Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial step of glycerolipids biosynthesis and contributes to oil production, membrane stabilization, and stress responses in plants. In major field crops, little information on the GPAT gene family and their potential stress-related functions were available. In this study, 15 GPAT gene family members were identified from the maize genome and designated as ZmGPAT1–ZmGPAT14 and ZMS1. The ZmGPAT proteins contained 371–557 amino acids and had a molecular weight between 42.7 and 61.2 kDa. Phylogenetic analysis revealed that ZmGPATs fell into four clusters. All 15 ZmGPAT proteins possessed conserved PlsC/LPLAT (phosphate acyltransferases/lysophospholipid acyltransferases) domains and featured multiple acyltransferase motifs. The expression profiles of ZmGPAT genes were different in various tissues of maize and the elevated expression of several ZmGPAT genes occurred at early seed developmental stages. In response to environmental stresses, differential expression of ZmGPATs had been observed, highlighted by the significant induction of transcripts accumulation of some ZmGPATs under cold treatment. This study will help to better understand the potential roles of GPAT in oil production and development and abiotic stress responses in field crops.

The bHLH (basic/helix-loop-helix) protein is one of the largest transcription factors (TFs) that is essential in regulating plant growth and development. Although the bHLH family has been identified in some organisms, a systemic study has not been performed in Brassica napus, which is the third most important oilseed crop worldwide. In the present study, a total of 460 bHLH TFs were identified from the genome of B. napus and clustered into 25 subfamilies. Structural analysis was used to identify the DNA binding type and conserved amino residues of the identified sequence in the bHLH domain. In addition, a comparative genomic analysis of B. napus and its progenitors (Brassica rapa and Brassica oleracea) and two basal angiosperms (Amborella trichopoda and Vitis vinifera) was performed to trace the change during expansion and evolution of the bHLH family. The bHLH TFs in leaves and roots showed various expression patterns. The homologs of the AA-subgenome and CC-subgenome exhibited similar expression patterns, but were more divergent between the homologs caused from other duplicate events.

A high-density genetic map of apricot (Prunus armeniaca L.) was constructed using an F1 population constructed by crossing two main Chinese cultivars ‘Chuanzhihong’ and ‘Luotuohuang’, coupled with a recently developed reduced representation library (RRL) sequencing. The average sequencing depth was 38.97 in ‘Chuanzhihong’ (female parent), 33.05 in ‘Luotuohuang’ (male parent), and 8.91 in each progeny. Based on the sequencing data, 12 451 polymorphic markers were developed and used in the construction of the genetic linkage map. The final map of apricot comprised eight linkage groups, including 1991 markers, and covered 886.25 cM of the total map length. The average distance between adjacent markers was narrowed to 0.46 cM. Gaps larger than 5 cM only accounted for <0.33%. To our knowledge, this map is the densest genetic linkage map that is currently available for apricot research. It is a valuable linkage map for quantitative trait loci (QTLs) identification of important agronomic traits. Moreover, the high marker density and well-ordered markers that this linkage map provides will be useful for molecular breeding of apricot as well. In this study, we applied this map in the QTL analysis of an important agronomic trait, pistil abortion. Several QTLs were detected and mapped respectively to the middle regions of LG5 (51.005∼59.4 cM) and LG6 (72.884∼76.562 cM), with nine SLAF markers closely linked to pistil abortion. The high-density genetic map and QTLs detected in this study will facilitate marker-assisted breeding and apricot genomic study.

Annual companion crops are often used in new seedings of perennial forages in western Canada. Fast-establishing grass species that do not overwinter in this region have potential as companion crops to increase seeding year yields without reducing perennial forage establishment. Trials were seeded in two different years at Saskatoon and Melfort, SK, in the Dark Brown and Black soil zones, respectively. Crested wheatgrass [Agropyron cristatum (L.) Gaertn.], meadow bromegrass (Bromus riparius Rehm.), and alfalfa (Medicago sativa L.) were seeded in pure stands and mixtures with or without an annual ryegrass (Lolium multiflorum Lam.) or Festulolium (Lolium × Festuca) companion crop at two seeding rates. Forage dry matter yield in the establishment year was increased with annual ryegrass companion crops compared with no companion crop regardless of seeding rate, but was increased only with the higher rate of Festulolium at Saskatoon. Despite using low companion crop seeding rates, stand densities of most of the perennial forage stands were lower than with no companion crop at Saskatoon, but in Melfort, most stand densities did not differ. The annual ryegrass companion crop reduced yields the year after seeding at both sites, while the Festulolium also reduced yields, but not at Melfort for the lower companion crop seeding rate. Dry matter yields were usually not different between companion and no companion crop treatments in the second year after seeding and for 3-yr total yields. The use of these companion crops increased the percentage of the 3-yr total yield produced in the seeding year.

