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Effects Of Scarification, Phytohormones, Stratification, Soil Types And Warming On The Germination And/Or Performance Of Three Tamaulipan Thornscrub Species, Paula Luera

Theses and Dissertations

The Tamaulipan thornforests of south Texas and northeast Mexico are an ecologically and economically important conservation hotspot. Thornforest restoration is limited by native tree and shrub seedling availability for planting. Seedling shortages arise from low seed availability and knowledge gaps regarding best practices for germinating and growing the 70+ thornforest species desired for restoration plantings. To fill key knowledge gaps, we investigated three ecologically important thornforest species with low or highly variable germination or seedling survival rates: Ebenopsis ebano, Cordia boissieri, and Zanthoxylum fagara. For each, we quantified the effects of different dosages of chemical seed treatments …

Morphological Characterization And Functional Assessment Of Trichomes In Solanaceae, Sakshi Watts

Theses and Dissertations

Chapter 1: This chapter provides an overview of various trichome types in plants, and also empirically examines their variation on abaxial and adaxial leaf surface of 14 Solanum species. Detailed nomenclature, density, and dimension measurements of each trichome type has been provided using scanning electron-microscopy.

Chapter 2: Scanning electron microscopy was major component of methodology used in my thesis for scanning leaf samples to estimate trichome traits. In this chapter, a more efficient and cost-effective methodology for scanning electron microscopy has been explored.

Chapter 3: This chapter examines the relationship of trichome density and herbivore feeding behavior using abaxial and …

Characterization Of Soil Nematode Community As Influenced By Weedy Plants And Edaphic Properties, Orlando Garcia

Theses and Dissertations

Nematodes are one of the most critical species globally as they are part of most nutrient recycling. While nematodes play a vital role in nutrient cycling, little is known about them from an ecological standpoint. The majority of current research has focused on a singular component of the community, being those of herbivore/plant-parasitic nematodes. In this study, the community shifts of the nematode trophic groups were analyzed as influenced by native and invasive grasses species in the Lower Rio Grande Valley (LRGV) with the addition of edaphic soil properties.

In our study, the results indicate changes in the composition of …

Examining The Role Of Buzzing Time And Acoustics On Pollen Extraction Of Solanum Elaeagnifolium, Mandeep Tayal, Rupesh R. Kariyat

Biology Faculty Publications and Presentations

Buzz pollination is a specialized pollination syndrome that requires vibrational energy to extract concealed pollen grains from poricidal anthers. Although a large body of work has examined the ecology of buzz pollination, whether acoustic properties of buzz pollinators affect pollen extraction is less understood, especially in weeds and invasive species. We examined the pollination biology of Silverleaf nightshade (Solanum elaeagnifolium), a worldwide invasive weed, in its native range in the Lower Rio Grande Valley (LRGV) in south Texas. Over two years, we documented the floral visitors on S. elaeagnifolium, their acoustic parameters (buzzing amplitude, frequency, and duration of buzzing) and …

Pre-Sowing Treatments Improve Germinability Of South Texas Native Plant Seeds, Kaitlynn Lavallee, Pushpa Soti, Hansapani Rodrigo, Rupesh R. Kariyat, Alexis Racelis

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The incorporation of native plant species is central to restoration efforts, but this is often limited by both the availability of seeds and the relatively low viability and germination rates of commercially available seeds. Although pre-sowing treatments are commonly used to improve germination rates of seeds, the efficacy of these treatments is found to vary across species. In this study, we tested how four pre-sow treatments (physical scarification, acid scarification, cold stratification, and aerated hydropriming) affected the viability and seed germination rates of 12 commercially available plant species native to south Texas and commonly used in restoration efforts. Our results …

Lignin, Sugar, And Furan Production Of Industrial Hemp Biomass Via An Integrated Process, Jikai Zhao, Jason Griffin, Kraig Roozeboom, Juhee Lee, Donghai Wang

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Traditional pretreatment of lignocellulosic biomass is often accompanied by washing and disposal of wastewater, which leads to overuse of water and loss of by-products. The objectives of this study were to validate the potential of an acid-base integrated process for simultaneous sugars, furans, and lignin production without washing and wastewater discarding. The difference in conversion performance among different biomass resources was also demonstrated. Parallel acetic acid (HOAc, pH = 2.25) and sodium hydroxide (NaOH, pH = 13.46) pretreatments followed by solid and liquid integration were applied to four genotypes of industrial hemp (Cannabis sativa L.) biomass that were harvested …

Do Early-Successional Weeds Facilitate Or Compete With Seedlings In Forest Restoration? Disentangling Abiotic Versus Biotic Factors, Mylen Arias, Rupesh R. Kariyat, Kimberly Wahl-Villarreal, Stephany Mendez, Jesus Chavana, Bradley O. Christoffersen

Biology Faculty Publications and Presentations

1. Semi-arid forests need cost-effective restoration strategies to address their severe degradation. Tree shelters are often used to minimize abiotic and biotic stress during seedling establishment. We asked if early-successional weeds act as a natural shelter by facilitating native seedlings, contingent on abiotic and biotic stressors and seedling ecological strategy.

