Harker, K. N., O'Donovan, J. T., Turkington, T. K., Blackshaw, R. E., Lupwayi, N. Z., Smith, E. G., Klein-Gebbinck, H., Dosdall, L. M., Hall, L. M., Willenborg, C. J., Kutcher, H. R., Malhi, S. S., Vera, C. L., Gan, Y., Lafond, G. P., May, W. E., Grant, C. A. and McLaren, D. L. 2012. High-yield no-till canola production on the Canadian prairies. Can. J. Plant Sci. 92: 221-233. Relatively high prices and increasing demand for canola (Brassica napus L.) have prompted growers to produce more canola on more cropland. Here we determine if canola seed yield and oil concentration can be increased over current levels with high levels of crop inputs. From 2008 to 2010, direct-seeded experiments involving two seeding rates (75 vs. 150 seeds m^-2), two nitrogen rates (100 vs. 150% of soil test recommendation), and the presence or absence of polymer-coated nitrogen or fungicides, were conducted at eight western Canada locations in canola-wheat-canola or continuous canola rotations. Herbicides, insecticides and fertilizers other than nitrogen were applied as required for optimal canola production. Increasing recommended nitrogen rates by 50% increased canola yields by up to 0.25 Mg ha^-1. High (150 seeds m^-2) versus lower (75 seeds m^-2) seeding rates increased canola yields by 0.07 to 0.16 Mg ha^-1. Fungicide treatment or polymer-coated nitrogen blended with uncoated urea increased canola yields by 0.10 Mg ha^-1 in 2010, but not in 2008. The highest canola input combination treatment following wheat (3.50 Mg ha^-1) yielded substantially more than the same high input treatment following canola (3.22 Mg ha^-1). Average site yields were influenced by site conditions such as soil organic matter, days to maturity, and temperature, but these site and environmental predictors did not alter treatment rankings. Using higher than the soil test recommended rate of nitrogen or planting 150 versus 75 seeds m^-2 increased canola yields consistently across western Canada. Canola oil concentration varied among canola cultivars, but was consistently low when N rates were high (150% of recommended). Higher than normal seeding rates led to high canola seed oil concentration in some cases, but the effect was inconsistent.

Steppuhn, H., Acharya, S. N., Iwaasa, A. D., Gruber, M. and Miller, D. R. 2012. Inherent responses to root-zone salinity in nine alfalfa populations. Can. J. Plant Sci. 92: 235-248. Alfalfa productivity can be enhanced by growing crops from cultivars tolerant of root-zone salinity. Rangelander, Keho, Bridgeview, Halo, CW054038, CW064027, Rugged, Bullseye and TS4002 alfalfa plants (respectively designated Ra, Ke, Br, Ha, C8, C7, Ru, Bu and T4) were grown in sand tanks irrigated with nutrient-sulphate solutions averaging 1.53 (nutrients only), 8.03 and 15.61 dS m^-1 in electrical conductivity. Except for Br and C7, seedlings emerged equally under the 1.5 and 8.0 dS m^-1 treatments, but decreased in the 15.6 dS m^-1 treatment by percentages ranging from 3.1 through 29.5. Average shoot biomass among the populations respectively decreased by 49.6, 43.6 and 37.6% in the 1st, 1st 2nd, and 1st 2nd 3rd harvest-cuts as salinity increased from 1.5 to 8.0 dS m^-1 and by 80.1, 73.2 and 67.1% from 1.5 to 15.6 dS m^-1. At 1.5 dS m^-1, the C7 plants consistently produced more shoot biomass than the T4, Bu, Ha, Ru, Ra, or Ke plants. At 8 dS m^-1, the relative yields of the Ha plants (scaled by their 1.5 dS m^-1 production) exceeded those from the other populations, although the Ha plants produced no greater actual shoot biomass than the C7 or the C8 plants.

