Agriculture Commons^™

Growth Kinetics Of Salmonella Spp. During Post-Harvest Storage Of Fresh And Fresh-Cut Papaya, Amandeep Singh

Theses and Dissertations

Fresh produce safety is major concern in United States. Fresh produce has been associated with numerous food-borne outbreaks each year. Salmonella has been a recurring issue in the papaya industry. Since 2010, imported papayas have been implicated in 8 multistate outbreaks associated with Salmonella spp. causing 480 illnesses, 113 hospitalization and 3 deaths. The main reason behind this problem is as fresh papaya is grown on fields where they are constantly exposed to preharvest microbial contamination through contaminated irrigation water, agricultural soil, raw manure and/or feces deposited by intruding domestic or wild animals. Moreover, majority fresh papaya is also consumed …

Bullet-Proof Boll Weevil: The History Of Boll Weevil Eradication, Evan A. Berg

Theses and Dissertations

Farmers and entomologists have all experimented with various methods to find the best way to defeat the United States' boll weevil. The techniques themselves, while expansive, can be examined within the scope of the years that they were used. This provides an exciting insight into how cotton pest management became more complex as the decades moved on and revealed how the science of cotton pest management evolved to deal with the boll weevil and other future cotton threats.

A Gis-Based Model To Assess On-Site Sewage Facility (Ossf) Contamination Risk To Local Water Resources, Alvaro Garcia

Theses and Dissertations

In a collaborative effort between Texas Water Resources Institute (TWRI), Cameron County Public Health (CCPH), Texas A&M AgriLife Extension (TAMAE), and the University of Texas Rio Grande Valley (UTRGV), a GIS database that includes relevant OSSF information, such as location, system age, lot size, and other important parameters was created.

This OSSF database, along with publicly available GIS data, was used to create an integrative GIS-based risk assessment model where OSSF risk parameters were assigned a risk factor and combined into a spatial contamination risk for surrounding areas and their receiving waterbodies. Parameters were broken down into two categories: environmental …

A Sugarcane G-Protein-Coupled Receptor, Shgpcr1, Confers Tolerance To Multiple Abiotic Stresses, Manikandan Ramasamy, Mona B. Damaj, Carol Vargas-Bautista, Victoria Mora, Jiaxing Liu, Carmen S. Padilla, Sonia Irigoyen, Tripti Saini, Nirakar Sahoo, Jorge A. Dasilva, Kranthi K. Mandadi

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Sugarcane (Saccharum spp.) is a prominent source of sugar and serves as bioenergy/biomass feedstock globally. Multiple biotic and abiotic stresses, including drought, salinity, and cold, adversely affect sugarcane yield. G-protein-coupled receptors (GPCRs) are components of G-protein-mediated signaling affecting plant growth, development, and stress responses. Here, we identified a GPCR-like protein (ShGPCR1) from sugarcane and energy cane (Saccharum spp. hybrids) and characterized its function in conferring tolerance to multiple abiotic stresses. ShGPCR1 protein sequence contained nine predicted transmembrane (TM) domains connected by four extracellular and four intracellular loops, which could interact with various ligands and heterotrimeric G …

Variation In Trichome Types And Density Mediates Plant-Herbivore Interactions In Two Cucurbitaceae Members, Ishveen Kaur

Theses and Dissertations

Plant structural defenses such as trichomes and spines exert a significant selection pressure on insect herbivores. However, how species variation affects structural defense trait expression in closely related species is less understood. Through our studies, we tried to dissect the role of trichomes in mediating plant-insect interactions, in two non-model cultivated species in Cucurbitaceae: Lageneria siceraria, and Cucumis sativa family, and Trichoplusia ni as our major herbivore of interest. We observed that species differed in their attractiveness to different herbivores and their feeding behavior in common garden experiment. To tease apart structural and chemical defenses and their independent roles …

Species-Specific Responses To Restoration Interventions In A Tamaulipan Thornforest, Faeqa Mohsin, Mylen A. Arias, Clifton Albrecht, Kimberly Wahl-Villarreal, Alejandro Fierro-Cabo, Bradley O. Christoffersen

School of Integrative Biological & Chemical Sciences Faculty Publications

In the Lower Rio Grande Valley (LRGV) of south Texas, native thornscrub forest restoration has been ongoing for the past four decades, yet few assessments of their efficacy exist, and no study has yet quantified species-specific responses. Seedling transplantation in conjunction one or more restoration interventions (RIs) remains the method of choice at most sites, and thus the initial months following transplantation, when seedlings are especially vulnerable to drought and animal damage, are a critical time for determining restoration success. To this end, we evaluated the survival, growth, and animal damage of 3600 native seedlings of 24 thornforest species in …

