Harker, K. N., O'Donovan, J. T., Smith, E. G., Johnson, E. N., Peng, G., Willenborg, C. J., Gulden, R. H., Mohr, R., Gill, K. S. and Grenkow, L. A. 2015. Seed size and seeding rate effects on canola emergence, development, yield and seed weight. Can. J. Plant Sci. 95: 1-8. Canola (Brassica napus L.) is the most common dicotyledonous crop in Canada. Here we determine the effect of canola seed size and seeding rate on canola emergence, development, yield and seed weight. In 2013, direct-seeded experiments were conducted at nine western Canada locations. Four canola seed sizes (1000-seed weights ranging from 3.96 to 5.7 g) and one un-sized treatment (4.4 g average) were seeded at two rates (75 and 150 seeds m^-2). Higher seeding rates led to higher canola emergence and stubble density at harvest. Higher seeding rates also increased early crop biomass, 1000-seed weights and seed oil content and reduced days to start of flowering and days to crop maturity. Seed size effects on canola emergence, yield or seed quality were not significant. Increasing seed size had a positive linear association with early canola biomass and 1000-seed weights, whereas, both days to flowering and days to the end of flowering had a negative linear association with seed size. Greater biomass from large seeds increases crop competition with weeds and also hastens flowering, shortens the flowering period and reduces the risk that canola will be exposed to high temperatures that can negatively impact flowering and pod development.

Harker, K. N., O'Donovan, J. T., Turkington, T. K., Blackshaw, R. E., Lupwayi, N. Z., Smith, E. G., Johnson, E. N., Gan, Y., Kutcher, H. R., Dosdall, L. M. and Peng, G. 2015. Canola rotation frequency impacts canola yield and associated pest species. Can. J. Plant Sci. 95: 9-20. Canola (Brassica napus L.) production has been steadily increasing in western Canada. Here we determine the effect of canola rotation frequency on canola seed yield, quality and associated pest species. From 2008 to 2013, direct-seeded experiments involving continuous canola and all rotation phases of wheat (Triticum aestivum L.) and canola or field pea (Pisum sativum L.), barley (Hordeum vulgare L.) and canola were conducted at five western Canada locations. Fertilizers, herbicides, and insecticides were applied as required for optimal production of all crops. Canola rotation frequency did not influence canola oil or protein concentration or the level of major (composition>1%) seed oil fatty acids. High canola yields were associated with sites that experienced cooler temperatures with adequate and relatively uniform precipitation events. For each annual increase in the number of crops between canola, canola yield increased from 0.20 to 0.36 Mg ha^-1. Although total weed density was not strongly associated with canola yield, decreased blackleg disease and root maggot damage were associated with greater canola yields as rotational diversity increased. Long-term sustainable canola production will increase with cropping system diversity.

Wang, Z., Ma, B.-L., Gao, J. and Sun, J. 2015. Effects of different management systems on root distribution of maize. Can. J. Plant Sci. 95: 21-28. Characterization of root distribution in maize (Zea mays L.) is important for optimizing agronomic management to match crop requirements, while maximizing grain yield, especially under intensive management. The objectives of this study were to examine the differences in maize root distribution between two management systems and to identify root-related factors that could be adjusted for further yield improvement. A 4-yr field experiment examined maize root distribution under two management systems: farmers' practices (FP: low plant density, unbalanced fertilization) and high yield strategies (HY: high plant density, sufficient fertilization). Root mass distribution within the soil profile was more restricted horizontally within 10 cm from the stalk base and vertically below 20 cm in HY compared with FP. HY had a greater proportion of fine roots (diameter ≤ 0.5 mm) and more roots per 100 kernels than FP. However, per-plant root weight was not significantly affected by type of management system. Yield was positively correlated with total root number and the ratio of root mass below 20 cm to total root mass. Our data indicate that HY maize overcame the negative effect of crowding stress by producing more roots with smaller root diameters, and maize root systems became narrower and were distributed deeper under intensive management compared with traditional famers' practices.

