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Investigating Limitations To Nitrogen Fixation By Leguminous Cover Crops In South Texas, Stephanie L. Kasper
Investigating Limitations To Nitrogen Fixation By Leguminous Cover Crops In South Texas, Stephanie L. Kasper
Theses and Dissertations
Many farms use leguminous cover crops as a nutrient management strategy to reduce their need for nitrogen fertilizer. Biological nitrogen fixation (BNF) depends on a symbiotic relationship between legumes and nitrogen-fixing rhizobia. Under certain conditions despite inoculation with appropriate rhizobial strains, this symbiosis fails to form. Such failure was observed in a 14-acre winter cover crop trial in the Rio Grande Valley of Texas when three legume species (forage pea, crimson clover, and hairy vetch) produced no signs of nodulation and nitrogen fixation. This study examined nitrogen, phosphorus, moisture, micronutrients and biotic interference as potential causes for the failure and …
Effect Of Land Use Change On South Texas Bats, Katharine Leigh Jones
Effect Of Land Use Change On South Texas Bats, Katharine Leigh Jones
Theses and Dissertations
Bats were acoustically recorded in South Texas over the summer of 2017. Nine species of bats were recorded and identified.
Genetic Variation In Two Economically Important Arthropod Vectors Of Citrus Diseases, Alejandra Fuentes
Genetic Variation In Two Economically Important Arthropod Vectors Of Citrus Diseases, Alejandra Fuentes
Theses and Dissertations
Arthropod vectors are agriculturally and ecologically important because they transmit numerous plant pathogens. Commonly, control strategies for vector-borne plant pathogens focus on suppression of vector populations. Genetic variation studies in pest populations provide useful information for biological control, understanding pesticide resistance, and inferring global movement patterns. In chapter I, genetic variation of worldwide populations of Diaphorina citri, the vector of Citrus greening disease, was examined to assess potential sites of origin of invasive populations. The results showed population structure at regional levels, suggesting limited gene flow and revealing patterns of invasion. In chapter II, I explored the community of …
Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg
Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg
Theses and Dissertations
Situated in deep South Texas, the Lower Rio Grande Valley (LRGV) is considered one the most productive agricultural regions in the southern US. With the highest concentration of organic farms in the state (Hidalgo county), finding management practices that comply with organic certification is increasingly pertinent. Cover cropping can serve multiple functions in an agroecosystem such as: suppressing weeds, increasing soil organic matter (SOM), increasing soil nitrates, and enhancing soil biodiversity. The four cover crops (lablab, sunn hemp, sudangrass, and pearl millet) were assessed to see their potential to increase soil nitrogen, to increase soil organic matter, and to suppress …
Management Of Silverleaf Whitefly, Bemisia Argentifolii Bellows And Perring (Hemiptera: Aleyrodidae), Using Non-Crop Companion Plants In Organically-Managed Cantaloupe Systems In South Texas, Ruth Renee Colyer
Theses and Dissertations - UTB/UTPA
Field trials in three separate phases of research were carried out from March, 2010, to August, 2012, to determine the effects of inter-cropping cantaloupe (Cucumis melo var. inodorus) with select non-crop companion plants in an effort to develop organic production strategies for melons in South Texas without the use of pesticides. A research program was designed and initiated to assess the effects of the companion plants and their ability to: 1) attract insect pollinators, and 2) repel or suppress pest species without affecting beneficial natural enemy complexes. The hypotheses were: 1) that organically-managed cantaloupe systems grown with non-crop companion plants …
Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez
Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez
Theses and Dissertations - UTB/UTPA
Soil fertility and plant nutrition is crucial for a better yield and consistent harvest in the Rio Grande Valley for local farmers growing citrus trees. A field of oranges and a field of grapefruits were monitored and nutrition deficiencies were noticed that played an important role during fruit set. Soil samples that were taken throughout the year were analyzed via a carbon dioxide extraction method that mimics the way plants naturally take up nutrients or extract nutrients from every soil type. Macronutrients such as the N, P, K, Na, Ca, Mg and some of the micronutrients (Zn, Fe, Mn, and …
Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia
Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia
Theses and Dissertations - UTB/UTPA
Non-native grasses can modify the soils they invade. This study investigated microbial variation among native and non-native grasses in the Lower Rio Grande Valley. We hypothesized that rhizospheres of non-native grasses would support a higher density of microorganisms; therefore microbial communities of invasive plants would exploit more carbon sources than those of native plants. A second hypothesis stated that Streptomyces bacteria from the rhizosphere of non-native grasses would be better competitors. Samples of grasses, and soil from their respective rhizospheres were obtained in Arroyo City, TX. Results indicated a higher bacterial colony density, total activity and number of substrates utilized …
Evaluation Of Streptomycetes For Biological Control Of Gummy Stem Blight Disease Of Cantaloupe, Shima Chaudhary
Evaluation Of Streptomycetes For Biological Control Of Gummy Stem Blight Disease Of Cantaloupe, Shima Chaudhary
Theses and Dissertations - UTB/UTPA
Studies were conducted to evaluate the efficacy of Streptomyces isolates for the biological control of gummy stem blight (GSB) in cantaloupes (Cucumis melo var. ‘Primo’) in south Texas. Plants were monitored for seedling emergence, lesions, mortality and plant growth under laboratory, greenhouse and field conditions. Comparison of treatment groups indicated a significant reduction in plant mortality and enhanced growth of infected plants exposed to three Streptomyces isolates (MA1F4#2, WI1B#5, and MA2A4 #2), which appear to be most effective when used in combination. In all three experiments, GSB infection was associated with a significant reduction in reflectance of near-infrared wavelengths (700-1,100 …