R. J. Graf

Weed-competitive ability of spring and winter cereals in the northern Great Plains.

Abstract The inclusion of winter cereals in spring-annual rotations in the northern Great Plains may reduce weed populations and herbicide requirements. A broad range of spring and winter cereals were compared for ability to suppress weeds and maximize grain yield at Lacombe (2002 to 2005) and Lethbridge (2003 to 2005), Alberta, Canada. High seeding rates (≥ 400 seeds/m2) were used in all years to maximize crop competitive ability. Spring cereals achieved high crop-plant densities (> 250 plants/m2) at most sites, but winter cereals had lower plant densities due to winterkill, particularly at Lethbridge in 2004. All winter cereals and spring barley were highly effective at reducing weed biomass at Lacombe for the first 3 yr of the study. Weed suppression was less consistently affected by winter cereals in the last year at Lacombe and at Lethbridge, primarily due to poor winter survival. Grain yields were highest for spring triticale and least for spring wheat at Lacombe, with winter cereals intermediate. At Lethbridge, winter cereals had higher grain yields in 2003 whereas spring cereals had higher yields in 2004 and 2005. Winter cereals were generally more effective at suppressing weed growth than spring cereals if a good crop stand was established, but overlap in weed-competitive ability among cultivars was considerable. This information will be used to enhance the sustainable production of winter and spring cereals in traditional and nontraditional agro-ecological zones.

Phenotypic and marker-assisted evaluation of spring and winter wheat germplasm for resistance to fusarium head blight

Fusarium head blight (FHB) caused by Fusarium species, is among the most devastating wheat diseases, causing losses in numerous sectors of the grain industry through yield and quality reduction, and the accumulation of poisonous mycotoxins. A germplasm collection of spring and winter wheat, including nine reference cultivars, was tested for Type II FHB resistance and deoxynivalenol (DON) content. Genetic diversity was evaluated on the basis of Simple Sequence Repeat (SSR) markers linked to FHB resistance quantitative trait loci (QTLs) and Diversity Arrays Technology (DArT) markers. The allele size of the SSR markers linked to FHB resistance QTLs from known resistance sources was compared to a germplasm collection to determine the presence of these QTLs and to identify potentially novel sources of resistance. Forty-two accessions were identified as resistant or moderately resistant to Fusarium spread, and two also had very low DON concentrations. Genetic relationships among wheat accessions were generally consistent with their geographic distribution and pedigree. SSR analysis revealed that several resistant accessions carried up to four of the tested QTLs. Resistant and moderately resistant lines without any known QTLs are considered to be novel sources of resistance that could be used for further genetic studies.

Characterization of Wheat-Triticale Lines Resistant to Powdery Mildew, Stem Rust, Stripe Rust, Wheat Curl Mite, and Limitation on Spread of WSMV

High yield potential and the wide adaptability of wheat-rye T1BL·1RS translocation lines are attractive to breeders. The wheat-rye lines Lankao 1, 3, 4, and 5 were resistant to a wide spectrum of wheat powdery mildew (Blumeria graminis f. sp. tritici) isolates from both China and Canada. They also were resistant to a mixture of wheat stem rust (Puccinia graminis f. sp. tritici) pathotypes (98WSR) and wheat stripe rust (P. striiformis f. sp. tritici) races from western Canada and China. Colonization of wheat curl mite (WCM) (Aceria tosichella) resulted in slower development of rolling and trapping leaves in the Lankao lines than in the WCM-susceptible check cultivars. The delayed development of Wheat streak mosaic (WSM) symptoms on Lankao lines was observed when transmitted by viruliferous WCM, even though they were susceptible to Wheat streak mosaic virus (WSMV). This effect of Lankao lines on limiting the spread of WSM was comparable with other known sources of WCM resistance. Sequential C-banding and genomic in situ hybridization analyses revealed the presence of a pair of T1BL·1RS translocated chromosomes in the Lankao lines. Segregation analysis of the F2 progeny plants derived from crosses between Lankao 4 and the susceptible wheat cvs. Mingxian 169 and Lovrin 13 indicated that a single dominant gene was responsible for the isolate-specific resistance against wheat powdery mildew in Lankao 4. Polymerase chain reaction analysis using an STS marker amplified rye chromatin in powdery mildew-resistant and -susceptible F2 plants of the Mingxian 169 × Lankao 4 cross demonstrated that the resistance of Lankao 4 was not controlled by a gene or genes located on the rye chromosome arm of T1BL·1RS. The resistance of the Lankao lines to diseases and limitation of the spread of WSMV, in combination with good quality and high yield potential, makes them useful for wheat improvement and production.

