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Dormancy in canola (Brassica napus L.) is a complicated process due to many overlapping and interacting factors affecting the absolute dormancy levels. It is unknown if seed dormancy plays a role in the poor stand establishment of planted canola but given that germination and dormancy are two ends of the same continuum, it has been suggested that dormancy may be a culprit of poor establishment. This review synthesizes literature pertaining to secondary dormancy in B. napus and the interaction of genetic, physiological, environmental, and agronomic factors. Seed germination and vigour and the interaction with dormancy are also addressed. The persistence of volunteer canola seed in the soil seedbank is a result of the induction of canola seed into secondary dormancy under adverse environmental conditions such as low temperature or low light. Genetics is a major influencing factor on absolute secondary dormancy (∼50%) in canola. Plant hormones abscisic acid and gibberellic acid and their interactions also influence dormancy with highly dormant genotypes having increased abscisic acid concentration in the seed. Seed sugars, seed storage proteins, glucosinolate content, and growth habit are all additional factors affecting absolute dormancy in B. napus. Furthermore, maternal environmental conditions affect dormancy levels. In addition to genetic, physiological, and environmental factors, farming practices such as harvest timing, and tillage regimes can influence secondary dormancy of canola seed that has entered the seedbank unintentionally. Given the documented high heritability of secondary dormancy, it is feasible to reduce secondary dormancy in canola cultivars; however, consideration of all interacting factors must be given.
The soybean industry in Canada aimed to extensively expand soybean production to benefit from new early-maturing varieties and the warming climate. However, setbacks in the soybean industry since 2017 demonstrated the impacts of climate risk and global market uncertainty. Therefore, a better understanding of future climate conditions that will impact soybean growth in Canada is needed for decision-making in the sector, such as prioritizing regions for expansion and developing climate change adaptation strategies through either agronomic management practices or breeding new cultivars. Based on climate projections from a set of global climate models, we analyzed climate conditions for growing soybeans, including growing season start, crop heat units, precipitation, precipitation deficits and climate extremes, in the near-term (2030s), the mid-term (2050s) and the distant future (2070s). We found that a future warmer climate with an increase of 1.6, 2.8 and 4.1 °C in the growing season (May–September) mean temperature averaged over Canada’s land area in the near-term, mid-term and distant future under SSP3-7.0 would favour the expansion of soybean production further north and west. However, an increase of approximately 200 mm in precipitation deficits on the semiarid Canadian Prairies in the mid-term would constrain soybean production unless irrigation could be introduced. Heat- and drought-tolerant cultivars should be developed to adapt soybean production to a changing climate, in addition to the adoption of late-maturing cultivars that would benefit from the lengthened growing season and increased crop heat units.
Extreme climatic events, such as drought and heavy rainfall, are increasing with climate change. These events can threaten agroecosystems, including vineyards. Cover crops are often grown in vineyards for various reasons and can be an effective strategy for climate change adaptation. Understanding which cover crop species can establish well under extreme climate conditions is important. We conducted a greenhouse experiment to investigate the responses of nine cover crop species to overwatered and water-deficit conditions. Treatments included (1) overwatered soil condition, watered at 100% field capacity daily, (2) control, watered at 60%–70% every other day, and (3) water deficit, watered at 15%–20% weekly for 53 growing days. Results indicated that the total dry weight of all species decreased (most significantly) under water-deficit conditions. However, pubescent wheatgrass and red fescue did not exhibit any stress symptoms. Apart from alfalfa, all species established well under overwatered conditions despite slight yellowing of foliage for crimson clover and hairy vetch. Pearl millet and yellow sweet clover had the best establishment regardless of conditions. Our results provide important information on the selection of cover crops that can withstand climatic variability and thrive in the extreme conditions linked to the climate change scenario in Canada.
Irrigated agriculture in semi-arid regions is expected to increase in the future, which puts greater demands on scarce water resources. Sustainable irrigation strategies in semi-arid regions will support agricultural resilience to climatic change. The response of “Sweetheart”/Mazzard sweet cherry trees (Prunus avium L.) to postharvest deficit irrigation (PDI), as a water conservation method, was studied over three seasons (2019–2022) in the semi-arid Okanagan Valley of British Columbia, at five commercial orchards. The following irrigation treatments were applied; (i) a control of full irrigation, irrigated according to conventional growers’ practice at each orchard, (ii) PDI-30: 27%–33% reduction in irrigation volume, after harvest (67%–73% of control), and (iii) PDI-50: 47%–52% reduction in irrigation volume, after harvest (48–53% of control). Spring phenology (the timing of flower bud development, from side green to full bloom), flower bud moisture content and cold hardiness, and fruit yield and quality (before and after cold storage and shelf-life conditions) were assessed to determine if PDI altered fruit development over the subsequent growing season. Neither PDI-30 nor PDI-50 caused changes in the timing of flower bud phenology, cold hardiness or moisture content relative to the control. PDI treatments also had no effect on fruit yield or fruit quality at harvest or after storage and shelf-life conditions. These results suggest PDI could be used to reduce irrigation water use in semi-arid regions, like the Okanagan Valley, without affecting sweet cherry production or fruit quality.
