Plant Science & Landscape Architecture Theses and Dissertations

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    A Place in Public Space: Designing an Autism-Friendly Experience for Adults in Palmer Park
    (2023) Ada, Micaela; Sachs, Naomi A; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In 2023, the CDC reported that approximately 1 in 36 children in the U.S. is diagnosed with autism spectrum disorder (ASD). Prevalence rates have nearly doubled every decade since the CDC began tracking this data in 2000. When these children come of age and enter adulthood, they face new milestones and challenges such as working, living away from the family home, and navigating the world with more autonomy. Design professions —including architecture, interior design, and landscape architecture— have progressively incorporated considerations for ASD into their spaces. Adult-specific, autism-friendly design guidelines existing today have honed in on improving workplace, home, and therapeutic environments. There is a noticeable gap in addressing landscapes made for the social and leisure aspects of life. To address this gap, this research design thesis focuses on implementing design interventions in Landover, MD’s Palmer Park Community Center outdoors space to create an autism-friendly space for adults seeking comfortable recreation opportunities.
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    Understanding organic and conventional management programs and rhizosphere microbiome for sports turf in Maryland
    (2023) Peddigari, Shravya; Carroll, Mark; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In response to public concerns about exposure to pesticides, some state and local municipalities have placed restrictions on the use of pesticides on athletic fields. When such restrictions are implemented athletic field management often transitions to the use of natural or organic turf care with little understanding of how the transition away from conventional management practices may affect surface conditions and soil microbial properties.This thesis examined the use of organic and conventional management programs on the turf quality, surface hardness, and shear strength of engineered soil cap, hybrid bermudagrass (Cynodon dactylon x Cynodon transvaalensis) athletic fields, as well as the impact of the two programs on the rhizosphere microbiome. Turf quality was assessed by visual means and by obtaining normalized difference vegetative index (NDVI) readings of the turf canopy. Surface hardness was determined using a Clegg impact surface tester. The rotational shear strength of the surface was measured using a shear vane. The study was conducted for 3 years at two different locations; research plots at the University of Maryland Research Facility and on athletic fields at Laytonia Recreational Park, in Gaithersburg, MD. Surface property data was collected monthly. Turf visual quality and NDVI data revealed use of the organic management program led to higher visual quality during spring, which was primarily the result of the spring retention of fall overseeded intermediate ryegrass (Lolium x hybridum Hausskn) and early season use of natural based fertilizers. In the summer months, crabgrass (Digitaria ischaemum Schreb.) encroachment was limited to the organically managed turfgrass. At both locations, clover (Trifolium repens) encroachment developed by the third year of the study, but the presence of this weed had limited impact on turfgrass quality. There were few significant differences in surface hardness and shear strength between the two management practices over the entire study period. The rhizosphere microbiome data, which was collected 12, 20, and 24 months after the initiation of two programs, did not show any significant difference between the organic and conventional management athletic fields in microbial abundance and/or diversity. The results of this study emphasize that the adoption of organic management programs on bermudagrass athletic fields should, in most instances, center on the establishment of acceptable weed tolerance levels for these fields. The use of organic management programs in the transition zone offers a viable alternative to the conventional chemical management of athletic fields, however over time, growing weed seed banks may necessitate the need for the occasional use of conventional herbicide materials.
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    POSITIONAL CLONING OF BROAD-SPECTRUM LEAF RUST RESISTANCE GENE, LR57, FROM AEGILOPS GENICULATA, A TERTIARY GENE POOL MEMBER OF WHEAT
    (2023) Schulden, Taylor Francis; Rawat, Nidhi; Erwin, John; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The tertiary gene pool of wheat includes wild relatives like Aegilops geniculata (UUMM, 2n=4x=28) that are valuable genetic reservoirs for novel abiotic and biotic resistance genes. However, modern wheat varieties share limited genomic commonality with these gene pool members presenting barriers to recombination and genetic mapping of desirable genes. We mapped a broad-spectrum leaf rust resistance gene Lr57 located on chromosome 5Mg of Ae. geniculata using a simple but powerful methodology for high-resolution genetic mapping in tertiary gene pool members of wheat. Five gene candidates were revealed all with possible defense related functions. Strategic application of differential expression analysis, Virus-Induced Gene Silencing, and mutagenesis analysis reduced the candidate gene of interest to a singular and novel ID-NLR resistance gene containg a protein kinase, NB-Arc, and LRR domain. Using multiple strategies, validation of Lr57 candidate was completed. Gene complementation by transformation of Lr57 candidate is currently being conducted.
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    REVIVING CONNECTIONS: A PROPOSAL TO IMPROVE WATER QUALITY OF THE ANACOSTIA RIVER AND CONNECT THE CITY TO ITS RIVER THROUGH SUSTAINABLE URBANISM
    (2023) Shah, Jainee Priyesh; Ellis, Christopher D; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    A very significant element of the city of Washington D.C. are its rivers. These rivers have been supporting the civilization around them for years. The Anacostia river has been subject to industrialization for centuries and it has been exposed to pollution mainly due to urban waste and storm water runoff. This pollution not only affects the water quality of the river but also impacts the nearby population, aquatic life and other species in many harmful ways. It is essential that development should take place considering the needs of people as well as the environment. Here, application of various green infrastructure techniques plays an important role in creating a balance. This thesis is an effort towards improving the water quality of the Anacostia River, reconnecting the city to its river and ensuring a healthy environment for humans and other dependent species.
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    The kinetics and quantum yield of photophosphorylation in Anacystis nidulans (Richt.) Drouet
    (1972) Owens, Olga v. H.; Krauss, Robert W.; Plant Physiology; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
    The active metabolite, ATP, serves not only as a high energy intermediate but also as a controller of some enzymatic reactions. In plant cells, the larger part of the ATP is formed by photophosphorylation. In this paper the rates, the quantum yields, and the wavelength dependencies of photophosphorylation in the blue-green alga Anacystis nidulans are reported. A fluorometric method for determination of enzymatically produced NADPH from ATP was adapted for use on cell extracts. In the light, the ATP level was 0.15 to 0.25 µmoles/mg chl. In the dark, the ATP level was 70% of that in light. In both darkness and anaerobosis, the level was 20%. A return to the light restored the ATP level from both conditions. Dark, anaerobic cells were exposed to measured irradiancies of 710 nm and 620 nm. The rate of ATP formation was measured within the first few seconds and found to be directly proportional to absorbed intensity. Saturation of the rates occurred at an intensity one-tenth the optimum for oxygen production. Quantum requirements of 6-8 were similar for each of the two wavelengths. The system II inhibitor DCMU, had a greater effect at 620 nm that at 710 nm indicating an involvement of system II in photophosphorylation only at 620 nm. At low intensities and over long time periods white light failed to produce a saturating steady-state level of ATP indicating a simultaneous consumption of ATP. Measurements in short dark periods following marginal illumination showed consumption of ATP to be 2 to 4 times greater that production in weak light. Thus, the quantum requirement can be calculated to be 2. ATP formation, therefore, is not the limit ing factor in co2 fixation. The evidence is the high quantum yield of photophosphorylation and the unsaturation of co2 fixation at intensities at which ATP synthesis is saturated.