Complex pasture mixtures are advantageous, but little information exists on the best forage species and nitrogen (N) management in eastern Canada. We compared under mob stocking four complex mixtures of one of two legume species [alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.)] plus one of two grass mixes [No. 1 — timothy (Phleum pratense L.), meadow fescue (Schedonorus pratensis (Huds.) P. Beauv.), reed canarygrass (Phalaris arundinacea L.), and Kentucky bluegrass (Poa pratensis L.); No. 2 — tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.), meadow bromegrass (Bromus biebersteinii Roem. and Schult.), reed canarygrass, and Kentucky bluegrass] under three N application rates at three sites over the first three post-seeding years. Legume species had little effect on most forage attributes mainly because of their low contribution to forage dry matter (DM) yield (<30%) in second and third years. The grass mix with tall fescue and meadow bromegrass (No. 2) yielded similar or slightly better than the one with timothy and meadow fescue (No. 1) but tended to have a greater neutral detergent fibre concentration, and lower N and total digestible nutrient concentrations. Nitrogen fertilization increased forage DM yield only in second and third years when the legume contribution to forage DM yield was <30%, and it increased N concentration and decreased nonstructural carbohydrate concentration. These results highlight the challenge of maintaining legume species in rotationally grazed pastures of eastern Canada and confirm recommendations of applying no or little N fertilizer on grazed legume–grass mixtures when the legume contribution to forage DM yield is >30%.

There are some major obstacles in practical applications of date palm tissue culture in the laboratory such as reduced number of shoots, vitrification of tissues, and browning of cultured tissues. The objective of the present study is to determine the effect of boron (B) and calcium (Ca) on enhancing organogenesis of buds from callus, shoot multiplication, and phytochemicals of in vitro cultures of date palm ‘Barhee’. Addition of calcium chloride and boric acid to the medium was most effective on callus for shoot regeneration and number of shoots per jar, where the best result (88.89%, 8.2 shoots per jar, respectively) was obtained by using 660 mg L^-1 Ca + 9.3 mg L^-1 B, compared with other treatments. It was observed that the interaction between 660 mg L^-1 Ca + 9.3 mg L^-1 B resulted in the highest tissue content of B [(4.75 mg L^-1 dry weight (DW)]. The highest medium calcium chloride level (880 mg L^-1) increased Ca content in the shoots. The combined application had the effect in reducing the vitrification. Application of Ca and B induced synthesis of proteins bands with molecular weights of 88.0, 55.6, 52.8, 43.0, 41.1, 38.3, 28.3, and 16.6 KDa in a medium supplemented with 660 mg L^-1 Ca + 9.3 mg L^-1 B.

Amaranthus hybridus L. is a nutritious leafy vegetable amaranth species grown primarily in tropical regions. Weedy amaranth species thriving in southern Ontario suggest the edible biotype could also grow efficiently as a crop. Field trials in Guelph, Simcoe, and Stouffville, Ontario, examined yield in response to three harvest frequencies (weekly, every 2 wk, and every 3 wk) cut at 15 cm above ground level, using two traditional harvest practices (Afro-Caribbean and European) cut every 2 wk, and a control which was not cut until the final harvest. The highest marketable yields and quality measures were observed in plants cut every 2 wk, every 3 wk, and using the Afro-Caribbean cutting technique which selects and harvests thicker stems while leaving new shoots for later harvests. The difference in growth among sites suggests plants prefer warm, well-drained soil. Marketable yield was as high as 4.02 ± 0.340 kg m^-2 in Simcoe with an average yield across all three sites of 2.37 ± 0.229 kg m^-2. This demonstrates that A. hybridus has the potential to be grown as a vegetable crop in southern Ontario and that marketable yield can be optimized by method of harvest.

Four field experiments were conducted over a 2 yr period (2017 and 2018) in Ontario to determine the control of annual ryegrass (ARG) seeded in the fall of 2016 and 2017 (as a cover crop) with spring-applied glyphosate alone and in a tankmixure with clethodim, fluazifop-P-butyl, quizalofop-P-butyl, sethoxydim, or saflufenacil prior to seeding glyphosate-resistant corn. The doses of glyphosate needed to provide 50%, 80%, and 90% control of ARG were 439, 1757, and >2700 g a.e. ha^-1 at 3 wk after treatment application (WAA); 526, 2105, and >2700 g a.e. ha^-1 at 4 WAA; and 703, >2700, and >2700 g a.e. ha^-1 at 6 WAA, respectively. Glyphosate (1350 g a.e. ha^-1) controlled ARG 27%, 61%, 77%, 72%, and 68% at 1, 2, 3, 4, and 6 WAA, respectively. The tankmix of glyphosate (1350 a.e. ha^-1) with clethodim (30 g a.i. ha^-1), fluazifop-P-butyl (125 g a.i. ha^-1), quizalofop-P-ethyl (36 g a.i. ha^-1), sethoxydim (150 g a.i. ha^-1), or saflufenacil (25 g a.i. ha^-1) controlled ARG as much as 82%, 79%, 82%, 84%, and 81%, respectively. ARG control with the tankmixes of glyphosate (1350 a.e. ha^-1) with the Group 1 herbicides evaluated increased corn yield as much as 66%. Additionally, reduced ARG interference with the tankmix of glyphosate (1350 a.e. ha^-1) +saflufenacil (25 g a.i. ha^-1) increased corn yield 69%. The best control of ARG was achieved with high doses of glyphosate alone and glyphosate (1350 g a.e. ha^-1) tankmixed with a Group 1 herbicide or saflufenacil.

