stripe rust scores up to 1.6 (on a 1 to 9 scale), but also increased grain yield up to 196 kg ha−1 without affecting maturity. Results from this study could aid spring wheat breeders in selecting the best parental combinations and/or marker-assisted selection to integrate disease resistance with early maturity and short stature.

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.

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.

Isolated microspore culture (IMC) has been used to develop doubled haploid lines and to generate homozygous lines in a single generation for varietal development. Phytosulfokine has been previously used in promoting cell growth and embryo development in various systems. In this study, phytosulfokine alpha (PSK-α) supplemented IMC induction medium was evaluated in triticale and wheat cultivars, and the production of embryo-like structures (ELS), green and albino plants were recorded. In addition, the contribution of ovary co-culture was also evaluated in IMC on a NPB99 + 10F induction medium. Over a range of concentrations up to 10−7M, PSK-α yielded more ELS and green plants in wheat and triticale cultivars at the highest dose, when compared to the control. It also minimized albinism in wheat cultivars, but not in triticale. Interestingly, 10−7M PSK-α also supported the formation of a large number of embryos and a few green plants in the absence of nursing ovaries.

We recently reported three earliness per se quantitative trait loci (QTL) associated with flowering and maturity in a recombinant inbred lines (RILs) population derived from a cross between the spring wheat (Triticum aestivum L.) cultivars ‘Cutler’ and ‘AC Barrie’ using 488 microsatellite and diversity arrays technology (DArT) markers. Here, we present QTLs associated with flowering time, maturity, plant height, and grain yield using high density single nucleotide polymorphic (SNP) markers in the same population. A mapping population of 158 RILs and the two parents were evaluated at five environments for flowering, maturity, plant height and grain yield under field conditions, at two greenhouse environments for flowering, and genotyped with a subset of 1809 SNPs out of the 90K SNP array and 2 functional markers (Ppd-D1 and Rht-D1). Using composite interval mapping on the combined phenotype data across all environments, we identified a total of 19 QTLs associated with flowering time in greenhouse (5), and field (6) conditions, maturity (5), grain yield (2) and plant height (1). We mapped these QTLs on 8 chromosomes and they individually explained between 6.3 and 37.8% of the phenotypic variation. Four of the 19 QTLs were associated with multiple traits, including a QTL on 2D associated with flowering, maturity and grain yield; two QTLs on 4A and 7A associated with flowering and maturity, and another QTL on 4D associated with maturity and plant height. However, only the QTLs on both 2D and 4D had major effects, and they mapped adjacent to well-known photoperiod response Ppd-D1 and height reducing Rht-D1 genes, respectively. The QTL on 2D reduced flowering and maturity time up to 5 days with a yield penalty of 436 kg ha-1, while the QTL on 4D reduced plant height by 13 cm, but increased maturity by 2 days. The high density SNPs allowed us to map eight moderate effect, two major effect, and nine minor effect QTLs that were not identified in our previous study using microsatellite and DArT markers. Results from this study provide additional information to wheat researchers developing early maturing and short stature spring wheat cultivars.

Photoperiod response impacts the adaptation of spring wheat (Triticum aestivum L.) to specific areas of the world. Both photoperiod sensitive (PS) and photoperiod insensitive (PI) cultivars are grown successfully in the northern regions of the western United States and the Canadian plains. The goal of the present experiment was to determine the relative performance of PI and PS genotypes as related to planting date and to interpret results in view of climate trends for the region. Three sets of near-isogenic lines that differed for alleles at the Ppd-D1 locus for photoperiod sensitivity were tested at three planting dates in 15 environments in Montana, Washington, Saskatchewan, and Alberta. Results showed that PS lines headed later than PI lines at all planting dates. Grain yield was significantly greater for PS lines at the first two planting dates although no difference between PS and PI lines occurred for the latest planting date. Our results suggest that PS lines are superior to PI lines for this region. This difference is likely to be significant for regional adaptation as planting date becomes earlier due to increasing spring temperatures.