Rahman, H., Bennett, R. A. and Séguin-Swartz, G. 2015. Broadening genetic diversity in Brassica napus canola: Development of canola-quality spring B. napus from B. napus × B. oleracea var. alboglabra interspecific crosses. Can. J. Plant Sci. 95: 29-41. The narrow genetic base in spring Brassica napus (AACC) canola is a limitation for continued improvement of this crop. This research focused on broadening of genetic diversity in spring canola by using B. oleracea (CC). Seeds of B. oleracea contain high levels of erucic acid and glucosinolates, which are undesired in canola. Therefore, inheritance of these traits and the prospect of developing spring canola with allelic diversity introgressed from B. oleracea were investigated in B. napus×B. oleracea interspecific progenies. Zero-erucic plants in F₂ generation occurred at a lower frequency than expected based on segregation involving only the C-genome erucic acid alleles. Selection in F₂ to F₃ focused on zero erucic acid, while focus in later generation was for low glucosinolate and B. napus plants. In the F₆, 31% zero-erucic families had low glucosinolate content. Flow cytometry analysis of the F₈ families showed no significant difference from the B. napus parent. Genetic diversity analysis by using simple sequence repeat markers from the C-genome chromosomes showed that the F₈ families received up to 54% alleles from B. oleracea. The results demonstrate the feasibility of enriching genetic diversity in B. napus canola by using B. oleracea.

Miller, A. J., Bork, E. W., Hall, L. M. and Summers, B. 2015. Long-term forage dynamics in pastures sprayed with residual broadleaf herbicide: A test of legume recovery. Can. J. Plant Sci. 95: 43-53. Legumes such as alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) are important components of northern temperate pastures where they increase forage productivity and quality, but are susceptible to decline when exposed to broadleaf herbicides. Little is known about the long-term sward responses following herbicide use in northern temperate pastures, including the recovery of legumes and their subsequent contribution to forage production. We established five field sites over 2 yr to assess changes in grass, legume, total forage (grass+legume) and other forb biomass, as well as the recovery of a common weed, dandelion (Taraxacum officinale Weber), for up to 3 yr following a single application of two broad leaf herbicides with residual properties (aminopyralid and aminocyclopyrachlor). The importance of defoliation and the legume seed bank in facilitating legume biomass recovery were also evaluated with mowing and legume overseeding, respectively, in a strip/split-split design. Both herbicides had similar functional impacts on sward composition based on peak annual biomass, reducing legume biomass by an average of 71-100% across the 3 yr, equivalent to 63.4-22.6 g m^-2 from year 1 to year 3, respectively. Although grass biomass did not change significantly with herbicides, net reductions in total forage were limited to 6.8% (28 g m^-2) over the study, suggesting at least some ability of grasses to compensate for legume removal. Legume biomass was greater following overseeding and only in non-sprayed controls, but then decreased over time. Conversely, biomass of other forbs and cover of dandelion were lower shortly following herbicide application, only to reach levels similar to non-sprayed controls by the second growing season. Defoliation also influenced sward composition, favoring dandelion recovery following herbicide application. As both weed control and legume re-establishment are important objectives for livestock producers, the result of this study provides useful insight into the long-term impact of broad-leaf weed control on forage production in mixed swards of northern temperate pastures.

