HARVEST
University of Saskatchewan's Repository for Research, Scholarship, and Artistic Work
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Recent Submissions
NITROGEN USE EFFICIENCY IN SPRING CANOLA (Brassica napus)
(2025-02-13) Dhakal, Rajeev; Bueckert, Rosalind Ann; Vail, Sally Lynne; Bett, Kirstin Elizabeth; Parkin, Isobel A P; Robinson, Steve J; Schoenau, Jeff John; Warkentin, Tom Dale; Stahl, Andreas
The abstract of this item is unavailable due to an embargo.
Modeling the lagged and nonlinear effects of weather conditions on abundance of Culex tarsalis mosquitoes in Saskatchewan, Western Canada using a bi-dimensional distributed lag nonlinear model
(Elsevier, 2024-12-24) Gizaw, Zemichael; Vidrio-Sahagún, Cuauhtémoc Tonatiuh; Pietroniro, Alain; Schuster Wallace, Corinne
The establishment of West Nile Virus (WNV) competent vectors continues to pose a major public health challenge in Canada, especially in the south. While studies have examined the association between weather conditions and the abundance of mosquitoes over trap weeks, there is limited research on the effects of weather conditions on the abundance of Culex tarsalis (Cx. tarsalis) mosquitoes for a lapse of time beyond the trap week in Saskatchewan, Western Canada. To address this gap, we analyzed provincially available weekly mosquito trap and co-incident meteorological station data in Saskatchewan from 2010 to 2021 using a bi-dimensional distributed lag and nonlinear model. Data indicate that 171,141 Cx. tarsalis mosquitoes were trapped across much of Saskatchewan, from 2010 to 2021. Cx. tarsalis were found to be most abundant between weeks 26 and 35 (July and August) and peaked in weeks 30 and 31. Based on the WNV-positive pools, mosquito infection rates increased from week 23 to 36. While weekly average maximum air temperatures between 20 °Cand 30 °C were associated with more Cx. tarsalis across all lags (0 – 8 weeks), higher weekly average minimum air temperatures had a strong and immediate effect that diminished over longer lags. Higher weekly average rainfall amounts (> 20 mm) were associated with fewer Cx. tarsalis mosquitoes across all lags, while average weekly rainfall between 8 and 20 mm was strongly associated with a high abundance of Cx. tarsalis mosquitoes over longer lags (5 -7 weeks). Additionally, increasing wind speed was associated with lower abundance of Cx. tarsalis across all lags. Findings identified nonlinear lag associations for weekly average maximum air temperature and rainfall, but linear associations for weekly average minimum air temperature and wind speed. Identified lags and thresholds for temperature, rainfall, and wind speed at which mosquito abundance peaked could help to inform public health authorities in timing of vector control measures to prevent WNV transmission.
Principles, barriers, and challenges of Indigenous water governance around the world
(Elsevier, 2025-01-02) Bharadwaj, Lalita; Bataebo, Sonia; Schuster Wallace, Corinne
Globally, Indigenous Nations are disproportionately faced with water challenges. This is partly because current approaches to water governance continue to systematically exclude Indigenous peoples and their worldviews from contemporary water governance structures. Given the need to reform current water governance systems to redress injustices and secure water resources for Indigenous peoples, this paper presents the findings of a scoping review designed to identify the principles, values, challenges/problems, and existing models of Indigenous water governance around the globe. Findings indicate that “water is life” is a fundamental principle of Indigenous water governance frameworks, as is “water as an interconnected whole” that forms a greater part of a community’s life and identity. The “Living Water, First Law” model and the Kistihtamahwin framework are examples of Indigenous water governance models identified. Colonization and the relegation of Indigenous knowledge remain a critical challenge to effective implementation of existing models of Indigenous water governance systems. This requires reform of contemporary water governance structures or formation of new systems that unsettle colonial legacies and privilege Indigenous worldviews and governance frameworks. These must focus on the overall health of the rivers, lakes, or freshwater entity and the holistic health of communities and be preceded by genuine nation-to-nation relationships.
