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PARTIAL SPECIAL ISSUE: 2017 JOINT MEETING OF THE CANADIAN PHYTOPATHOLOGICAL SOCIETY AND THE CANADIAN SOCIETY OF AGRONOMY, 18-21 JUNE 2017, WINNIPEG, MB
Production agriculture relies primarily on seeding of annual crops for food, feed, fuel, and fibre in western Canada. Annual seeding and harvesting commonly leave land non-productive for a portion of the year. There is the potential for both soil and nutrient loss from this unused land base and, just as important, we are missing the potential for photosynthesis. The capture of carbon in these off-season times may aid in carbon sequestration. Forage production (feed) relies on an animal market for its consumption. Forage seed production in Canada accounts for approximately 65 000 ha yr-1 and is almost exclusively located in western Canada. It is unlikely, however, that forage seed production area will dramatically increase due to limited markets. Perennial grains could greatly increase the land area dedicated to perennial seed production and provide alternative markets for forage products and forage seed. Intermediate wheatgrass [Thinopyrum intermedium (Host) Bark. & Dewey] (Kernza™) is the perennial grain closest to release and some potential niche markets are currently emerging. Improvement has been made through selection for grain production on individual plants for characteristics that are likely of importance at field-scale production. Agronomic packages for intermediate wheatgrass production are lacking, although forage seed production agronomy will guide this development. Agronomic benefits attributed both to perennial seed production and the inclusion of perennials in cropping systems will be greatly enhanced when the potential for perennial grain production (breeding and agronomy) is realized.
Extending the grazing season by maintaining beef cattle on pasture in the fall/winter has been adopted by many producers on the Prairies as it reduces the need for mechanical harvesting and can lower labour and manure management costs relative to feeding cattle in confinement. Annual and perennial forages, alone or in combination, offer the potential for low-input grazing while maintaining animal productivity. Using a range of data sources, this paper will review the methods available for extending the grazing season of beef cattle using annual and perennial forages and discuss level of adoption and the practical implications and considerations for producers. These methods included stockpile grazing, bale grazing, swath grazing, and corn grazing, with the suitability of methods based on a range of factors including the nutritive requirements of the target class of cattle, environmental conditions, and costs of inputs. In an effort to maximise the efficiency of maintaining cattle on pasture in the fall/winter period, the ability to be flexible and adaptive to changing climatic and economic conditions within and between years is essential. Furthermore, a combination of the aforementioned methods may be employed in an integrated effort to enhance the productivity and sustainability of overwintering of beef cattle.
The sustainability of purpose-grown biomass production on marginal lands in Canada is uncertain. In this study, an assessment of biomass yield and sustainability was performed for two poplar clones (Poplus deltoides × P. nigra, DN-34—PDN, and P. nigra × P. maximowiczii, NM-6—PNM) and two switchgrass cultivars (Panicum virgatum ‘Cave-in-Rock’—SGC, and P. virgatum ‘Nebraska’—SGN) on three marginal lands in Guelph (ON), Kemptville (ON), and Nappan (NS) in Canada. The differences in stem biomass across sites were not significant; however, differences in stem biomass among plants were statistically significant between poplar and switchgrass (p < 0.0001) and between poplar clones (p < 0.0001). The 2-yr stem biomass yield in PNM (15.27 ± 1.28 t ha-1) was significantly higher than those in PDN (7.02 ± 0.54 t ha-1), SGC (2.57 ± 0.28 t ha-1), and SGN (1.45 ± 0.22 t ha-1). Two sustainability indices based on macronutrients (MBSI) and nitrogen (NBSI), were developed to assess sustainability. Both indices show that the biomass production system of high-yielding poplar clone PNM depicts nutrient loss and may require external nutrient inputs via fertilization during the establishment phase. Higher index values for switchgrass SGC (1.47 ± 0.22, 1.11 ± 0.15) and SGN (1.37 ± 0.16, 1.17 ± 0.12) for MBSI and NBSI, respectively, indicate that despite low stem biomass yields, switchgrass biomass production is sustainable. These findings suggest that, from a nutrient perspective, sustainable biomass production systems can be established on marginal lands in Canada; however, there is a trade-off between high yield and long-term sustainability in purpose-grown biomass production systems.
