Wang, H., Gan, Y., Brandt, K., He, Y., Qin, X. and Li, Z. 2015. Can surface residue alleviate water and heat stress? Can. J. Plant Sci. 95: 197-200. Surface-placed residue increased the near soil surface moisture and reduced root heat stress. The improved micro environment resulted in greater root length for wheat (Triticum aestivum L.) and canola (Brassica napus) and 34, 8 and 8% higher yield, 7, 52 and 20% more straw and 7, 5, and 7.5 cm taller than the non-residue check for wheat, canola and dry pea (Pisum sativum), respectively.

Hucl, P. and Ramachandran, A. 2015. Agronomic characteristics of hard red spring wheat (Triticum aestivum L.) near-isogenic lines differing at the Waxy (Wx) locus. Can. J. Plant Sci. 95: 201-204. Null mutations of the Waxy gene in all three genomes of hexaploid wheat (Triticum aestivum L.) produce a waxy starch phenotype. The agronomic performance of 32 waxy, partially waxy and wild-type near-isogenic spring wheat lines and four check cultivars was assessed at two locations over three cropping seasons. Differences in grain yield, kernel weight and test weight among allelic groups were generally small. The results of our study suggest that no significantly negative effects are likely to occur in the commercial cultivation of partially waxy wheat lines derived from a CWRS cultivar.

Knight, J. D. 2015. Delayed inoculation of alfalfa with Sinorhizobium meliloti and Penicillium bilaiae. Can. J. Plant Sci. 95: 205-211. The persistence of perennial forage legume crops relies on the establishment of an effective symbiotic relationship with the appropriate Rhizobium species and strain. Situations can arise where a forage legume crop fails to symbiotically fix N₂. This study investigates if inoculation of alfalfa with a commercial Sinorhizobium meliloti inoculant 1 yr after seeding can induce biological N₂ fixation at levels similar to those achieved when the inoculant is applied at seeding. Alfalfa (Medicago meliloti cv. Algonkwin) was grown at two sites in Saskatchewan and inoculated with S. meliloti or S. meliloti plus the P-solubilizing fungus Penicillium bilaiae. The inoculants were applied at seeding or applied 1 yr after seeding. Biological N₂ fixation was measured in the fall of the delayed inoculation year as percentage of N derived from atmosphere (%Ndfa) using the ¹⁵N isotope dilution technique. Inoculation with S. meliloti increased %Ndfa at both sites relative to uninoculated and fertilized controls but had no effect on total N content or yield. Inoculating alfalfa the year after seeding increased %Ndfa relative to the controls at both sites, and at one of the sites %Ndfa in the delayed treatments was at the same levels measured in the year of seeding treatments.

Gu, C., Wang, L., Korban, S. S. and Han, Y. 2015. Identification and characterization of S-RNase genes and S-genotypes in Prunus and Malus species. Can. J. Plant Sci. 95: 213-225. Most Rosaceae fruit trees such as Prunus and Malus species exhibit gametophytic self-incompatibility that is genetically controlled by the S-locus. In turn, the S-locus contains at least two tightly-linked S-determinant genes, a pistil S-RNase and a pollen SFB. In this study, S-genotypes of 120 cultivated and wild Prunus accessions (peach) and seven wild Malus accessions (crabapple) have been characterized. Among cultivated Prunus genotypes, four S-RNase alleles, designated S₁, S₂, S₃, and S₄, have been identified, and they share typical structural features of S-RNases from all other self-incompatible Prunus species. Four S-genotypes, S₁S₂, S₁S₃, S₁S₄, and S₂S₂, were identified in peach cultivars, while only one S-genotype S₁S₂ for wild Prunus species. The S₁S₂ genotype is predominant in peach cultivars, accounting for 58.3% of all evaluated accessions. Similarly, four SFB alleles were identified in peach cultivars and wild accessions. However, all the four SFB alleles encode truncated proteins due to a frame-shift mutation, resulting in loss of hyper-variable and/or variable regions. For Malus species, a total of 14 S-RNase alleles are identified, and of those, two alleles encode truncated proteins. Overall, the genetic variation of both S-RNase and SFB genes in peach is significantly lower than that of S-RNase and SFB genes in self-incompatible Malus and/or Prunus species. The relationship between the genetic variation of SFB genes and the diversification of S-RNase genes in Rosaceae is also discussed.