Bélanger, G., Rochette, P., Chantigny, M., Ziadi, N., Angers, D., Charbonneau, E., Pellerin, D. and Liang, C. 2015. Nitrogen availability from dairy cow dung and urine applied to forage grasses in eastern Canada. Can. J. Plant Sci. 95: 55-65. Nitrogen availability from dung and urine excreted by dairy cows has been studied extensively but few studies have been conducted in areas with short growing seasons and cold winters. We assessed N availability from dairy cow urine and dung applied to forage grasses under the cool conditions of eastern Canada, with a focus on soil- and plant-based indicators. The experiment was conducted with timothy (Phleum pratense L.)-dominated swards on two soil types (clay, sandy loam) with three periods of application (mid-September, early June, early July) and four treatments: Control, Dung (1.75 kg fresh weight m^-2), Diluted urine (U-50; 50 g N m^-2), and Urine (U-100; 100 g N m^-2) from lactating cows. Dry matter (DM) yield and N concentration were measured from several successive clippings. Ion exchange membranes (IEM) and crop N nutrition index (NNI) were used, respectively, as soil-based and plant-based indicators of N availability. Relative cumulative DM yields, calculated as cumulative DM yield over all clippings for a given treatment divided by maximum cumulative DM yield among the four treatments, increased from Control (clay: 31 - 69%; sandy loam: 21-63%) to Dung (clay: 39-84%; sandy loam: 46-86%) and U-50 (clay: 81-83%; sandy loam: 78-100%). Relative values of cumulative N uptake were close to those of DM yields. The percentage of applied N taken up by the crop from all clippings was greater with urine (8-28%) than with dung (3-12%) on both soil types. Nitrogen from dung and urine was available to timothy at all periods of application, but urine N availability was greater than that of dung N. Nitrogen exposure, calculated as cumulative mineral N on IEMs, and NNI were both related to relative DM yield (R²>0.61; P<0.001), confirming their capacity to assess N availability to forage grasses receiving dung and urine excreted by dairy cows.

Liu, Y. and Coulman, B. E. 2015. Morphological and agronomic variation of Puccinellia nuttalliana populations from the Canadian Great Plains. Can. J. Plant Sci. 95: 67-76. Native grass species are adapted to local environments and have the potential for development as forage or turf grass cultivars for semiarid environments. Nuttall's alkali grass [Puccinellia nuttalliana (Shultes) Hitchc.] is a salt-tolerant grass with potential for forage or turf use, and is widely distributed across western North America. Understanding the morphological and agronomic variability of this species is a prerequisite for developing populations suitable for dry and saline regions of western Canada. A collection of 24 Puccinellia nuttalliana populations from the provinces of Manitoba, Saskatchewan and Alberta were established in a field nursery in Saskatoon, Saskatchewan. Plant height, crown diameter, tiller number, seed yield, dry matter yield, leaf colour, leaf length, leaf width, spring growth and late summer regrowth of individual plants or plots were measured for each collection in 2011 and 2012. Significant variation was found among the 24 populations for all measured characters in both years. The populations Eston and Westbourne09 had taller plants with greater basal diameter, high tiller number, and high seed and dry matter yields, which suggest they may be useful for forage purposes. The population St. Denis had shorter plants with more tillers, greater basal diameter darker green leaf colour and high seed yields; thus, it may useful as a turfgrass. Within certain populations, individual genotypes were identified which would have potential for production of synthetic cultivars for forage or turf purposes. Cluster analysis was conducted using the unweighted pair group method with arithmetic mean (UPGMA) and principal coordinate analysis (PCoA). These analyses showed six distinct groups within the collected populations; however, there was no distinguishable pattern of clustering of populations by region.

Shi, H., Wang, Y., Zhang, D., Chen, L. and Zhang, Y. 2015. Pear PIP1 gene is regulated during fruit development and is invovled in response to salicylic acid and ethylene. Can. J. Plant Sci. 95: 77-85. Plasma membrane intrinsic proteins (PIPs), a subfamily of aquaporins, are widely implicated in plant growth and development. A gene encoding a plasma membrane intrinsic protein and designated PpPIP1 was isolated from pear (Pyrus pyrifolia). Using PCR amplification techniques, the genomic clone corresponding to PpPIP1 was isolated and shown to contain three introns with typical GT/AG boundaries defining the splice junctions. The deduced PpPIP1 protein contains the conserved features of PIPs: six transmembrane a-helices, a major intrinsic protein domain, and a conserved asparagine-proline-alanine (NPA) signature sequence. Phylogenetic analyses clearly demonstrated that PpPIP1 has the highest homology with apple (Malus×domestica) MdPIP1a and Malus hupehensis MhPIP1-1. PpPIP1 transcripts were mainly detected in young leaves, shoots, petals and mesocarp of fruit, but a relatively low expression signal was detected in anthers. In particular, expression of PpPIP1 was developmentally regulated in fruit. Further study demonstrated that PpPIP1 expression in pear fruit was down-regulated by salicylic acid (SA) and up-regulated by ethylene. These data suggest that PpPIP1 may be involved in the response to SA and ethylene during fruit development, which would provide valuable information for water permeability studies in pear.

