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Forage mixtures containing legume out-yield monocultures, fix atmospheric nitrogen, and have lower carbon footprints. However, evidence-based information on creating forage mixtures by direct seeding legumes into existing pastures is limited, and information on bloat-free legumes is nonexistent. Traditionally, pastures requiring improvement in western Canada were fully replaced by breaking up the old stand and reseeding. With new and improved forage cultivars, better seeding equipment, and increased knowledge about pasture management, there is a growing interest among producers in rejuvenating pastures instead of replacing them. Pasture rejuvenation refers to the improvement in biomass productivity and (or) nutritional quality of existing pasture without removing the existing vegetation. This can be done through fertilizer application, which is generally expensive and causes negative environmental impacts. Amelioration of compacted pastureland via mechanical aeration is short-lived and can lead to weed problems. As an alternative, direct seeding of productive, nutritive and bloat-free legume species into existing pasture is an attractive option for pasture rejuvenation. For high performance grazing systems, identification of suitable bloat-free legumes and methods for direct seeding into old grass and legume stands will be essential strategies. This review includes information on the benefits of mixed pastures and seeks possible methods of introducing bloat-free forage legumes into existing pastures in western Canada for rapid improvement in productivity and quality while positively influencing animal, soil, and environmental health.
Basic helix-loop-helix (bHLH) transcription factors (TFs) are known to play significant roles in plant growth and development, secondary metabolite synthesis, and stress responses. However, the functions of soybean [Glycine max (L.) Merr.] bHLH TFs have been less widely explored. The main purpose of this study was to explore the function of a bHLH TF subfamily gene, GmbHLH3, by overexpression in wild type Arabidopsis thaliana (L.) Heynh. GmbHLH3 is a homolog of Arabidopsis bHLH3 (AtbHLH3) that participates in the regulation of jasmonic acid (JA) signaling. Several cis-regulatory elements responding to methyl-jasmonate (MeJA), including G-Box CGTCA and TGACG motifs, were found in the promoter of GmbHLH3. GmbHLH3 is located in the nucleus. It can form dimers with AtbHLH3, AtbHLH13, and GmbHLH3a, respectively, by yeast two-hybrid and bimolecular fluorescence complementation assay. GmbHLH3 induced root growth by suppressing expression of AtPDF1.2, AtVSPP1, AtLOX2, and AtTAT1 under MeJA treatment. GmbHLH3 inhibited JA-induced leaf senescence by limiting transcription levels of the senescence-related genes AtSAG29, AtAZF2, AtWRKY22, and AtMKP2, and the chlorophyll degradation genes AtSGR, AtNYC1, AtCLH1, AtPPH, and AtPAO. Under long day conditions, in the absence of JA treatment the GmbHLH3-overexpression lines tended to have a reduced time to flowering. Moreover, GmbHLH3 transcript expression pattern analysis revealed that MeJA treatment could induce GmbHLH3 transcript in soybean. This study provides evidence that JA treatment alters the effects of GmbHLH3 on the regulation of plant growth and gene expression. It contributes to future research on the functions of bHLH TFs in soybean.
Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. & De Not., is an important disease of canola (Brassica napus L.) worldwide. In Canada, blackleg is managed mainly by the cultivation of resistant or moderately resistant canola hybrids. Field experiments were conducted in Edmonton, AB, Canada, in 2017 and 2018 to determine the relationship between blackleg disease severity and yield in the moderately resistant canola hybrids ‘73-15RR’ and ‘1950RR’. Blackleg severity was rated on a 0–5 scale, where 0 = no disease and 5 = plant death. Regression analysis showed that relationships between disease severity and pod number and seed yield were best explained by second-degree quadratic equations in all site-years for both cultivars. Percentage yield loss increased by 18%–99% and 26%–86% in plants of ‘73-15RR’ and ‘1950RR’, respectively, with disease severities of 2–5 compared with plants with severities of 0–1. An improved knowledge of the relationship between blackleg severity and yield losses is important for a more accurate evaluation of the agronomic efficacy and economic benefits of control measures.
Oil and gas development is often associated with the production of produced water or “brine”, which is a solution of dissolved salts (NaCl ≈ 90%) exhibiting electrical conductivity (EC) upwards of 200 dS m-1. Accidental releases of brine to soils inhibit seed germination through osmotic and ionic stressors. The final germination (FG; %) of four crop species, Hordeum vulgare L. (barley), Helianthus annuus L. (sunflower), Carthamus tinctorius L. (safflower), Beta vulgaris L. (sugar beet); and four graminoid species, Pascopyrum smithii (Rydb.) Barkworth & D.R. Dewey (western wheatgrass), Elymus hoffmannii K.B. Jensen & Asay (AC Saltlander), Leymus triticoides (Buckley) Pilg. (beardless wildrye), and Elymus trachycaulus (Link) Gould ex Shinners (slender wheatgrass), were determined using sodium chloride (NaCl) and brine solutions prepared at EC levels of 0, 4, 8, 16, 24, and 32 dS m-1. No differences (p > 0.05) in FG were found between NaCl and brine solutions across graminoid species or the crop species barley, sunflower, and sugar beet. AC Saltlander had the highest FG (81.9%) at the maximum EC level (32 dS m-1), compared with 47.2% and 0.8% for western wheatgrass and beardless wildrye, respectively. Within crop species, safflower exhibited the highest germination (10%–30%) across both solutions at 32 dS m-1. Barley (0%–2.9%), sugar beet (4.9%–7.7%), and sunflower (0%–1.4%) exhibited low germination at 32 dS m-1. The implications of this experiment are that previously established NaCl tolerance indices may be used to accurately determine the FG of plant species in brine-contaminated soils and that AC Saltlander, as well as western wheatgrass, have the highest FG at 32 dS m-1, indicating these species may have the greatest potential for successfully revegetating brine-contaminated soils.