The wheat stem sawfl y (Cephus cinctus Norton (Hymenoptera: Cephidae)) is a serious threat to wheat (Triticum aestivum L.) and other cereal grains in the northern Great Plains. Wheat cultivars with high expression of pith in the culm of the stem (stem solidity) can minimize losses associated with sawfl y infestations and subsequent stem boring of the larva. Based on the widespread area now sown to solid- stemmed wheat, our objective was to develop an integrated nutrient and planting strategy specifi c to solid-stemmed spring wheat using modern farming techniques. Five levels of banded N fertilizer (0, 30, 60, 90, and 120 kg N ha −1 ) were arranged in a factorial combination with three levels of sowing density (100, 300, and 500 seeds m −2 ) and grown at three sites in southern Alberta, Canada, from 2007 to 2009. Increased planting densities optimized yield, but an inverse relationship with pith expression (stem solidness) was observed. Low plant populations (100 seeds m −2 ) were often most effective at maximizing pith expression in solid-stemmed wheat and reducing sawfl y cutting damage. However, this usually required the highest rates of N fertilizer, so a system of low seeding rates and high N may not be economical based on fertilizer input costs and the generally lower grain yield response (−9%). An integrated planting and nutrient strategy for solid-stemmed spring wheat cultivars consists of seeding rates no greater than 300 seeds m −2 and basal N applications in the range of 30 to 60 kg N ha −1 .

Th e wheat stem sawfl y (Cephus cinctus Norton (Hymenoptera: Cephidae)) (WSS) has been a serious pest of wheat (Triticum aesti- vum L.) since the late 19th century. Adoption of solid-stemmed cultivars, which are available only in the spring bread wheat class in Canada, can mitigate damage but the trait that confers resistance tends to be variable. Five other classes of wheat are grown within the geographical range of C. cinctus and are vulnerable to WSS infestation, and the entire production area for durum (T. turgidum L.) in western Canada, Montana, and western North Dakota lies within the geographic range of C. cinctus. Our objective was to test the hypothesis that the response of hollow- and solid-stemmed cultivars to sowing density (150, 250, 350, or 450 seeds m -2 ) would diff er and subsequently aff ect infestation patterns of WSS and an endemic parasitoids. Th e lowest rates of infestation occurred in the hollow-stemmed durum cultivar AC Avonlea and declined with increased sowing density. Wheat pith expression was optimized at the lowest sowing density but the same level produced low and variable grain yield. In the solid- stemmed cultivar Lillian, pith expression was most stable at 250 or 350 seeds m -2 . For all cultivars, grain yield was optimized at the higher seeding rates of 350 and 450 seeds m -2 . Solid-stemmed wheat should be seeded at low to moderate density to maximize resistance to WSS, but hollow-stemmed cultivars should be seeded at higher seeding rates to optimize yield, lower WSS infesta- tion, and to increase overall crop competitiveness.

Most semiarid regions of the northern Great Plains are prone to wheat stem sawfl y (Hymenoptera: Cephidae, Cephus cinctus Norton) attack. As an alternative to the wheat (Triticum aestivum L.)–fallow system, our objective was to determine if continuous cropping infested wheat stubble would inhibit wheat stem sawfl y (WSS) emergence. Adult sawfl y emergence from undisturbed stubble was compared to stubble harrowed with heavy tine or rotary drum harrows before recropping. Adult emergence from a control of “no recropping” was compared to direct seeding infested stubble with (i) air drills confi gured with knife-type openers spaced 23 or 30 cm apart, (ii) an air drill confi gured with high disturbance shovel-type sweep openers, and (iii) a low disturbance air drill equipped with disc openers. Pre-seed heavy tine harrowing reduced adult sawfl y emergence but usually required a high tension setting. No-till planting into infested spring wheat stubble also lowered WSS emergence compared to leaving the fi eld fallow. A system of heavy tine harrows and an air drill equipped with knife openers spaced 30 cm apart reduced WSS adult emergence in spring by 50 to 70%. Grain yield was optimized in spring wheat with air drills equipped with narrow knife openers; in winter wheat optimal yield was obtained with the low disturbance disc drill confi gurations. Our results indicate incremental benefi ts from continuous cropping rather than fallowing fi elds infested with WSS, which is a sustainable alternative to conventional tillage. A systems approach is recommended that integrates these practices with diversifi ed nonhost crop phases and resistant cultivars.