Winter cereals provide distinct advantages over spring cereals. This includes higher grain yields and limiting weed pressure, soil erosion, and exposure to diseases and insect pests, which are regularly serious threats to spring cereals. The agronomic system for winter cereals in western Canada is built around ensuring that the crop survives winter. Critical to this system is uniform plant stands reaching an optimum growth stage to maximize cold tolerance and no-till production systems that maintain insulating snow cover through the use of stubble from a previous crop. Breeding has led to significant increases in grain yield for both winter wheat and fall rye, however, no progress in cold tolerance improvement has been realized by winter cereal plant breeders over the same period. Progress in fall rye breeding has led to more recent varieties having reduced lodging and plant height and increased seed size and test weight. For winter wheat, the incorporation of robust disease resistance packages ensures adaptation across the prairies and also enables the potential to lengthen the growing season and increase yield. Looking forward, winter cereals provide the potential to take advantage of predicted western Canadian climate change scenarios and play a significant role in productivity increases through utilizing double or relay cropping practices, which are currently being developed. Continued improvement in winter cereal agronomic practices and the introduction of new varieties means that winter cereals will continue to play an important role in maximizing productivity and extending the growing season in western Canada.
KEYWORDS: Malus × domestica, Alternaria alternata f. sp. mali, disease resistance gene, gene expression, gène de résistance à la maladie, expression des gènes
Alternaria blotch, caused by Alternaria alternata f. sp. mali, is a destructive defoliating disease that affects apple worldwide, especially in Asia. Despite previous efforts in characterizing this disease, few have reported on nucleotide binding sites (NBS)-encoding genes in response to pathogen infection. In this study, we characterized the morphological and gene expression response of ‘Golden Delicious’ and ‘Starking’ apples challenged by A. alternata. Inoculation of detached leaves of ‘Golden Delicious’ resulted in a rapid initiation of disease symptoms but a slow spread of the infection from the point of inoculation. In contrast, detached leaves of ‘Starking’ exhibited a delayed visibility of infection but a rapid spread of the infection once it was established. Based upon quantitative reverse transcription polymerase chain reaction data, we characterized the expression of 12 NBS-encoding genes in response to infection by A. alternata. We further characterized the structure, chromosomal location, and physico-chemical properties of the encoded proteins for these 12 NBS-encoding genes. Temporal gene expression profiles following inoculation indicated that the 12 NBS-encoding genes were all involved in the response in the two apple cultivars. The most highly expressed genes, MDP0000127009, MDP0000292810, and MDP0000710999, appear to have great potential for breeding resistant apple cultivars through genetic engineering.
KEYWORDS: LBD transcription factors, Fragaria vesca, strawberry, callus formation, early fruit development, facteurs de transcription des gènes LBD, fraise, formation du cal, début du développement du fruit
The LATERAL ORGAN BOUNDARIES DOMAIN (LBD) gene family encodes plant-specific transcription factors that play crucial roles in the growth and development in many plant species. However, no systematic study of LBD genes has been conducted in strawberry. In this study, 35 LBD (FvLBD) genes were identified in the diploid woodland strawberry genome (Fragaria vesca L.). These LBD proteins could be classified into two groups based on the structure of their lateral organ boundaries domain. The promoters of FvLBD genes contain different regulatory elements associated with potential response to different environmental stimuli and plant developmental signals. Furthermore, we analysed the expression patterns of the LBD genes during the callus formation in strawberry and the results suggested that FvLBD16 might play a prominent role in the regulation of callus formation. In addition, we investigated the expression profiles of FvLBD genes during early fruit development based on transcriptome data. We found that some FvLBD genes show a specific expression pattern. These results indicate that FvLBD genes may have a function in early fruit development. Together, the present study provides insights into possible functions of FvLBD genes and provides a basis for further functional research of FvLBD proteins.