Acosta-García, G., Chapa-Oliver, A. M., Millán-Almaraz, J. R., Guevara-González, R. G., Cortez-Baheza, E., Rangel-Cano, R. M., Ramírez-Pimentel, J. G., Cruz-Hernandez, A., Gueara-Olvera, L., Aguilera-Bibian, J. E., Hernández-Salazar, M. and Torres-Pacheco, I. 2015. CaLEA 73 gene from Capsicum annuum L. enhances drought and osmotic tolerance modulating transpiration rate in transgenic Arabidopsis thaliana. Can. J. Plant Sci. 95: 227-235. Late embryogenesis abundant (LEA) proteins are an important group of proteins related to the protection of several kinds of abiotic stresses in plants. A LEA gene was cloned from Capsicum annuum seeds and named CaLEA73. This gene was expressed in C. annuum plants during several phenological stages as well as in cold stress and exogen ABA applications. The CaLEA73 gene was ectopically expressed in transgenic Arabidopsis thaliana plants in order to analyse its role under drought and salt stress. Our results displayed an increase in tolerance to drought and osmotic, but not under salt stress in the transgenic lines evaluated. Interestingly, proline levels in transgenic lines were not higher than azygous control plants, when the drought stress was evaluated. Transpiration levels in transgenic plants were lower than control, suggesting an improvement in water efficiency use in CaLEA73 transgenic lines. The stomatal density and index were significantly minor in transgenic plants in comparison to azygous control, likely indicating a reason of the minor transpiration in transgenic plants. Our results are discussed in the context of drought stress physiology aspects for crop improvement.

Yang, S., Li, X., Ma, Y., Sun, X., Yang, Y. and Yang, Y. 2015. Proteome response of wild wheat relative Kengyilia thoroldiana to drought stress. Can. J. Plant Sci. 95: 237-249. Wild relatives of crops provide plant breeders with a broad pool of potentially useful genetic sources. The genus Kengyilia, being a member of the tribe Triticeae, is related to wheat, barley, and other cereals and forage grasses. We studied proteomic changes in K. thoroldiana seedlings in response to drought stress after withholding water for 0, 3, 6, 9 and 15 d. To determine the proteomic changes that occurred in leaves of K. thoroldiana under drought stress, two-dimensional gel electrophoresis (2-DE) and mass spectrometry were performed to identify protein expression changes. Seventy proteins showing reproducible and significant expression changes were identified. Among them, 28 proteins were up-regulated, whereas seven proteins were down-regulated. Based on database-annotated functions, these 70 proteins were categorized as energy metabolism, stress response, antioxidative enzyme, transcript and signal transduction, predicted proteins, and chloroplast-related proteins. Cluster analysis further showed that the up-regulated proteins were mainly stress response proteins and antioxidative enzymes. These results suggest that K. thoroldiana may resist drought stress by increasing the expression of stress response proteins and by producing antioxidative enzymes to remove reactive oxygen species. We conclude that the K. thoroldiana drought stress response mechanism could represent a useful genetic resource for related studies in wheat.

Clark, M. J. and Zheng, Y. 2015. Species-specific fertilization can benefit container nursery crop production. Can. J. Plant Sci. 95: 251-262. To determine the responses of six container-grown shrub species to different controlled-release fertilizer (CRF) application rates, plant growth and root-zone traits were evaluated following fertilization with Polyon^® 16-6-13, 5-6 month CRF incorporated at 0.60, 0.89, 1.19, 1.49 and 1.79 kg m^-3 N. The six species tested at a southwestern Ontario, Canada, nursery were Cornus stolonifera ‘Flaviramea’ (yellow-twig dogwood), Euonymus alatus ‘Compactus’ (dwarf winged euonymus), Hydrangea paniculata ‘Grandiflora’ (Pee Gee hydrangea), Physocarpus opulifolius ‘Nugget’ (Nugget ninebark), Spiraea japonica ‘Magic Carpet’ (Magic Carpet spirea), Weigela florida ‘Alexandra’ (Wine and Roses weigela). Different species responded differently to the CRF rates applied. For the majority of species at the final harvest, growth index, plant height, canopy area, leaf area and above-ground dry weight were greater in high vs. low CRF rates; however, different species had different optimal CRF application rates or ranges: 1.49 kg m^-3 N for Hydrangea and Spiraea, 1.19 kg m^-3 N for Weigela, 1.19 to 1.49 kg m^-3 N for Cornus and Physocarpus, and =0.60 kg m^-3 N for Euonymus. Based on these species-specific optimal fertilizer rates or ranges, growers can group plant species with similar fertilizer demands, thereby reducing fertilizer waste and maximizing plant production.

Zhang, H., Zhu, L., Zhang, C., Ning, Y. and Zhang, Y. 2015. Effect of water stress on dry mass accumulation and allocation in sweet potato based on stable isotope analysis. Can. J. Plant Sci. 95: 263-271. Pot experiments were conducted to study the effect of water stress on the dry mass accumulation, allocation, ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activity and stable carbon isotope composition in sweet potato (Ipomoea batatas L.). Three water regimes (50, 75 and 100% field water capacity, respectively) were investigated. Water stress effects on dry mass accumulation, allocation, gas exchange, stable carbon isotope composition and Rubisco enzyme activity were detected in sweet potato at different stages (seedling, vegetative, early maturity, and late maturity). In addition, relationships between Rubisco activity and photosynthetic rate, dry stress allocation and Δ¹³C under different water regimes were explored. The allocation of dry mass and Δ¹³C in leaves, petioles, stems and roots exhibited highest level in soil with 100% moisture content at different growth stages. The photosynthetic rate, transpiration, stomatal conductance, and RuBisCo activity of sweet potato at different growth stages also increased with increasing soil water content. The regression equations between the activity of RuBisCo and photosynthetic rate in 50, 75 and 100% field capacity were y=0.675x - 1.846, y=0.798x - 1.370, and y=0.516x 3.887. A positive correlation between dry mass allocation and Δ¹³C was observed. Water stress could affect dry mass accumulation, allocation, gas exchange, RuBisCo activity, and Δ¹³C content in sweet potato organs during plant development stages.