Wang, A.-y., Li, Y. and Zhang, C.-q. 2012. QTL mapping for stay-green in maize (Zea mays). Can. J. Plant Sci. 92: 249-256. Stay-green is a desirable character for crop production. In order to explore the genetic basis for stay-green traits in maize, 112 polymorphic simple sequence repeat (SSR) markers were used to analyze 189 F₂ individuals derived from a single cross of inbred lines A150-3-2 (a stay-green inbred line) and Mo17 (a normal inbred line). A total of 14 quantitative trait loci (QTLs) were detected for three stay-green related traits, green leaf area per plant at 30 d after flowering (GLA2), green leaf area per plant at the grain-ripening stage (GLA3), and left green leaf number per plant at the grain-ripening stage (LLN). Single QTL explained from 3.16 to 12.50% of the phenotypic variance. Among them, three were major QTLs. In addition, we analyzed the other two traits, green leaf area per plant in the whole growing period (GLA1) and total leaf number per plant in the whole growing period (TLN), and detected eight QTLs for them. Our results will be helpful to the maize breeders for marker-assisted selection.

Molnar, S. J., Charette, M. and Cober, E. R. 2012. Mapping quantitative trait loci for water uptake in a recombinant inbred line population of natto soybean. Can. J. Plant Sci. 92: 257-266. Small-seeded natto soybeans are soaked in the first step of producing natto. Water uptake traits play a role in the quality of the end product. The objectives of the current study were to use a recombinant inbred line (RIL) mapping population contrasting for water uptake traits to develop its molecular marker recombination map, and to use quantitative trait locus (QTL) analysis to characterize the genetics of water uptake and identify molecular markers for marker assisted breeding. A RIL population (AC Colibri×OT91-3) was tested for multiple years at Ottawa, Ontario, Canada. Two water uptake parameters (a16 and b) were estimated by fitting a curve for an exponential rise to a maximum. Both parameters were affected by year, genotype and the interaction effects. Seed yield, seed composition and agronomic traits were also measured. Simple sequence repeat (SSR) markers were used to genotype the population and develop a recombination map. QTL analysis identified two QTL for a16 on molecular linkage groups (MLG) D2 and E and three QTL for b on A2, J and M. Three of these QTL map to similar intervals as known QTL for seed weight, seed yield and seed fill in diverse populations. The fourth may correspond with a known QTL for water absorbability during germination and the fifth maps at or near known flowering time and maturity QTL.

Hampson, C. R., Randall, P. and Sholberg, P. 2012. Short communication:Tolerance of Vineland apple rootstocks to waterlogging andPhytophthorainfestation. Can. J. Plant Sci. 92: 267-269. The Vineland (V) apple (Malus) rootstock series has displayed a range of dwarfing potential and fire blight resistance in research test plots. Knowledge of their resistance to crown and root rot, incited by Phytophthora spp., is desirable before recommending them for on-farm testing, but information on this subject is lacking. Therefore, we tested the response of V.1, V.2, V.3 and V.4 clonal rootstocks to Phytophthora (P. cactorum and P. cryptogea) and waterlogging (0, 24 or 48 h per week for 4 mo) in a factorial greenhouse experiment on potted plants, using M.9 (moderately resistant to Phytophthora) and MM.106 (susceptible) as standards for comparison. Root fresh weight was reduced equally by both pathogens relative to uninoculated controls; rootstocks differed in their response to flooding but not to pathogen treatment. Shoot fresh weight was depressed by flooding in a rootstock- and pathogen-dependent manner. In general, all four V rootstocks had better root and shoot growth than MM.106 in the flooding treatments, and all grew as well as, or better than M.9.

