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Water Conservation Through Drought-Resilient Landscape Plants And Deficit Irrigation, Ji-Jhong Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Increases in urban population and inadequate rainfall result in imbalanced water budgets in urban and sub-urban regions. Water conservation becomes important in urban landscapes because of increased water demands. Modern landscape designs require drought-resistant plants to maintain urban landscape greenness during water scarcity. Irrigating plants at their irrigation requirements, which is the minimum irrigation rate that can achieve acceptable aesthetic quality, can also conserve water. However, the drought tolerance and irrigation requrements of most landscape plants have not been widely evaluated. Shepherdia ×utahensis ‘Torrey’ (‘Torrey’ buffaloberry) and Penstemon species (beardtongues) are low-water-use landscape plants, but their drought resistance mechanisms are …

Evapotranspiration And Energy Balance Of Irrigated Urban Turfgrass, Matthew D. Miksch

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Water usage for irrigation is a big consumer of water resources in urban areas in Utah and other parts of the Intermountain Region of the Western United States. As populations continue to increase in these states, it is important to understand how much water is being used by urban landscapes in order to plan and manage future water resources. Evapotranspiration (ET), or the amount of water leaving a surface over a certain timeframe due to both transpiration from plants and evaporation from the soil, is a key variable in understanding how much water urban landscapes are really using to grow …

Practical Improvements For Pivot And Surface Irrigation, Jonathan A. Holt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Irrigation is critical to meeting global food and fiber demands. Optimizing agricultural irrigation may help sustain production levels, while reducing its demand for water. This research evaluated precision sprinklers and drip irrigation for pivots, five pivot track mitigation tools, three scientific irrigation scheduling (SIS) methods, sensors for surface irrigation cutoff, and automating surface systems to implement surge irrigation. With pivots and surface irrigation being the most common methods for irrigation in the West, small improvements from these tools could result in significant water savings.

Low energy precision application (LEPA) sprinklers and mobile drip irrigation (MDI) were tested on two pivots. …

Evaluating Quaking Aspen's Influence On Fire Behavior, Kristin A. Nesbit

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In western North America, quaking aspen (Populus tremuloides Michx.) forests have long been described as low flammability, “fireproof” forest types that are less likely to burn or burn less intensely than coniferous forests. While this assumption has been based on limited scientific research and is largely anecdotal, there is growing interest in the western U.S. to promote aspen near human developments to reduce fire risk. I investigated the available evidence for aspen forests reducing fire occurrence, behavior, and severity, and assessed possible factors that affect flammability in aspen forests to better understand when and where aspen burn, and when …

Dust Deposition Changes Production, Chlorophyll-A And Community Composition In Mountain Lakes, Jiahao Wen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Increasing quantities of dust emitted from semi-arid soils, agricultural soils, and urban regions are blown to remote mountain lakes in the American West. Remote mountain lakes lacking local nutrient inputs and presenting simple food webs that are easily affected by climate changes. Dust can carry nutrients (e.g., nitrogen and phosphorus) to mountain lakes and potentially enhance algae growth and change algal communities. However, experimental tests of this hypothesis are lacking. Using in situ experiments, we investigated the effects of dust enrichment on the production, biomass, and primary algal species in three mountain lakes in the American West. We found that …

Approaches To Supplementing Silicon In Soilless Media And The Value Of Silicon In The Mitigation Of Drought Stress, Mackenzie Grace Dey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Silicon (Si) is not considered an essential element for plants to complete their lifecycle, but is known to be beneficial for plants under environmental stress such as drought. Unlike natural soils, Si is minimally bioavailable in soilless media. With indoor agriculture and greenhouse production increasing, the benefits of Si have been seen and Si should be supplemented. This work aimed to characterize and quantify the dissolution of Si from media substrates and additives to achieve a steady-state release of Si in soilless media. Typical media components such as coconut coir, peat moss, perlite, rock wool, sand, and vermiculite minimally released …

Evaluating Strategies For Anemone And Ranunculus Cut Flower Production In The Us Intermountain West, Shannon Rauter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

