Theses and Dissertations at Montana State University (MSU)

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Multi-environment evaluation of winter pea genotypes for winter survival and yield stability
(Montana State University - Bozeman, College of Agriculture, 2024) Poudel, Amrit; Chairperson, Graduate Committee: Kevin McPhee; This is a manuscript style paper that includes co-authored chapters.
Winter pea can be grown as a rotational crop for soil moisture conservation and nutrient recycling in the wheat-growing region of Montana. Development of winter hardy cultivars would increase seed yield and expand the area of adaptation of this crop. Harsh winter conditions present a significant challenge to the production of winter peas. The objective of this study was to screen pea germplasm and breeding lines for winter survival and identify genotypes with good winter hardiness for future crop production. Field trials were conducted to evaluate genotypes at Bozeman, Havre, Huntley, and Moccasin, MT in 2021, 2022, and 2023. These lines included elite winter cultivars and several checks. Winter hardiness was evaluated as the percentage of surviving plants and by agronomic performance including yield. Genotypes were evaluated based on the GGE biplot method. This analysis captured multiple variables including yield, protein content, seed size, and their overall stability across multiple years and locations of study to aid in selecting lines. Differential winter survival was observed across locations and years. Higher winter survival was seen in Bozeman and Havre. Few lines were identified as having high seed yield and stable production over years and locations. Breeding lines had higher mean yield with few good lines having stable production of greater than 2500 kg/ha. Germplasm lines showed better winter survival than breeding lines. Protein content ranged from 20% to 31%. Larger seeds were observed in Moccasin, whereas Havre had the highest protein content. Mega- environment differentiation helped to select specific genotypes based on the trait of interest for a particular environment. Several European and US lines used in the experiments having high winter hardiness record performed better for seed yield and resistance to stress. The lines identified as having high levels of cold tolerance can be used as a prospective genetic resource in pea breeding programs. Genotypes having high and stable seed yield can be considered for release as a variety and made available to producers.
Consider the roots: examining barley belowground in the search for adaptation
(Montana State University - Bozeman, College of Agriculture, 2024) Williams, Jessica Lynn; Chairperson, Graduate Committee: Jamie Sherman; This is a manuscript style paper that includes co-authored chapters.
Barley is important for global food security and sustaining the economically valuable malt industry. Montana is a top barley producer in the United States, but terminal drought stress poses a significant threat to this production by negatively impacting yield and quality. New crop varieties with enhanced environmental adaptation and soil resource extraction would help address this and other issues facing modern agriculture. Stay-green is a trait that extends grain fill in cereals and can stabilize yield and quality under drought. However, this trait and its benefits can be inconsistent across environments and its successful incorporation into breeding strategies would benefit from expanded understanding of stay-green. Roots may play a role in stay-green physiology. Roots provide plants with the water and nutrients needed for growth and are important for crop performance in their own right. Different root system architectures provide adaptation to different environmental stressors, but studying these belowground structures is challenging. Adaptation is also impacted by soil properties and microbial communities. For this dissertation, roots were examined in greenhouse seedling assays and field trials in Montana. Agronomic performance was also assessed for malt barley and spring wheat cultivars varying for stay-green, a biparental barley population segregating for stay-green, and a diverse mapping population of barley lines from different breeding programs. Stay-green cultivars had a greater percentage of deep roots, more prolonged root growth during grain fill, and greater yield. Analysis of the biparental population identified genetic co-segregations of stay-green, root phenotypes, grain quality, and quality stability between environments, further supporting the benefit of stay-green in dry environments and its connection to roots. The diverse mapping population was used to find associations between the relative abundances of bacteria in the rhizosphere and barley genetic loci, that were mostly environment specific. Rhizospheric bacteria may be involved in local adaptation of plants. Finding plant genetic signal for these microbial characteristics supports the idea that it may be possible to breed crops with enhanced ability to recruit beneficial microbiomes if environmental influence and agronomic impact can be understood. Root examination remains a challenging but worthwhile avenue to pursue in crop adaptation research.
