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search.filters.applied.f.department: search.filters.department.Plant Sciences & Plant Pathology.Subject: search.filters.subject.Soils

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Now showing 1 - 10 of 26
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    Screening field pea (Pisum sativum L.) for tolerance to high salinity conditions
    (Montana State University - Bozeman, College of Agriculture, 2020) Tracy, Jacob D.; Chairperson, Graduate Committee: Kevin McPhee
    Field pea (Pisum sativum L.) is an important salt-sensitive crop utilized in rotation with cereals in semi-arid cropping systems in the Northern Great Plains (NGP). Saline soils (EC > 4 dS m -1) negatively impact over 10.8 million acres in Montana, the second largest producer of field pea in the US. Despite its global importance, few studies have explored field pea response to high salinity conditions outside of germination testing and even fewer have looked at tolerance to sodium sulfate (Na 2SO 4), the dominant salt affecting plant growth in the NGP. In this study, 311 accessions comprising the genetically diverse USDA Pisum single plant (PSP) core collection were screened under high Na 2SO 4 conditions in germination and seedling experiments. Germination screening was conducted in petri dishes within a dark growth chamber. Accessions received H 2O (control) or 16 dS m -1 Na 2SO 4 (highly saline) solution for 8 days. The mean percent germination compared to the control was used as the indicator for tolerance. A preliminary greenhouse concentration series experiment using 7 levels of Na 2SO 4 (0, 3, 6, 9, 12, 15, and 18 dS m -1), supported screening seedlings at 9 dS m -1 Na 2SO 4. Greenhouse screening was conducted in plastic pots of coarse sand media. Accessions received a nutrient solution (control) or 9 dS m -1 Na 2SO 4 and nutrient solution daily. Salinity symptom scores were assessed on days 21, 28, 35, and 38 post-sowing using a visual growth response scale of 1-9 (healthy-dead). Phenotypic measurements and the Area Under the Injury Curve (AUIC) were used as indicators for tolerance. A Genome Wide Association Study (GWAS) was conducted using the phenotypic data collected and a large dataset of 68,222 Single Nucleotide Polymorphisms developed from the USDA PSP plus core collection. Potential candidate breeding germplasm conferring high salinity tolerance at the germination and seedling growth stages was identified. Significant marker-trait associations were discovered for all traits measured, providing potential Marker-Assisted Selection (MAS) opportunities.
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    Elucidating the effect of anthropogenic land management on soil nematode community structure
    (Montana State University - Bozeman, College of Agriculture, 2019) Burkhardt, Andy; Chairperson, Graduate Committee: Jamie Sherman; Shabeg S. Briar, John M. Martin, Patrick M. Carr, Jennifer Lachowiec, Cathy Zabinski, David W. Roberts, Perry Miller and Jamie Sherman were co-authors of the article, 'Perennial crop legacy effects on nematode community structure in semi-arid wheat systems' in the journal 'Applied soil ecology' which is contained within this thesis.; Shabeg S. Briar, John M. Martin, Patrick M. Carr and Jamie Sherman were co-authors of the article, 'Characterization of soil nematode community structure in semi-arid dryland barley (Hordeum vulgare L.) systems' which is contained within this thesis.
    Nematodes as a taxonomic phylum are incredibly diverse and play an important role in soil biology, nutrient cycling, and soil food web function. Nematodes can be categorized into five major trophic groups including bacterivores, fungivores, herbivores, predators, and omnivores. Plant-parasitic nematodes (PPNs) affect soil food web resources through direct herbivory, while free-living (non-pathogenic) bacterivores and fungivores graze on microbes and contribute significantly to soil nutrient pools. Predatory nematodes regulate the soil food web by preying on other nematodes and invertebrates in the soil. An unbalanced soil food web community can lead to unintended impacts to other species and create a cascading effect. In agriculture, this impact can lead to low crop production and reduced revenue by means of soil ecological degradation. The goal of this project was to elucidate the nematode community structure changes under different management strategies in both agricultural and range settings. The hypotheses we tested were 1) that crop rotations eliminating fallow would positively and significantly impact the soil nematode community that would in turn self-regulate the PPN population and 2) native sagebrush steppe would have a more diverse nematode community than converted sagebrush steppe managed for livestock grazing or other uses. We did so with the following studies: 1. Quantitatively assessed nematode community structure under barley monoculture and barley-fallow vs. barley-pea rotations using multiple ecological measures and indices and correlated those measures and indices with soil chemical and physical properties as well as agronomic parameters of each system. 2. Quantitatively assessed nematode community structure under wheat-tilled fallow, wheat-no-till fallow, and no-till wheat monoculture vs. several no-till wheat-pulse rotations using multiple ecological measures and indices to evaluate long term impacts of cropping system to the nematode community. 3. Quantified taxonomic diversity and ecological indices of disturbed and undisturbed sagebrush steppe in the Bangtail Mountains west of Wilsall, Montana to evaluate disturbance regimes in a reclaimed environment.