Status, Distribution, And Conservation Of The Black-Spotted Newt (Notophthalmus Meridionalis) In South Texas, Padraic S. Robinson

Theses and Dissertations

The Black-spotted Newt (Notophthalmus meridionalis) is a chronically understudied species, with much information on the natural history, ecology, and distribution of this species poorly known. Previous studies using traditional methodologies have had limited success detecting N. meridionalis. A novel eDNA assay was designed and implemented with the goal of better understanding N. meridionalis distribution in south Texas. Primers were designed to amplify N. meridionalis DNA and tested against DNA from sympatric amphibians. This assay combined with traditional methods was implemented at 62 sites throughout south Texas, and N. meridionalis was detected at eight localities. At each site …

Practical Challenges Of Using Sunn Hemp As A Cover Crop In The Lower Rio Grande Valley, Qulina Rai

Theses and Dissertations

Sunn hemp (Crotalaria junceae) is an emerging cover crop with many reported benefits such as nitrogen fixation, carbon sequestration, and suppression of weeds and nematodes. Relatively little is known about appropriate ways to inoculate sunn hemp ensuring nitrogen fixation, and diseases that affect sunn hemp within the Lower Rio Grande Valley of Texas.

Four sticking agents, peanut oil, jaggery, gum arabic, and water used to aid inoculation of Bradyrhizobium japonicum in sunn hemp was checked on nodulation. Water treatment was least effective. Peanut oil and jaggery treatment showed better performance in overall total nodules, and active nodules. Gum …

Civic Agriculture In Review: Then, Now, And Future Directions, Allison Kaika, Alexis Racelis

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

"Civic agriculture," a term first coined by rural sociologist Thomas Lyson, refers to forms of agriculture that occur on a local level, from production to consumption, and are linked to a community's social and economic development. Sixteen years since its original articulation, the term "civic agriculture" has taken on greater significance in research, political activism, and community organizing. Grown from the roots of civic community theory, civic agriculture functions as a new branch of civic community theory that is ripe for theorization. In revisiting the foundations of the term, this review paper seeks to consolidate current and future research in …

Characterizing Nematode Communities In Carrot Fields And Their Bioindicator Role For Soil Health, A. Habteweld, D. Brainard, A. Kravchencko, Parwinder Grewal, H. Melakeberhan

School of Earth, Environmental, & Marine Sciences Faculty Publications

Plant-parasitic nematodes (PPN) are known to reduce quality and yield of carrot (Daucus carota var. sativus). Efficient nematode management begins with identifying the predominant PPN present in a given field before taking any management decisions. The management decisions should also consider suppression of PPN and promotion of beneficial nematodes represented by bacterivores, fungivores, omnivores, and predators to improve soil health conditions. We selected four carrot fields suspected to have PPN problems in Mason and Oceana counties in Michigan, USA. The counties are located in the major carrot-producing regions of Michigan. These sites have not been previously sampled for …

Weeds As Hosts Of Plant Parasitic Nematodes In Subtropical Agriculture Systems, Habraham F. Lopez, Pushpa Soti, Ganpati B. Jagdale, Parwinder Grewal, Alexis Racelis

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

With a nearly year-round growing season, tropical and subtropical regions are plagued with a myriad of agro-nomic challenges, including near-continuous weeds and invertebrate pests including plant-parasitic nematodes (PPNs). A poor understanding of the presence and geographical distributions of these pests complicate their man-agement, especially in organic farming systems. This work attempts to document the interaction of PPNs with the major weeds in the semi-arid region of south Texas. Five organically managed farms were surveyed for four weeds of regional agronomic importance including silverleaf nightshade (Solanum elaeagnifolium), common sunflower (Helianthus annuus), false ragweed (Parthenium hysterophorus), and London rocket (Sisymbrium irio). Soil …

Discerning Competitive Vs. Facilitative Relationships Of Weeds On Forest Restoration Efforts At La Sal Del Rey, Tx, Mylen A. Arias

Theses and Dissertations

Dryland ecosystems need effective restoration strategies to address severe degradation. It is often assumed that voluntary forb weeds either compete with or have no effect on native seedlings. In contrast, theory and empirical work suggest a potential facilitative role for such forb weeds. We conducted a manipulative weed exclusion experiment at a semi-arid site in South Texas targeted for large scale forest restoration and subsequently dominated by early successional forb weeds to discern the net effect of these weeds on the growth and survival of target thornscrub tree and shrub seedlings. Overall, weed presence did not significantly affect seedling mortality …