Soybean seeding rates in the cool growing environment of Atlantic Canada are much higher than other regions impacting economic return. Recent studies across North America have suggested that soybean seeding rates can be lowered to maximize profitability. Seed treatments have been shown to improve abiotic stress tolerance and may be another mechanism to reduce seeding rates. Therefore, the objectives of the present study were to (i) determine the economically optimal seeding rate (EOSR) for conventional soybean in Atlantic Canada and (ii) determine if fungicide seed treatments can reduce this rate. Field studies were conducted in 2020 and 2021 to evaluate the effects of four seeding rates and four fungicide seed treatments on soybean stand establishment, growth, resource use efficiency, yield, and profitability. Price received had a dramatic effect on producer return and the EOSR which ranged from 24 3000 seeds ha−1 under a low price received scenario ($0.45 kg−1) up to 613 000 seeds ha−1 under a high price received scenario ($0.82 kg−1). In contrast, seed and pesticide costs had a minimal impact on expected returns. Soybean resource use efficiency was not impacted by seeding rate or by seed treatments. Further seed treatments did not impact soybean stand establishment or profitability. Soybean yield increased with seeding rate and plateaued at a seeding rate of 741 000 seeds ha−1, whereas individual plant yield dramatically declined as seeding rate increased. Results of this study suggest that soybean producers in Atlantic Canada should base their seeding rates on contracted or expected price received to maximize profitability.
In the agricultural sector, innovation is a vital economic driver for increasing food production. New crop varieties are developed and commercialized, greatly contributing to improved global food security through higher yields, improved nutrition and climate resiliency. Canada is a competitive and innovative actor in the global seed market. This article quantifies the degree of improvement for numerous crop traits required for commercialization success. We use empirical data from seed producers in the prairies to identify their adoption criteria to multiply new seed varieties. Results show that yield potential, disease resistance and lodging resistance are the key traits for pedigreed seed growers regardless of crop type, while other agronomic traits depend on the crop type. Quality factors such as malting or milling properties for cereals, protein content for pulses and oil content for oilseeds are also part of the variety selection decision process for prairie pedigreed seed growers.
In 2021, an unprecedented heat event caused widespread damage to tree fruit crops across western North America. In a preliminary trial conducted that summer in an apple (var. “Fuji”) orchard in the Okanagan Valley, British Columbia, a calcium carbonate-based foliar protectant reduced severe sunburn by 9% and fruit asymmetry by 17% but had no other effects on fruit quality, water stress, or leaf gas exchange. With climate change, extreme heat events are projected to become more frequent and extreme. Foliar protectants show potential for preserving fruit quality, but further research is urgently required to optimize their use in Canada.
Multiple herbicide-resistant kochia [Bassia scoparia (L.) A.J. Scott] is a growing weed management concern for farmers in the Canadian prairies. A randomized–stratified survey of 319 sites in Alberta was conducted in 2021 to determine the frequency and incidence of glyphosate, fluroxypyr, and dicamba resistance in kochia samples four and nine years after the previous rounds of surveys. Kochia samples exhibiting resistance to glyphosate, fluroxypyr, and dicamba were found at 78%, 44%, and 28% of the sites, respectively. Triple herbicide-resistant kochia samples, resistant to acetolactate synthase inhibitors, glyphosate, and at least one synthetic auxin, were found at 45% of the sites.
J.W. Mitchell Fetch, K.T. Nilsen, N. Ames, T.G. Fetch Jr., C. McCartney, J. Menzies, X. Wang, A. Burt, S. Kumar, D. Green, K. Stewart, W. Yan, W. Dyck, K.D. Hamilton
AAC Douglas is a white-hulled spring oat (Avena sativa L.) cultivar, with superior grain-yield potential in the western Canadian oat production areas, yielding 3.5% higher than Summit. AAC Douglas was registered for commercial production in Canada (Reg. No. 8950) on 21 February 2020. AAC Douglas has high protein (5% higher significantly (P=0.05) than AC Morgan) and beta-glucan content (10.6% higher than the nearest check, Summit), making it attractive for milling purposes. AAC Douglas is resistant to loose smut and covered smut, with moderately resistant to intermediate reactions to other diseases encountered in western Canada.
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