Converting land use–land cover to E. coli contamination potential classes for improved management of groundwater wells: a case study in Ontario, Canada
(Springer, 2024-12-19) White, Katie; Schuster Wallace, Corinne; Dickson-Anderson, Sarah
Land use-land cover (LULC) types have been used as a proxy for Escherichia Coli (E. coli) sources and transport mechanisms. This study aims to advance the understanding of the relationship between LULC and E. coli presence in wells for the 11 major LULC categories. This represents a novel approach for assessing the broad potential for well contamination and informing groundwater management strategies. The approach combines insights gained from regression analyses conducted using a combination of large datasets with the Intergovernmental Panel on Climate Change (IPCC) method for consistent treatment of uncertainties within literature. Generalized Additive Models for Location, Shape, and Scale (GAMLSS) regression analyses were used to identify and support relationships between a large dataset of E. coli presence in wells and LULC data, identifying potential risk classes. A raster dataset for Ontario, Canada identifying areas of low to very high potential for E. coli presence in wells was created. Notably, the pastoral/agricultural LULC category was found to be in the very high-risk class, urban and aggregate mines in the high-risk class, forest in the moderate risk class, and water and grasslands in the low-risk class. However, gaps in understanding the relationship between some LULC categories and the presence of E. coli in wells remain in the disturbance, bedrock, and scrubland LULCs due to data limitations in both the study area and literature. These results provide private well users, who may lack technical expertise, with an accessible source of information on the potential for E. coli contamination.
Chronic radium-226 bioaccumulation and toxicity in the aquatic invertebrate Daphnia magna
(Springer, 2025-01-06) Lacroix-Durand, Charlotte; Janz, David; Liber, Karsten
Mining operations in Canada, including uranium mining and milling, generate by-products containing radionuclides, including radium-226 (226Ra), a long-lived, bioaccumulative calcium (Ca2+) analog. Despite strict discharge regulations, there is limited evidence to suggest that current thresholds for 226Ra adequately protect aquatic organisms. Furthermore, Canada lacks a federal water quality guideline for 226Ra, underscoring the need for protective limits to safeguard aquatic ecosystems. Hence, this research aimed to generate data on 226Ra toxicity to the model aquatic invertebrate Daphnia magna. For this purpose, two 21-day chronic toxicity tests with D. magna were conducted, with survival and reproduction as the endpoints, as well as a reduced water hardness experiment, a multigenerational study, and a bioaccumulation assay. These experiments demonstrated that a high activity concentration (nominal 50 Bq/L) of 226Ra can significantly impact the survival of D. magna. 226Ra was also found to bioaccumulate in D. magna with a BAF of 72.8. Since the Canadian Metal and Diamond Mining Effluent Regulations (MDMER) monthly mean effluent limit is currently set at 0.37 Bq 226Ra /L, the limit for composite samples at 0.74 Bq/L 226Ra, and the limit for grab samples at 1.11 Bq/L 226Ra, it is unlikely that toxic effects to aquatic cladocerans like D. magna from 226Ra will be observed downstream of Canadian mines and mills.
Chronic Radium-226 Toxicity to and Oxidative Stress in the Aquatic Invertebrate Chironomus dilutus
(Oxford University Press, 2025-01-12) Lacroix-Durand, Charlotte; Janz, David; Liber, Karsten
The mining industry, including uranium mining and milling, is of high importance in Canada. It is, however, important to consider that ore processing can result in the creation of by-products that contain radionuclides such as radium-226 (226Ra). Even with the strict discharge regulations in place, there is limited evidence to suggest that the current Canadian regulatory thresholds for 226Ra are protective for aquatic life. This concern underscores the importance of generating toxicity data for 226Ra, as no federal Canadian water quality guidelines for 226Ra currently exist to safeguard aquatic ecosystems. The potential ecological risks of 226Ra are significant due to its high mobility under typical environmental conditions, long half-life (t1/2 ~ 1,600 years), bioaccumulative properties, and similarity to calcium (Ca2+). Considering this, the primary objective of this research was to gather data on the toxicity of 226Ra to the aquatic invertebrate Chironomus dilutus. For this purpose, a partial life cycle experiment was conducted, with larval growth, survival and pupation, and emergence and sex ratio of emerged adults, as the experimental endpoints. In addition, an assessment of oxidative stress as a potential cause of toxicity was performed. These experiments revealed that elevated activity concentrations of 226Ra (25.5 Bq/L) can significantly impact the growth of C. dilutus. However, none of the other nonlethal endpoints were significantly affected by 226Ra exposure, and there was no evidence of oxidative stress in exposed C. dilutus. Finally, 226Ra was shown to adsorb onto the silica sand used as a substrate for all experiments and desorbed following acid extraction.