National growth in small-scale, specialty cut flower farms is reflected in Utah, where 145 members have joined the Utah Cut Flower Farm Association since its 2019 founding. Cool season cut flower production is limited in Utah and the Intermountain West by a narrow harvest window and elevated soil salinity. The objective of this research was to optimize production systems for anemone (Anemone coronaria L.) and ranunculus (Ranunculus asiaticus L.) in the Intermountain West by evaluating season advancement methods within a high tunnel and field production system, as well as the salinity sensitivity of each species. Fall planting dates, …

Management Of Garlic Mustard (Alliaria Petiolata), Sahara Mustard (Brassica Tournefortii), And Elongated Mustard (Brassica Elongata) In Utah, Natalie Layne Fronk

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The invasive mustard species Sahara mustard (Brassica tournefortii), garlic mustard (Alliaria petiolata) and elongated mustard (Brassica elongata) negatively impact a variety of ecological systems across the state of Utah. The distribution of these species in Utah is relatively limited at the current time. If prompt action is taken, it may be possible to contain and manage these species before irreparable ecological and agricultural damage occurs. For this reason, all three mustards are listed by the State of Utah as weeds of high priority for management.

This project tested multiple strategies to determine effective species-specific …

Dairy Breed, Grass-Birdsfoot Trefoil Mixture, And Pasture Nutrition Effects On Intake, Feed Efficiency, And Grazing Adaptation, Michael Greenland

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dairy cattle have lower dry matter intake (DMI) on pastures thus leading to less weight gain and milk production than feedlot cows. This study was conducted to determine whether different dairy breeds are better adapted to lower or higher quality pastures as measured in DMI and feed efficiency. The eight treatments consisted of Jersey, Holstein, Holstein-Jersey crossbreds, and 3-breed crossbreds (Montbéliarde-Swedish Red-Holstein) heifers on grass monocultures and grass-BFT mixtures. We observed greater DMI on grass-BFT mixtures. Among breeds, Holstein had the greatest DMI, then the two crossbreds, and Jersey had the least. Feed efficiency was most favorable for Jersey, less …

Soil Genesis Across A Climo-Lithosequence Of Western Haleakalā, Maui, Ryan C. Hodges

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The soils of western Haleakalā are incredibly diverse due to two primary reasons: 1) they receive varying levels of rainfall based on location relative to Haleakalā, and 2) volcanic vents upwind of the area indicate that volcanic ash has blanketed much of western Haleakalā in the past. Ash can weather to form short-range-order materials, which contribute to the classification of andic soil properties. Due to their structure, short-range-order materials impart soil behavior that creates benefits and challenges in land management. Therefore, an understanding of how these soils formed and differ, and where andic soils occur is crucial.

The objectives of …

Development Of Late-Heading Orchardgrass Germplasm, Megan Marie Getz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dactylis glomerata L., orchardgrass, is commonly grown with perennial forages such as alfalfa (Medicago sativa L.). However, commercial orchardgrass cultivars currently grown in the Intermountain West generally flower earlier than alfalfa. This results in a reduction in grass nutritional value if harvested to maximize the alfalfa yield, because the two species mature at different rates. Thus, there is a need to better understand the genetic basis of flowering time in orchardgrass and develop late-flowering populations. The objectives of this research were to evaluate the ability to identify and use molecular markers to identify and select late-heading orchardgrass; and to …

4r Nitrogen And Water Optimization Combinations For Intermountain West Field Crops, Tina Sullivan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The concept of 4R (right source, rate, placement, and timing) management needs little introduction due to the surplus of nutrient studies in the literature for most cultivated crops. However, few studies have looked at these practices in the Intermountain West with nitrogen use, and fewer looked at 4R irrigation management. A survey was conducted to explore the interactions of nitrogen and irrigation management, test sensitivity to supply and price changes of nitrogen and irrigation for Utah and Idaho growers of small grains, corn, and potatoes, and determine the current adoption of precision agriculture options and identify the opportunities to improve. …