Van Eerd, L. L., Loewen, S. A. and Vyn, R. J. 2015. Winter wheat straw management on subsequent processing tomato yield, quality, economics and nitrogen dynamics. Can. J. Plant Sci. 95: 273-283. The removal of crop residues to meet the anticipated demand for the bioeconomy sector may impact subsequent crop productivity. A field experiment was designed to evaluate the response of processing tomato (Solanum lycopersicum L.) on winter wheat (Triticum aestivum L.) straw management practices of: (1) retaining straw, (2) removing straw, or (3) retaining straw with a fall application of calcium ammonium nitrate at 34 kg N ha^-1 to enhance straw decomposition. At two locations in 2006-2009, a split-plot design within a randomized complete block experiment, with wheat straw management as main-plot factor and nitrogen fertilizer (0 and 145 or 224 kg N ha^-1) to the tomato crop as split-plot factor. At Ridgetown, marketable and total yield and profit margins were significantly higher with straw retained compared with straw removed treatments (total yield of 74.4 vs. 66.3 Mg ha^-1 yr^-1, respectively) but the straw retained plus fall N treatment (total yield 72.8 Mg ha^-1 yr^-1) was not different. However, at Leamington, straw management had no effect on yield or profit margins likely due to the rye (Secale cereale L.) cover crop used in the production system. At both locations, tomato quality (color, pH, soluble solids) was not influenced by straw or N management. Nitrogen fertilizer application to tomato had a significant effect on total processing yield, soil mineral N, and plant N, but wheat straw management had no effect on these parameters and there were no N fertilizer by straw management interactions. Winter wheat straw management did not impact soil N fertility for subsequent crop production. Thus, there may be significant undesired effects of removing crop residues on a subsequent crop yield; however, planting a cover crop may mitigate subsequent yield losses associated with biomass removal.

Mahoney, K. J., Vyn, R. J. and Gillard, C. L. 2015. The effect of pyraclostrobin on soybean plant health, yield, and profitability in Ontario. Can. J. Plant Sci. 95: 285-292. Prophylactic fungicides have been advocated to manage foliar diseases, optimize plant heath, and increase yields. Studies were conducted in 2009, 2010, and 2011 using 20 soybean cultivars to determine if pyraclostrobin, a strobilurin, induced plant health effects to increase yield and profitability under conditions with low levels of foliar disease. Pyraclostrobin applied at the R3 stage significantly reduced leaf defoliation caused by brown spot (Septoria glycines Hemmi) compared with the untreated control with 27 and 45% defoliation, respectively, across all cultivars. Pyraclostrobin delayed maturity, but the response varied among cultivars. For example, cultivars with low levels of leaf defoliation responded with an increase in the number of days to maturity, whereas cultivars with high levels of defoliation generally did not. Pyraclostrobin increased yield by 4.1% compared with the untreated control across all cultivars with 4.49 and 4.31 t ha^-1 harvested, respectively. Increased revenue from increased yield was offset by increased fungicide costs, resulting in a negligible effect on profitability; however, effects of pyraclostrobin application on profit margins in individual environments ranged from -$50.02 ha^-1 in 2009 to $53.73 ha^-1 in 2011. Overall, these results suggest that if environmental conditions are conducive for foliar disease, a pyraclostrobin application could be warranted.

Hwang, S. F., Ahmed, H. U., Turnbull, G. D., Gossen, B. D. and Strelkov, S. E. 2015. Effect of seeding date and depth, seed size and fungicide treatment on Fusarium and Pythium seedling blight of canola. Can. J. Plant Sci. 95: 293-301. Seedling blight has a substantial impact on stand establishment and productivity of canola (Brassica napus) on the Canadian prairies. The effects of seeding date, seed size, seeding depth, and seed treatment fungicides on seedling blight of canola caused by Fusarium avenaceum and Pythium ultimum were evaluated under field conditions. In the trials inoculated with P. ultimum, early seeding reduced seedling emergence and seed yield in all 3 yr of the study. However, the interaction of F. avenaceum with seeding date was not consistent; inoculation with F. avenaceum reduced seedling emergence in early seeded canola in 1 of 4 yr, but emergence was higher in early than in mid-seeded treatments in 2 yr and there was no difference among seeding dates in 1 yr. Late seeding reduced seed yield in 2 of 4 yr in the F. avenaceum study. Seed size and seeding depth generally did not have an effect on seedling establishment or seed yield for either pathogen. Seed treatment with Helix Xtra (thiamethoxam difenconazole metalaxyl fludioxonil) and Prosper FX (clothianidin carboxin trifloxystrobin metalaxyl) fungicides increased seedling emergence and yield compared with the F. avenaceum-inoculated control. Seed treatment with Helix Xtra also increased seedling emergence and seed yield compared with the P. ultimum-inoculated control. Manipulation of seeding date did not substantially improve stand establishment or yield of canola when inoculum pressure was high. Seed treatment was the most effective strategy for reducing losses caused by seedling blight of canola in fields infested with F. avenaceum or P. ultimum.