Spatial variability of berry composition was studied over a 3-yr period in 10 Riesling vineyards in the Niagara Peninsula in Ontario. Vineyards were delineated using global positioning systems (GPS), and 75–80 sentinel vines were georeferenced within a sampling grid for data collection. During 2005–2007, vine water status measurements [leaf water potential (ψ)] were collected biweekly from a subset of these sentinel vines. Data were collected on soil texture and composition, soil water content (SWC; %), leaf ψ, and fruit composition. These variables were mapped using GIS software, and relationships between them were elucidated. Temporal stability in spatial patterns of soil texture and composition, SWC, leaf ψ, soluble solids (Brix), titratable acidity, and monoterpenes were examined. Spatial trends in leaf ψ and (or) SWC showed widespread evidence of temporal stability. Fruit composition variables were not as stable over a 3-yr period. Spatial trends in Brix were temporally stable in seven vineyards, free volatile terpenes were temporally stable in three vineyards, and potentially volatile terpenes were temporally stable in two vineyards. Consistent leaf ψ zones were identified, and these were temporally stable despite different climatic conditions. Furthermore, some soil variables, and particularly vine water status, may contribute significantly to the terroir effect through their effects on vine size and fruit composition. For some vineyards, many viticulture and fruit composition variables were also temporally stable. There was evidence of strong spatial relationships between leaf ψ and fruit composition, suggesting a strong relationship between berry composition and vine water status.
Moveable high tunnels offer the possibility of increasing the number of crops harvested from a given piece of ground in northern latitudes where there is a short growing season. In an effort to expand crop scheduling options, three leafy greens and three root vegetables were grown in the spring in a movable high tunnel, and in the fall were sown outside and the tunnel was moved over the crops in late September. The effects of seeding date and addition of row cover were further explored on fresh weight and days to harvest. Using row cover within the high tunnel increased growing degree hours (GDH) by an average of 29% in the spring and 17% in the fall over a high tunnel without row cover. Soil degree hours (SDH) in the high tunnel with row cover increased an average of 9% in the spring and 12% in the fall over the high tunnel without row cover. The addition of row cover increased yield of leafy greens and turnip by an average of 35% in spring 2018 when the outside air temperature was considerably below average. Early-seeded fall leafy greens out-yielded late-seeded by 52% due to the ability to make a second harvest. Using row cover within the high tunnel increased GDH and SDH during both spring and fall seasons and increased the yield of cool season vegetables when outside air temperatures were considerably below average.
The global demand for hazelnuts is increasing steadily, driven by increasing use by chocolate companies, pharmaceuticals, health products, and others. North America only produces 5% of the world crop, of which 99% is produced in Oregon (OR, USA). Most available cultivars are adapted to areas with mild winters and thus do not perform well in Ontario (ON, Canada). Our objective was to identify genotypes capable of supporting the newly formed hazelnut industry in southern Ontario. In the last several decades, selections have been identified in ON, New York (NY, USA), and Michigan (MI, USA) that may be better adapted in ON than cultivars from Europe and OR. To test our hypothesis that these new selections would outperform cultivars from Europe and OR in southern Ontario, two trials were performed to evaluate yield, nut quality, and winter hardiness. As hypothesized, selections from ON and NY such as ‘Gene’, ‘Alex’, and ‘Slate’ were winter hardy and highest yielding, followed by ‘Butler’ and ‘Gamma’ from OR; however, these selections did not perform well in other assessed parameters such as nut quality and catkin survivability. Possible explanations for the poor performance of the European and OR cultivars include (i) longer time needed to acclimatize and enter production phase relative to selections from ON, NY, and MI, and (ii) cold susceptibility during the initial establishment phase. The need to allocate resources towards survival probably delays the ability of the European and OR cultivars to enter the production phase. In conclusion, hazelnut cultivars brought from regions with a different climate need to be tested for cold hardiness.