Opportunities For Optimal Apple Production Management In Arid Conditions, Sam Johnson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Apple trees are susceptible to biotic and abiotic stresses in the Intermountain West. The arid climate along with non-ideal soils make apple production challenging. Also, as high-quality agricultural land is developed, crop production gets pushed to land that often is saline. Apple trees grow poorly in saline soils. If apples are going to be grown in Utah, rootstocks must be identified that will tolerate saline soils. The USDA rootstock breeding program produced some rootstocks that may show salt tolerance. This project assessed the salt tolerance of these apple rootstocks in the greenhouse and in the field. Test rootstocks were compared …

Control Of Three Invasive Annual Grasses In Utah Using Herbicides Including Indaziflam, Hailey L. Buell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Invasive grasses pose a threat to rangeland ecosystems in Utah. Three grasses in particular: downy brome, medusahead, and ventenata can push out native plants and prevent other vegetation from germinating. These grasses can also degrade grazing lands for cattle and act as kindling for wildfires. The use of herbicides is the most common way to rid a site of invasive plants. Herbicides that prevent germination for many years work well to keep annual grasses at bay while not harming the many long-living native plants that are already growing.

A study was designed on a site infested with downy brome to …

Soil Health Monitoring And Management In Corn And Soybean Agroecosystems Of The Midwestern U.S., Bradley S. Crookston

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soil health is a concept and condition of the soil where measurable soil properties represent the capacity of a soil fulfilling its intended use, such as producing crops, without constraint to its agro-ecological quality. Soil health assessments are used to estimate the health of a soil by assessing soil biological, chemical, and physical attributes, called soil health indicators, and scoring them on a scale, usually 0 to 100, to guide soil and crop management. However, there are few large-scale analyses of soil health assessment scores and their relationships with crop yield. Understanding how soil health assessments relate to crop yield …

The Plant Growth Promoting Ability Of The Microbiome Of Ceanothus Velutinus From The Intermountain West Region, Jyothsna Ganesh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to the ever-changing climate and deterioration of the earth’s ecosystem, environmental stresses like abiotic (drought, salinity) and biotic stresses (pathogen infection) gravely affected plant growth. Native plants are a great way of improving these effects on the urban landscape. They can be used as ornamental plants in landscaping as they are accustomed to their natural environment. The Center for Water-Efficient Landscaping at Utah State University has released a list of plants to be used for low water use landscaping. One such native plant is Ceanothus velutinus (snowbrush ceanothus). They are evergreen plants that can grow in dry and harsh …

Phytochrome Physiology And Plant Perception Of Far-Red Photons, Paul Kusuma

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Photons are the primary energy source for most life on Earth, as they drive photosynthesis, a process that turns the CO₂ in air into food. One crucial parameters for the optimization of growth is leaf area, which determines the ability of a plant to capture photons for photosynthesis. In order to gain access to photons in shaded environments, plants have evolved unique sensors, called photoreceptors, which respond to changes in the color and intensity of light.

Far-red photons (photons at the edge of human vision that appear as dim red light) hold particular promise in regulating plant shape and …

Season Advancement Of Cool Season Cut Flower Crops Snapdragon And Peony, Maegen A. Lewis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Demand and production of specialty cut flowers is growing across the U.S., but research is lacking in the U.S. Intermountain West, where the semi-arid and high elevation climate offers unique challenges for growers. The goal of this study was to evaluate the stem quality, harvest timing, and yield of snapdragon (Antirrhinum majus) ‘Chantilly’, ‘Potomac’, and ‘Rocket’ and peony (Paeonia lactiflora) ‘Coral Charm’ as cool-season cut flower crops under high tunnel and field production in North Logan, Utah. Snapdragons were transplanted at three-week intervals beginning in early-February in high tunnels and ending in late-May in the field. …

Seeding Rate, Nitrogen Fertilzer, And Cutting Timing Effects On Teff Forage Yield And Nutritive Value, Michael C. Laca