Asparagus (Asparagus officinalis L.) acquires freezing tolerance during a period of fall acclimation when both photoperiod and temperature decrease. The above-ground vegetative growth may be important for sensing changing environmental conditions and translocating compounds to the below-ground crown. Defoliation experiments, repeated over 2 yr, were conducted by removing fern in mid-August, -September, and -October and evaluating crown metabolites and LT₅₀, the temperature at which 50% of plants die, at monthly intervals to mid-November. Spring emergence and vigor were also assessed in separate experiments. In the first year, only mid-August defoliation affected LT₅₀ values, decreasing freezing tolerance, which was associated with diminished rhizome proline concentration and storage root low- and high-molecular-weight fructan concentrations. All defoliation treatments in the second year decreased LT₅₀ values, or increased freezing tolerance, possibly resulting from an interaction between defoliation and drought which increased rhizome sucrose concentrations. Defoliation decreased spring vigor in both experiments; the response was proportional to the earliness of the treatment and associated with rhizome and storage root fructan levels. Crowns of plants defoliated in mid-August had increasing proline concentrations during the fall, similar to control plants, suggesting the below-ground organs may have sensed soil temperature to cold acclimate. Autumn defoliation to control disease, harvest seed, or implement other cultural practices can reduce vigor and likely attenuate long-term performance of a plantation.

Witchweed [Striga hermonthica (Del.) Benth] is a major parasitic weed of most cereal crops in Africa, including maize. Seed treatment with low doses of acetolactate synthase–inhibiting herbicides, such as imazapyr, was introduced in the 1990s to control witchweed. Field trials were conducted in four locations in Nigeria in 2007 and 2008, to assess the effect of coating seeds of several maize hybrids with imazapyr on witchweed control. The hybrids had genes for imidazolinone herbicide resistance (IR), as well as genetic tolerance to witchweed (ST). Treatments were 12 IR maize hybrids with ST and three checks without the IR gene (commercial, witchweed tolerant, and witchweed susceptible hybrids). Averaged across all locations, the coated IR hybrids with ST yielded more and supported fewer witchweed plants than the uncoated IR hybrids with ST. The IR hybrids with ST yielded 57%–60% more than the commercial and witchweed tolerant hybrid checks that were not coated. The witchweed susceptible hybrid check suffered a yield loss of 88% under infestation without seed coating. The IR hybrids with ST yielded 3564 kg ha^-1 of grain when coated with imazapyr and 3266 kg ha^-1 otherwise. The findings indicate that coating of IR/ST maize seeds with imazapyr improved tolerance to witchweed.

The potential market for locally produced organic cherry tomatoes (Solanum lycopersicum var. cerasiforme) is large in Canada, but it is challenging to grow this warm-season crop in open fields (OFs) due to the cool and short growing season. To test the feasibility of using high tunnels (HTs) for improving organic production in southern Ontario, plant growth, fruit yield and quality, and pest and disease incidence were compared for ‘Sarina hybrid’ cherry tomato among three production systems: OF, HT, and high tunnel with anti-insect netting (HTN) in Guelph, ON, in 2015 and 2016. Averaged over the 2 yr, the highest marketable fruit yield was achieved in HT (≈70 t ha^-1), followed by HTN (≈50 t ha^-1), with the lowest yield obtained in OF (≈24 t ha^-1). Compared with OF, increased plant growth, extended harvest period, reduced pest numbers, and increased proportion of marketable fruits all led to the higher marketable yields in HT and HTN. Under HT vs. OF, fruit quality attributes, such as soluble solids content and post-harvest water loss, were better in 2015 and similar in 2016. Although the insect netting reduced pest incidence and disease infection, fruits harvested from HTN had lower yield, smaller size, and lower soluble solids content than those from HT in both years. Therefore, HT can be recommended for organic production of cherry tomatoes in southern Ontario.

Boron-doped diamond anodes and stainless-steel cathodes were employed in an electrochemical flow cell and evaluated for inactivation efficacy on the plant pathogen Rhizoctonia solani J.G. Kühn [Thanatephorus cucumeris (A.B. Frank) Donk] in hydroponic fertigation water. The electrochemical system showed promise as an electrochemical advanced oxidation process (EAOP) in that significant reductions in R. solani (AG-8) were achieved; however, to achieve complete inactivation the system required supplemental chloride (20 mg L^-1), while using 9.09 mA cm^-2. The chloride allowed for low levels of free chlorine (≤0.17 mg L^-1) that were more active in the bulk solution, complementing the electrode surface EAOP reactions. Perchlorate production was an initial concern but was found to be negligible under the conditions tested. Small but significant increases in nitrate, ammonium, and sulphate were observed following treatment. These increases are hypothesized to originate from the degradation of proteins and amino acids released during pathogen cell disruption.