Landry, E. J. and Wolyn, D. J. 2012. A method to assess cold acclimation and freezing tolerance in asparagus seedlings. Can. J. Plant Sci. 92: 271-277. Assessment of winter-hardiness using field-grown asparagus is complicated by variable, yearly climatic conditions and the large crown growing below the soil surface. The development of a seedling assay in controlled environments would be beneficial to study the physiology of winter-hardiness and to facilitate the selection of superior genotypes in breeding programs. Two cultivars, Guelph Millennium (GM) and Jersey Giant (JG), with differing patterns of autumn fern senescence in the field, where GM senesces earlier than JG, were compared. Seedlings were analyzed for physiological parameters after cold acclimation (10°C day/5°C night) or cold acclimation followed by sub-freezing (3°C to -3°C) in controlled environment chambers. Cold acclimation induced greater chlorophyll loss in GM than JG, consistent with previous field observations. LT₅₀, the temperature at which 50% mortality occurs, decreased to approximately -8°C for both cultivars after the initial cold acclimation treatment. Subsequent subfreezing acclimation increased the LT₅₀ for JG to -5°C, decreased freezing tolerance, while that for GM did not change. Early senescence and high proline concentration as well as stable protein and reducing sugar concentrations were associated with the freezing tolerance observed in GM. Further studies are required to establish if the cultivar differences for freezing tolerance identified here are correlated with experiments from field-grown plants.

Bastien, M., Huynh, T. T., Giroux, G., Iquira, E., Rioux, S. and Belzile, F. 2012. A reproducible assay for measuring partial resistance toSclerotinia sclerotiorumin soybean. Can. J. Plant Sci. 92: 279-288. In eastern Canada, Sclerotinia stem rot in soybean is an important disease, and resistance is systematically assessed in cultivar performance trials. The reference method used in these trials closely mimics the natural infection process, but is very demanding, and its success is highly subject to environmental conditions. Here we describe a simple, quick and reproducible inoculation method to measure resistance to pathogen progression on the main stem. Importantly, this method is the first to reproducibly identify quantitative trait loci (QTLs) conferring partial resistance to Sclerotinia stem rot in soybean. In this method, a cotton pad saturated with a mycelial suspension is applied to a floral bud and resistance is estimated by measuring lesion length on the main stem. The method was found to discriminate clearly between known resistant and susceptible checks in both the field and greenhouse. Clear discrimination between 26 recombinant inbred lines (RILs) contrasted for QTLs controlling resistance to Sclerotinia stem rot was also achieved in four independent trials, and lesion length was significantly correlated among all trials. When tested on 38, 42 and 40 lines in registration trials, the results of this method were significantly correlated with those of the reference method in 2 of 3 yr.

Conner, R. L., Gossen, B. D., Hwang, S. F., Chang, K. F., McRae, K. B. and Penner, W. C. 2012. Field assessment of partial resistance to mycosphaerella blight inPisumsubspecies accessions. Can. J. Plant Sci. 92: 289-296. Mycosphaerella blight, caused by Mycosphaerella pinodes (Berk. & Bloxam) Vestergr., the teleomorph of Ascochyta pinodes Jones, is an important foliar disease of field pea in the major production areas of the world. Partial resistance to mycosphaerella blight has been reported in some field pea cultivars, but, at best, they are only moderately susceptible. A 3-yr field study was conducted to evaluate the mycosphaerella blight reactions of 28 accessions from a number of subspecies of Pisum sativum L. and one accession of P. fulvum Sibth. A few of the accessions carried mutations for the genes af, tl, and st that affect the morphology of the leaflets, stipules and tendrils. Reactions to mycosphaerella blight were characterized based on the mean of the severity ratings taken on the two final assessment dates before the crop matured and also on the change in mycosphaerella blight severity between these two dates. In many of the accessions, severity ratings were similar to that of the moderately susceptible check cultivar, CDC Peko, while a few had high severity ratings similar to those of the susceptible check cultivars. The accession PI 512079, which has small stipules, branched petioles with many leaflets but no tendrils, had the lowest ratings for mycosphaerella blight severity. Four other accessions exhibited the smallest change in mycosphaerella blight severity at the end of the growing season. Differences in leaf morphology likely influenced the change in disease severity, since all the semi-leafless and leafless accessions had smaller changes in mycosphaerella blight severity than the susceptible check cultivars. In a detached leaf assay with two isolates of Mycosphaerella pinodes (Berk. & Bloxam) Vestergr., the smallest lesions formed on PI 512079, but otherwise the results failed to show a relationship with the observed severity values in the field trials.