Micronutrient deficiencies in the diet of many people are common and wheat is a staple food crop, providing a carbohydrate and micronutrient source to a large percentage of the world’s population. We conducted a field study to compare five Canadian red spring wheat cultivars (released over the last century) grown under organic and conventional management systems for yield, grain micronutrient concentration, and soil phospholipid fatty acid (PLFA) profile. The organic system had higher grain Zn, Fe, Mg and K levels, but lower Se and Cu levels. There was no trend in the results to suggest that modern western Canadian hard red spring cultivars have lower grain micronutrient content than historical cultivars. Wheat cultivar choice is important for maximizing grain nutrient levels, which was influenced by management system. It is evident that the emphasis on elevated grain quality in the western Canadian hard red spring class has resulted in the retention of micronutrient quality characters. Three fungal PLFAs were indicators for the organic system, and all three of these indicators were positively correlated with grain Cu concentration. In the organic system, percent arbuscular mycorrhizal fungi were negatively correlated with grain Zn and Fe concentrations, and positively correlated with grain Mn, Cu, K concentrations and grain yield. The organic system had higher levels of fungi in the soil, including arbuscular mycorrhizal fungi. Organic management practices appear to result in elevated levels of grain micronutrient concentration. The hard red spring breeding effort in and for the black soil zone of the northern Great Plains also appears to have led to no diminishment of grain micronutrient concentration. It is evident that both the agronomic system and breeding strategies in this region can be exploited for future increases in grain micronutrient concentration.

Breeding spring wheat (Triticum aestivum L.) specifically for organic production has been suggested by producers and researchers alike. To investigate the effects of management systems on selected spring wheat breeding line performance in multi-location tests in the northern Great Plains, we used a randomly derived population of 79 F6-derived recombinant inbred lines (RILs) from a cross between the Canadian hard red spring wheat cultivar AC Barrie and the CIMMYT derived cultivar Attila. The population, including the parents, was grown on conventionally and organically managed land in 12 environments over 3 years. Direct selection in each management system (10% selection intensity based on grain yield) resulted in three lines being retained in each management system, over the multi-location testing. Gains from 10% selection for grain yield in a ‘selection’ year were 3.4 times greater in conventional multi-site yield trials than in organically managed trials. Two lines (BA 05 and BA 36) ranked in the top 10% of both the conventional and organic selection trial of 2005, remained ranked 2nd and 1st, respectively, under conventional management in multi-site yield trials. However, these lines ranked 53rd and 21st, respectively, for grain yield in the multi-site organic yield trials. Selected lines were each yield stable within the management system in which they were selected. Following replicated multi-location yield trials, three lines from the population (BA 02, 29 and 58) ranked within the highest 10% yielding lines in both conventional and organic systems. The results of this study suggest that selection differences occur across multi-location tests, and that selection for grain yield in organic systems should be conducted within organic systems. It is evident, however, that data obtained from conventional yield trials also has some relevance towards breeding for organic environments.

SUMMARYWheat (Triticum aestivum L.) variety mixtures represent a relatively unexplored avenue for maintaining and stabilizing yield for both organic and conventional producers. The present study examined the responses of three Canadian western red spring wheat varieties in sole crop and in variety mixtures to varying levels of simulated and natural competition, as well as environmental stress at one conventionally and two organically managed locations in central Alberta, Canada, between 2003 and 2005. Three modern hard red spring wheat varieties (Superb, semi-dwarf; AC Intrepid, early maturing and 5600HR, tall), along with 13 two- and three-way variety mixtures, were planted under two levels of simulated weed (Brassica juncea L.) competition at each of the eight location-years. The B. juncea weed competition treatment decreased yields at all locations. Overall yield was lowest at the certified organic farm and highest under conventional management. Sole-crop semi-dwarf Superb and all three Superb–Intrepid mixture entries consistently yielded among the highest, regardless of management system, testing location or competition treatment. The 1:1 and 1:2 Superb–Intrepid mixture entries were the most stable of all entries tested. Early season vigour was strongly associated with yield, with the strongest correlation occurring under low-moisture, low-nutrient, high-competition conditions at the certified organic farm. Spring wheat variety mixtures may provide greater stability with little or no reduction in yield, while providing greater competitive ability.