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Teff [Eragostis tef (Zucc.) Trotter] is a relatively new forage gaining popularity in the United States; however, information regarding agronomic production practices is lacking. This study was conducted to determine the combination of seeding rate, fertilization, and harvest timing to optimize teff dry-matter yield (DMY) and nutritive value. Four seeding rates (2, 5, 8, and 11 lb/acre), four nitrogen (N) fertilizer rates (0, 25, 50, and 100 lb/acre), and two harvest strategies [boot stage (2-cut) and full seed-head stage (1-cut; stockpiled)] were evaluated in 2010 and 2011 in Kaysville, UT and Yerington, NV. The effects of harvest (1- vs …

Fatty Acid Composition Of Forages And Their Effect On The Fatty Acid Composition In Beef Cattle, Britney G. Allen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study focused on how diet changes the rumen microbiome in the cattle and the effects of that on the long chain fatty acids (LCFA) by microbes in the rumen, and on the short chain fatty acids (SCFA) these microbes produce from feed carbohydrates like fiber and starch. The abundance of bacteria belonging to the phyla Tenericutes and Proteobacteria increased in response to high-fiber or high-starch diets, respectively. The production of two SCFA was positively correlated with the presence of increased Tenericutes (acetate) and Proteobacteria (propionate). A greater acetate to propionate ratio is associated with elevated production of enteric methane …

Seeding Rate, Herbicide, And Irrigation Effects On Spring-Seeded Oat-Alfalfa Companion Crops, Carson D. Roberts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Small grain companion crop seeding rate recommendations for alfalfa (Medicago sativa L.) establishment are dated and inconsistent, and how a small grain companion crop seeding rates should be adjusted at different moisture levels is unknown. A study was conducted to provide clarity about oat (Avena sativa L.) companion crop seeding rates that maximize weed suppression and forage yield and minimize the effect on alfalfa stand establishment. This experiment considered oat companion crop seeding rates at various irrigation levels. Companion crop treatments consisted of oats sown at 89, 45, 22, 10, and 0 (with and without herbicide) kg ha …

Innovative Water Management Using Advanced Irrigation Systems And Biochar, Jonathan A. Holt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Two approaches to water optimization in agriculture are to increase soil water retention and improve the efficiency of irrigation. A soil amendment that has received attention for its ability to increase soil water retention is biochar, the remaining biomass after high C materials have been pyrolyzed (burned with limited oxygen and heat). Two studies were conducted at a total of 10 site-years in Utah from 2018 to 2020 to evaluate how wood biochar influences the productivity and crop quality of irrigated alfalfa (Medicago Sativa L.), corn (Zea mays L.), and wheat (Triticum L.), along with soil water tension. One study …

Compost And Cover Crop Effects In Dryland Organic Wheat, Michael D. Deakin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Producers of dryland organic wheat (Triticum aestivum L.) in the western USA struggle to maintain adequate soil fertility due to the high cost of organic fertilizers and concerns over moisture use of cover crops. Low soil fertility results in decreased wheat yield and quality, and increased year-to-year variability in yield and quality based on weather. This study was conducted to measure the effects of, and interactions between, cover crop mixes and a one-time compost application on soil health and winter wheat yield and quality. The study was located on three adjacent certified organic wheat farms near Snowville, UT, each …

Mechanisms Of Overyielding And Coexistence In Diverse Tallgrass Prairie Communities, Leslie E. Forero

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plants compete for the same basic nutrient and water resources. According to the competitive exclusion principle, when a substantial overlap in resource pools exists, the best competitor for resources should drive all other species to extinction. The ability for plants to coexist in violation of the competitive exclusion principle is the “biodiversity paradox”. Coexistence is actually beneficial for plants: as species diversity increases, you typically see increases in plant biomass production (known as the biodiversity-productivity relationship). The mechanisms behind coexistence and the biodiversity-productivity relationship remain an ecological mystery. One hypothesis is that plants obtain water and nutrients from different places …