Developing Methods To Survey, Collect, Process, And Screen Endemic Entomopathogenic Fungi Against The Asian Citrus Psyllid In The Lower Rio Grande Valley, Jonathan Cisneros

Theses and Dissertations

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), vectors “Candidatus Liberibacter spp.”, the causative agent of Citrus Greening Disease. Managing ACP is imperative given the continuous increase in HLB positive trees. An aspect of integrated pest management (IPM) is the use of entomopathogenic fungi for the biological control of D. citri.

In order to identify endemic entomopathogenic fungi actively infecting D. citri, ACP were collected from local residential areas, surface sterilized, and plated on a semi-selective agar medium. Collection of over 9,300 samples from 278 sites throughout the LRGV led to the positive identification of …

Incorporation Of Native Plants For Biodiversity Conservation In South Texas Agroecosystems, Kaitlynn M. Lavallee

Theses and Dissertations

I address the concerning disconnect between food production and regenerative ecological principles. First, understanding the foundational processes of seed-dormancy and germination are essential for successful restoration efforts using native species. We examine four common seed treatments (aerated hydroprime, acid scarification, cold stratification, sand scarification) on twelve commercially available species native to south Texas. Pappophorum bicolor Fourn. (pink pappusgrass) was sown in the field with the aerated hydroprime treatment, D. virgatus (Willd.) B.L. Turner (prostrate bundleflower) was planted after sand scarification treatment, and Ratibida columnifera (Nutt.) Woot. & Standl. (Mexican hat) was seeded without treatment. Small-scale field trials were conducted to …

Native Plant Allelopathy: A Potential Approach To Limit Invasive Grass Encroachment In Thorn Forest Restoration, Emily A. Mullins

Theses and Dissertations

Less than 5% of the Tamaulipan thorn forest remains in the United States. For this reason, there have been many attempts at restoration of this ecosystem. Oftentimes these attempts are unsuccessful due to the high prevalence of invasive African grasses that outcompete the seedlings. In an effort to improve the efficacy of these restoration efforts, native plant allelopathy has been examined for its ability to exclude invasive guineagrass. Native species were surveyed and selected species were tested for allelopathy in laboratory bioassays. The species that exhibited allelopathy in the laboratory were then evaluated in pot experiments for their ability to …

Examining The Efficacy Of Cover Crops As An Integrated Pest Management Tool In Organic Farms In The Lower Rio Grande Valley, Lili M. Martinez

Theses and Dissertations

The Lower Rio Grande Valley (LRGV) consists of a mix in subtropical and costal habitats, a combination that provides a favorable environment for the animals and plants that inhabit it. This is a problem for organic farmers as they refrain from using synthetic chemicals and therefore led them to seek other methods of dealing with insect herbivory. Of the many alternative methods available, we looked specifically at integrated pest management methods (IPM) to determine their efficacy in reducing insect herbivory among cash crops. Chapter II discusses an experiment performed in an organic farm in Edinburg, Texas consisting of a two-year …

Aquatic Stage Mosquito Biocontrol: Effects Of Entomopathogenic Fungi Blastospores And Conidia On Aedes Aegypti Pupae, Ricardo Alberto Ramirez Garcia Rojas

Theses and Dissertations

Fungal entomopathogens present an opportunity to produce mosquito controls on-site, from remote locations to developing communities. Locally produced biopesticides have the potential to empower communities to develop internal disease vector control initiatives to protect local public health. We tested the effectiveness of the conidia solution and blastospore solution of Metarhizium anisopliae E9, Metarhizium anisopliae E1037, Isaria fumosorosea A97, and Isaria fumosorosea 9901 in controlling Aedes aegypti pupae. We observed that entomopathogenic fungi liquid blastospore solution induce mortality in Aedes aegypti pupae at a significantly greater rate than conidia solution and control treatment.