KEYWORDS: greenhouse design, greenhouse microclimate, controlled-environment production, modèle de serre, microclimat en serre, production sous environnement contrôlé
Food insecurity amongst First Nation populations living on reserves across Canada is purported to be about 27% of the national average. However, crop production is limited by factors such as climate and soil conditions. A 2-yr study was carried out to assess production of collard (Brassica oleracea L. var. acephala DC. ‘Champion’), carrot (Daucus carota L. ‘Adelaide’), and tomato (Lycopersicon esculentum Mill. ‘Beefsteak’) in three separate greenhouses with contrasting design technologies. The greenhouses were categorized as (i) high technology (HTG), (ii) medium technology (MTG), and (iii) low technology (LTG) greenhouses. The MTG and LTG were basic facilities but the MTG had in-floor heating. The HTG was fully equipped with climate control systems. Mean monthly air temperature was stable at 23 °C ± 1 °C in the HTG but fluctuated in the MTG and LTG. Air temperature and water loss were highest in the MTG. Vapour pressure deficit and daily light integral followed the trends LTG > MTG > HTG > ambient and ambient > MTG > HTG > LTG, respectively. The growth rate of collard plants was equally high in the MTG and the LTG compared with the HTG. Comparatively, the growth and yield of carrot plants were highest in the HTG. Conditions in the HTG and the MTG favored the growth and yield of the tomato plants. Thus, the different greenhouse design technologies created different microclimates, which differentially affected growth and yield performances of the different vegetable species. Future work should consider the economic benefits of greenhouse technology and production management for northern and remote communities.
We isolated a gene encoding a putative MADS-box protein designated RcAGL15 from a protocorm-like body (PLB), a somatic embryogenetic structure) of Rosa canina L. RcAGL15 encodes a predicted protein of 251 amino acid residues with a molecular weight of 28 kDa and a theoretical isoelectric point of 7.5. Reverse-transcription polymerase chain reaction shows that RcAGL15 is mainly expressed in PLB and regenerated PLB, but not in leaves of aseptic seedlings, incubated leaflets before callus formation, calli, rhizoids, or leaves of regenerated shoots. Transgenic, ectopic expression of RcAGL15 in Arabidopsis changes numbers of floral organs and reduces content of indole-3-acetic acid, but increases levels of abscisic acid. Thus, RcAGL15 appears to be a new MADS-box gene that plays regulatory roles in morphological development and the number of flower organs, as well as somatic embryogenesis.
There are two taxonomic varieties of spinach (Spinacia oleracea L.), the spiny variety [S. oleracea var. spinosa (Moench)] and the spineless variety [S. oleracea var. inermis (Moench) Peterm.], based on the spines of spinach fruits. Between the two varieties, there are obvious differences in the leathery fruit coat but no significant differences in the macro-morphological appearance of seeds. Differences between the two varieties are hard to see without the fruit coat, which makes seed purity analysis difficult. In this study, the morphological structures of fruits and seeds from 31 spinach cultivars were compared. The results showed that there were significant differences in the macro-morphology of spinach fruit in terms of fruit shapes and the presence of spines, but no significant differences in the micro-morphology of the fruit surface under a scanning electron microscope (SEM) between the spineless and spiny varieties. In addition, there were no clear and stable differences between the two varieties in seed macro-morphology based on stereomicroscopy, or in the internal seed structure based on micro-computed tomography imaging. However, significant differences in seed micro-morphology could be observed under SEM, particularly for the surface reticulation of the seed coat, such as the depth of interspaces, sidewall angle, and the bottoms of interspaces. The differences in seed micro-morphology allowed for clear discrimination between the two varieties. These results provide morphological evidence for distinguishing fruits and seeds between the two spinach taxonomic varieties, and these similarities and differences can be used to classify spinach cultivars and to analyze seed purity.