The conservation of crop genetic resources is an international priority and requires the continued collection and characterization of farmer varieties. We collected and characterized maize and upland rice populations cropped by farmers in Panama's Azuero region. The objective of our study was to evaluate the crop genetic diversity of farmer varieties of maize and upland rice grown by poor farmers in Panama. We found that: (1) farmers' naming practices only partially corresponded to genetic relationships and were the strongest for rice populations; (2) farmers' classification of populations as ‘modern’ or ‘traditional’ was reflected in phenotypic differences; (3) Panamanian maize populations were molecularly distinct from populations collected elsewhere in Latin America; and (4) heterogeneous rice populations were common and heterogeneity was often due to admixture of recognized farmer varieties. Our results indicate that poor farmers in Panama continue to farm ‘traditional’ varieties that harbour genetic diversity of interest. There has, however, been substantial adoption of ‘modern’ varieties.

Organically managed production systems often experience greater weed pressure than their conventional counterparts, potentially causing yield losses and increased weed seed build-up. The use of competitive crop cultivars and the cultural practice of increasing seeding rates may moderate such production constraints. Field trials were conducted at two organically managed locations in Alberta, Canada for 2 yr to determine the effect of competition with tame oat (Avena sativa L.), cultivar, and crop seeding rate (300 and 600 seeds m -2 ) on the competitive ability and agronomic performance of Canadian spring wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). Cultivars were selected based on their differing heights, tillering capacities, and times to maturity. Simulated weed competition from tame oat reduced grain yield by an average of 27%. Barley cultivars were generally more competitive than wheat cultivars. Height and early maturity were more closely associated with weed suppression and yield maintenance than tillering capacity. The modem semidwarf CDC Go was the highest yielding wheat cultivar, but was a poor weed suppressor. Doubling the seeding rate increased grain yield and weed suppression. This effect was not cultivar specific, which implies that doubling the seeding rate may be a generally effective method of overcoming yield losses and weed seed build-up associated with increased weed populations under organic production.

SUMMARYNine spring wheat cultivars, selected on the basis of height, tillering capacity and maturity, were grown in differing levels of natural weed presence at three locations in Edmonton and New Norway, Alberta between 2003 and 2004. The objectives of the study were to (1) identify competitive traits in wheat cultivars, (2) determine whether traits associated with competitive ability differ under increasing weed pressure and (3) assess cultivar stability in and adaptation to environments differing in yield potential and weed competition. Eight experimental environments (including conventionally and organically managed fields with and without common oats sown as a weed analogue) were grouped into low, medium and high weed pressure levels, based on mean total weed biomass. Tallness and early heading and maturity were related to increased grain yield at the highest weed level. Greater spikes/m2, tallness and early heading were associated with reduced weed biomass, depending on weed level. Principal component analysis (PCA) revealed that height accounted for a small amount of variation in low weed environments, yet was more important as weed pressure increased. Finlay–Wilkinson (Finlay & Wilkinson 1963) stability analysis demonstrated that cultivars responded differently in environments differing in yield potential and in weed pressure. Older wheat cultivars were generally more yield-stable across environments, while modern semidwarf cultivars were more sensitive to changes in weed level. The cultivar Park (released in 1963) was the most yield- and weed-stable cultivar, coupled with relatively high yields and average weed biomass accumulation, and may therefore be well adapted to low yielding or high weed environments.

High grain yield and grain protein content, and early maturity are important traits in global bread wheat (Triticum aestivum L.)-breeding programmes. Improving these three traits simultaneously is difficult due to the negative association between grain yield and grain protein content and the positive association between maturity and grain yield. We investigated the genetic relationship between maturity, grain yield and grain protein content in a population of 130 early maturing spring wheat lines in a high latitude (52-53°N) wheat-growing region of Canada. Grain protein content exhibited negative genetic correlation with maturity (-0.87), grain fill duration (-0.78), grain fill rate (-0.49), grain yield (-0.93) and harvest index (-0.71). Grain yield exhibited positive genetic correlation with maturity (0.69), rate (0.78) and duration (0.49) of grain fill, and harvest index (0.55). Despite the positive association between maturity and grain yield, and negative association between grain yield and grain protein content, higher yielding lines with medium maturity and higher grain protein content were identified. Broad-sense heritabilities were low ( 0.40) for grain weight, days to anthesis and maturity, and plant height. Selection for longer preanthesis and shorter grain fill periods may help circumvent the negative association between grain yield and grain protein content. Selection for shorter grain fill periods and higher grain fill rate may be a useful strategy for developing early maturing cultivars with acceptable grain yields in northern wheat-growing regions.