Virulence of Puccinia striiformis f. sp. tritici, cause of stripe rust on wheat, in western Canada from 1984 to 2002

Fifty-seven isolates of Puccinia striiformis f. sp. tritici, causing stripe rust on wheat, were collected in western Canada from 1984 to 2002. The virulence of these isolates was tested on the 17 World and European differentials as well as 7 supplemental differentials. Thirty-nine races were identified. Before 2000, races virulent on wheat ‘Lee’ (Yr7, Yr22, Yr23) and ‘Owens’ mainly originated from Creston, British Columbia, while most of the races from the prairies were avirulent on these two cultivars. New races detected in Canada since 2000 were virulent on both ‘Compair’ (Yr8, Yr19) and ‘Clement’ (Yr9, YrCle). Race 33 (238E150) was repeatedly detected from 2000 to 2002, and other new races had a virulence spectrum that was similar to that of race 33. Some of the prevalent races of stripe rust in the prairie provinces were also detected in the Creston area of British Columbia, suggesting a possible link in the source of inoculum between these two areas. None of the races were virulent on Triticum spelta var. album (Yr5). ‘Chinese 166’ (Yr1), ‘Moro’ (Yr10, YrMor), ‘Hybrid 46’ (Yr3b, Yr4b), Triticum dicoccoides selection G-25 (Yr15), and ‘Spalding Prolific’ (YrSP) were resistant to more than 90% of the races detected in western Canada, and all of them were resistant to the new races detected since 2000. Climatic conditions and cultivar resistance play an important role in the survival and propagation of these races on the Canadian prairies.

Different reactions to the Wheat curl mite and Wheat streak mosaic virus in various wheat-Haynaldia villosa 6V and 6VS lines

Wheat curl mite (WCM), Aceria tosichella, is the vector of Wheat streak mosaic virus (WSMV), a destructive viral pathogen in wheat (Triticum aestivum). Genetic resistance to WCM colonization can reduce the incidence of wheat streak mosaic. Chromosome 6V in Hay-naldia villosa is a new source of WCM resistance. We compared variation in resistance among different sources of H. villosa chromosome 6V and 6VS lines to WCM and WSMV and their effectiveness in controlling the incidence of WSMV following exposure to viruliferous WCM. WCM resistance varied among the 6V and 6VS lines depending on the H. villosa parent. The 6V substitution lines Yi80928, GN21, and GN22 derived from an accession of H. villosa from China, and the 6VS translocation lines 92R137, 92R178, and Sub6V from an H. villosa accession collected from the United Kingdom were uniformly resistant to WCM colonization. In contrast, the 6V substitution line RW15 and a 6VS translocation line Pm33 developed from an H. villosa collection from the former Union of Soviet Socialist Republics were susceptible to WCM. All 6V and 6VS lines were susceptible to WSMV when manually inoculated. However, symptom expression was delayed in the WCM-resistant 6V and 6VS lines after exposure to viruliferous WCM. The 6V and 6VS lines differed in their ability to control WSMV infection. WCM-susceptible lines RW15 and Pm33 had no effect on controlling the infection by WSMV. Lines GN21 and GN22 were the most effective of the three H. villosa sources in limiting the spread of WSMV. Their high yield potential and protein content, in combination with resistance to stripe rust (Puccinia striiformis f. sp. tritici) and powdery mildew (Erysiphe graminis f. sp. tritici), make GN21 and GN22 promising sources of WCM resistance.

Evaluation of crossability between triticale (X Triticosecale Wittmack) and common wheat, durum wheat and rye

Development of transgenic triticale as a platform for novel bio-industrial products is predicated on an environmental biosafety assessment that quantifies the potential risks associated with its release. Pollen-mediated gene flow to related species and conventional triticale varieties is one pathway for transgene movement. A tier 1 quantification of triticale hybridization was conducted by emasculating and hand pollinating flowers under greenhouse conditions. Approximately 2000 manual pollinations were conducted for each cross and its reciprocal between two triticale genotypes: a modern triticale cultivar (AC Alta) and primary triticale (89TT108), and common wheat, durum wheat and rye. The frequency of outcrossing, hybrid seed appearance and weight, and F(1) emergence and fertility were recorded. Outcrossing, F(1) emergence and fertility rates were high from crosses between triticale genotypes. Outcrossing in inter-specific crosses was influenced by the species, and the genotype and gender of the triticale parent. In crosses to common and durum wheat where triticale was the male parent, outcrossing was > or =73.0% and > or =69.5%, respectively, but < or =23.9% and < or =3.0% when triticale was the female parent. Overall, outcrossing with rye was lower than with common and durum wheat. F(1) hybrid emergence was greater when triticale was the female parent. With the exception of a single seed, all wheat-triticale F(1) hybrid seeds were non-viable when triticale was the male parent in the cross. Only seven durum wheat-triticale F(1) hybrids emerged from 163 seeds sown, and all were produced with triticale 89TT108 as female parent. With rye, 8 F(1) hybrids emerged from 38 seeds sown, and all were produced from crosses to AC Alta; five with AC Alta as the female parent and three as the male. Interspecific F(1) hybrids were self-sterile, with the exception of those produced in crosses between common wheat and triticale where triticale was the female parent. Tier 2 hybridization quantification will be conducted under field conditions.

