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Disturbance, Defense And Fitness In Silverleaf Nightshade (Solanum Elaeagnifolium) In Their Native Range In South Texas, Jesus Chavana Dec 2020

Disturbance, Defense And Fitness In Silverleaf Nightshade (Solanum Elaeagnifolium) In Their Native Range In South Texas, Jesus Chavana

Theses and Dissertations

The role of human disturbance in accelerating weed growth is well understood. While most of these studies have focused on soil mediated disturbance, mowing is also a management practice that could impact weed traits. Using silver leaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, we asked whether continuous mowing affects growth and plant defense traits. We found that mowed plants produced significantly less fruits, had lower total seed fitness, but had higher seed mass, and germinated significantly faster. When three common herbivores were allowed to feed on the seedlings; tobacco hornworm (Manduca sexta), a generalist Solanaceae caterpillar gained more …


Native Plant Allelopathy: A Potential Approach To Limit Invasive Grass Encroachment In Thorn Forest Restoration, Emily A. Mullins Dec 2020

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 …


Optimizing Species Selection For Forest Restoration In The Lower Rio Grande Valley, Faeqa Mohsin Aug 2020

Optimizing Species Selection For Forest Restoration In The Lower Rio Grande Valley, Faeqa Mohsin

Theses and Dissertations

Over the past four decades, the Lower Rio Grande Valley has been reforested with over 3.3 million native thornscrub plants in old agricultural land through transplanting native species. However, assessments of LRGV forest restoration efforts are scarce, and to address the knowledge gap, this study examined species-specific responses to restoration interventions (RIs) aimed at minimizing seedling mortality for optimizing species selection. A critical period for forest restoration in old croplands is the seedling stage, where high mortality occurs due to the interactive effects of abiotic stress, compromised soil nutrient status from intensive agriculture, and mammalian herbivory. So, we evaluated seedling …


Examining The Efficacy Of Cover Crops As An Integrated Pest Management Tool In Organic Farms In The Lower Rio Grande Valley, Lili M. Martinez Aug 2020

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 …


Exploring Plant-Plant Interactions And Nutrient Manipulation As Strategies For Thorn Scrub And Thorn Forest Restoration, Edgar D. Vasquez Aug 2020

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 Effects Of Salvia Hispanica On Biochemical Markers Related To Immune System, Hormone Regulation, And Lumbar Vertebrae In Postmenopausal Rat Model, Daisy M. Mendez May 2020

The Effects Of Salvia Hispanica On Biochemical Markers Related To Immune System, Hormone Regulation, And Lumbar Vertebrae In Postmenopausal Rat Model, Daisy M. Mendez

Theses and Dissertations

In women, with age and menopause there is increase in body weight and decreased immunity and bone mass. Due to severe side effects of currently available drugs for obesity and bone loss, new therapies with less side effects are sought after and alternative medications are becoming more popular. Recently, Salvia hispanica (SH), a herbal supplement is implicated in losing body weight. Currently, there is no information on how SH modulates obesity or bone health. In this study, effects of SH seed extract was investigated in a postmenopausal rat model on certain hormones, immune markers, and fourth lumbar vertebrae. The highest …


Investigating The Potential Of Weeds As Host Reservoir For Plant Parasitic Nematodes In South Texas, Habraham F. Lopez Jul 2019

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 …


Progress And Potential Of Two Biological Control Agents Of The Invasive Giant Reed (Arundo Donax L.), Madeline Marshall May 2018

Progress And Potential Of Two Biological Control Agents Of The Invasive Giant Reed (Arundo Donax L.), Madeline Marshall

Theses and Dissertations

Biological control, or the use of natural enemies for pest management, may the best long-term option for managing the invasive Arundo donax , a noxious weed dominating riparian habitats globally and along the Rio Grande River. This work reports on the progress and potential of two arundo biological control agents permitted for release in Texas and Mexico. The arundo wasp, Tetramesa romana, released in 2009, is having significant impacts as reported from various field locations around the world, described here using standard exit hole counts. The highest density levels were found in Texas (introduced range) compared to relatively low …


Calculating Evapotranspiration Of Arundo Donax Along The Rio Grande, Jose R. Escamilla Jr. Dec 2016

Calculating Evapotranspiration Of Arundo Donax Along The Rio Grande, Jose R. Escamilla Jr.

Theses and Dissertations

Invasive species have been recorded to cause large economic and ecological impacts on various ecosystems and their services. Locally, giant reed (Arundo donax L.), a woody grass native to the Mediterranean, adversely impacts riparian ecosystems in southwestern United States by aggressively displacing their native flora and fauna. Giant reed also has become a cause of concern for national water security, especially in water-limited areas of the arid southwestern United States. The main objective of this study is to provide the first, landscape-level estimates of water use by giant reed in the United States. Evapotranspiration was monitored using the eddy …