Infection by Leptosphaeria maculans (Desm.) Ces. & de Not., the causal agent of blackleg of canola (Brassica napus L.), can result in seedling death, foliar lesions, and the development of stem cankers on adult plants. Strobilurin fungicides such as pyraclostrobin are popular, as they are effective against a broad range of fungal pathogens, have novel target specificity, and translaminar activity within the plant. The seed treatment Prosper FX (carbathiin + trifloxystrobin + metalaxyl) and an experimental formulation BAS 720 F (pyraclostrobin + fluxapyroxad + metalaxyl) were evaluated for their efficacy in managing blackleg when applied alone or in combination with the foliar fungicides Priaxor (pyraclostrobin + fluxapyroxad) or Tilt 250 EC (propiconazole). Experiments were conducted with the blackleg-susceptible cultivar ‘Westar’ and the moderately resistant cultivar ‘Dekalb 73-15 RR’ under greenhouse and field conditions in 2012 and 2013. In one greenhouse trial, all fungicide treatments significantly reduced stem blackleg severity on ‘73-15’ and ‘Westar’ compared with the inoculated–untreated controls. During 3 of 4 site-years, the combination of the experimental seed treatment BAS 720 F and Priaxor significantly reduced stem disease severity relative to the inoculated–untreated control by 60%–77% for ‘73-15’ and by 50%–75% for ‘Westar’. This treatment also resulted in a significant yield increase relative to the inoculated–untreated control in ‘Westar’ in 2 site-years by 24% and 56%. The results of the study suggest a reduction in blackleg symptoms and improved yields when canola is treated with a combination of seed and foliar fungicides, especially when cropping a susceptible cultivar.
Interseeding red clover (RC; Trifolium pratense L.) to winter wheat (WW; Triticum aestivum L.) is a recommended management practice for wheat growers in Ontario, as it is known to provide a host of services including a significant nitrogen credit for the subsequent crop. However, fewer Ontario wheat acres are being interseeded with RC because of challenges with nonuniform stands. A survey was developed to explore why growers use the winter wheat – red clover (WWrc) system and to evaluate the management practices being used. We received 179 responses, 142 which were from growers currently practicing WWrc and the rest were from growers who had used WWrc in the past. Of those who were currently practicing WWrc, increasing degrees of tillage, wider WW row spacing, and higher RC seeding rates showed some indication of improved RC stand uniformity, and qualitative feedback from growers in the survey supports this. It is recommended that these management practices receive formal evaluation to increase the success of the WWrc system in Ontario.
Abelmoschus manihot (L.) Medik. is a medicinal and edible plant. To evaluate its suitability for cultivation on the coastal saline-alkali land in northern China for high quality functional products, salt-tolerance identification and flavonoid contents were evaluated under saline treatments. Results showed that the salt-tolerance threshold of A. manihot ranged from 4.1 to 6.9 g L-1; however, low soil salt content (<3 g L-1) had the best growth and accumulation of total flavonoids. Sixteen kinds of common functional components such as hyperoside, rutoside, and quercetin were found. Of these components, the four (myricetin-3-0-glucoside, rutoside, quercetin-3′-0-glucoside, and gossypetin-8-0-β-d-glucuronic acid) with the highest content were chosen as the quality evaluation indexes. High levels of quality and yield occurred at a soil salt content of 3 g L-1. Our results suggested that soil salt content should not exceed 3 g L-1 in field cultivation for high quality and high yield of A. manihot.
This study investigated the relationships between numbers of Delia species (Delia spp. Rob.-Desv., Diptera: Anthomyiidae) flies or eggs and root injury levels of Brassica napus L. and Brassica rapa L. (Brassicaceae) canola (oilseed rape), and between root injury levels and canola seed yields. Wild-collected Delia species adult flies or laboratory-obtained Delia radicum (L.) eggs were introduced into laboratory or field cages containing B. napus or B. rapa plants. The degree of root injury was strongly associated with infestation level using both flies and eggs. Linear response curves between numbers of Delia flies and root injury levels and quadrilinear response curves between numbers of D. radicum eggs and root injury levels showed that root damage increased with increasing levels of infestation; at high egg infestation levels, root damage levelled off in both Brassica species. Seed yield was not clearly related to fly or egg infestation rate, nor to ensuing root damage. No consistent yield relationship in B. napus ‘AC Excel’ was found with levels of root damage seen in the investigation. Conversely, B. rapa cultivar ‘AC Boreal’ seed yields tended to increase above uninfested controls when feeding damage was light but decreased with increased root injury. Despite procedures used to prevent infestation in Delia-free control cages, some root maggot damage was found in control cages in all 4 yr of the field study. Changes in climate, land use patterns, and cropping systems could influence the economic impact of this pest complex on canola in the future.
The Redekop Seed Control Unit™ is an integrated reversible cage mill with a blade system added, but the effects of this addition on harvest weed seed control efficacy and chaff flow are not known. Volunteer canola control when processed by a cage mill with either eight fan blades or four fan blades plus four cutting blades at 5 and 10 Mg h-1 was tested. Blade configuration in combination with chaff feeding rate did not affect volunteer canola control, which remained above 99%. If the blade system allows for reduced energy requirements, it will be a useful development in integrated mill systems.
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