Factorial experiments were conducted at two locations in Quebec to measure the combined effects of cover crop (CC) [mix of red (Trifolium pratense L.) and white clover (Trifolium repens L.)], fertilizer type [mineral (27–0–0) or organic (pig slurry)], and nitrogen (N) rate (0, 50, 100, 150 kg N ha-1) on canola (Brassica napus L.) yield and N uptake in a split-plot design reproduced twice (2013–2014 and 2014–2015) at each location. At crop killing, the clover biomass contained 28–151 kg N ha-1. Cover cropping did not change canola N uptake but increased yield and had a mineral fertilizer replacement value of 22–82 kg N ha-1. Without N fertilizer application, CCs increased canola yields by 6%–42%, diminishing with increasing fertilizer N rate. Canola N uptake and yield were lower with pig slurry compared with the mineral fertilizer. Maximum canola yield was reached at rates of 120 kg N ha-1 and higher with the mineral fertilizer. Therefore, clover CCs may help reducing fertilizer application rates in canola without compromising yields.
Common ragweed (Ambrosia artemisiifolia L.) is frequently observed in Québec carrot fields. Carrot growers essentially rely on linuron, a photosystem II inhibitor, to control this broadleaf weed. A linuron-resistant biotype had been identified but its prevalence was unknown and the genetic basis of resistance was not established. Consequently, a survey was conducted and plants suspected to be resistant were collected in 2012 and 2013. Progeny from these plants were sprayed with a diagnostic rate of linuron and tested for the presence of target site mutations in the psbA gene. Common ragweed was the most reported species (95% of accounts) and 94% of populations were diagnosed as resistant. A new target site mutation was found in 37.5% of resistant populations tested. No mutations in the psbA gene known to confer resistance to linuron were found in the other resistant populations. Except for two populations, target site resistant plants were located in the muck soil production area, while those diagnosed as non-target site resistant were found in sandy fields located in a different area. To our knowledge, this is the first report of a Val219Ile mutation in the psbA gene of common ragweed and of evolved non-target site resistance to linuron.
The effects of the genotypes of donor plants and three steps of culture media (induction, differentiation, and regeneration media) were evaluated in unpollinated ovary culture of cucumber (Cucumis sativus L.) to obtain the best combination of culture media for doubled haploid (DH) production of recalcitrant cultivars. Embryo-like structure (ELS) formation was significantly affected by differentiation and regeneration media. The highest percentages of ELS formation (59.89%) were obtained when the ovaries were cultured on the D2 second step culture medium and transferred to the newly developed MS medium supplemented with several plant growth regulators and additives, MST3 , the third step culture medium. However, there was no significant effect of the genotypes and induction (first step culture) media on ELS and callus formation. The ELSs developed into shoots when transferred to the third step culture media and complete plantlets were obtained after rooting on the MS medium with no supplement (MS0). Among the 10 regenerated plantlets that survived after transplanting to soil, three were identified as haploid (H) plantlets (2n = x = 7), one was a triploid plantlet (2n = 3x = 21), and six were diploid plantlets (2n = 2x = 14). Inter-simple sequence repeat analysis confirmed that these six diploids were DH plantlets. These results suggest that the newly developed media are useful for the future production of cucumber DHs.