Competition from weeds can reduce grain yields in both conventional and organic systems. Plant height, tillering, and elevated photosynthetically active radiation interception are some of the traits thought to help confer competitive ability in cereal grains. Crop cultivars developed before the advent of modem, high-input agriculture may be better suited to lower soil nutrient levels and elevated weed competition. Twenty-seven spring bread wheat (Triticum aestivum L.) cultivars, representing 114 yr of Canadian wheat breeding, were grown at conventionally and organically managed sites in north central Alberta over a 3-yr period. Average conventional yields were 63% greater than organic yields, and average overall weed biomass was significantly greater under organic management. Earlier flowering and maturity were more important for achieving high grain yield in organic fields than in conventional fields. Greater numbers of spikes m-2 were associated with increased grain yield in organic fields but were not in conventional fields. In organic fields, increased plant height and early maturity were associated with reduced weed biomass, while strong early season vigor was related to increased yield, increased spikes m -2 , and reduced weed biomass. A competitive crop ideotype for organically grown spring wheat in northern growing regions of the Canadian Prairies should include taller plants, with fast early season growth, early maturity, and elevated fertile tiller number.

Vernalization response (Vrn) genes play a major role in determining the fl owering times of springsown wheat (Triticum aestivum L.). The objective of this study was to investigate the effect of Vrn genes on fl owering and maturity times and important agronomic traits in a set of reciprocal whole-chromosome substitution lines and eight western Canadian spring wheat cultivars of known Vrn genes, grown over three seeding dates in Alberta, Canada over 2 yr. The genotype carrying spring habit alleles at Vrn-A1, Vrn-B1, and VrnD5 fl owered and matured the earliest, and had the highest grain protein content but the lowest grain yield. Genotypes with spring habit alleles Vrn-A1 and Vrn-B1 were early maturing and high yielding. Genotypes with the spring habit Vrn-D5 allele either singly or in combination with Vrn-A1 were late maturing. The spring habit allele of VrnA1 was not completely epistatic to Vrn-B1 and Vrn-D5 for fl owering or maturity time. The spring habit allele of Vrn-B1, however, was epistatic to that of Vrn-D5 for these traits. In northern wheat growing regions, breeding preference should be given to Vrn genotypes with three spring habit alleles or those with spring habit alleles of VrnA1 and Vrn-B1. Genotypes carrying spring habit Vrn-D5 allele singly or in combination with Vrn-A1 should be planted as early in the growing season as possible to realize their full yield potential.

Genetic control of yield under reproductive-stage drought stress was studied in a population of 436 random F 3 -derived lines from a cross between the upland rice (Oryza sativa L.) cultivars Vandana and Way Rarem. Screening was conducted under upland conditions at IRRI during the dry seasons of 2005 and 2006. Lines were evaluated in drought stress and nonstress trials in both years to identify QTL contributing to drought resistance. For QTL detection, a set of random lines and the highest and lowest-yielding lines under both stress and nonstress conditions were genotyped by 126 SSR markers. A QTL (qtl12.1) with a large effect on grain yield under stress was detected on Chromosome 12 in both years. The whole population was genotyped for additional markers on Chromosome 12, allowing QTL localization to a 10.2 cM region between SSR markers RM28048 and RM511. Under stress conditions, the locus also increased harvest index, biomass yield, and plant height while reducing the number of days to flowering. Under nonstress conditions, qtl12.1 did not significantly affect any trait. The additive effect of this QTL on grain yield under stress was 172 kg ha-1 per year over the 2 yr of testing, representing 47% of the average yield under stress and explaining 51% of the genetic variance. The yield-increasing allele was derived from the susceptible parent, Way Rarem, suggesting an epistatic effect. This is the first QTL reported in rice having a large and repeatable effect on grain yield under severe drought stress in the field.