Promising genetic resources for resistance to wheat streak mosaic virus and the wheat curl mite in wheat-Thinopyrum partial amphiploids and their derivatives

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM),Aceria tosichella Keifer, is one of the most destructive viral diseases of wheat found in many wheat producing areas of the world. Host resistance is the most effective method for controlling this disease and its vector. Symptomatological analysis and enzyme-linked immunosorbent assay (ELISA) were used to characterize WSMV-resistance in wheat-alien partial amphiploid lines and their derivatives. The results showed that most of partial amphiploids derived fromThinopyrum ponticum andTh. intermedium were free of systemic symptoms with very low ELISA readings that were similar to that of the non-inoculated Chinese Spring control. While the partial amphiploid lines 693 and PWM706 were identified as new genetic resources of resistance to WSMV. The present study demonstrated that both symptomatological and ELISA methods efficiently assessed WSMV-resistance in the wheat-alien hybrids and systemic symptom incidence and ELISA absorbance readings were highly correlated (r2 = 0.8658−0.9323) over time following inoculation. The ELISA results also indicated that the virus did not buildup in the plant tissues of these virus-resistant partial amphiploids. Similar results were observed in chromosome translocation and substitution lines that have the geneWsm1 conferring WSMV resistance. However, the lines containing the geneWsm1 and all the partial amphiploid lines, except Agrotana, were susceptible to the WCM. One line derived from a cross of wheat and Agrotana, was effective in controlling the spread of WSMV and was highly resistant to the WCM. Another line and an accession ofTriticum dicoccoides (Koern.) Schweinf. were highly susceptible to WSMV and WCM. Early disease development was delayed in a new hard red winter cultivar McClintock. The partial WSMV-resistance of McClintock was demonstrated by initially low ELISA readings, and a lower percentage of infected plants than other WSMV-susceptible wheat. The use of the identified promising sources of resistance to WSMV and the WCM in wheat breeding is discussed.

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.

Post-emergence application of N fertilizer to improve grain yield and quality of irrigated durum and bread wheat

Field studies were conducted for 3 yr (2001 to 2003) at two irrigated sites in southern Alberta to determine if post-emergence N application (38 kg N ha-1) was warranted for durum (Triticum turgidum L.) and bread wheat (T. aestivum) in soils with relatively high N. Greater efficacy occurred with in-crop surface-applied granular ammonium nitrate (AN) compared with foliar-applied urea-ammonium-nitrate (UAN) solution. Early AN application usually improved grain yield compared with the fertilized control (38 k g N ha-1 applied at seeding), while late application reduced grain yield, but increased grain protein concentration and end-use quality. Key words: Triticum turgidum, Triticum aestivum, nitrogen fertilizer, foliar, timing, split N, grain protein concentration

The influence of moisture regime, N management, and cultivar on the agronomic performance and yield stability of soft white spring wheat

Field studies were conducted for 4 yr (2000–2003) in southern Alberta to determine the agronomic suitability and yield stability of soft white spring wheat across an array of moisture and fertility regimes. Two soft white spring wheat cultivars (AC Reed and AC Nanda) with contrasting maturity and quality profiles were compared to nine varieties representing the Canada Prairie Spring White, Canada Prairie Spring Red, and Canada Western Extra Strong wheat classes. The cultivars were managed with five varying rates of mid-row banded ammonium nitrate 0, 19, 38, 57, and 76 kg N ha-1. AC Reed matured earlier than most cultivars except AC Vista, and had the highest average yield. Yield stability analyses showed that AC Reed was well adapted to all environments but AC Nanda was less stable. AC Vista, AC Crystal, and AC Karma had average to good stability, but produced less grain than both AC Reed and AC Nanda. For non-irrigated production, yield was generally optimized at the mid-row banded rate 38 kg N ha-1 of a...