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    Population dynamics of coexistence by plant pathogens of the rhizosphere of spring wheat
    (Montana State University - Bozeman, College of Agriculture, 2015) Troth, Erin Elizabeth Gunnink; Chairperson, Graduate Committee: Alan T. Dyer
    The dryland root rot complex is a collection of root pathogens that significantly affect small grain production in the semiarid regions world-wide. The complex includes Cochliobolus sativus, Fusarium pseudograminearum, Rhizoctonia solani, Pythium ultimum, and Penicillium sp. The purpose of this thesis was to document the interactions among these pathogens that commonly coexist within the wheat rhizosphere. The thesis had two objectives: 1) examine variation in interactions amongst isolates of C. sativus and F. pseudograminearum within the wheat crown and 2) identify interactions among pathogens in the dryland root rot complex (C. sativus, F. pseudograminearum, R. solani, P. ultimum, and Penicillium sp.) in-field, as reflected in plant response variables. For objective 1, wheat in both field and greenhouse settings were inoculated singly and in all pathogen isolate combinations. Both C. sativus and F. pseudograminearum, alone and in combination, reduced yield (P<0.001, P=0.003, respectively), but C. sativus isolates had a greater effect on both yield and emergence (P<0.001). Inoculations with some isolates of C. sativus and F. pseudograminearum were suppressive on populations of each other. Significant variability in suppressiveness was observed among isolates for both species. For objective 2) plant health as measured by emergence, vigor, plant height and yield, was observed in response to inoculations with all single, pairwise, four-pathogen and five-pathogen combinations of C. sativus, F. pseudograminearum, R. solani, P. ultimum, and Penicillium sp. Antagonistic relationships that favored overall plant health were observed between several pathogens, including P. ultimum, Penicillium sp. and C. sativus. These antagonistic interactions affected seedling emergence and plant vigor. Conversely, F. pseudograminearum in combination with R. solani significantly reduced emergence beyond expected (P=0.002). Within the community interaction studies overall, F. pseudograminearum was the dominant pathogen, causing more disease and more consistent disease than any other pathogen, and generating increased damage to emergence when inoculated in the community (P=0.017). In conclusion, interactions among members of the dryland root rot complex is a dynamic process, one that varies by species and pathogen isolate. These interactions are more often antagonistic, with one pathogen suppressing another. Additional studies may improve how disease control measures are deployed in the future.
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    The effect of various soil amendments and preceding crops on seedling disease of sugar beets caused by Aphanomyces cochlioides Drechs
    (Montana State University - Bozeman, College of Agriculture, 1949) Bellingham, Roscoe C.
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    The phytoavailability of potassium to small grains as influenced by edaphic and environmental factors
    (Montana State University - Bozeman, College of Agriculture, 1988) Miller, Robert Olson
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    Microbiological characterization of Montana soils suppressive and conducive to take-all disease of wheat caused by Gaemannomyces graminis var. tritici
    (Montana State University - Bozeman, College of Agriculture, 1992) Andrade, Orlando Armando
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    Efficient bacterial colonizers of wheat roots
    (Montana State University - Bozeman, College of Agriculture, 1987) Juhnke, Monica L.
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    Minesoil resources in the Northern Great Plains: characterization, evaluation and potential
    (Montana State University - Bozeman, College of Agriculture, 1979) Schafer, W. M.
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    Precipitation of calcium phosphates in the presence of soluble organic matter
    (Montana State University - Bozeman, College of Agriculture, 1991) Grossl, Paul Rudolf
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