Biochemical, physiological, and genetic investigations of multiple herbicide resistant Avena fatua L.
(Montana State University - Bozeman, College of Agriculture, 2023) Wright, Lucas Arlin; Chairperson, Graduate Committee: William Dyer; Barbara K. Keith (co-chair)
Intense herbicide usage has led to the evolution of herbicide resistant weeds, which threaten food production and security. The multiple herbicide resistant (MHR) Avena fatua (wild oat) lines investigated here are resistant to all members of selective herbicide families available for A. fatua control. The research in this thesis is designed to help understand some of the ecological, biochemical, and genetic aspects of MHR. First, MHR lines with elevated volatile organic compound (VOC) levels and herbicide susceptible lines were used to compare the feeding behavior of Spodoptera exigua (beet armyworm), and potential role of VOCs to mitigate herbicide injury. Results for feeding behavior were mixed, possibly being influenced by environmental and genetic changes more than VOCs. Exposing VOCs to A. fatua lines found that linalool reduced flucarbazone injury of HS plants, while a combined VOC treatment generally increased herbicide injury. MHR responded differently than HS plants to some treatments, suggesting that MHR has fundamental VOC perception alterations. Other studies compared plant pigments and energy management capabilities and showed that MHR lines had higher beta-carotene and chlorophyll b concentrations, as well as enhanced photosynthetic and excess energy management capabilities in MHR lines. Finally, two populations of recombinant inbred lines (RILs) were phenotyped for herbicide resistance and used to discover several quantitative trait loci (QTL) associated with resistance. Overall, this work contributes to our understanding of MHR and will lay the groundwork for future studies.
Effects of time, cultivar, and storage environment on winter squash in semiarid Montana
(Montana State University - Bozeman, College of Agriculture, 2023) Sheild, Victoria Marie; Chairperson, Graduate Committee: Mac Burgess
Winter squash can be stored for months after harvest while taste, texture, and color attributes improve. The potential for producers to attain greater storage longevity and produce better squash would benefit farmers, consumers, and economies. Due to variation in local climates and the respective vendors' needs, understanding how to control a storage environment can be challenging. This research looks at how storage environment and storage period affect biochemical and physical attributes of ten varieties of winter squash in a semiarid climate. The varieties include three Cucurbita pepo, one Cucurbita moschata, one Cucurbita maxima x moschata hybrid, and five Cucurbita maxima cultivars. Two storage environments were used for analysis. One was located indoors and cooled to 53 degrees F while the other was built into an existing barn with a heating unit and insulation to keep the temperature above freezing. A total of 240 winter squash were placed in each storage space. A completely randomized design was used to assign categorical treatments of storage time to each winter squash, with six levels of treatment being implemented. Each variety of squash (n=4) was analyzed monthly in each storage environment for changes in soluble solids, dry matter, starch content, interior color and exterior color (using CIELAB color values L*, a*, b*), and mass. The temperature and relative humidity of each storage environment were also monitored and recorded hourly during the same period. Cultivar was always the most significant factor. There was no simple effect of the storage environment on dry matter, soluble solids, starch content, or mass. There was a strong significant interaction observed between time and cultivar for each response variable, which shows us that the type of squash and how long it should be stored for are important when discussing quality. Storage did have a significant effect on the a* value of interior color, which is an indicator of quality and nutritional value. The biochemical and physical attributes of each cultivar analyzed varied greatly in its response to the amount of time in storage which in turn influences the taste, texture, and sensory quality of each cultivar uniquely.