SARS-CoV-2 Infection Affects Glucose Homeostasis, Glucoregulatory Hormones and Pancreatic Cellular Processes in Male Syrian Golden Hamsters (Mesocricetus auratus)
(2025-02-12) Sasikumar, Shruti; Unniappan, Suraj; Kelvin, Alyson; Macphee, Daniel; Meachem, Melissa
The abstract of this item is unavailable due to an embargo.
The Effect of Maturity and Ensiling on the Nutritional Quality of Fall Rye (Secale Cereale L.) Forage
(1993-12) Stefanyshyn-Cote, Barbara Ann; Christensen, Dave
The effect of maturation and ensiling on recommended fall rye (Secale cereale L.) cultivars was evaluated to provide insight into the selection of new varieties and to resolve claims of fall rye ensiling poorly. Current research in fall rye has been directed at the development of low viscosity and semi dwarf cultivars and the effect of these selection pressures on the forage component of fall rye is unknown. Three experiments of a completely randomized design were conducted. In the first experiment, chemical composition and in vitro organic matter digestibility of fall rye (cultivars Musketeer and Prima) were compared to barley (cultivar Bonanza) at five stages of maturity (heading, flowering, mid-milk, early dough and firm dough). Crude protein content was lower (p < 0.05) for fall rye than barley at each stage. Water soluble carbohydrates, acid detergent fibre (ADF), neutral detergent fibre (NDF) and buffering capacity were higher in the fall rye, but not always significantly. Starch deposition occurred at earlier stages of maturity for fall rye (p <0.05). At each stage, in vitro organic matter digestibility was highest for barley (p <0.05) although, earlier stages of fall rye greenfeed were equivalent to later stages of barley.
In experiment two, fall rye (cultivar Prima) ensiled at flowering and mid-milk was compared to Virden barley ensiled at mid-dough. Chemical composition of the silages was similar to the original forages of experiment one. Organic acid content, pH, acid detergent insoluble nitrogen and ammonia production of both fall rye and barley silages fell within the limits suggested for good to excellent quality silage. In vivo digestibility was similar between fall rye ensiled at flowering and barley ensiled at mid-dough, but significantly lower for fall rye ensiled at mid-milk. Voluntary dry matter intake of fall rye (1.0 and 0.7% of body weight (BW) for fall rye ensiled at flowering and mid-milk respectively) was significantly lower than barley silage intake (1.9% BW).
The third experiment compared fall rye and barley silage digestibility in situ. In situ digestibility of fall rye was higher than in vitro or in vivo digestibility found earlier, although the ranking of the cereals was the same in vitro or in vivo. Organic matter disappearance was lower for fall rye than barley (p<0.05).
Although chemical composition responds similarly to maturation for both fall rye and barley, it is recommended that fall rye be ensiled prior to the early milk stage to produce forage of similar quality to barley. Fermentation characteristics indicate that fall rye was successfully ensiled at either the flowering or mid-milk stages, however, at heading or flowering thy matter digestibility was maintained while intake and degradability were maximized. Low voluntary intake is the predominant factor limiting fall rye utilization, whether due to low digestibility or other factors. Selection of fall rye plants with higher leaf content, directly or on the basis of fibre and digestibility analyses may alleviate low voluntary intake and improve digestibility.