Biochar application on agricultural soils is an interesting emerging technology with promising potential for long-term carbon storage and the enhancement of soil fertility. The effect of a biochar compost mixture with and without standard NPK fertilizer was assessed to determine the effects on the growth of cabbage over 3 yr at two locations. Field trials were established at the Holland Marsh and Simcoe Research Station in Ontario. The main purpose of this study was to determine the effect of biochar soil amendment on cabbage yield and quality. Biochar (a blend of 1:1 composted duck manure and biochar based on dry weight) was applied at rates of 0.6 and 2.4 kg m^-2 with and without standard NPK fertilizer and compared with compost at the rate of 1.2 kg m^-2, which was the rate applied with the high rate of biochar. The biochar used was somewhat alkaline (pH 8.1) and increased the pH (>0.5) of the top 0–15 cm of the soil. It also had a high cation-exchange capacity (CEC > 25) and contained elevated levels of some trace metals and exchangeable cations (K, Ca, and Mg) in comparison to the untreated soil. None of the biochar or compost treatments increased yield compared with the nonamended check at either location. Treatments that included the standard NPK fertilizer resulted in the highest yields.

The effects of light quality on photosynthesis and transpiration of chrysanthemums during the vegetative and flowering stages are not known. Leaf and whole-plant CO₂ and H₂O exchanges of chrysanthemums during long-day (LD) and short-day (SD) photoperiods were measured under varying intensity levels of high-pressure sodium (HPS) and different monochromatic and multicolour light-emitting diode (LED) lights. All light sources induced leaf photosynthesis effectively, including green and orange LEDs. During both LD and SD, HPS, white, and notably orange light produced high rates of photosynthesis, whereas blue light had the lowest rates. In addition, there were only subtle changes in the response of leaf functions to light quality during flowering induction. Diurnal patterns of whole-plant net C exchange rate were similar under HPS and two commercial LED lights, one red–blue (RB) and one red–white (RW), during both LD and SD. The RB and RW LED lights were as effective at maintaining whole-plant C gain during the day as traditional HPS lights. However, in comparison to HPS, the RB and RW LEDs increased whole-plant transpiration and decreased water-use efficiency (WUE). A decrease in WUE under these LEDs was not evident from the leaf measurements, which emphasizes the importance of examining responses to light quality at the whole-plant level as well and not at the leaf level alone. In commercial production, the wavelength of supplementary lighting may heavily influence WUE and subsequent nutrient uptake, and ultimately growth and quality of cut flower crops.

Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess of the plant’s needs and can be reduced without causing adverse effects. Previous studies have reduced the level of specific nutrients or suite of nutrients over the entire crop cycle or at the onset of reproductive growth. Here, two split-plot experiments (four blocks each) were conducted with subirrigated, potted, disbudded chrysanthemums (Chrysanthemum morifolium Ramat.) grown under greenhouse conditions with sulphate treatment (2.25 mmol L^-1 S supplied continuously over the crop cycle in experiment 2 only and 2.25, 1.125, or 0.5625 mmol L^-1 S interrupted at inflorescence emergence) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the sub-plot. Morphological characteristics of plants with fully-expanded inflorescences were unaffected by decreasing S delivery over the crop cycle. Dry mass (DM) yields and S budgets revealed that supply-based S use and S uptake efficiencies increased markedly in both cultivars with decreasing S delivery. Minor amounts of reduced-S, rather than sulphate, were lost from leaves of ‘Covington’ during inflorescence development. High quality chrysanthemums had sufficient leaf-S (0.17%–0.23% DM) at inflorescence emergence even with the lowest S supply, which would deliver an approximate 87.5% reduction in S over the crop cycle compared with industry standards. The primary mechanism to obtain sufficient S for the growth of chrysanthemums in these studies was increased uptake efficiency.