Soltani, N., Shropshire, C. and Sikkema, P. H. 2012. Co-application of glyphosate plus an insecticide or fungicide in glyphosate-resistant soybean. Can. J. Plant Sci. 92: 297-302. Six field trials were conducted from 2008 to 2010 in Ontario to evaluate soybean injury and weed control efficacy with glyphosate tankmixed with various insecticides or fungicides. There was minimal visual injury (less than 4%) in glyphosate-resistant soybean and no adverse effect on soybean height and yield when cyhalothrin-lambda (Matador^®), dimethoate (Lagon^®), imidacloprid/deltamethrin (Concept^®), spirotetramat (Movento^®), pyraclostrobin (Headline^®), azoxystrobin (Quadris^®), propiconazole (Tilt^®), azoxystrobin/propiconazole (Quilt^®), tebuconazole (Folicur^®) and trifloxystrobin/propiconazole (Stratego^®) were tankmixed with glyphosate. Velvetleaf, pigweed species, common ragweed, common lambsquarters and green foxtail control ranged from 91-97, 94-99, 92-99, 80-94 and 98-100%, respectively. However, there was no adverse effect on velvetleaf, pigweed, common ragweed, common lambsquarters and green foxtail control, density and dry weight when one of the insecticides or fungicides evaluated was tankmixed with glyphosate. Based on these results, glyphosate tankmixed with cyhalothrin-lambda, dimethoate, imidacloprid/deltamethrin, spirotetramat, pyraclostrobin, azoxystrobin, propiconazole, azoxystrobin/propiconazole, tebuconazole or trifloxystrobin/propiconazole causes minimal crop injury and has no adverse effect on weed control in glyphosate-resistant soybean under Ontario environmental conditions.

Park, K. W., Kolkman, J. M. and Mallory-Smith, C. A. 2012. Point mutation in acetolactate synthase confers sulfonylurea and imidazolinone herbicide resistance in spiny annual sow-thistle [Sonchus asper (L.) Hill]. Can. J. Plant Sci. 92: 303-309. Suspected thifensulfuron resistant spiny annual sow-thistle was identified near Colfax, Washington, in two fields with a winter wheat and lentil rotation. Therefore, studies were conducted to examine resistance of spiny annual sow-thistle to thifensulfuron and cross-resistance to other acetolactate synthase inhibitors and to determine the physiological and molecular basis for herbicide resistance. Whole-plant bioassay confirmed that the biotype was highly resistant to the sulfonylurea (SU) herbicides, thifensulfuron, metsulfuron, and prosulfuron. The resistant (R) biotype was also highly resistant to the imidazolinone (IMI) herbicides, imazamox and imazethapyr. An in vivo acetolactate synthase (ALS) assay indicated that the concentrations of SU and IMI herbicides required for 50% inhibition (I₅₀) were more than 10 times greater for R biotype compared with susceptible (S) biotype. Analysis of the nucleotide and predicted amino acid sequences for ALS genes demonstrated a single-point mutation from C to T at the als1 gene, conferring the substitution of the amino acid leucine for proline in the R biotype at position197. The results of this research indicate that the resistance of spiny annual sow-thistle to SU and IMI herbicides is due to on altered target site and caused by a point mutation in the als1 gene.

Jin, C.-W., Sun, Y.-L. and Cho, D.-H. 2012. Changes in photosynthetic rate, water potential, and proline content in kenaf seedlings under salt stress. Can. J. Plant Sci. 92: 311-319. As irrigation water salinization has become a serious constraint for crop production, as well as soil salinity, the selection and use of salt-tolerant species is urgently required. In this study, we describe the salt responses of three kenaf (Hibiscus cannabinus L.) cultivars and select the cultivar with high salt tolerance. Responses to salt stress were investigated in terms of growth, water potentials, photosynthesis, and proline contents. Photosynthesis, evaluated by net CO₂ assimilation rate, stomatal conductance, and intercellular CO₂ concentration, did not show any significant effects among the cultivars. Leaf water potential decreased depending on salt concentration and salt treatment period. Proline accumulation was enhanced, particularly depending on salt concentration, but not salt treatment period. As salt concentration increased, seedling growth was inhibited to a certain extent, and the inhibition of growth depended mainly on salt concentration. At the early stage of treatment, Dowling was more tolerant to salt stress than Everglade-41 and Tainung-2. Although Dowling showed a lower decrease in fresh weight, Tainung-2 always maintained a relatively high vegetative yield, even under high salt stress. Tainung-2, having greater salt adaptation, was therefore considered an ideal cultivar for popularization and farm cultivation.