However, further analysis of testing methods used in …

Exploring Plant-Plant Interactions And Nutrient Manipulation As Strategies For Thorn Scrub And Thorn Forest Restoration, Edgar D. Vasquez

Theses and Dissertations

Restoration of thorn scrub and thorn forest communities in South Texas is hindered by harsh environmental conditions and hypercompetitive invasive grasses. The success of thorn scrub/thorn forest restoration efforts depends on increasing seedling survival and growth by reducing stress after transplantation. Four experiments evaluated initial effects of plant-plant interactions and nutrient manipulation on thorn forest restoration. High density planting along with the use of nurse plants look promising; survival was generally higher under these conditions and growth was unaffected or in the case of high-density planting, promoted. Nutrient sequestration by sorghum had little effect on seedling performance and cover of …

The Application Of Advanced Technologies For Agriculture And Rangeland Management, Matthew D. Kutugata

Theses and Dissertations

This project demonstrates two applications of remote sensing in agricultural and rangeland environments. In the first, an unmanned aerial system (UAS) equipped with a multi-spectral sensor was used to estimate canopy cover across four different cover crop trials at four time periods. In the second, a local database of stationary camera trap images of wildlife was used to train a convolutional neural network to automatically catalogue images by identifying the animal in those images. Both projects aimed to provide an example of how remote sensing platforms and machine learning techniques can facilitate the rapid collection and processing of large-scale field …

Building Food Democracy In The Rio Grande Valley: Exploring The Relationship Between Civic Agriculture And Civic Engagement, Allison P. Kaika

Theses and Dissertations

Civic engagement is an important indicator of social capital in a community. The foundation of a strong democracy is dependent on citizens willingness and ability to engage. To further understand these drivers of social network building, this study utilizes the theory of civic agriculture to measure the impact of food procurement systems on civic engagement. A survey of over 400 residents in the Lower Rio Grande Valley of South Texas measures how involvement in local food systems impacts a participants’ contribution to and perception of his or her community, while considering important third factor variables that also influence food procurement …

Impact Of Cover Crops On Insect Community Dynamics In Organic Farming, Lili Martinez, Pushpa Soti, Jasleen Kaur, Alexis Racelis, Rupesh R. Kariyat

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Manipulating cover crops as an integrated pest management strategy has recently gained popularity in both traditional and organic agroecosystems. However, little information is available for producers to make informed decisions about cover crop selection, management, and their potential use as a pest management tool. To address this, we conducted a two-year, four-season field experiment on the potential of various cover crops during the summer seasons of both years, followed by monocultures of cash crops during winters. We hypothesized that the cover crop treatments would attract beneficial insects and repel damaging herbivores in a species-specific manner, and the insect community dynamics …

Comparing Novel And Traditional Sampling Methodologies To Analyze The Population Status Of The Rio Grande Cooter (Pseudemys Gorzugi), Amy P. Bogolin

Theses and Dissertations

The Rio Grande Cooter, Pseudemys gorzugi, is an understudied aquatic turtle species of conservation concern in the Rio Grande, Pecos, and Devils river systems. Traditional sampling methodologies for aquatic turtle species face numerous challenges, but novel sampling methodologies, such as drone-based surveys and environmental DNA analysis, may address these issues. This study compared novel sampling methodologies to traditional sampling methodologies in mean detections and identifications of aquatic turtle species, developed and implemented an environmental DNA assay to detect P. gorzugi, and characterized P. gorzugi habitat. Following an introductory chapter, each task is addressed by chapter and formatted to …

Comparing Outdoor Vertical Hydroponic Farming Systems And Conventional Hydroponic Farming Systems With A Focus On Efficiency, Itohan A. Edokpolo

Theses and Dissertations

Combining hydroponics and vertical farming creates unique growing system that reduces the need for excessive water and land usage to grow more food. The main critique of this system is the high cost of setup, run and the potential drawbacks of shading on plant productivity. Five species were grown in three hydroponic designs known as horizontal, vertical and a-frame. The designs were compared in terms of productivity, space and energy. Results showed variability in plant productivity in the designs can be attributed to other factors other than light. Differences in species performance were seen in response to different factors. Horizontal …

Effects Of Arbuscular Mycorrhizal Fungi (Amf) On Growth And Herbivore Defenses In Sorghum Sudangrass (Sorghum X Drummondii), Jasleen Kaur

Theses and Dissertations

Chapter 2: In this chapter we have examined the role of trichomes in plant stress biology, reviewed the studies on herbivore X trichome interactions, and their role in plant defences. Ultimately, we have proposed new areas of research for future work.