Natural variation in camelina nitrogen responses
(Montana State University - Bozeman, College of Agriculture, 2023) Gautam, Shreya; Chairperson, Graduate Committee: Chengci Chen; Chaofu Lu (co-chair)
Camelina (Camelina sativa L.Crantz) is an oilseed crop with the potential to be planted for biofuel production. It is crucial to select camelina genotypes with higher nitrogen use efficiency (NUE) so that the superior cultivar has higher crop productivity. To select genotypes of camelina that exhibit higher biomass yield and nitrogen use efficiency, two field experiments were conducted in 2021 and 2022 in Sidney, MT with different nitrogen regimes, low (unfertilized) and high (fertilized). Distinct projects were carried out, one of them emphasizing canopy area and normalized difference vegetation index (NDVI), and the other focusing on biomass yield and NUE. The experiments highlighted the response of camelina to nitrogen application and the variation among genotypes. The study identified canopy image analysis effectively differentiated the canopy size and growth rate of camelina genotypes under two nitrogen regimes, demonstrating the influence of nitrogen on camelina growth. The NDVI measurement proved to be useful in evaluating plant health and greenness, offering a time-saving and efficient approach. Additionally, some of the genotypes were identified that exhibited high canopy area, NDVI, and nitrogen use efficiency in both 2021 and 2022, providing potential for enhancing crop productivity. This study reveals the potential to use canopy area, NDVI for biomass yield and nitrogen use efficiency screening in camelina.
Evaluating alfalfa weevil (Hypera postica) resistance to mode of action group 3A pyrethroid insecticides in the western United States
(Montana State University - Bozeman, College of Agriculture, 2023) Rodbell, Erika Adriana; Chairperson, Graduate Committee: Kevin Wanner; This is a manuscript style paper that includes co-authored chapters.
Alfalfa weevil (Hypera postica Gellenhal [Coleoptera: Curculionidae]) is an insect pest of forage alfalfa (Medicago sativa L. [Fabales: Fabaceae]) in the western United States. Over the last half-century, insecticides have been the primary control tactic used by alfalfa producers. However, in 2015 numerous reports of pyrethroid insecticide (mode of action (MoA) 3A) failure to control alfalfa weevil populations were made. In 2019, Montana producers were reporting the same failures in their production systems. Therefore, research efforts in the Wanner Lab commenced in 2020 with the exclusive research goal of identifying pyrethroid resistant alfalfa weevil populations in the western United States. The focus of the research is four-fold. The first was to identify alfalfa weevil lambda-cyhalothrin resistance and susceptibility in Montana. The second was to identify lambda-cyhalothrin resistance and susceptibility in Arizona, California, Montana, Oregon, Washington, and Wyoming. The third was to identify if resistance to lambdacyhalothrin resulted in the loss of efficacy of other MoA 3A active ingredients. The fourth was to develop a case study addressing integrated resistance management recommendations for alfalfa weevil pyrethroid resistance mitigation. We conducted our research through contact bioassays, molecular genomics, and field trials, to corroborate our results and to identify if alfalfa weevil strain was a factor influencing our documented pattern of resistance. Cumulatively, our results suggest that alfalfa weevil lambda-cyhalothrin resistance is present in Arizona, California, Montana, Oregon, Washington, and Wyoming, and that susceptible populations remain in the western region. Our data further illustrate that regardless of alfalfa weevil strain, alfalfa weevils resistant to lambda-cyhalothrin will be resistant to other type II pyrethroid active ingredients and permethrin. A pattern seen in three distinct alfalfa production zones in the western United States (i.e., Arizona, Montana, and Washington), determined by both contact bioassays and field trials. In conclusion, our results illustrate a challenge that forage alfalfa production faces in the western United States and provides strategies that western forage alfalfa producers can employ to mitigate pyrethroid resistance from developing.