McNaughton, A. J. M., Shelp, B. J. and Rajcan, I. 2015. Impact of temperature on the expression of Kennedy Pathway genes in developing soybean seeds. Can. J. Plant Sci. 95: 87-101. The main oil storage molecule, triacylglycerol (TAG), can be created by the Kennedy Pathway. The objective of this study was to determine the impact of growing temperature on the expression of the Kennedy Pathway genes, glycerol-3-phosphate acyltransferase (G3PAT), lysophosphatidic acid acyltransferase (LPAAT), and diacylglycerol acyltransferase 1 (DGAT1), in developing seed of four soybean genotypes with altered fatty acid composition using quantitative polymerase chain reaction. The three growing temperatures were: high, 30°C day/25°C night; normal, 25°C day/20°C night; and low, 20°C day/15°C night. The expression of G3PAT steadily declined following 15 d after flowering (DAF), suggesting that it is likely to be more highly expressed earlier in development than was measured in the study. As a result, the expression of G3PAT did not correspond to fatty acid accumulation. LPAAT expression coincided with accumulation of oleic acid (18:1Δ⁹) and linolenic acid (18:3Δ^9,12,15) in a temperature-dependent manner. The expression of DGAT1 corresponded to accumulation of linoleic acid (18:2Δ^9,12), which varied among the soybean genotypes, indicating a genotypic effect on the expression of DGAT1. This study suggests that the expression of the acyltransferase enzymes of the Kennedy Pathway influences the fatty acid composition in seed of four altered fatty acid soybean genotypes.

Hannam, K. D., Neilsen, G. H., Neilsen, D. and Bowen, P. 2015. Cluster thinning as a tool to hasten ripening of wine grapes in the Okanagan Valley, British Columbia. Can. J. Plant Sci. 95: 103-113. Achieving fruit maturity can be a challenge on some Okanagan vineyards in some years. Cluster thinning is widely used to hasten ripening, but may not be effective on sites with balanced crop loads. In a Merlot vineyard in Summerland, BC, the effects of cluster thinning on juice soluble solids (an indicator of fruit maturity), yield and vine growth were examined between 2008 and 2011 across a range of treatments that manipulated the frequency and quantity of applied irrigation water. Cluster thinning increased juice soluble solids in 2 out of 3 study years and consistently increased cluster weights, but had few effects on juice pH, titratable acidity or yield. In 2 of 3 yr, correlation analyses showed that cluster thinning was most effective at improving the maturity of fruit with low soluble solids. Irrigation treatments did not have a consistent effect on juice composition but year-to-year variability was significant. Response ratios calculated from values reported in the literature show that cluster thinning in this region causes small but inconsistent improvements in juice soluble solids across a range of crop loads.

Misran, A., Padmanabhan, P., Sullivan, J. A., Khanizadeh, S. and Paliyath, G. 2015. Composition of phenolics and volatiles in strawberry cultivars and influence of preharvest hexanal treatment on their profiles. Can. J. Plant Sci. 95: 115-126. Biochemical changes of quality-determining components were evaluated in strawberry fruit subjected to preharvest spray treatments using a hexanal-containing formulation that is known to enhance shelf life and quality of fruits. Phenolic compounds and volatiles of fruits of four strawberry cultivars (Mira, Jewel, Kent, and St. Pierre) grown in southern Ontario were characterized by HPLC-MS and solid phase micro extraction (SPME) analysis. Qualitative and quantitative profiles of phenolic compounds varied among the cultivars. In all the cultivars, anthocyanins constituted the most prominent class of phenolic compounds. Volatile profiles of strawberry homogenate differed among the cultivars. Changes in phenolics and volatiles composition were determined in fruits of Mira and Jewel after spraying with a hexanal-containing formulation at weekly intervals. In Jewel, preharvest hexanal spraying altered the profiles of polyphenolic components, while minimal changes were noticed in Mira. Interestingly, very few differences were identified in ester profiles of treated and untreated Mira. In general, hexanal spray application resulted in a decrease in the abundance of several volatile components including esters, ketones, and lactones in treated Jewel compared with the control. The results suggest that cultivar-specific quality changes may result from a preharvest application of hexanal formulations, which may also imply different patterns of metabolite channeling and delay of fruit ripening processes.