MicroRNAs (miRNAs) are highly conserved, endogenous, short (21–24 nucleotides), non-coding RNA molecules that play significant roles in post-transcriptional gene silencing by directing target mRNA cleavage or translational inhibition. Nonetheless, highly nutritious “super grain” quinoa (Chenopodium quinoa) is an extreme abiotic stress tolerant Andean seed crop of many potential uses, with outstanding protein quality and a load of vitamins, minerals, as well as flavonoid antioxidants. In this study, applying genome-wide in silico approaches (referring to the recently published quinoa genome) and following a set of stringent filtering measures, a total of 22 potentially conserved microRNAs belonging to 18 families were characterized from quinoa and 11 randomly selected putative microRNAs (cqu-miR160a, cqu-miR162a, cqu-miR164a, cqu-miR166b, cqu-miR167a, cqu-miR172a, cqu-miR319a, cqu-miR390a, cqu-miR393a, cqu-miR394a, and cqu-miR398b) were validated successfully by RT-PCR. Using the psRNATarget tool, a sum of 59 potential miRNA targets, mostly transcription factors, were identified that are involved in biosynthesis, metabolic processes, and signal transduction. Among the detected targets, six target transcripts (F-Box proteins, TCP, MYB, WD protein, NAC, and CSD) were reported to have specific roles in both flavonoids biosynthesis and stress response signaling in some plants. To the best of our knowledge, this is the first report of quinoa microRNAs and their targets.

The occurrence of low natural light levels during winter months is a major limiting factor for greenhouse plant production in northern regions. To determine the effects of supplemental lighting (SL) on winter greenhouse production of pea pods, plant growth, pod yield, and quality were investigated under SL at a photosynthetic photon flux density (PPFD) of 50, 80, 110, and 140 μmol m^-2 s^-1, plus a no-SL control treatment, inside a Canadian greenhouse from January to March. Light-emitting diodes with a red-to-blue PPFD ratio of 4:1 and a 16 h photoperiod were used for the lighting treatments. During the trial period, the average natural daily light integral (DLI) inside the greenhouse was 6.6 mol m^-2 d^-1 and the average daily temperature was around 13 °C. Compared with the control, SL treatments increased pod yield and promoted plant growth, as demonstrated by faster main stem extension and greater aerial biomass. Also, total pod yield (g plant^-1 or no. plant^-1) and some growth traits (e.g., stem diameter, branch number, leaf thickness, and leaf chlorophyll content) were proportional to supplemental PPFD within the range of 0–140 μmol m^-2 s^-1. However, SL levels of 50–80 μmol m^-2 s^-1, corresponding to a total (natural + supplemental) DLI of 9.4–11.1 mol m^-2 d^-1, resulted in the best pod quality based on evaluations of individual fresh mass, length, soluble solids content, succulence, and firmness. Therefore, a total DLI ranging between 9.4 and 11.1 mol m^-2 d^-1 can be recommended as a target light level for greenhouse production of pea pods using SL under winter environment conditions.

Stomatal opening/closure plays a key role in balancing a plant’s need to conserve water, while still allowing for the exchange of photosynthetic and respiratory gasses with the atmosphere. Stomatal opening/closure can be induced by differences in light quality but a detailed knowledge of the role of light in stomatal regulation in tomato is limited. In this study, we evaluated red and blue light-dependent stomatal opening processes in tomato seedlings and explored the mechanisms involved using different light-quality treatments. After 10 h of darkness, tomato seedlings were subjected to the following five treatments: monochromatic red light (R), 33% blue (2R1B), 50% blue (1R1B), 67% blue (1R2B), and monochromatic blue light (B) at 200 μmol m^-2 s^-1 light intensity. The highest stomatal conductance recorded were for 1R1B. Stomatal aperture under 1R1B showed a 92.8% increase after 15 min and a 28.6% increase after 30 min compared with under R alone. Meanwhile, the study shows that the expressions of the plasma membrane H⁺-ATPase in the leaf were regulated by different proportions of blue light. The results show that the expressions of HA1 and HA4 increased under 1R1B and 1R2B after 15 min of exposure compared with under R alone. Under 1R1B, our results also show net photosynthesis increased compared with R and B after longer treatments, which may be related to chloroplast ultrastructure, and leaf dry weight increased compared with under 1R2B or B alone, but there were no differences under the R and 2R1B light treatments.