Due to the short growing season in the high northern latitudes, the development of early maturing spring wheat (Triticum aestivum L.) cultivars is important to avoid frost damage which can lower production and quality. We investigated earliness of flowering and maturity, and some associated agronomic traits, using a set of randomly selected high northern latitude adapted spring wheat cultivars (differing in maturity) and their F1 and F2 crosses made in a one-way diallel mating design. The parents, and their F1 and F2 crosses were evaluated under field conditions over 2 years. Anthesis and maturity times were controlled by both vernalization response and earliness per se genes, mainly acting additively. Non-additive genetic effects were more important in controlling grain fill duration, grain yield and plant height. Additive × additive epistatic effects were detected for all traits studied except time to anthesis. Segregation analyses of the F2 populations for time to anthesis indicated the presence of different vernalization response genes. Molecular genetic analyses revealed the presence of Vrn-A1 and Vrn-B1 genes in the parental cultivars. Narrow-sense heritability was medium to high (60–86%) for anthesis and maturity times but low to medium (13–55%) for grain fill duration, plant height and grain yield. Selection for early flowering/maturity in early segregating generations would be expected to result in genetic improvement towards earliness in high latitude spring wheats. Incorporation of the vernalization responsive gene Vrn-B1 in combination with vernalization non-responsive gene Vrn-A1 into spring wheats would aid in the development of early maturing cultivars with high grain yield potential for the high latitude wheat growing regions of the northern hemisphere.

Characterizing variety testing sites and identification of sites with negligible genotype × environment crossover interaction is important for plant breeders wishing to identify superior germplasm and (or) cultivars for a wide range of environments. Long-term multilocation grain yield data from the regional hard red spring wheat (Triticum aestivum L.) variety trials from 1981 to 2002 (472 location years assessing 64 wheat genotypes) in Alberta, Canada, were employed for this study. The shifted multiplicative model (SHMM) and the site regression model (SREG) were used to group testing sites into subsets with reduced crossover interaction. Both models identified yearly subsets of testing sites with negligible crossover interaction. However, the yearly site groupings did not generally follow a repeatable pattern over years. Clustering did not correspond with provincial agroclimatic classification, nor did it correspond with site-specific yield potential. Genotype × environment patterns were therefore inconsistent over the years, mainly because of complex, highly variable, and unpredictable year × location effects. We identified sites appearing to be more discriminative and predictive of average genotype performance. This suggests that regional variety trials may be conducted at a fewer more representative locations predictive of average varietal performance. We conclude that the spring wheat growing areas in Alberta (and in the northern Great Plains in general) belong to a single megaenvironment with unpredictable crossover interaction patterns. Because of the highly variable and unpredictable genotype x environment interaction patterns in Alberta, genotypic selection targeting wide adaptation is recommended. Although genotype x environment patterns were not repeatable, the yearly high yielding and stable varieties were repeatedly selected over years. These varieties were the most popular varieties grown by farmers during the testing time period.

Plant need-based N management approaches may increase the efficiency of N fertilizer application in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The leaf chlorophyll concentration estimated through the SPAD-502 meter gives a relative assessment of N status in crop. Field trials were conducted near St John's, Newfoundland, between 1997 and 2000 to describe the relationship between winter wheat and spring barley grain yield, protein content, protein yield and SPAD measurements, as affected by differential stage of crop growth, seeding rate and topdress N fertilizer. Grain yield, protein content, and protein yield of winter wheat and spring barley exhibited linear responses to increasing N topdress application rate. SPAD-502 values were moderately to highly positively correlated with grain yield, protein content, and protein yield as a result of increasing topdress N fertilization, and moderately negatively correlated as a result of increasing seeding rate. It may be difficult to make an N-application rate recommendation based on SPAD measurements, as a critical SPAD value may vary among years, locations, cultivars and soil characters.