Yu, L., Van Eerd, L. L., O'Halloran, I., Sikkema, P. H. and Robinson, D. E. 2015. Response of four spring-seeded cover crops to residues of selected herbicides. Can. J. Plant Sci. 95: 303-313. Although herbicide labels provide crop rotation restrictions, information is limited on the influence of herbicide residues on cover crops. Field experiments were conducted in 2011/2012 and 2012/2013 in Ontario, Canada, to characterize the effects of soil residues of selected herbicides on establishment and growth of buckwheat (Fagopyrum esculentum Moench), annual ryegrass (Lolium multiflorum Lam.), sorghum sudangrass [Sorghum bicolor (L.) Moench×Sorghum sudanense (P.) Stapf], and spring wheat (Triticum aestivum L.) spring-seeded cover crops planted 1 yr after application. Imazethapyr (100 and 200 g ha^-1) was applied pre-emergence (PRE) to processing peas (Pisum sativum L.), while S-metolachlor/atrazine plus mesotrione (2880 140 and 5760 280 g ha^-1) and saflufenacil/dimethenamid-P (735 and 1470 g ha^-1) were applied PRE to sweet corn (Zea mays L.). Imazethapyr residues from 200 g ha^-1 caused 75 and 48% visible injury in buckwheat and sorghum sudangrass, respectively. Plant light attenuation, shoot dry weight, and nitrate-nitrogen content were reduced up to 82, 64 and 67% in buckwheat, and 40, 11 and 24% in sorghum sudangrass, respectively, by residues from imazethapyr. S-metolachlor/atrazine plus mesotrione residues caused up to 53% visible injury to annual ryegrass and reduced plant light attenuation, shoot dry weight, and nitrate-nitrogen content by as much as 59, 48, and 55%, respectively. There were no observable adverse effects of visible injury, light attenuation, shoot dry weight, and nitrate-nitrogen content on spring wheat regardless of herbicide or rate. These results indicate that buckwheat and sorghum sudangrass should not be grown in the year following imazethapyr, and that annual ryegrass should not be grown in the year after application of S-metolachlor/atrazine plus mesotrione. However, no restrictions are needed for growing spring wheat following these herbicides.

Darras, S., McKenzie, R. H., Olson, M. A. and Willenborg, C. J. 2015. Influence of genotypic mixtures on field pea yield and competitive ability. Can. J. Plant Sci. 95: 315-324. Field pea breeding programs have been very successful at improving plant and disease resistance; however, limited success has been achieved in improving the competitive ability of field pea. A study was conducted to determine whether growing field pea in two-way genotypic mixtures could improve the crop's yield and competitive ability. A second objective was to determine if genetic relatedness had any effect on the mixing ability of genotypes. Genotypes were chosen on the basis of pedigree and included two sister lines (CDC1987-3 and CDC1897-14), their common parent (Eclipse), and a distantly related genotype (Midas). The four genotypes were grown as pure stands and as all possible two-way mixtures in field experiments conducted at Lethbridge and St. Albert, Alberta, from 2010 to 2011. The results revealed that CDC1897-3×Eclipse suppressed the model weed (barley); it reduced seed production by 47% (442 kg ha^-1) and 61% (391 kg ha^-1) compared with the same components within pure stands at Lethbridge 2010 and Lethbridge 2011, respectively. The same mixture also reduced model weed (barley) biomass production by 61% (831 kg ha^-1) at St. Albert in 2010, and by 41% (1372 kg ha^-1) at Lethbridge in 2010. Although mixtures demonstrated the potential to improve field pea competitive ability, results were not consistent across site-years. However, some mixtures did improve yield and competitive ability over the most poorly competitive genotypes in pure stand.

Robinson, M. A., Letarte, J., Cowbrough, M. J., Sikkema, P. H. and Tardif, F. J. 2015. Winter wheat (Triticum aestivum L.) response to herbicides as affected by application timing and temperature. Can. J. Plant Sci. 95: 325-333. Field studies were conducted to determine the effects of cold temperatures and physiological growth stage at the time of application on the tolerance of winter wheat (Triticum aestivum L.) to 10 herbicides used in Ontario, Canada. Herbicides were applied: early during a frost event (when forecasted temperatures ≤ 0°C); at a normal timing (Zadoks 21-29); and a late timing (Zadoks 39). Visible injury, yield, plant height at maturity, test weight and 1000-kernel weight were measured to determine if environmental conditions or growth stage at the time of herbicide application influenced wheat tolerance. Cold temperatures at the time of herbicide application resulted in injury with three treatments: 2,4-D, dicamba/MCPA/mecoprop and dichlorprop/2,4-D. Visible injury was greatest at 14 d after treatment (DAT); it was, however, transient and yield, plant height, test weight and 1000-kernel weight were not affected. The herbicides 2,4-D, dichlorprop/2,4-D, and fenoxaprop-p-ethyl caused visible injury 14 DAT when applied at the normal timing, while 2,4-D at this timing, also caused injury 7 DAT. Dicamba/MCPA/mecoprop was the most injurious herbicide, causing 4% injury at the normal timing and 11% injury at the late application timing (42 DAT). Dicamba/MCPA/mecoprop caused yield reductions of 11 to 24% at two locations in 2010 when applied at the normal timing. Dicamba/MCPA/mecoprop reduced yield at 6 of the 8 site-years when applied late, and also reduced plant height. Cold temperatures at the time of application did not affect tolerance of winter wheat; however, visible injury was more likely to occur when herbicides were applied at later growth stages. In most cases, herbicide injury was transient and no impact on yield was observed. Dicamba/MCPA/mecoprop was the most injurious herbicide, causing prolonged injury at all application timings and reducing yields when applied at the normal timing. In addition, yield and plant height were affected negatively when this herbicide was applied late.