Grain protein content (GPC) is an important nutritional quality trait of wheat. Aegilops tauschii Coss. is a progenitor of common wheat and has been shown to have high GPC. The objective of this study was to identify quantitative trait loci (QTL) for GPC using A. tauschii–Triticum aestivum L. recombinant lines. An advanced BC₂F₆ population (112 lines) containing A. tauschii segments was developed using synthetic octaploid wheat (hexaploid wheat Zhoumai 18 × A. tauschii T093), which displayed significant phenotype variances. Two quality traits, GPC and wet gluten, and four yield-related traits, thousand kernel weight, spikelet number per plant, grain number per spike, and grain weight per spike, were evaluated. The results show that the mean GPCs of these lines were significantly higher than those of Zhoumai 18. Correlation and mapping analyses indicated that quality traits were weakly negatively correlated with yield traits. Furthermore, 16 A. tauschii-derived QTL for GPC were detected in the recombinant inbred lines, and four stable QTL that have no significant negative effects on yield and are located within the same marker interval were detected in both environments. Additionally, high-protein, high-yield lines 150228 and 150368 with stable QTL were obtained, and both can be directly utilised for fine mapping of the GPC genes and molecular marker–assisted selection to achieve synergistic improvement of wheat yield and protein content.

Grain yield and its variability is a major driver of seeding rate and inorganic fertilizer use at planting among grain growers. Recommended rates for fertilizer application with regard to crop utilization and soil management are discretionary and vary between producer and agronomist. This observational case study with Bayesian inference examines the association between application rates of inorganic nitrogen, phosphorus, potassium chloride and sulphur at planting, and yield of durum wheat (Triticum turgidum L.), large green lentils (Lens culinaris Medik.), canola (Brassica napus L.), canaryseed (Phalaris canariensis L.), and spring barley (Hordeum vulgare L.). Using precision agriculture, input and crop yield information for each parcel of cultivated land was collected over a 4 yr period from 2015 to 2018 on a continuous no-till farming operation in the semiarid region of Saskatchewan, Canada. Hierarchical models were derived that accounted for yield variability in crop types due to the random effects of field, cultivar, crop planted in previous year, planting year, combine machine, observation location within field, and elevation. Evidence from this longitudinal study suggests that seed-placed fertilizer above the recommended safe rate can be associated with yield decline on farming operations in the semiarid environment of Saskatchewan, Canada.

Alfalfa is an important economic crop; a mutant (M) strain was identified during planting and production. M plants consistently had better relative water content and relative electrical conductivity under higher salt conditions compared with the wild type (WT) plants, suggesting that M plants have higher tolerance for salt. To understand the microRNAs (miRNAs) involved in salt stress response in alfalfa, 128 miRNAs were identified from the WT and M alfalfa plants under normal and saline conditions. Of the 128 miRNAs, 29 and 23 differentially expressed miRNAs were identified in the M vs. WT control (M-CK vs. WT-CK) and salt-stressed M vs. WT (M-salt vs. WT-salt) comparison, respectively. These miRNAs responded to salt stress and showed different expression patterns after salt treatment. Their potential target genes were predicted and further analysed by GO classification and KEGG pathway analysis, where the majority of target genes were associated with plant growth and development, and exhibited significant changes in WT and M plants. In addition, compared with the WT plants, miR172-CNGC, miR319-CAX2, miR408-NHX and miR2590-CHX14/15 showed significant upregulation in M alfalfa plants, suggesting that M plants have higher ion transport levels. The differential expression profiles of miRNAs and putative target genes were further validated by quantitative real-time polymerase chain reaction. It is speculated that these miRNAs are involved in the increased salt tolerance of the M alfalfa plants.

Sap flow was measured to determine transpiration rates for CanAm and Walker poplars grown in the semiarid Canadian prairie. CanAm poplars had higher sap flow rates and were better able to supply water to actively growing regions for all water availabilities (well-watered to drought). CanAm poplars were better able to survive drought.

Unrooted cuttings of ‘Prestige Red’ and ‘White Star’ poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) were stored in a box at 10 °C for 0, 2, 4, 6 or 8 d to simulate shipping and holding. Visual root ratings decreased following ≥4 d of storage but did not differ from the non-stored cuttings. Root rating of ‘White Star’ was 0.5 higher and cuttings maintained higher fructose and glucose concentrations compared to ‘Prestige Red’. Glucose (r² = 0.4824) followed by fructose plus glucose (r² = 0.4222) were the best predictors of rooting. Carbohydrate maintenance may be an indicator of storage tolerant and better-rooting cultivars.