Intercrops of berseem clover (Trifolium alexandrinum L.) and silage cereals offer potential for high quality forage and partitioning of yield between silage harvest and fall grazing. Forage yield and quality of cereal-berseem clover intercrops may differ among oat (Avena saliva L.) and barley (Hordeum vulgare L.) cultivars and with semidwarf or early maturing cereal cultivars. Berseem clover was intercropped with five oat and four barley cultivars at Edmonton, Alberta, in 2000 and 2001 on orthic black chemozem (Typic Cryoboroll) soil. Forage yield, composition, and quality were measured with a two-cut harvest. Silage-stage yield (Cut 1) averaged 9.9 Mg ha -1 of dry matter (DM) with 18% berseem clover by dry weight. Berseem clover regrowth (Cut 2) averaged 2.8 Mg ha -1 DM with crude protein (CP) of 215 g kg -1 . Intercrops with oat cultivars had greater Cut 1 DM yield, and intercrops with barley had greater yields of Cut 2 DM and total CP. The earlier maturity of barley provided for longer periods of berseem clover regrowth. Intercrops with semidwarf barley had equal yields of total DM and CP and greater Cut 2 DM yield than those with conventional-stature barley. Intercrops with early maturing oat cultivars had equal total DM yield and greater yields of Cut 2 DM and total CP than those with late-maturing oat cultivars. Forage quality indicators suggested that intercrops with barley were superior to those with oat. To maximize fall forage and increase the legume component of silage harvest, early maturing and shorter-stature cultivars of oat and barley are recommended for cereal-berseem clover intercrops.

Selection for lodging resistance in Canadian hard red spring wheat under natural conditions is difficult due to the sporadic and often random nature of lodging events. We conducted field trials in Edmonton AB Canada (2000-2002) to determine if either a high seeding rate, or artificially inducing lodging (by dragging a weighted apparatus across plots at the early milk stage), would be an effective screen for determining genetic lodging resistance in wheat breeding programmes. For the 25 genotypes tested, applying artificial lodging at the experimental mean early milk stage was a suitable method to screen and identify lodging tolerant and susceptible genotypes. Tolerance to artificially induced lodging was mainly found within semi-dwarf genotypes, and susceptibility was mainly found within Canadian bread wheat genotypes. Severe lodging resulted in yield losses as high as 40%. Lodging tolerant genotypes identified in this study are now being crossed into elite western Canadian bread wheat in an effort to increase genetic lodging resistance within Canadian breeding lines.

Wheat is one of the most important cereal crops. It covers the largest area under any single crop in the world. It feeds about 40 % of the world’s population and provides 20 % of the caloric and protein requirements in human nutrition. Wheat also occupies a central position in maintaining world’s food security. Following incorporation of semi-dwarfing genes, wheat production doubled in the 1960s, an era called the Green Revolution. The Green Revolution resulted in the development of semi dwarf wheat cultivars that were highly responsive to inorganic fertilizer application, were early maturing and resistant to lodging. Semi dwarf cultivars also remained resistant to various diseases for many decades. Wheat genetic gains are less than 1 % per annum which are not sufficient to meet the future food demand of ever increasing human population. This chapter addresses importance, history, production and utilization of wheat from different perspectives.

Plant breeders around the globe emphasize on improving yield, adaptation, disease resistance and quality in conventional management systems where the use of synthetic fertilizers, pesticides and herbicides is routine and thus, precluding selection for traits conferring competitive ability. This Chapter focuses on breeding wheat cultivars for disease resistance, grain quality, allelopathy and earliness for organically managed lands. The combined effect of allelopathy and competitive ability can determine the competitiveness of a given crop species to achieve maximum weed suppression. Weed suppressive rice cultivars have been developed and released for commercial cultivation in USA and China, whereas breeding efforts are being done in various parts of the world including Canada to develop weed suppressive/competitive wheat and barley ideotypes.