2. We conducted a manipulative weed exclusion experiment at a semi-arid site in South Texas targeted for large-scale forest restoration to discern the net effect of weeds on the growth and survival of target thornscrub tree and shrub seedlings. We assessed the roles of contrasting seedling ecological strategies (fast vs. slow growth …

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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 …

Uptake Analysis Of As(Iii) And As(V) By Cassia Fistula Seedlings, Valeria Velazquez

Theses and Dissertations

The natural and anthropogenic contamination of water by arsenic has become a major concern to the environment and public health. Phytoremediation is an attractive alternative to ecologically friendly remove contaminants at a potential high efficiency and low cost. Absorption of As(III) and As(V) was evaluated by the measuring the content of arsenic in the roots, leaves and stems Cassia fistula grown under controlled conditions in a hydroponics system. After seeds were germinated, the plants were grown in Hoagland nutrient solution individually supplemented with 1, 2, 5 ppm of As(III) and As(V). After two weeks of exposure, samples of leaves, roots, …

Chemical Investigation Of Camu Camu (Myrciaria Dubia) Leaves And Roots, Jorge L. Flores

Theses and Dissertations

Flores, Jorge L., Chemical Investigation of Camu Camu (Myrciaria dubia) Leaves and Roots. Master of Science (MS), December, 2020, 45 pp., 8 Tables, 28 Figures, 21 references, 12 titles.Being the largest on the planet, the Amazon rainforest also has the greatest biodiversity of plant life on earth. In the lowland regions of the Amazon grows the Peruvian camu camu (Myrciaria dubia) plant. A short and shaggy shrub, camu camu produces a tasty but sour fruit. Camu camu’s berry-like fruit is widely consumed by the native people of the Amazon. Its distinguished richness in vitamin C, as …

Winners And Losers In Reforestation Efforts In The Lower Rio Grande Valley Of Texas, And The Predictive Power Of Xylem Anatomy On Long-Term Growth And Survival, Clifton F. Albrecht

Theses and Dissertations

Reforestation has been ongoing in the Lower Rio Grande Valley annually since the 1980s, and to date over 6400 ha of land has been reforested in this area. However, there has been little subsequent study of the change and development of those forests as they mature. This thesis consists of two, interrelated, studies: (1) surveys of a five-site chronosequence of restored forests and (2) quantification of xylem anatomical traits of a subset of species present at the reforestation sites. Surveys showed a consistent reduction in species diversity and stem number density on the landscape, and identified a suite of species …

Physical And Chemical Defense Mechanisms In Aloe Barbadensis Against Insect Herbivores, Zachary Johnson

Theses and Dissertations

Chapter 1: This chapter provides an overview of insect herbivore impacts on plants and plant defense mechanisms to combat them. I particularly focused on physical and chemical defenses in the broader sense.

Chapter 2: This chapter describes the experiments that showed the effects of extracts from Aloe barbadensis on the growth and development of tobacco hornworm (Manduca sexta) and fall armyworm (Spodoptera frugiperda), model herbivores used to understand herbivore growth and plant defenses. This study shows that extracts from the Aloe differentially affected the growth and development of M. sexta and S. frugiperda. This chapter …

Understanding The Ecological Role, Population Dynamics, And Geographic Distribution Of Manihot Walkerae, Gisel Garza

Theses and Dissertations

Walker’s Manihot, Manihot walkerae Croizat (Euphorbiaceae), is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion. Understanding M. walkerae’s geographic distribution, populations, and species interactions can provide essential information for the development of sound conservation strategies. To this aim, I asked the following questions: 1) What is the potential geographic distribution for M. walkerae? and, will it be affected by climate change? 2) Using global and regional extinction risk assessments, what is the extinction risk category for M. walkerae after incorporating species distribution models? 3) What do natural history observations reveal about M. walkerae’s population …

Unravelling The Role Of Pgpr "Pseudomonas Fluorescens" In Semi- Arid Soils Of The Rio Grande Valley, Mandip Tamang

Theses and Dissertations

Chapter 1: In this chapter, we have provided a review on the components of rhizosphere engineering and the potential use of PGPR and its challenges to serve as an efficient component for sustainable agriculture.

Chapter 2: In this chapter, we isolated 35 different strains of a PGPR, Pseudmonas fluorescens and characterized various plant growth promoting traits such as production of ammonia, protease, Indole acitic acid (IAA), 1-aminocyclopropane-1-carboxylate deaminase (ACC) deaminase, ammonia, hydrogen cyanide (HCN), and souliblization of zinc and phosphate.

Chapter 3: In this chapter, we tested the influence of plant beneficial soil microbe, P. fluorescens, on the growth and …

The Multifunctional Roles Of Polyphenols In Plant-Herbivore Interactions, Sukhman Singh, Ishveen Kaur, Rupesh R. Kariyat

Biology Faculty Publications and Presentations

There is no argument to the fact that insect herbivores cause significant losses to plant productivity in both natural and agricultural ecosystems. To counter this continuous onslaught, plants have evolved a suite of direct and indirect, constitutive and induced, chemical and physical defenses, and secondary metabolites are a key group that facilitates these defenses. Polyphenols—widely distributed in flowering plants—are the major group of such biologically active secondary metabolites. Recent advances in analytical chemistry and metabolomics have provided an opportunity to dig deep into extraction and quantification of plant-based natural products with insecticidal/insect deterrent activity, a potential sustainable pest management strategy. …

Tropical Milkweed Herbivore And Predator Dynamics In Suburban South Texas, Daniela Rivera, Jose Adrian Noval, Lilly Elliott, Hannah J. Penn

Biology Faculty Publications and Presentations

Tropical milkweed is commonly grown to conserve pollinators, but the presence of non-caterpillar herbivores may prompt treatment. Management is limited to non-chemical methods like biological control, but potential natural enemies have not been well studied in the Lower Rio Grande Valley (LRGV). We documented the arthropod community on tropical milkweed in garden and potted settings then analyzed associations between organisms. In the garden, oleander aphids and large milkweed bugs were the primary herbivores, overlapping on seedpods. Natural enemies (lady beetles, syrphid fly larvae, and aphid parasitoids) were positively associated with oleander aphids but not milkweed bugs. The arthropod community experienced …

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

Biology Faculty Publications and Presentations

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 …