O'Donovan, J. T., Turkington, T. K., Edney, M. J., Juskiw, P. E., McKenzie, R. H., Harker, K. N., Clayton, G. W., Lafond, G. P., Grant, C. A., Brandt, S., Johnson, E. N., May, W. E. and Smith, E. 2012. Effect of seeding date and seeding rate on malting barley production in western Canada. Can. J. Plant Sci. 92: 321-330. Barley (Hordeum vulgare L.) growers in western Canada often have difficulty achieving malting grade. This is usually due to unfavourable climatic conditions, but sub-optimal agronomic practices may also be a factor. Field experiments were conducted in 2006, 2007 and 2008 at eight locations in western Canada (24 site-years) to evaluate the effects of seeding date (relatively early and late) and seeding rate (100, 200, 300, 400 and 500 seeds m^-2) on AC Metcalfe barley yield and malt quality parameters. Delayed seeding often resulted in negative effects including increased protein concentration, decreased kernel plumpness and yield. However, at 6 site-years, higher yields occurred at the later seeding date. 300 seeds m^-2 was usually optimal; maintained or improved yield, decreased protein concentration, increased kernel uniformity and time to seed maturity, and decreased tillering. In most cases, seeding at more than 300 seeds m^-2 did not result in an improved outcome, and there was a risk of reduced yield and kernel plumpness at rates above this level. A multivariate analysis indicated that relatively low barley plant densities were associated primarily with northern locations with low soil pH.

Ziadi, N., Bélanger, G. and Claessens, A. 2012. Relationship between soil nitrate accumulation and in-season corn N nutrition indicators. Can. J. Plant Sci. 92: 331-339. Nitrogen management tools are required to optimize crop growth and yield while minimizing the likelihood of N losses to the environment. We previously determined that non-limiting N conditions for near maximum corn (Zea mays L.) grain yield are reached with the following threshold values for three in-season plant-based indicators of corn N nutrition determined at approximately the V12 stage of development: N nutrition index (NNI)=0.88, leaf N (N_L) concentration =32.7 mg N g^-1 leaf DM, and relative chlorophyll meter (RCM) values =0.95. Our objective was to study the relationship between these plant-based indicators and soil NO₃-N content in an effort to develop tools to reduce the likelihood of soil NO₃-N accumulation without affecting grain yield. This study at 5 site-years in Québec consisted of six N fertilizer rates (20-250 kg N ha^-1). The NNI, N_L concentrations, RCM values, and soil (0-0.15 m) NO₃-N content were measured weekly from July to early August, while soil NO₃-N content to a 0.90-m depth was measured in late August and October. During the growing season from July to early August, the proportion of data points above the average soil NO₃-N content was greater under non-limiting N conditions (NNI ≤ 0.88, N_L concentrations ≤ 32.7 mg N g^-1 leaf DM, or RCM values =0.95) than under limiting N conditions. Furthermore, the mean soil NO₃-N content of the data points above the general average was much higher under non limiting than limiting N conditions in late August (167 vs. 78 kg NO₃-N ha^-1 for NNI and RCM; 166 vs. 112 kg NO₃-N ha^-1 for N_L concentration) and October (68 vs. 49 kg NO₃-N ha^-1). High soil NO₃-N accumulation during the season and at harvest occurs only when in-season plant-based N indicators are greater than their threshold values.