An, H. and Carew, R. 2015. Effect of climate change and use of improved varieties on barley and canola yield in Manitoba. Can. J. Plant Sci. 95: 127-139. A stochastic production function was estimated to investigate the effect of fertilizer inputs, changes in weather conditions and the use of improved varieties on barley and canola yields and its variability in Manitoba. Adoption of improved barley varieties did not have a significant effect on yield, while the adoption of herbicide-tolerant hybrid canola varieties was positively correlated with yield. An increasingly warmer climate in Manitoba is expected to have a slightly negative effect on mean barley yield and yield variance. In contrast, a warmer climate is expected to have a negligible effect on mean canola yield, but a positive effect on yield variability. Our results showed that a projected 50% increase in growing degree days would lead to a decrease of less than 1% in barley and canola yields.

Eryigit, T., Akis, R. and Kaya, A. R. 2015. Screening of different nitrogen rates and intra-row spacing effects on yield and yield components of safflower (Carthamus tinctorius L.) under microclimate conditions, Igdir Plain, Turkey. Can. J. Plant Sci. 95: 141-147. The yield of safflower (Carthamus tinctorius L.) is affected by many factors, among which nitrogen fertilization and plant density are significant. This study was conducted as a split plot in a randomized complete block design arrangement with four replications, during the successive seasons 2011 and 2012, to determine the effects of nitrogen application rate and intra-row spacing on the growth, yield and yield components of safflower under the ecological conditions of the Igdir Plain, Turkey. The main plots were three intra-row spacing (IRS₁, IRS₂ and IRS₃) and subplots were four nitrogen rates (N₁, N₂, N₃ and N₄). Intra-row spacing had significant effects on all parameters except plant height and seed oil content. There were significant effects of fertilizer rate on all parameters except seed oil content. The interaction of nitrogen rate and years had significant effects on seed yield. Correlations showed significant negative results between 1000-seed weight and seed oil content (-0.217). However, there was a high seed yield in 2011 compared with 2012. Among intra-rows, IRS₂ and IRS₃ gave greater yield compared with IRS₁, while N₃ gave a higher yield than other N rates (0, 100, 150, 200 kg ha^-1) in both years of the study, especially 2011.

Cardillo, M. J., Bullock, P., Gulden, R., Glenn, A. and Cutforth, H. 2015. Stubble management effects on canola performance across different climatic regions of western Canada. Can. J. Plant Sci. 95: 149-159. Previous research in the most arid region of the Canadian prairies has shown that wheat stubble cut tall the previous year can improve performance of the following canola crop. This study aimed to determine if tall stubble could benefit canola across the climatic conditions typically experienced in western Canada. Tall stubble impacts on canola were monitored over 11 site-years located throughout the prairies. At each site, tall stubble (50 cm) was compared with short stubble (20 cm). At some sites the stubble lodged allowing an unintended comparison between stubble that remained intact and stubble that was flattened. The comparison of snow water equivalent showed tall stubble caught more snow than short stubble but the benefit of additional spring soil moisture was masked by heavy spring precipitation in both 2011 and 2012. Canola biomass and yield were significantly lower in damaged versus intact stubble, either short or tall. In both years, wet spring conditions were followed by hotter and drier weather in the mid to late growing season. Soil under the damaged stubble (short or tall) likely warmed and dried more slowly in the spring, limiting early-season growth, biomass and yield. At sites where both tall and short stubble remained intact, there was a significant yield advantage with tall stubble. The intact tall stubble may have slowed evaporation and soil drying compared with intact short stubble, which reduced moisture stress later in the growing season, imparting a yield advantage.