Understanding Lodging in Oat (Avena sativa L.) through Root, Stem, and Leaf Characteristics
(2025-02-12) Ferre, Celine; Beattie, Aaron; Feurtado, Allan; Biligetu, Bill; Noble, Scott; Caffe, Melanie
Lodging is the permanent displacement of stems from their upright positions and is a critical issue for oat (Avena sativa L.) producers as it reduces harvestability, yield, and quality, while increasing disease load. To help prevent lodging, producers can utilize management strategies that include: (i) agronomic practices, such as using plant growth regulators or altering seeding, nitrogen or irrigation rates, and (ii) the choice of cultivar. Typically, the development of lodging-resistant cultivars entails the visual assessment of lodging when suitable environmental conditions or management techniques promote lodging. However, in the absence of such conditions it becomes challenging to develop lodging resistant cultivars. It is therefore important to develop methods that will allow plant breeders to continue selecting for lodging resistant breeding lines, even in the absence of visual lodging, by understanding and assessing the underlying traits relevant to lodging. Given the equally important genetic and agronomic influences on lodging, this thesis had three main objectives: 1) to evaluate stem biomechanical, root crown architecture, and whole plant traits to determine those which are correlated to lodging resistance, 2) to understand the impact of seeding rate on traits important to lodging resistance, and 3) to assess the potential of indoor root imaging to identify root system traits which are important for lodging resistance. To address the first objective, 14 spring oat genotypes adapted to western Canada and representing a diverse range of height and lodging resistance were grown over six site-years and assessed for whole plant, stem, and root crown traits. A correlation analysis showed that plant height, internode length, flag leaf angle, whole plant bending resistance, root plate angle, and stem inner and outer diameters were significantly associated to lodging resistance. Imaging of root crowns revealed that root volume and root length were significantly correlated to lodging. A decision tree created using inner diameter, internode length, and force per panicle was able to predict lodging resistance with an accuracy of 79%. Finally, a structural equation model showed that plant height, internode length, flag leaf angle, bending resistance, root plate angle, and inner diameter all directly influenced lodging. To address the second objective, four genotypes were grown at three seeding rates: 200 (low recommended rate), 300 (high recommended rate), and 400 (very high rate) plants/m2. Analysis of variance and post-hoc testing revealed that whole plant bending resistance, stem outer and inner diameters, solidity, and root plate spread were significantly impacted by seeding rate and displayed no cultivar or site-year interactions. Plant height displayed a seeding rate by genotype interaction, while both root volume and root length displayed three-way interactions between seeding rate, genotype and site year. Overall, the lowest seeding rate provided the greatest benefit towards reducing lodging without negatively impacting yield. For the third objective, seedlings of 22 oat genotypes, including the 14 field-grown genotypes from objective 1, were assessed using 2-dimensional hydroponic pouch imaging from early germination to the 4 leaf-emergence stage. Image analysis of 23 root system traits revealed that the number of holes in the root system and median number of roots were significantly correlated to lodging rating. When assessed visually, it was observed that genotypes with higher lodging resistance had a larger number of lateral roots that were also longer, which suggested root systems with potentially greater soil gripping capacities. Growth of the 14 field-grown genotypes in rhizoboxes did not reveal any traits significantly correlated to lodging, however, tiller number was correlated to tiller angle and height. Overall, this thesis demonstrated that oat lodging resistance is complex, being influenced by several above-ground architectural traits, mechanical traits, and root architecture traits, with resistance being attainable via different combinations of these traits. Some traits, such as plant height, whole plant bending resistance and flag leaf angle, are suitable for early-generational screening in breeding programs with inexpensive and high-throughput measurement. Other traits such as internode length, stem diameters and field root architecture traits may need to be reserved until the final stages of breeding due to their low throughput and more technical nature to measure. Finally, this thesis indicated that a lower seeding rate (200 plants/m2) would be most beneficial to reduce lodging. This rate altered values of five lodging-related traits to improve lodging resistance, with four target traits showing no cultivar or site-year interactions, thus indicating the universal benefit to oat producers of using a lower seeding rate to decrease lodging risk.
The Preferences of Lumbricus terrestris Earthworms for Weed Seeds Typical of The Canadian Agricultural Ecosystems
(2025-02-12) Ji, Pengfei; Willenborg, Christian; Bourgault, Maryse; Congreves, Kate; Sharbel, Timothy; Helgason, Bobbi
The abstract of this item is unavailable due to an embargo.