Van Wely, A. C., Soltani, N., Robinson, D. E., Hooker, D. C., Lawton, M. B. and Sikkema, P. H. 2015. Glyphosate and acetolactate synthase inhibitor resistant common ragweed (Ambrosia artemisiifolia L.) in southwestern Ontario. Can. J. Plant Sci. 95: 335-338. Common ragweed (Ambrosia artemisiifolia L.) was found to be resistant to glyphosate in Ontario. Field surveys were conducted from 2011 to 2013 to determine the distribution of glyphosate-resistant (GR) and acetolactate synthase inhibitor resistant common ragweed. GR common ragweed was confirmed in Essex County. All GR populations were found to be resistant to acetolactate synthase-inhibiting herbicides.

Walsh, K. D., Soltani, N., Hooker, D. C., Nurse, R. E. and Sikkema, P. H. 2015. Biologically effective rate of sulfentrazone applied pre-emergence in soybean. Can. J. Plant Sci. 95: 339-344. Sulfentrazone is a protoporphyrinogen (PPO)-inhibiting herbicide under evaluation for use in soybean in Ontario, Canada. The primary objective of this study was to determine the dose of sulfentrazone applied pre-emergence (PRE) needed to provide 50 and 90% control of redroot pigweed, common ragweed, common lambsquarters and green foxtail. Seven field trials were conducted over a 3-yr period (2007, 2008 and 2009) in southwestern Ontario to evaluate the efficacy of sulfentrazone applied PRE at doses ranging from 26 to 1120 g a.i. ha^-1. The doses of sulfentrazone applied PRE to reduce redroot pigweed, common ragweed, common lambsquarters and green foxtail dry weight by 50% were 104, 139, 15 and 65 g a.i. ha^-1; doses of 241, 514, 133 and 721 g a.i. ha^-1 of sulfentrazone were required for 90% reduction in above-ground biomass of those weed species, respectively. Sulfentrazone applied PRE caused soybean injury only at 560 and 1120 g a.i. ha^-1, with 6 and 13% soybean injury at 4 wk after herbicide application (WAT), respectively. Weed control provided by sulfentrazone applied PRE at a dose of 600 g a.i. ha^-1 was sufficient to maintain 90% of the soybean yield compared with the weed-free control. Therefore, PRE application of sulfentrazone has the potential to provide excellent (>90%) control of selected weeds with minimal to no crop injury; however, weed control varied by species, and thus broad spectrum weed control is not feasible using sulfentrazone alone.

Beckie, H. J., Gulden, R. H., Shaikh, N., Johnson, E. N., Willenborg, C. J., Brenzil, C. A., Shirriff, S. W., Lozinski, C. and Ford, G. 2015. Glyphosate-resistant kochia (Kochia scoparia L. Schrad.) in Saskatchewan and Manitoba. Can. J. Plant Sci. 95: 345-349. Previous surveys have documented the occurrence of glyphosate-resistant (GR) kochia in Alberta in 2011 and 2012. To determine the incidence of GR kochia in Saskatchewan and Manitoba, a stratified-randomized survey of 342 sites (one population per site) in southern and central regions of Saskatchewan and a similar survey of 283 sites in southern Manitoba was conducted in the fall of 2013. Mature plants were collected, seed threshed, and progeny screened by spraying with a discriminating glyphosate dose of 900 g ae ha^-1 under greenhouse conditions. Screening confirmed 17 GR kochia populations in nine municipalities in west-central or central Saskatchewan, but only two GR populations from different municipalities in the Red River Valley of Manitoba. While the majority of GR kochia populations in Saskatchewan originated in chemical-fallow fields, some populations were found in cropped fields (wheat, Triticum aestivum L.; lentil, Lens culinaris Medik.; GR canola, Brassica napus L.) and non-cropped areas (oil well, roadside ditch). In Manitoba, the two populations occurred in fields cropped to GR corn (Zea mays L.) and soybean (Glycine max L. Merr.). Agronomic and economic impact of this GR weed biotype is compounded because of consistent multiple resistance to acetolactate synthase-inhibiting herbicides. However, GR kochia is susceptible to dicamba, an increasingly important auxinic herbicide used for control of this multiple-resistant weed biotype.