Evaluating the genetic and phenotypic responses of Camelina sativa to heat stress
(Montana State University - Bozeman, College of Agriculture, 2023) Smith, Brian Edward; Chairperson, Graduate Committee: Chaofu Lu
Camelina sativa (L.) Crantz is a low-input oilseed crop with a unique fatty acid profile in its seed oil. Camelina oil can be used in biodiesels, jet fuels, and industrial lubricants. Improving the abiotic stress tolerance of camelina is a crucial step for increasing agronomic viability. Climate change is threatening production of camelina with rising global temperatures and shorter growing seasons. Elucidating the phenotypic and genetic responses to high temperatures is essential for successful breeding of heat tolerant camelina varieties. Three experiments were conducted to understand these responses. Two genotypes, Suneson (MT5) and Pryzeth (MT102) were exposed to a transient 14-day heat stress during the reproductive stage and evaluated for agronomic and seed quality traits along the main stem. Next, a mapping population consisting of 257 recombinant inbred lines (RILs) were grown under the same temperature regimes for 14 days beginning at the onset of the reproductive stage. Finally, reproductive tissues undergoing heat stress from two genotypes with contrasting heat responses, RIL23 and RIL167, were examined with RNA sequencing, and the phenotypes along the main stem were compared. From the phenotype evaluation, both MT5 and MT102 were significantly impacted by heat. Both genotypes experienced reductions in seed and pod size, seed weight, and total oil contents. As reported in other oilseed crops, camelina is negatively affected by heat, characterized primarily by lower yield and reduced oil content. The QTL analysis identified several key gene regions with co-located traits on chromosomes 8, 10, and 12. This demonstrates the ability to identify heat-responsive gene regions via phenotyping along the main stem. The transcriptomes of RILs 23 and 167 contrasted in both sampled tissue types, with RIL23 appearing more responsive to heat. Phenotypic analysis of these genotypes confirmed the transcriptional differences, as RIL23 was more resistant for several traits associated with fertility. These studies provide resources and protocols for future studies that may assist in improving the heat-tolerance of camelina.
Characterization and assessing fungicide sensitivity of Fusarium spp. causing root rot and wilt in lentils in the northern Great Plains
(Montana State University - Bozeman, College of Agriculture, 2022) Bugingo, Collins; Chairperson, Graduate Committee: Mary Burrows; This is a manuscript style paper that includes co-authored chapters.
Fusarium root rot and wilt are yield limiting diseases caused by Fusarium spp. in lentils globally. Seedborne Fusarium species and races of Fusarium oxysporum f. sp. lentis (Fol) have not been characterized. The sensitivity of commonly used fungicides on prevalent species is not fully known. In 2019 and 2020 commercial lentil fields were surveyed and seed lots collected from infected patches and further isolation, morphological and molecular characterization was conducted in the laboratory. Additional isolates and lentil seed were received from Washington, Montana, Idaho, North Dakota, southern Canada, and Spain for fungicide, seedborne Fusarium spp. and race-characterization of Fol respectively. In addition to assessing presence of seedborne Fusarium pathogens on the seed coat, the cotyledon and embryo were assessed for the presence of Fusarium spp. Fungicide sensitivity was assessed using mycelial assays and an additional spore assay for pyraclostrobin. A total of 84 seed lots from the Northern Great Plains (NGP) were assayed where a total of 486 and 228 Fusarium isolates were isolated in 2019 and 2020, respectively and all the representative isolates were virulent with a 1.5-4.5 root rot severity rating. Most isolates were found in the seed coat (57- 75%), cotyledon (19-23%) and embryo (6-20%) for the 2019 and 2020 isolates, respectively. F. oxysporum and F. acuminatum were all either sensitive or intermediately sensitive to prothioconazole and ipconazole. A total of 51 isolates were race-typed and 9 races identified whereby race 7 and 1 were the predominant at 53% and 16%, respectively. This study underscores the importance of understanding Fusarium spp. composition in lentil production, role of seedborne inoculum, fungicide efficacy in root rot/wilt management and race composition upon developing effective Integrated Pest Management (IPM) strategies.