Sweet pearl millet [Pennisetum glaucum (L.) R. Br.] and sweet sorghum [Sorghum bicolor (L.) Moench], previously tested for ethanol production, were evaluated as high sugar crops for animal feeds to possibly replace silage corn (Zea mays L.). We compared the forage yield, nutritive value, and ensilability of one hybrid of sweet pearl millet and two of sweet sorghum to a locally adapted silage corn hybrid in five Canadian ecozones. Forage yields of sweet pearl millet and sorghum were similar to that of silage corn in the Boreal Shield, Mixedwood Plain, and Atlantic Maritime ecozones, greater in the Prairies, and lower in the Pacific Maritime ecozone. Across sites, forage dry matter concentration was less for sweet pearl millet (289 g kg^-1) and sweet sorghum (245 g kg^-1) than for silage corn (331 g kg^-1). Sweet pearl millet had a lower total digestible nutrient (TDN) concentration (452 g kg^-1 DM) and aNDF digestibility (NDFd) than sweet sorghum and silage corn along with greater neutral detergent fibre (aNDF) and water-soluble carbohydrate (WSC) concentrations than silage corn. Sweet sorghum had greater aNDF and WSC, lower starch, and similar TDN (534 g kg^-1 DM) concentrations, but greater NDFd compared with silage corn. Sweet pearl millet and sorghum fermented as well as silage corn, reaching low pH values and acceptable concentrations of lactic and volatile fatty acids. Sweet sorghum is therefore a viable alternative to silage corn in Canada except in the Pacific Maritime ecozone, but early-maturing hybrids with acceptable DM concentration at harvest are required.

Soybean [Glycine max (L.) Merr.] production has moved rapidly westward on the Canadian prairies, most recently arriving in southern Alberta. Adjusting row spacing (RS) and seeding density (SD) to maximize soybean productivity is well-documented for rainfed conditions but not where irrigation is obligatory. A 3 yr study was conducted at two irrigated locations in southern Alberta using two early-maturity [maturity group 00] soybean genotypes planted at two RSs and three SDs. Soybean reached 95% maturity in 114–132 d and only one of six growing environments experienced a killing frost prior to maturity. Wide rows led to 1 d earlier maturity for one genotype in all six environments and increased grain yield (5%–20%) in four out of six environments compared with narrow rows. Increasing SD from 30 to 80 seeds m^-2 generally led to increased pod clearance (from 5.0 to 8.4 cm in one environment) and grain (mean increase of 33%, from 2100 to 2800 kg ha^-1) and straw yield, but decreased seeds plant^-1 (from 94 to 46). Notwithstanding 9% lower cumulative corn heat units during the study, and an average 5 d longer maturity requirement at Lethbridge, soybean performance was equal to Bow Island in many parameters including grain yield. Our findings will help develop recommendations for new soybean growers in the irrigated region of southern Alberta.

Endozoochory by cattle has been considered an important method for population self-regeneration; however, the effects of cattle digestive tracts on the viability and germinability of purple prairie clover (Dalea purpurea Vent.), a native North American species, remain understudied. The experiment was conducted at the Agriculture and Agri-Food Canada Swift Current Research and Development Centre in the semiarid prairie of western Canada. Purple prairie clover seeds extracted from cattle dung pats were tested for germination and compared with uningested and scarified seeds from the same paddock. The germination percentage (within 200 d) of the ingested seeds was 16.5% ± 0.8%, two times higher after passing through digestive tracts than uningested seeds (8.3% ± 1.2%), while 76.6% ± 1.5% of ingested seeds remained dormant. As many as 92.4% ± 0.9% of purple prairie clover seeds survived digestion due to their high hard seed rate (90.5% ± 1.0%), which was lower than the uningested seeds by 6.9%. Therefore, cattle dispersing purple prairie clover seeds with high viability and germinability is a low-cost method to increase and rejuvenate purple prairie clover for late-season grazing pastures.

Intercropping winter cereals into Kura clover (Trifolium ambiguum M. Bieb.) has the potential to improve forage nutritive value without reducing yields. The objective of this research was to compare forage yield and nutritive value of cereal–legume mixtures to cereals or Kura clover grown in monoculture and harvested at two different maturity stages in spring. Winter rye (Secale cereale L.), winter wheat (Triticum aestivum L.), and winter triticale (×Triticosecale Wittmack) were sown in autumn at two locations as monocultures and into herbicide suppressed and non-suppressed Kura clover and harvested for forage the following spring. Harvested at the cereal crop boot stage at Arlington, forage yields averaged 4.7, 4.8, 5.3, and 1.7 Mg ha^-1 and 3.5, 3.7, 4.1, and 2.6 Mg ha^-1 at Lancaster for mixtures with non-suppressed Kura clover, suppressed Kura clover, monoculture cereals, and monoculture clover, respectively. At the milk stage, yields across all mixture treatments increased by 46% to 115% compared to the boot stage at Arlington and by 88% to 101% at Lancaster. Kura clover in mixtures increased crude protein by 34% to 46% and in vitro true digestibility by 3% to 6%, neutral detergent fiber digestibility by 0% to 6%, and reduced neutral detergent fiber concentration by 8% to 18% relative to cereal monocultures. The nutritive value of mixtures and monoculture Kura clover was always greater than that of monoculture cereals. Winter cereals can be successfully managed with Kura clover for forage production by maximizing nutritive value with boot stage harvests or achieving higher yields by harvesting at the milk stage.