Selection And Propagation Of Pinyon Pine, Kylie M. Lawson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Single-leaf pinyon pines are drought tolerant trees native to the Great Basin. This species is a source of wild-collected, edible pine nuts that are in great demand. With no previous research apparent, this thesis aimed to identify wild trees with high cone production as sources for evaluating grafting onto immature and mature trees. Wild sources of scions were identified from four wild stands and six trees per stand. Counting and analyzing the number of scars left by mature cones along the leader branch provided an estimate for each tree‚Äôs productivity and identified trees with greater productivity within a stand. The …

Fruit Tree Responses To Water Stress: Automated Physiological Measurements And Rootstock Responses, William D. Wheeler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

New orchard plantings utilize trees grafted to dwarfing rootstocks planted close together to facilitate larger harvests. These dwarfing rootstocks have not been comprehensively studied for their ability to withstand drought. This is of special importance in the Intermountain West which has limited rainfall. Additionally, orchard growers face competition for water from a growing population and increased uncertainty in rainfall from climate change. My research examined the use of dendrometers, which measure changes in trunk diameter, and sap flow sensors, which measure how quickly sap moves, as methods to inform growers about tree water status. I also used a weighing lysimeter …

Propagation Of Two Utah Native Plants: Ceanothus Velutinus And Cercocarpus Montanus, Asmita Paudel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Among various water conservative approaches, the use of native plants in landscape, such as Ceanothus velutinus (snowbrush ceanothus) and Cercocarpus montanus (alder-leaf mountain mahogany), is attractive. Efficient propagation methods are required to allow these native species to use in water-efficient landscaping. Sexual (seed) and asexual/vegetative (cuttings and micropropagation) propagation methods were evaluated.

Seeds of both C. velutinus and C. montanus were scarified and/or stratified and treated with gibberellic acid (GA₃) to break dormancy. The results showed hot water scarification and 2-3 months of stratification effectively broke the dormancy of C. velutinus seeds, and stratification for 2-3 months was …

Effects Of Wi-Fi-Enabled Smart Irrigation Controllers On Water Use And Plant Health Of Residential Landscapes In The Intermountain West, Shane R. Evans

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Residential and commercial landscapes provide home and business owners with several benefits. These benefits range from improved air quality and flood control to the reduction of noise and breakdown of organic chemicals. However, these landscapes are routinely overwatered which can lead to plant disease, nutrient pollution, and large amounts of water being wasted. Utah State University, in conjunction with the Center for Water Efficient Landscaping (CWEL), the Utah Division of Natural Resources and Weber Basin Water Conservancy District, conducted an experiment to determine if Wi-Fi-enabled smart irrigation controllers conserve water as compared to average residential irrigation amounts and manually programmed …

Water Use In Jujube (Ziziphus Jujuba) With Applications In Irrigation Timing And Quantity, Preston S. Colver

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Jujube (Ziziphus jujuba) is a major fruit crop in China where it has been a favored cash crop and successfully used to address erosion problems in the Loess Plateau region of western China. Further use of jujube in forestry projects and improved agricultural efficiency are very promising. This study sought to repeat a water-use study in two climates: a hot, semi-arid climate in Yangling, Shaanxi, China and a dry-summer, continental climate in Logan, Utah, USA. The study took physiological measurements on the trees with the aim of characterizing the way that jujube uses water. This would help to …

Nodulation And Growth Of Shepherdia × Utahensis ‘Torrey’, Ji-Jhong Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Shepherdia ×utahensis ‘Torrey’ (Elaeagnaceae) is a hybrid of two native actinorhizal plants in the Intermountain West, S. argentea (silver buffaloberry) and S. rotundifolia (roundleaf buffaloberry). Due to actinorhizal symbiosis, atmospheric nitrogen (N₂) can be converted to ammonium, a bioavailable form. Actinorhizal plants have great value in sustainable nursery production and urban landscape use. However, nitrogen fertilizer negatively affects the nodulation of actinorhizal plants. As a newly developed hybrid, both the symbiont identity and nodule formation of S. ×utahensis ‘Torrey’ remain largely unknown. Therefore, experiments were conducted to investigate the nodule formation of S. ×utahensis ‘Torrey’ inoculated with field …