Glyphosate-resistant (GR) waterhemp is the fifth confirmed GR weed in Canada and was first confirmed in 2014 in the province of Ontario. In 2015 and 2016, two field experiments were conducted across four site–years each to determine the effectiveness of dicamba at two rates (300 and 600 g a.i. ha-1) in addition to dimethenamid-P (693 g a.i. ha-1) in a single and sequential management program. Due to traited soybean seed availability, all treatments were applied in corn. Waterhemp density, biomass, visual control estimates, and corn yield were collected. Waterhemp density and dryweight were found to be lower in treatments including a sequential application of dicamaba and those that included dimethenamid-P. The sequential management strategy provided >95% control of GR waterhemp at 12 weeks after application. Dicamba applied after emergence at 300 and 600 g a.i. ha-1 controlled GR waterhemp 80% and 91%, respectively; in contrast, dicamba applied before emergence at 300 and 600 g a.i. ha-1 provided only 9% and 30% control of GR waterhemp, respectively. Dimethenamid-P controlled waterhemp better than dicamba when applied before emergence. Corn yield was also impacted by herbicide timing as corn yield was reduced by 17%–23% comparing preemergence vs postemergence applications in the experiments presented.
Six field trials were conducted over a 2-yr period (2014 and 2015) at two locations in southwestern Ontario to compare the level of weed control provided by dicamba applied alone and in combination with dimethenamid-P applied before planting (preplant, PP) in glyphosate- and dicamba-resistant soybean to current industry standards when used in a two-pass weed management program. Crop injury, weed control, soybean seed yield, environmental impact (EI), and profitability were evaluated in this study. No statistically significant injury was documented. Several PP herbicides provided excellent early-season grass and broadleaf weed control, although early-season weed control of those weed species was not acceptable with glyphosate applied alone or in combination with dicamba, dicamba dimethenamid-P, 2,4-D, or saflufenacil. At 8 wk after application, the sequential application of a PP herbicide followed by glyphosate applied after emergence (POST) provided at least 86% control of the weed species evaluated in this study. Weed interference with no herbicide treatments caused a soybean seed yield loss of 64%. The sequential application of glyphosate had the lowest EI value. The addition of chlorimuron metribuzin or chlorimuron imazethapyr did not increase the EI substantially but did improve the level of weed control and reduced weed density and biomass. The inclusion of a PP herbicide in a weed management program has several stewardship benefits and may reduce the selection for herbicide resistant weeds.
Arundo donax L. is a perennial grass species of Mediterranean origin. Its high biomass yield potential in its native climate has contributed to A. donax being an important biofuel feedstock crop. This study investigates the potential of A. donax as a purpose-grown biomass feedstock for advanced biofuel production in Nova Scotia. The effects of nine different growth-promoters (bacterial and fungal species, a seaweed extract, and a lipo-chitooligosaccharide) and two inoculation methods on A. donax biomass productivity were investigated through three experimental trials: one greenhouse and one field trial inoculated by a post-planting application of the supplements around the plant stem (soil drenching) and one greenhouse trial with inoculation by root soaking just prior to planting (2016). The survival of A. donax over the winter was also evaluated over two winter seasons (2014–2015 and 2015–2016). Penicillium bilaiae Chalab. illustrated the most consistent positive effects on biomass productivity across experimental trials and the plants’ higher phosphorus concentrations suggest that P. bilaiae was helping the plant access soil phosphorus. The root soaking inoculation method resulted in more positive effects in measured growth parameters compared with the soil drench method. Despite a very mild winter in one of the 2 yr tested, A. donax did not successfully overwinter in the field in either year. The presence of growth-promoters did not enhance biomass productivity substantially in the field. Moreover, due to its low overwintering survivability, this study suggests that A. donax is not well suited as a biomass feedstock crop in Nova Scotia.