Mohr, R., Nelson, A., Tomasiewicz, D., McLaren, D., Monreal, M., Irvine, B., Khakbazan, M., Moulin, A., Derksen, D. and Volkmar, K. 2015. Nutrient status and crop productivity following a 14-year irrigated potato rotation study. Can. J. Plant Sci. 95: 351-360. Well-managed crop rotations contribute to high productivity and quality in subsequent crops, and neither excessively deplete nor increase soil nutrient levels. A field experiment was conducted in the year following completion of a 14-yr irrigated potato (Solanum tuberosum L.) rotation study to assess the impact of preceding rotation on soil P, K and micronutrient concentrations, and on soybean (Glycine max) productivity, yield and seed nutrient levels. Soybean was grown on six established rotations [potato with canola (PC), wheat (PW), canola-wheat (PCW), oat-wheat (POW), wheat-canola-wheat (PWCW), and canola underseeded to alfalfa-alfalfa-alfalfa (PCAA)] arranged in a randomized complete block design (RCBD) with four replicates. Soil nutrient levels fell within ranges typical of the region, as did soybean yield and quality. Lower P and K concentrations in spring soil samples, and in soybean seeds, were typically associated with PCAA, suggesting that fertilizer additions did not account for high rates of P and K removal by alfalfa hay in this rotation. While preceding rotation had minimal effects on soil Cu and Zn, soybean established after PCAA or after potato contained comparatively higher seed Cu and Zn concentrations suggesting that including mycorrhizal crops such as potato and alfalfa in rotation may have contributed to enhanced micronutrient availability. Soybean yield was 4-6% higher following potato than canola or cereals, and 6% higher following POW than PCW. Seed protein increased and oil concentration decreased where preceding rotations included alfalfa. The limited yield differences observed may have been due, in part, to the selection of soybean as an indicator crop, which likely minimized differences among rotations arising from disease, weeds and nitrogen. These findings suggest that, with careful management of irrigated potato systems over the longer term, crop productivity and nutrient availability may be maintained within acceptable levels for agricultural production.

Tamburic-Ilincic, L., Brinkman, J. M. P., Sparry, E. and Hooker, D. C. 2015. Optimizing inputs for winter durum wheat in Ontario. Can. J. Plant Sci. 95: 361-368. Best management practices need to be determined for a new wheat class in Ontario: winter durum. The objectives of this study were to determine optimal nitrogen rates (75, 100, and 125 kg N ha^-1), seeding rates (400, 440, and 480 seeds m^-2), and fungicide applications on the grain yield, grain protein, and leaf disease control of ‘OAC Amber’ winter wheat durum at five field locations in Ontario. Seeding rates between 400 and 480 seeds m^-2 did not impact performance. Overall, fungicide applications at flag leaf and flowering increased grain yield by an average of 0.52 Mg ha^-1, increased seed weight and test weight, reduced powdery mildew [Blumeria graminis (DC.) Speer f. sp. tritici emend. É.J. Marchal] and septoria leaf blotch [Mycosphaerella graminicola (Fuckel) J. Schröt.] in the canopy, but decreased grain protein from 128 to 126 g kg^-1. Grain yields did not increase with N rates higher than 100 kg N ha^-1, and the response to N rate did not depend on the application of fungicides. Grain protein concentrations increased with N rates up to 125 kg N ha^-1, which was the highest N rate investigated in this study. An economic analysis is needed to determine the impact of agronomic management strategies specific to winter durum wheat in Ontario.

McNaughton, K. E., Blackshaw, R. E., Waddell, K. A., Gulden, R. H., Sikkema, P. H. and Gillard, C. L. 2015. Effect of application timing of glyphosate and saflufenacil as desiccants in dry edible bean (Phaseolus vulgaris L.). Can. J. Plant Sci. 95: 369-375. Early application of desiccants in dry edible bean may cause yield reductions and unacceptable herbicide residue levels, resulting in rejection of exported shipments. The effect of application timing of two registered desiccants, glyphosate and saflufenacil, was examined in 12 field trials conducted over a 4-yr period (2009-2012) at Exeter, Ontario, Carman, Manitoba, and Lethbridge, Alberta. Desiccants were applied alone and in combination at five crop maturation stages. When glyphosate or saflufenacil alone, or in combination, was applied at 100% crop maturity, herbicide residue levels were acceptable (less than 2.0 and 0.01 ppm for glyphosate and saflufenacil, respectively) and there was no reduction in yield or hundred seed weight. Glyphosate residues remained below 2.0 ppm when the desiccant was applied alone or with saflufenacil at 75% crop maturity, but crop yield decreased by 16% compared with the untreated control when glyphosate and saflufenacil were combined. Residue levels were unacceptable when glyphosate was applied at 0, 25, and 50% maturity; generally the earlier glyphosate was applied, the greater the residue concentration in the seeds at harvest. Although no application timing resulted in saflufenacil residues above 0.01 ppm, crop yield was reduced when the desiccant was applied at 0, 25, 50, and 75% crop maturity. This information will provide dry bean processors with the necessary information to design guidelines concerning the application timing of glyphosate and saflufenacil so that bean yield and quality remain unaffected and seed residues remain below accepted levels.