Karamanos, R. E., Flore, N. A., Harapiak, J. T. and Stevenson, F. C. 2012. The effect of non-targeted application of propiconazole on the yield and quality of malt barley. Can. J. Plant Sci. 92: 341-349. There is a desire to use non-targeted applications of foliar fungicide to improve malting barley production under higher fertility situations. An experiment was conducted at 80 sites (location by year combinations) with a 12 combinations of N/P/K rate-placement to determine if applications of propiconazole improve malt barley yield and quality under high fertility conditions. Treatment differences for days to maturity were no greater than about 1 d. Fungicide by fertility treatment interactions were not significant (P>0.05). Applications of propiconazole improved yield by 305 kg ha^-1 (6%) and plump kernels by 3 g kg^-1 (3%) across all fertility treatments, which included N fertilizer rates ranging from 0 to 90 kg N ha^-1. The effect of fungicide on yield was greatest at sites with highest yield potentials (ca. 8000 kg ha^-1) and was not statistically significant at lower-yielding sites (ca. 3000 kg ha^-1). Application of propiconazole also improved net returns [barley revenue - (N cost propiconazole cost other operating costs)] by $22 ha^-1 with higher barley priced ($190 T^-1) and high yield potentials. At sites with low yield potential, the application of propiconazole resulted in net losses of about $7 ha^-1 compared with not applying propiconazole. Nitrogen fertilizer rates from 0 to 90 kg N ha^-1 (15/30-0 P-K fertilizer treatment combinations) increased yield and protein concentration, and reduced plump kernels in a curvilinear fashion when averaged across fungicide treatments. Net returns were maximized at N fertilizer rates slightly less than 90 kg N ha^-1, depending on the price/cost regime. Consequently, malt barley producers will have to consider tradeoffs regarding N fertilizer rate that optimizes yield/returns and kernel quality. Also, decisions regarding fungicide applications and N/P/K fertilizer rate-placement applications can be made independent of each other for malt barley production.

Smith, T. H., Michaels, T. E., Navabi, A. and Pauls, K. P. 2012. Rexeter common bean. Can. J. Plant Sci. 92: 351-353. Rexeter common bean (CFIA registration no. 7019) is a full season maturity white bean (Phaseolus vulgaris L.) cultivar with an upright growth habit with excellent yield potential, resistance to common bacterial blight and acceptable cooking quality.

Thomas, J. B. and Graf, R. J. 2012. AC Readymade and AC Tempest, selections from Redwin hard red winter wheat. Can. J. Plant Sci. 92: 355-361. AC Readymade and AC Tempest are hard red winter wheat (Triticum aestivum L.) cultivars selected from the Montana cultivar ‘Redwin’ to conform to the kernel visual distinguishability requirements of the Canada Western Red Winter (CWRW) wheat class. AC Readymade and AC Tempest were registered in 1991 and 1999, respectively, following 3 yr of testing in the Western Winter Wheat Cooperative registration trials relative to various checks including Winalta, Norstar, CDC Clair and CDC Osprey. The survival characteristics of these cultivars demonstrated that they were well-suited to the relatively mild winter climate of southern Alberta. In this region of the prairies, AC Tempest had 4% higher grain yield than AC Readymade and was not significantly different from the other checks except Winalta, which was lower yielding. Both cultivars displayed relatively late maturity, moderate height, exceptional straw strength, high test weight, large kernels, high grain protein content and moderate resistance to common bunt. AC Tempest had significantly higher flour yield than AC Readymade.

Beres, B. L., Skovmand, B., Randhawa, H. S., Eudes, F., Graf, R. J. and McLeod, J. G. 2012. Sunray spring triticale. Can. J. Plant Sci. 92: 363-367. Sunray, a spring triticale (×Triticosecale Wittmack) cultivar, is adapted to the Canadian prairies and represents an improvement in ergot resistance for Canadian triticale. Sunray is resistant to the prevalent races of leaf rust, stem rust, common bunt and common root rot and is moderately resistant to grain sprouting. Sunray is short-statured with excellent lodging resistance and grain yield; grain volume test weight and seed mass were similar to the check cultivars. Sunray matures 2 d earlier than Pronghorn and AC Certa, and similar to AC Ultima. Sunray is eligible for the grades of Canada Triticale.