Digital Commons Network^™

Beef Average Daily Gain And Enteric Methane Emissions On Birdsfoot Trefoil, Cicer Milkvetch And Meadow Brome Pastures, Lance R. Pitcher

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Conventional production of meat products from ruminant animals in the United States requires inputs including the cultivation and nitrogen fertilization of annual grains such as corn and barley, and transportation of cattle and grain to feedlots. Consumers have concerns about the impact of feedlot conditions on animal health, and about the implications of pharmaceutical inputs such as growth hormones and antibiotics on the environment and human health. These concerns have led to a growing interest in pasture-finished meat production by consumers. Such smaller-scale livestock production systems can be healthier and lower-stress for animals, are integrated into local food systems and …

Introducing Two New Weed Control Tools: A "Smart" Spray Wand And A Wildland Weed Treatment Time Model, Bryan E. Dayton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wildland invasive weed treatment, a primary task of land managers, is expensive. Variables including weed canopy cover, slope, land cover, and weed visibility can affect treatment time and cost. A partnership was established with the Department of Plants, Soils, and Climate at Utah State University, Providia Management Group (PMG Environmental LLC) and Jardyne Technologies to develop a wildland weed treatment time model to better understand the effect of these variables on treatment time.

The “smart” spray wand (SSW) is a new precision tool used to develop this model. The SSW is a spray wand with an integrated GPS and a …

Effects Of Blue And Green Light On Plant Growth And Development At Low And High Photosynthetic Photon Flux, Michael Chase Snowden

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Research in photobiology dates back over 200 years with studies using primitive light sources. This early research identified photoreceptors and action spectra for specific regions of the light spectrum that are paramount for photosynthesis as well as growth and development that are still topics of interest today.

Photobiological research has become an area of increasing interest since the introduction of light-emitting diodes which allow for evaluating endless combinations of light spectra. Red light-light emitting diodes were the first to be introduced that had an electrical efficiency comparable to existing light sources. The research found that red light alone was not …

Validation Of Tissue Nutrient Status For Tart Cherry (Prunus Cerasus) And Peach (Prunus Persica) In Utah, Emily Tsai

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fruit tree nutrition requirements change during the growing season as buds form, shoots grow, fruit sets, and internal reserves are filled. Nutrient concentrations in plant tissues are directly correlated with the nutritional status and productivity of fruit trees. Plant tissue testing is used to effectively and accurately determine the nutritional status of perennial plants. Tissue test analyses were performed on tart cherry (Prunus cerasus) and peach (Prunus persica) leaves to validate tissue sufficiency levels used in Utah and to determine optimal timing of tissue sampling for prediction of harvest nutrient status, focusing on phosphorus (P), potassium …

Population And Community Dynamics Of Freshwater Decapods In Response To Ecological And Anthropogenic Factors In Subtropical Streams In The Caribbean, Omar Perez-Reyes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Historically, cities were established in close proximity to the richest agricultural lands and freshwater resources. In tropical islands, urbanization occupies a large percentage of land use along streams and rivers and strongly affects the biota and habitat quality. I studied freshwater decapod population and community dynamics in tropical streams of Puerto Rico across human and elevational gradients. I found that: 1) streams with less urbanization had higher decapod species richness and population sizes than the highly urbanized streams; 2) changes in the food webs in the streams are the result of the influence of changes in land use and environmental …

Novel Techniques To Determine Soil Evaporation Rates: Heat Pulse Probe And Automated Microlysimeter, Kashifa Rumana

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Increase in world population rate has augmented the global water use in municipal, industrial, and agricultural sectors, with renewable water resources changing
very little with time. Climate change and variability, degradation of water quality as a result of industrial waste streams, animal manure and waste, application of chemicals, pesticides, pharmaceuticals, heavy metals, etc. have largely influenced the quantity and quality of soil water. Root zone water helps sustain the agricultural industry by providing much of the water needed for irrigation. It is critical to monitor the soil water availability, especially within the plant root zones. The subsurface water tends to …

Potential Of Forage Kochia And Other Plant Materials In Reclamation Of Gardner Saltbush Ecosystems Invaded By Halogeton, Rob C. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Gardner saltbush ecosystems are increasingly being invaded by halogeton, a competitive annual weed that increases soil surface salinity and reduces plant biodiversity. This study was established on the Flaming Gorge National Recreation Area, in the Ashley National Forest near Manila, UT to evaluate the ability of forage kochia, Russian wildrye, tall wheatgrass, Indian ricegrass and Gardner saltbush, in monocultures and binary mixtures with Gardner saltbush, to establish and compete in ecosystems dominated by halogeton. A dormant seeding, with and without prior disking, was conducted to determine the ability of plant materials to establish. A spaced-plant evaluation was used to determine …

Effects Of Plant Stress On Facultative Apomixis In Boechera (Brassicaceae), Mayelyn Mateo De Arias

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In flowering plants, apomixis is asexual reproduction by seeds. Apomixis allows the production of offspring with the same genetic characteristics as the mother plant. Fertilization is not required. Apomixis could become a tool for naturally cloning high-yielding crop hybrids through their own seed. However, apomixis does not occur in major crop plants, except for citrus. In the present study, genes that might cause apomixis in naturally occurring apomictic plants were investigated. Sexual and apomictic species of the genus Boechera were exposed to stressed and non-stressed conditions. Effects of these treatments on the expression of apomixis was then measured. Stress triggered …

Postharvest Degradation Of Microalgae: Effect Of Temperature And Water Activity, Jacob A. Nelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Though usually a nuisance in swimming pools and ponds, algae has the potential to be a valuable commodity for use as food and fuel. But before algae butter and biofuel become commonplace, issues with harvesting and storing this new crop need to be overcome. Though there has been ample research into how to grow and use algae, scientists have spent little time figuring out what to do after you pull it out of the water and before you eat it (or turn it into biodiesel). Algae, like all food products, starts to spoil as soon as it is harvested.

This …