Double cropping is not presently a common practice in Canada. The long-term climate averages, however, suggest that the practice should be possible in the most southern portions of the country. The study described herein represents the first simultaneous evaluation of three crops—maize, soybean, and white bean—seeded at five seeding dates spanning late June through early August in the most southern region of Canada. Germplasm was chosen such that physiological maturity could theoretically be reached if seeded following winter wheat. Results indicate that, following summer seeding, development in all three crops was primarily driven by thermal requirements. Only the pod filling stage of soybean was influenced by the declining daylengths of autumn, and this effect was most pronounced in germplasm of longer relative maturity. Yields of white bean and maturity group 00 soybean were unaffected by seeding up to the third week of July, whereas yield of maize and higher maturity group soybeans declined from June onward. For the latter, declining yields were primarily attributable to the interaction of seeding date and relative maturity and their effect on season length. These results clearly demonstrate that with the appropriate selection of germplasm, there is a seeding date window where maize, soybean, or white bean can be expected to reach physiological maturity as a double crop in Canada.

One advantage of high-density apple orchard systems is homogeneity in fruit maturity and quality. However, even in modern orchard systems, variation in fruit quality occurs. ‘Honeycrisp’ apple is susceptible to numerous disorders including bitter pit, soft scald, and poor colour development. Heterogeneity in fruit quality and nutrient distribution can lead to variation in fruit storability. Here, we tested the effect of within-canopy position on fruit calcium and potassium concentrations, quality, and disorder development for fruit across nine representative high-density orchards. Calcium concentrations were greater in the upper part of the canopy compared with the lower part. Potassium was more evenly distributed within the canopy. Calcium concentrations and potassium-to-calcium ratios were significantly correlated with mean bitter pit incidence, which was between 20% and 30% in the lower half of the tree and <15% in the upper half. Fruit quality was significantly affected by the position in the canopy and was not constrained to only colour, but also other quality metrics such as dry matter, size, and firmness. Additionally, the internal ethylene concentrations (IECs) of fruit in the upper canopy were approximately 50% of the IECs for fruit from the lower canopy. With an increased emphasis on uniformity and predictability of fruit for long-term storage, these results underscore the importance of understanding variation within the canopy. Even for high-density systems, significant variation in fruit quality can occur and fruit from the upper canopy has lower disorder incidence and higher fruit quality than fruit from the lower canopy.

Little is known about legume green manure productivity on organic farms. Soil and plant tissue were sampled in annual, biennial, and perennial green manures on 41 fields in the eastern prairies. Green manure biomass averaged 4572 kg ha^-1; 53% was legume plant material and 18% was weeds. Soil test P and plant tissue P concentrations were below critical levels in about half of all green manures. Mean N fixation was estimated at 71 kg ha^-1. This observational study provides a baseline for future research to optimize green manure and nutrient management in organic grain production systems.

AAC Chrome is a semi-leafless, yellow cotyledon field pea (Pisum sativum L.) variety developed at the Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB. It has high yielding potential, medium maturity, and good lodging resistance. AAC Chrome has a maturity of 95 d and thousand-seed weight of 241 g. AAC Chrome is resistant to powdery mildew (caused by Erysiphe pisi), moderately tolerant to mycosphaerella blight (caused by Mycosphaerella pinodes), and moderately susceptible to fusarium wilt (caused by Fusarium oxysporum). AAC Chrome is adapted to all field pea growing regions in western Canada.

AAC Olive is a semi-leafless, green cotyledon, and high-yielding marrowfat pea (Pisum sativum L.) variety developed at the Lacombe Research and Development Centre, Agriculture and Agri-Food Canada. It has a maturity of 102 d, average thousand-seed weight of 344 g, and is resistant to powdery mildew (caused by Erysiphe pisi). AAC Olive was certificated on 16 Apr. 2019 by the Canadian Seed Growers Association under the authority of the Canada Seeds Act. The certificate number is 2165-2019.