Characterization and testing of reduced height (RHT) hypomorphs in durum and spring wheat
(Montana State University - Bozeman, College of Agriculture, 2023) Ugrin, Josey Mackinsey; Chairperson, Graduate Committee: Michael J. Giroux
The Reduced Height (Rht) gene in wheat (Triticum aestivum L.) increases yield by partitioning less nutrients to stem elongation and more towards spike development. In hexaploid wheat, the mutations Rht-B1b and Rht-D1b, create high-yielding semi-dwarf varieties. While Rht-B1b and Rht-D1b have been widely adopted due to their ability to increase yield, they also have drawbacks such as smaller seed size and lower protein content. Furthermore, tetraploid durum wheat (Triticum. turgidum L), Rht-B1b creates plants that are shorter than in hexaploid wheat under Northern Great Plains growing conditions. This project aimed to further characterize Rht and to develop a plant height intermediate between current standard-height and semi-dwarf varieties to increase yield in both durum and spring wheat. To create novel Rht alleles, seeds were mutagenized with Ethyl-methanesulfonate (EMS) and mutations were identified. Near-isogenic lines (NILS) were developed for the two Rht-A1 alleles and Rht-B1b-E529K alleles in semi-dwarf (Rht-B1b) and standard height (Rht-B1a) varieties in durum. In spring wheat, NILs were developed for eight Rht-A1 alleles in two high-yielding Montana varieties. These NILS were planted in field trials and plant height and grain traits were measured. Four novel mutations, Rht-A1-E63K, Rht-A1-Q6*, Rht-A1-V55M, and Rht-A1-53T in spring wheat and two mutations in durum, Rht-B1b-E529K and Rht-A1-S50F all had either significantly changed height or grain traits. Along with developing and testing Rht alleles for field trait improvement, we did a study to characterize an Rht stop-codon dosage response in wheat. Previous studies in rice and barley have indicated that a lack of the functional SLR1/SLN1 gene respectively, results in an abnormal growth response characterized by taller height and slender appearance. This effect on Rht function has yet to be tested in wheat. Rht nonsense alleles were created by screening an EMS treated population created using seed of a standard-height Montana variety. We combined mutations creating lines homozygous for single, double, or triple mutations. In field trials, Rht triple mutants exhibited a slender, elongated phenotype with strike heads similar to SLN1 mutants in barley. Differences in height varied for the other crosses but did trend towards increased height with increased Rht-stop mutation dosage.
Using genetic and genomic techniques to uncover cryptic diversity for improving aquatic invasive plant management
(Montana State University - Bozeman, College of Agriculture, 2021) Chorak, Gregory Michael Thomas; Chairperson, Graduate Committee: Ryan Thum; This is a manuscript style paper that includes co-authored chapters.
Genetic diversity can be important at many levels of invasive species management. And, for different questions, it matters at which level we measure diversity to understand its relevance. Some invaders may look similar to other species, so identifying the species to be managed may be difficult without genetic tools. Once the species has been identified, understanding the diversity in that species may be important to identify management units, invasive traits, and the possibility of spread. Finally, understanding how the alleles an individual possesses determine the traits expressed can give managers the tools to control for unwanted traits of an invasive species. In this body of work, I uncover diversity at the species/taxon level, the genotype/clone level, and finally at the gene level in invasive aquatic weed species. At the taxon level, I found that one invasion of aquatic weeds in the northeastern US was actually two or more separate invasions and taxa. At the genotype level, I found that the same genotype responds the same to a common herbicide management regardless of where it is found, and that different genotypes have varying responses to a common herbicide treatment. And, at the gene level, I found that different genotypes with different growth rates have different gene expression in the control and transcriptional response to a common herbicide treatment. At each of these levels, managers have questions and concerns about management decisions. Understanding that there were two unique taxa in what was considered one invasion informed managers that there may be variance in management relevant traits between the two. In the genotype level study, we learned that determining which clones are present in a lake slated for herbicide management may inform which herbicides to use. And, at the gene level, we are starting to understand the molecular process of management relevant phenotypes so that one day managers can screen for molecular markers that will reveal herbicide response of individuals slated for management.

Theses and Dissertations at Montana State University (MSU)

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