Although most forage production in eastern Canada is comprised of species mixtures, little research has identified the best species to include in forage mixtures. Our objective was to identify binary legume–grass mixtures with high forage yield and nutritive value under either simulated grazing with frequent cutting or cattle grazing. The experiment was conducted at three sites in eastern Canada with 18 binary legume–grass mixtures of one of six grass species {Kentucky bluegrass (Poa pratensis L.), meadow fescue (Festuca pratensis Huds.), orchardgrass (Dactylis glomerata L.), tall fescue [Schedonorus phoenix (Scob.) Holub], timothy (Phleum pratense L.), and meadow bromegrass (Bromus biebersteinii Roem. & Schult.)} seeded in 2010 with a grazing-type alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), or birdsfoot trefoil (Lotus corniculatus L.). The six grass species grown in mixture with alfalfa, birdsfoot trefoil, or white clover persisted well under frequent cutting or rotational grazing at the three sites. White clover grown in a binary mixture with a grass species did not perform well under frequent cutting or rotational grazing. Meadow bromegrass based binary mixtures were overall the best performing in terms of dry matter yield; although their nutritive value was average, meadow bromegrass combined with alfalfa or birdsfoot trefoil were among the best legume–grass mixtures for estimated milk production per hectare. The greatest estimated milk production per hectare was obtained with birdsfoot trefoil mixed with meadow bromegrass followed by the alfalfa–timothy and the alfalfa–meadow bromegrass mixtures.
The ability of forage crops to out-compete foxtail barley (Hordeum jubatum L.) and downy brome (Bromus tectorum L.) weeds often fails in saline soils. Ten forage treatments [alfalfa (Medicago sativa L.)], Nuttall’s salt-meadow grass [Puccinellia nuttalliana (Schult.) Hitchc.], smooth bromegrass (Bromus inermis Leyss.), the “Saltmaster” forage blend, and six wheatgrass treatments: western [Pascopyrum smithii (Rydb.) Löve], northern [Elymus kronokensis (Kom.) Tzvelev], tall [Thinopyrum ponticum (Podp.) Barkw. & Dewey], and green (Elymus hoffmannii Jensen & Asay) in 30 and 15 cm rows and alternating rows with slender [Elymus trachycaulus (Link) Gould] were compared with plots left unseeded. After three growing seasons, the smooth bromegrass, tall, and the average for the three green wheatgrass treatments, respectively, limited foxtail barley shoot growth to 4%, 2%, and 1% of the total shoot biomass at a negligibly to moderately saline site near Warner, AB; downy brome was also limited to 4%, 4%, and 2%, respectively. The three green wheatgrass treatments at the moderately to severely saline site near Alsask, SK, required twice the time to limit foxtail barley growth to 5%, 8%, and 18%, respectively, of the total. At least 95% of the foxtail barley and 98% of the downy brome were suppressed by green wheatgrass in soils averaging ≤14 dS m-1.
Herbicide options are limited for the control of wild carrot in field crops in Ontario. This study, which comprised 25 field trials: 9 in corn [4 preemergence (PRE) and 5 postemergence (POST) herbicide trials], 8 in soybean [3 preplant (PP) and 5 POST herbicide trials], and 8 in winter wheat (8 POST herbicides trials), was completed to determine the most efficacious herbicides for the control of wild carrot in these crops. There was no significant visible injury in corn, soybean, and winter wheat with the herbicides evaluated. Atrazine, dicamba, dicamba/atrazine, isoxaflutole atrazine, mesotrione atrazine, saflufenacil, and saflufenacil/dimethenamid-P applied PRE provided inadequate (39%–75%) control of wild carrot in corn. Prosulfuron dicamba applied POST at 10 140 g a.i. ha-1 controlled wild carrot 93%–97%, with density and biomass similar to the weed-free control in corn. Among the PP herbicides evaluated in soybean, only glyphosate (2700 g a.i. ha-1) and glyphosate imazethapyr (900 100 g a.i. ha-1) controlled wild carrot >80%. None of the POST herbicides evaluated in soybean provided adequate control of wild carrot. In winter wheat, prosulfuron bromoxynil (10 140 g a.i. ha-1) controlled wild carrot 83%–86% compared with other herbicides, which controlled wild carrot 21%–73%.