Weeds compete for limited resources under field conditions and cause quantitative and qualitative grain yield losses. Weeds cause losses in both conventional and organically managed lands but competition from weeds is more challenging to organic farmers as synthetic herbicides cannot be used. Various strategies have been proposed that can enhance competitive ability of crop plant by reducing weed seed production and crop grain yield losses. In this Chapter, various management strategies have been discussed in detail that can facilitate farming community to enhance competitive ability in different environments. Competitive ability is a genetic trait that varies among crop cultivars. Research on wheat competitive ability has been conducted in various parts of the world suggesting that genetic differences exist for competitive ability between crop species and also within cultivars. This variation for competitive ability can be used to breed cultivars for improved competitiveness. Recent advancements in the field of biotechnology, especially relating to DNA marker technology have broadened the prospects of selecting suitable/desirable genotypes based on DNA markers. The chapter also highlights various studies designed to identify genomic regions (QTL) conferring competitive ability in various cereal crops.

Marker-assisted breeding provides an opportunity for wheat breeders to introgress/pyramid genes of interest into breeding lines and to identify genes and/or quantitative trait loci in germplasm to be used as parents. Molecular markers were deployed to assist selection for disease resistance, agronomic and quality traits in several wheat cultivars released for commercial cultivation in Canada. Marker-assisted breeding is routinely used in most wheat breeding programmes for rust resistance (leaf, stem and stripe rust), orange wheat blossom midge resistance, high grain protein concentration, Fusarium head blight and common bunt resistance. Markers are being used selectively within breeding programmes to target traits that relate to market class or regional adaptation. For example, marker-assisted breeding for low lipoxygenase activity and low grain cadmium is being performed in durum breeding programmes and for enhancing stem solidness in programmes targeting resistance to the wheat stem sawfly. Markers are also being utilized for ergot resistance in durum wheat. Increased gluten strength is being selected with a marker for the overexpression of the Bx7 high-molecular-weight glutenin subunit. Marker-assisted breeding is also being used to pyramid resistance genes against a group of stem rust races related to TTKS (Ug99), a disease that poses a serious threat to global wheat production. Development of tightly linked diagnostic markers and high-throughput genotyping with SNP markers will result in more effective molecular wheat breeding in the near future and will open the door to genomic selection.

Eight day-neutral and seven short-day strawberry (Fragaria ×ananassa, Duch.) varieties were evaluated on raised beds during 1990 and 1991 in the Fraser River valley, B.C. Among day-neutral varieties in 1990, total variation in marketable yield originated in fruit count (26%), total yield (18%), average leaf size (22%), and runner count (19%) per plant. In 1991, total variation in marketable yield originated in fruit count (38%), runner count (23%), crown count (13%), and total yield (16%) per plant. `Selva' was one of the most productive day-neutral varieties and had the heaviest fruit and the fewest culls during both years of the study. The short-day varieties had uniformly low yields of marketable fruit during the establishment year, 1990. Variation in marketable yield in 1991 originated in runner count (34%), total yield (18%), and fruit count (16%) per plant. Of the short-day varieties in 1991, `Shuswap' had the highest marketable yield and, along with `Pajaro' and `Sequoia', had the fewest culls. `Shuswap' was a prolific producer of runners, while `Sumas' and `Redcrest' yielded well without prolific runner production.

Spaner, D., Mather, D. E. and Hamilton, R. I. 1992. Genetic and agronomic evaluation of shortseason Quality Protein Maize. Can. J. Plant Sci. 72: ll,'71-1181. Development of early-maturing hybrid cultivars of Quality Protein Maize (QPM), a hard-endosperm high-lysine maize (Zea mays L.), could provide a balanced-protein alternative feed crop for northern temperate areas. A set of inbred lines dirived from QPM germplasm was used as the base population for three experiments conducted in eastern Canada: an eight-parent one-half diallel analysis, an evaluation of inbred perfbrmance, and an evaluation of resistanCe to Fusarium ear rot. In the diallel analysis, general combining ability effects were significant for grain yield, moisture at harvest, and kernel opacity. Specific combining ability effects were also significant and accounted for 20 and 13% ofthe genotypic variability for grain yield and moisture at harvest, respectively. Some QPM hybrids yielded wel1, but they had relatively high levels of grain moisture at harvest, indicating a need to breed for improved adaptation. Within the base population of QPM inbreds, the variation and repeatability for most agronomic traits and for resistance io Fusarium ear rot appeared to be adequate to allow development of agronomically superior QPM inbreds and hybrids for northern temperate maize growing regions.