Golabadi, M., Golkar, P. and Eghtedary, A.-R. 2015. Combining ability analysis of fruit yield and morphological traits in greenhouse cucumber (Cucumis sativus L.). Can. J. Plant Sci. 95: 377-385. Knowledge about the genetic control of the different quantitative characters related to fruit yield and its components is still insufficient in greenhouse cucumbers. This information is useful in planning breeding programs in this economically important crop. In this study, the genetics of morphological traits and fruit yield was investigated using a 9×9 full diallel population of cucumbers for the greenhouse market. Data were collected on internode length, leaf length, leaf width, fruit length, fruit diameter, number of fruits per plant, yield per fruit and yield per plant. Variance components showed that both the additive and the dominant gene effects played significant roles in the genetic control of the traits studied. Genetic control of internode length, leaf width and number of fruits per plant was accomplished by additive effects. The significant mean squares of reciprocal crosses for all of the studied traits suggested that maternal inheritance also played an important role in the inheritance of these traits. Significant general combining ability for fruit yield revealed that both selection and hybridization methods would lead to desirable genetic improvements in cucumber through accumulation of desirable alleles from parents in the target genotype, but that hybridization would be preferred.

Qu, C., Hasan, M., Lu, K., Liu, L., Zhang, K., Fu, F., Wang, M., Liu, S., Bu, H., Wang, R., Xu, X., Chen, L. and Li, J. 2015. Identification of QTL for seed coat colour and oil content in Brassica napus by association mapping using SSR markers. Can. J. Plant Sci. 95: 387-395. Association mapping identifies quantitative trait loci (QTL) based on the strength of linkage disequilibrium (LD) between markers and functional polymorphisms across a set of diverse germplasms. In this study, we used association mapping to detect QTL and genome-wide simple sequence repeat (SSR) markers linked to seed coat colour and oil content in a population of 217 oilseed rape (Brassica napus L.) accessions. We corrected for the population structure of B. napus using 389 genome-wide SSR markers. In total, 25 and 11 SSR markers linked to seed coat colour and oil content were detected, respectively, and these two sets of markers were in different linkage groups. Nine of these markers for seed coat colour spanned the major QTL region for seed coat colour, and been mapped to chromosome A9. Six of these markers showed high levels of association with both seed coat colour and oil content, and markers H081N08.8 and KS20291 were mapped to the major QTL region for seed coat colour on chromosome A9. Another marker, CB10364, was in high LD with all determined seed coat colour and oil content traits, and was mapped to the co-localized QTL region for them on chromosome A8. These data indicate that seed coat colour was found to be an important contributor to seed oil content. Further, we show that association mapping using a heterogeneous set of genotypes is a suitable approach for complementing and enhancing previously obtained QTL information for marker-assisted selection.

Thomas, E. C. and Lavkulich, L. M. 2015. Community considerations for quinoa production in the urban environment. Can. J. Plant Sci. 95: 397-404. Production of food crops in urban settings is an increasingly consumer-accepted means of contributing to local food security and access to fresh produce. Many urban gardens are located on former industrial sites (brownfields) that may be contaminated by heavy metals. Growing crops in trace metal contaminated soil can pose human health concerns. Little has been documented on the uptake of metals from urban sites by crops, and especially the partitioning of metals between roots, shoots and seeds. Human health impacts are of particular concern when locally grown produce constitutes a major proportion of the local diet. The results of this study show that quinoa grown on brownfield sites in Vancouver, Canada may contain elevated levels of metals such as Cd, Cu and Pb.

Espinosa, K., Boelter, J., Lolle, S., Hopkins, M., Goggi, S., Palmer, R. G. and Sandhu, D. 2015. Evaluation of spontaneous generation of allelic variation in soybean in response to sexual hybridization and stress. Can. J. Plant Sci. 95: 405-415. Intra-cultivar variation reported in pure lines of soybean has been hypothesized to result from genetic mechanisms contributing to de novo genetic variation. In this study we have detected allele switching by following segregation patterns of Aconitase-4 isozyme in sexual crosses and pure lines. In sexual crosses, one F₂ plant showed a switch at the Aconitase-4 (Aco4) locus from the expected heterozygous genotype Aco4-ac to Aco4-ab. In the pure lines grown in a honeycomb planting design and treated with an accelerated aging test, multiple cases of allele switching were detected at the Aco4 locus. Both single and double switches were detected that were stable and heritable. These findings indicate that the generation of endogenous variation continues in pure lines as a result of intrinsic genetic mechanisms. With a long-term goal of understanding the genetic nature of the changes, we genetically mapped the Aco4 gene to a 3.3 cM region on Chromosome 11. The corresponding physical region is ~293 kb with 39 predicted genes. Of these, Glyma.11g080600 is of particular interest, as it shows 93% and 88% identity to Medicago truncatula and Arabidopsis aconitase genes, respectively. Further characterization of the soybean Aco4 gene may shed light on genetic mechanisms responsible for allele switching.