Khakbazan, M., Henry, R., Haung, J., Mohr, R., Peters, R., Fillmore, S., Rodd, V. and Mills, A. 2015. Economics of organically managed and conventional potato production systems in Atlantic Canada. Can. J. Plant Sci. 95: 161-174. A rotation study was initiated in 2007 in Prince Edward Island (PEI), Canada, to determine the economic effects of converting from conventional potato production to organically managed systems. Seven organically managed rotations, which used various crop combinations to help control pests and soil-borne diseases as well as maintain nutrient levels, were assessed for 2 yr before and 2 yr after organic certification requirements were met in 2009. Each rotation included potato as the main cash crop and at least one other cash crop in a 4-yr rotation and these rotations were compared to a 4-yr conventional rotation. Results indicated that without an organic price premium, significant net revenue losses are expected for most of the seven rotations because of lower yields and high costs. The rotation that included carrots (potato, carrots and mixed peas-oats grain as the cash crops) produced the highest net revenue amongst all rotations studied; however, carrot yield and the net revenue associated with it also showed the greatest variability among all the crops. Organically managed cash crops generated higher net revenues than the conventional potato system only if the average PEI organic price premium was applied. Conventional potato systems produced economic benefits similar to most of the organic rotations when a traditional potato-cereal-green manure rotation was evaluated. The comparison of seven possible rotations provides producers with options if growing organic potatoes.

Balasubramanian, P., Mündel, H.-H., Chatterton, S., Conner, R. L. and Hou, A. 2015. AAC Whitehorse great northern dry bean. Can. J. Plant Sci. 95: 175-177. AAC Whitehorse is a high-yielding, early-maturing great northern bean (Phaseolus vulgaris L.) cultivar with an upright, indeterminate bush growth habit, large seed size and partial field resistance to white mould. AAC Whitehorse was developed at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Lethbridge, AB. AAC Whitehorse is suitable for irrigated wide row production in Alberta and Saskatchewan.

Balasubramanian, P., Mündel, H.-H., Chatterton, S., Conner, R. L. and Hou, A. 2015. AAC Burdett pinto dry bean. Can. J. Plant Sci. 95: 179-181. AAC Burdett is an early-maturing pinto bean (Phaseolus vulgaris L.) cultivar with an upright, indeterminate bush growth habit, lodging resistance, white mould avoidance and high yield potential. AAC Burdett was developed at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Lethbridge, AB. AAC Burdett is suitable for irrigated production in Alberta and Saskatchewan.

Reid, L. M., Voloaca, C., Wu, J., Woldemariam, T., Jindal, K. and Zhu, X. 2015. CO453 corn inbred line. Can. J. Plant Sci. 95: 183-188. CO453 is a short season corn (Zea mays L.) inbred line with excellent combining ability as well as intermediate resistance to common smut, common rust and eyespot. Excellent hybrid yields and performance data were achieved when CO453 was combined with the Iodent inbred MBS8148 and the stiff stalk inbred MBS1130.

Singh, A. K, Clarke, J. M., Knox, R. E., DePauw, R. M., Wise, I., Thomas, J., McCaig, T. N., Cuthbert, R. D., Clarke, F. R. and Fernandez, M.R. 2015. AAC Marchwell durum wheat. Can. J. Plant Sci. 95: 189-195. AAC Marchwell durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] is adapted to the durum production area of th Canadian prairies. AAC Marchwell is the first durum genotype registered for commercial production in Canada with the Sm1 gene for antibiosis-based resistance to orange wheat blossom midge [Sitodiplosis modellana (Gehin)]. It combines high grain yield, grain protein concentration, yellow pigment, test weight, and low grain cadmium concentration. AAC Marchwell has similar straw strength, plant height, and days to maturity as Strongfield. AAC Marchwell is resistant to leaf rust, stem rust, stripe rust, common bunt, loose smut, and common root rot. AAC Marchwell has end use quality suitable for the Canada Western Amber Durum class.