Growers are challenged to provide premium, ripe haskap fruit to market while limiting the negative attributes associated with over-ripening. Hexanal is an inhibitor of phospholipase D, an enzyme involved in membrane degradation, and has shown promise in extending the longevity of fruit. This study investigated the performance of a hexanal-based preharvest spray for enhancing the quality and shelf life of haskap fruit, an emerging crop in Canada. At two locations in 2015, 2016, and 2017, five cultivars were sprayed with a control treatment or a 0.02% hexanal formulation at 2–3 wk before harvest. Fruit was stored at 4 °C and assessed for quality at successive times. Although inconsistent, results suggest a hexanal spray may impart a small benefit to the postharvest quality of haskap fruit. Secondary objectives included describing important agronomic characteristics of haskap and assessing the potential of a hexanal preharvest spray for enhancing fruit retention. Hexanal did not reduce fruit drop and had no effect on quality at harvest. Fruit contained high levels of soluble solids and titratable acids, were very dark in colour, and did not degrade in quality as rapidly as softer fruit crops such as strawberry or raspberry.
Oats produce a group of natural products termed avenanthramides. These compounds are produced in both the vegetative tissue and the grain. They are produced in leaf tissue in response to crown rust infection and by chemical plant defense activators and likely other environmental stresses. Grain avenanthramide production tends to be constitutive but concentrations are highly variable and strongly influenced by environmental conditions. In this paper, we report the effect of a plant defense activator [benzothiadiazole (BTH)] on the temporal expression and tissue distribution of avenanthramides in the leaf, stem, root, panicle stem, glumes, lemma/palea, and filling grain in the oat plant. Hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyl transferase (HHT, a member of the BAHD acyltransferase family and the final enzyme in the biosynthetic pathway to the avenanthramides) activity is also determined in these tissues, as well as the relative expression ratios of HHT mRNA resulting from BTH treatment. Evidence for phloem transport of the avenanthramides is also presented. In summary, following BTH treatment, leaf tissue is the predominant location for avenanthramide biosynthesis. However, significant amounts are also found in the upper and lower stems, roots, panicle stems, and glumes. The lemma/palea and filling grain contained demonstrable but substantially lower amounts of avenanthramides. Avenanthramides were also detected in the phloem sap, indicating a source to sink transport of these metabolites following BTH treatment.
KEYWORDS: maize root, metaxylem vessel, X-ray micro-computed tomography, three-dimensional reconstruction, image segmentation, racines du maïs, vaisseau du méta-xylème, microtomographie aux rayons X assistée par ordinateur, reconstitution en relief, segmentation des images
Roots play an essential role in the acquisition of water and nutrients from soils in higher plants. Root anatomical traits have significant effects on root functions, including water transportation within the root system. Traits such as the size of xylem vessels influence axial water flow by controlling water conductance directly. Currently, two-dimensional microscopic images are often used to acquire root anatomical features; however, three-dimensional (3-D) anatomical analysis, which offers information of spatial distribution and connection relationships throughout root tissues, is hardly reported. We performed 3-D reconstruction and visualization of maize (Zea mays L.) root tissues based on X-ray micro-computed tomography and developed an image processing workflow for 3-D segmentation of metaxylem vessels. Three-dimensional quantitative analysis of metaxylem vessels from the first to the sixth whorl of maize crown roots was performed according to this procedure. The performance of this procedudure, based on accuracy validation, indicated that it was capable of making accurate analysis of root metaxylem vessel traits.
AAC Goldrush is a hard red winter wheat (Triticum aestivum L.) cultivar eligible for grades of Canada Western Red Winter wheat. It was developed using a modified pedigree breeding method. AAC Goldrush was tested in replicated trials across western Canada for 6 yr: 2 yr for initial characterization followed by 4 yr of evaluation in registration trials. Based on 41 station–years of registration trial data, AAC Goldrush yielded significantly more grain than CDC Buteo and was similar to Flourish, Moats, and AAC Elevate. AAC Goldrush expressed very good winter survival, intermediate maturity, medium height straw with good lodging resistance, and average size kernels. Disease ratings at the time of registration were resistant to the prevalent races of leaf rust, moderately resistant to stem rust, intermediate in resistance to stripe rust and Fusarium head blight, and susceptible to common bunt. Leaf spot reactions were similar to the best check. The grain yield, agronomic characteristics, and disease resistance attributes of AAC Goldrush make it particularly well-suited to the eastern Prairie region of western Canada where CDC Buteo has been popular.