Liu, L., Wang, Z., Zhao, X., Nan, L., Nan, H., Wang, S. and Li, H. 2015. Effects of different photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. Can. J. Plant Sci. 95: 417-426. The effects of two photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. were studied. The experiments used V. amurensis variety ‘Shuang hong’ as the experimental grape, NaHSO₃ (sodium bisulfite) and isoniazide (INH) as the photorespiration inhibitors with three different spray concentrations, respectively. Results show that both photorespiration inhibitors improved the soluble solids (SS) contents and SS/total acid (TA) ratios (except the 350 mg L^-1 INH treatment) in V. amurensis berries; two inhibitors can also improve the concentrations of glucose, sucrose, arabinose, lactose as well as monosaccharides (MS) and MS disaccharides (DS) contents, and at the same time decrease the TA contents in V. amurensis berries. Meanwhile, all NaHSO₃ treatments had higher SS, SS/TA, glucose, and sucrose than treatments with the same concentrations of INH. However, the arabinose contents in all the INH treatments were higher than those in NaHSO₃ treatments at the same concentrations. Compared with INH treatments, NaHSO₃ were better at increasing net photosythesis rate (Pn), Rubisco carboxylation efficiency (CE), intercellular CO₂ concentration (Ci) and decreasing photorespiration rate (Pr). However, the effects of NaHSO₃ and INH on fluorescent characteristics of V. amurensis leaves were not significant. The fact that maximal values for photochemical efficiency of photosystem II complex (PSII) in the dark (F_v/F_m) in this study were large indicate that both NaHSO₃ and INH had positive effects on chlorophyll fluorescence of V. amurensis leaves, which meant they had the ability to release surplus light energy and mitigate photoinhibition by inhibiting photorespiration at all three concentrations. Comprehensive analysis clearly indicates that NaHSO₃ had better effects on photorespiration inhibition and fluorescent characteristics, and improved photosynthesis and the quality of V. amurensis grape berries, especially at 250 mg L^-1.

Gravel, V., Dorais, M., Dey, D. and Vandenberg, G. 2015. Fish effluents promote root growth and suppress fungal diseases in tomato transplants. Can. J. Plant Sci. 95: 427-436. Aquaculture systems generate large amounts of wastes which may constitute a beneficial amendment for horticultural crop in terms of nutrients, plant growth promoter and disease suppressiveness. This study aimed to determine (1) the nutrient value of rainbow trout farming effluents coming from two feed regimes and (2) the plant growth and disease suppressiveness effects of those fish farming effluents on tomato transplants. The effluent sludge from Skretting Orient™ (SO) had a higher content of P (38 vs. 32 mg L^-1), K (23 vs. 11 mg L^-1), N (19 vs. to 11 mg NO₃ L^-1; 186 vs. 123 mg NH₄ L^-1), and a higher NO₃:NH₄ ratio (1:9 vs. 1:13) compared with the Martin Classic (MC), while MC was richer in Mg (42 vs. 24 mg L^-1) and Ca (217 vs. 169 mg L^-1). For the first trial, a stimulating effect of the fish effluent was observed on plant height, leaf area and root dry biomass, while only the root biomass was increased during the second trial. Fish sludge was rich in microorganisms (97 and 142 µg fluorescein h^-1 mL^-1 for SO and MC, respectively) and their ability to suppress Pythium ultimum Trow and Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyder & Hansen was observed. Both crude fish effluents reduced in vitro mycelial growth of P. ultimum and F. oxysporum, by 100 and 32%, respectively, while MC effluents showed a higher inhibition against F. oxysporum. When fish effluents were sterilized by filtration or autoclaving, lower in vitro inhibition of P. ultimum and F. oxysporum was observed. Mixed fish effluents reduced tomato plant root colonization by P. ultimum (by up to 5.7-fold) and F. oxysporum (by up to 2.1-fold). These results showed that fish effluent can be used as soil amendments to promote plant growth and increase soil suppressiveness, which in turn can prevent soil-borne diseases.

Balasubramanian, P. M., Mündel, H.-H., Conner, R. L., Chatterton, S. and Hou, A. 2015. AAC Black Diamond 2 dry bean. Can. J. Plant Sci. 95: 437-440. AAC Black Diamond 2 is a high-yielding black bean (Phaseolus vulgaris L.) cultivar with an upright, indeterminate bush growth habit, lodging resistance, shiny black seed coat and improved resistance to seed-borne common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli. AAC Black Diamond 2 was developed at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Lethbridge, AB. AAC Black Diamond 2 is suitable for irrigated production in Alberta and Saskatchewan.

Yu, K., Woodrow, L. and Poysa, V. 2015. AAC 26-15 soybean. Can. J. Plant Sci. 95: 441-443. AAC 26-15 is a high-yielding, high-protein, SCN resistant, food grade soybean cultivar with yellow hila and acceptable processing quality for foreign and domestic tofu and soymilk markets. It was developed at Agriculture and Agri-Food Canada (AAFC), Greenhouse and Processing Crops Research Centre (GPCRC), Harrow, Ontario. AAC 26-15 is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity of 2.3 (MG 2.3).