Chapter 3: In this chapter, we examined whether AMF has cascading effects on insect community dynamics through attraction/repulsion of beneficial and damaging insects using Sorghum-sudangrass (Sorghum x drummondii), either inoculated with commercial AMF mix or left as control in lab and field experiments. Our results suggest positive effects of AMF on plant growth, and a lower initial incidence of …

Polyphenol-Rich Purple Corn Pericarp Extract Adversely Impacts Herbivore Growth And Development, Mandeep Tayal, Pavel Somavat, Isabella Rodriguez, Tina Thomas, Bradley O. Christoffersen, Rupesh R. Kariyat

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Plant secondary metabolites such as terpenes, phenolics, glycosides, and alkaloids play various functional roles including pigmentation, foliar and floral volatile synthesis, hormonal regulation, and direct and indirect defenses. Among these, phenolic compounds are commonly found in plants, but vary in the distribution of their specific compounds among plant families. Polyphenols, including anthocyanins and tannins, are widely distributed and have been well documented for their roles- primarily in plant pigmentation and also in plant defenses. However, commercialization of such compounds for use in insect pest management is severely hampered by expensive, inefficient, and time-consuming extraction protocols. Using a recently developed inexpensive …

Review Of Major Crop And Animal Arthropod Pests Of South Texas, Holly N. Davis, John A. Goolsby, Donald B. Thomas, Ismael Badillo, Rupesh R. Kariyat, Christopher Vitek, Danielle Sekula

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

The Lower Rio Grande Valley is an area in Texas that consists of the four southern-most counties. This area contains a diverse range of agriculture and land-use including vegetable, row-crop and livestock production. The year-around cool to hot subtropical climate means that green vegetation is continually present, including many crops. Geographically, it shares an international border, making it a region vulnerable to new invasive species and the re-introduction of pests that have been previously eliminated in the United States. These combined factors lead to an array of arthropod pests that may have serious impacts on the crops, animals, and people …

Viability Of Wetland Crops For Use In Treatment Wetlands: Nitrogen Removal From Water And Production Of Food, Andrew Denson Corder

Theses and Dissertations

Treatment wetlands are used to treat wastewater from a variety of sources, but their functionality depends on the macrophytes present therein. To better understand the viability of wetland macrophytes both as sources of food and as agents of nitrogen removal from wastewater, this study quantified plant growth, food production, and nitrogen removal capacity of three common wetland crops as well as three locally dominant graminoid species in a variety of relevant ecological contexts. All six plant species and a control were grown over a ten-week period in three related experiments: (1) under three moisture regimes, (2) with or without competition …

Abiotic And Biotic Limitations To Nodulation By Leguminous Cover Crops In South Texas, Stephanie Kasper, Bradley O. Christoffersen, Pushpa Soti, Alexis Racelis

School of Earth, Environmental, & Marine Sciences Faculty Publications

Many farms use leguminous cover crops as a nutrient management strategy to reduce their need for nitrogen fertilizer. When they are effective, leguminous cover crops are a valuable tool for sustainable nutrient management. However, the symbiotic partnership between legumes and nitrogen fixing rhizobia is vulnerable to several abiotic and biotic stressors that reduce nitrogen fixation efficiency in real world contexts. Sometimes, despite inoculation with rhizobial strains, this symbiosis fails to form. Such failure was observed in a 14-acre winter cover crop trial in the Rio Grande Valley (RGV) of Texas when three legume species produced no signs of nodulation or …

Investigating The Potential Of Weeds As Host Reservoir For Plant Parasitic Nematodes In South Texas, Habraham F. Lopez

Theses and Dissertations

Presence and geographical distributions of three damaging nematode pest (R. reniformis, M. incognita, T. semipentrans) have been recorded in the LRGV. With year-round growing seasons, weed pest are a real problem for many LRGV growers. With some growers leaving the field fallow until planting season, these places can serve as potential host reservoirs for plant parasitic nematodes (PPN). This study examined the potential of weeds as host reservoirs for plant parasitic nematodes in the LRGV. Results demonstrated the presence of 5 of the 12 economically important plant parasitic nematode genus and demonstrated a difference in distribution of nematodes …

Contributions Of Historical Ecology To Ecological Services Assessments In The Lower Rio Grande Valley Texas, Julianna Katherine Schaefer Kurpis

Theses and Dissertations

Historic and current anthropogenic land-use activities affect ecological functions and ecosystem services quality. The clearing of native Tamaulipan thorn forest and riparian forests for agricultural use and expansion followed by rapid urbanization and population growth resulted in profound ecological impacts to the Lower Rio Grande Valley (LRGV), Texas. The goals of this study are 1) document trends in land use change and vegetation health in the LRGV 2) evaluate and demonstrate the application of the Ecosystem Services Identification & Inventory Tool (ESII Tool) for collecting ecological data and measuring percent ecological performance and 3) use historical ecology indicators to compare …