AAC Prevail (BW462) is a high-yielding spring wheat (Triticum aestivum L.) with high protein content and is adapted to the growing conditions in the Canadian prairies. AAC Prevail yielded similar to Unity, the highest yielding check in the Central Bread Wheat Cooperative Registration tests (2010–2012). Over 3 yr of testing in Manitoba (zone 1), AAC Prevail achieved 1.5% higher yield than Unity whereas in Saskatchewan (zone 2), it yielded 98.4% of Unity. AAC Prevail matured 1 d later than Unity and McKenzie, the earliest maturing checks. AAC Prevail was taller than all the checks but had better lodging resistance than Unity, McKenzie, and 5603HR. The test weight and kernel weight of AAC Prevail were similar to the checks. AAC Prevail was rated resistant to leaf rust (Puccinia triticina Erikss.) and moderately resistant to stem rust (Puccinia graminis f. sp. tritici) but susceptible to bunt [Tilletia caries (DC) Tul. & C. Tul.] and loose smut [Ustilago tritici (Pers.) Rostr.]. The Fusarium head blight (Fusarium graminearum Schwabe) rating was intermediate for visual rating index but the combined incidence, severity, and deoxynivalenol rating was moderately resistant. During 3 yr of evaluation, AAC Prevail was resistant to orange wheat blossom midge (Sitodiplosis mosellana Géhin). AAC Prevail was registered under the Canada Western Red Spring class for its high protein as well as good milling and baking performance.
AAC Congress durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] is adapted to the durum production area of the Canadian prairies. Averaged over three years, AAC Congress yielded significantly more grain than Strongfield and AC Navigator. AAC Congress had a protein concentration significantly lower than Strongfield but significantly higher than Brigade. AAC Congress is eligible for grades of Canada Western Amber Durum. It has lower grain cadmium concentration and higher yellow pigment concentration than all the check cultivars except AAC Cabri.
From 2013 to 2015, a survey was conducted to document the distribution of glyphosate-resistant (GR) and multiple-resistant Canada fleabane with resistance to glyphosate and cloransulam-methyl across Ontario. This survey shows that GR Canada fleabane is present throughout southern Ontario, from Essex county in the southwest to Glengarry county adjacent to the Quebec border.
Cover crop (CC) adoption has increased in North America corn and soybean production areas. The objective was to evaluate the impact of cereal rye CC on winter annual weeds. Cereal rye reduced winter annual weed density and biomass by >90% at time of spring termination, showing potential as a component of an integrated weed management program.
Increasing N fertilization decreased the in vitro digestibility of dry matter (IVTD) and neutral detergent fiber (NDF) but increased N concentration of sweet sorghum [Sorghum bicolor (L.) Moench] and sweet pearl millet [Pennisetum glaucum (L.) R.Br.] in eastern Canada. Sweet sorghum had lower NDF, acid detergent fiber, and N concentrations, and greater IVTD than sweet pearl millet.
‘AC Harrow Crisp’ pears could be stored at 0 °C without or with a controlled atmosphere (18 or 2.5 kPa O2, 2 kPa CO2) for 111 d with little effect on overall quality. 1-Methylcyclopropene-treated fruit could be stored for longer periods under refrigerated air but not under a controlled atmosphere.
Faba bean is a crop at high risk for late season frost injury, which results in reduced yield and marketability. After frost exposure, tannin-containing cultivars showed lower proportions of frost-damaged seeds when compared with zero-tannin cultivars. Tannin-containing cultivars may mitigate the risk of commercial downgrading due to frost damage.
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